AI Trajectory

null

{
  "EnableConfigs": [
    "DRM",
    "DRM_TTM",
    "DRM_TTM_HELPER",
    "DRM_QXL",
    "DRM_VMWGFX"
  ],
  "FocusSymbols": [
    "ttm_bo_swapout_cb",
    "ttm_tt_swapout",
    "ttm_global_swapout",
    "ttm_device_swapout",
    "ttm_resource_del_bulk_move_unevictable",
    "ttm_resource_move_to_lru_tail"
  ],
  "KMSANReasoning": "The patch fixes a logic bug in `ttm_bo_swapout_cb()` where the success condition of `ttm_tt_swapout()` was erroneously checked as `if (!ret)` instead of `if (ret \u003e 0)`. Because `ttm_tt_swapout()` returns the positive number of swapped-out pages on success or a negative error code on failure, the LRU management functions (`ttm_resource_del_bulk_move_unevictable` and `ttm_resource_move_to_lru_tail`) were never called upon successful swapout.\n\nThis change strictly touches LRU tracking control flow and list manipulation for buffer objects. It does not introduce, modify, or read any uninitialized stack or heap memory, does not alter copy-to-user operations or infoleak surfaces, and does not alter buffer allocation/initialization logic. Any memory corruption or locking issues in LRU manipulation would be caught by standard KASAN/LOCKDEP builds. Therefore, a dedicated KMSAN fuzzing session is not warranted.",
  "NeedsKMSAN": false,
  "Reasoning": "The patch corrects a return-value check in ttm_bo_swapout_cb() from 'if (!ret)' to 'if (ret \u003e 0)'. Because ttm_tt_swapout() returns the positive number of pages swapped out on success (and negative on error), the LRU management and bulk move removal logic guarded by bdev-\u003elru_lock was previously dead code during successful swapouts. This change re-activates list manipulation and runtime assertions (such as WARN_ON_ONCE in ttm_resource_del_bulk_move_unevictable and lockdep assertions in ttm_resource_move_to_lru_tail). The modified code is reachable in virtualized environments via QEMU-emulated GPUs (DRM_QXL, DRM_VMWGFX) under memory reclaim or debugfs shrink operations, warranting fuzzing.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit 79c3468273ed2cd535bb0b514da047e96cb00ad5\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Wed Sep 16 22:33:41 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c\nindex ef56c18ded1b8..9b85b5f388d41 100644\n--- a/drivers/gpu/drm/ttm/ttm_bo.c\n+++ b/drivers/gpu/drm/ttm/ttm_bo.c\n@@ -1434,7 +1434,7 @@ ttm_bo_swapout_cb(struct ttm_lru_walk *walk, struct ttm_buffer_object *bo)\n \n \tif (ttm_tt_is_populated(tt)) {\n \t\tret = ttm_tt_swapout(bdev, tt, swapout_walk-\u003egfp_flags);\n-\t\tif (!ret) {\n+\t\tif (ret \u003e 0) {\n \t\t\tspin_lock(\u0026bdev-\u003elru_lock);\n \t\t\tttm_resource_del_bulk_move_unevictable(bo-\u003eresource, bo);\n \t\t\tttm_resource_move_to_lru_tail(bo-\u003eresource);\n"
}

core

null

{
  "EnableConfigs": [
    "DRM",
    "DRM_TTM",
    "DRM_TTM_HELPER",
    "DRM_QXL",
    "DRM_VMWGFX"
  ],
  "FocusSymbols": [
    "ttm_bo_swapout_cb",
    "ttm_tt_swapout",
    "ttm_global_swapout",
    "ttm_device_swapout",
    "ttm_resource_del_bulk_move_unevictable",
    "ttm_resource_move_to_lru_tail"
  ],
  "Reasoning": "The patch corrects a return-value check in ttm_bo_swapout_cb() from 'if (!ret)' to 'if (ret \u003e 0)'. Because ttm_tt_swapout() returns the positive number of pages swapped out on success (and negative on error), the LRU management and bulk move removal logic guarded by bdev-\u003elru_lock was previously dead code during successful swapouts. This change re-activates list manipulation and runtime assertions (such as WARN_ON_ONCE in ttm_resource_del_bulk_move_unevictable and lockdep assertions in ttm_resource_move_to_lru_tail). The modified code is reachable in virtualized environments via QEMU-emulated GPUs (DRM_QXL, DRM_VMWGFX) under memory reclaim or debugfs shrink operations, warranting fuzzing.",
  "WorthFuzzing": true
}

You are an expert Linux kernel maintainer and security engineer.
Your job is to review a provided patch series and evaluate whether it warrants fuzzing with syzkaller.

IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on internal assumptions. You must actively use your code access
tools to inspect the actual source code, callers, and surrounding context.

================================================================================
1. CORE TRIAGE PHILOSOPHY
================================================================================
The goal of patch fuzzing is to discover crashes, regressions, exposed latent bugs,
and newly triggered assertions introduced by the patch series.

- REACHABILITY IS THE PRIMARY GATE:
  Fuzzing can only discover bugs in code that can actually execute in standard virtualized
  environments (GCE or QEMU, utilizing software-emulated devices like USB gadgets, netdev, tun/tap).
  If the modified code is structurally unreachable (see Section 2), it MUST NOT be fuzzed,
  regardless of whether it adds assertions or complex logic.

- DO NOT BLINDLY TRUST "NO FUNCTIONAL CHANGE" (NFCI) OR "REFACTORING" CLAIMS:
  Patch authors routinely label changes as "cleanups", "refactorings", or state
  "No functional change intended". Do NOT take these claims at face value.
  Code refactorings that rearrange logic, introduce helper functions, or alter state management
  in core subsystems frequently introduce subtle semantic shifts or uncover latent kernel bugs.
  If reachable executable code is modified or refactored, it MUST be fuzzed.

- NEW OR MODIFIED ASSERTIONS IN REACHABLE CODE MUST BE FUZZED:
  When a patch introduces or modifies runtime checks or assertions (e.g., WARN_ON*, VM_WARN_ON*,
  BUG_ON*, lockdep_assert*) in reachable code paths, it enforces new or stricter invariants.
  Even if the author believes the invariant always holds, fuzzing is essential to verify whether
  an unusual sequence of operations can violate it.

================================================================================
2. WHEN TO RETURN WorthFuzzing=false (NEGATIVE CRITERIA)
================================================================================
Return WorthFuzzing=false ONLY IF all modified code falls strictly into one or more of these categories:

- Non-kernel and non-executable changes:
  * Modifications to Documentation/, comments, or spelling fixes.
  * User-space directories, self-tests, samples, or scripts (e.g., tools/, samples/, scripts/, usr/)
    that do not affect the compiled kernel image (vmlinux) or kernel modules.
  * Purely decorative logging (e.g., message strings in pr_err, printk, dev_info) or tracepoints
    that do not alter control flow or data structures.
  * Build system or Kconfig changes that do not alter compiled C logic.
- Structurally unreachable hardware:
  * Vendor-specific PCIe switches, SmartNICs, or GPU drivers (e.g., mlxsw, pds_core, qed,
    ionic, amdgpu) requiring physical ASIC/PCIe cards not emulated in standard QEMU.
- Unreachable execution paths:
  * Driver teardown callbacks (.remove, .shutdown, pci_unregister_driver) executed only during
    physical PCI hot-unplug or manual sysfs driver unbinding.
  * Code paths exclusive to architectures other than the target architecture.

================================================================================
3. WHEN TO RETURN WorthFuzzing=true (POSITIVE CRITERIA)
================================================================================
Return WorthFuzzing=true whenever the patch touches reachable executable code, including:
- Core Subsystems:
  * Any logic modifications in memory management (mm/), synchronization/locking (kernel/locking/),
    BPF, scheduler, core networking, VFS, or syscall handling.
- Refactorings and Code Cleanups:
  * Any restructuring of reachable data structures, helper abstractions, or algorithm flows.
- Runtime Assertions and Defensive Checks:
  * Any introduction or alteration of assertions (WARN_ON*, VM_WARN_ON*, BUG_ON*, etc.) in reachable paths.
- Reachable Drivers and Protocols:
  * Drivers accessible via virtual buses (virtio, USB gadget, loopback, netlink, binder, sockets, etc.).

================================================================================
4. EXTRACTING FocusSymbols (PREVENTING DILUTION)
================================================================================
When WorthFuzzing=true, you must extract specific kernel functions into FocusSymbols to guide the fuzzer:

- AVOID UBIQUITOUS LIFECYCLE HOT-PATHS:
  Do NOT list generic, ubiquitous functions called by almost every program in the corpus
  (including, but not limited to: general memory allocators and deallocators, page fault
  and trap handlers, or core synchronization primitives; this is not an exhaustive list).
  Listing ubiquitous functions causes the fuzzer to classify thousands of unrelated tests as "focused",
  which severely dilutes fuzzing effort away from the actual changes.

- TARGET SPECIFIC FEATURE LOGIC AND ENTRYPOINTS:
  List functions that specifically implement the logic being added or altered, or direct API entrypoints
  for the subsystem feature under review.

- HANDLING STATIC INLINE FUNCTIONS IN HEADERS (.h):
  Compiler-inlined static functions (such as static inlines in mm/*.h or include/linux/*.h) lack
  distinct symbol addresses in vmlinux and cannot be targeted directly by symbol coverage filters.
  If the changes are primarily in static inline helpers, identify non-static, feature-specific caller
  functions in .c files that exercise them (avoiding ubiquitous lifecycle wrappers).

================================================================================
5. IDENTIFYING EnableConfigs
================================================================================
Identify any specific CONFIG_ options required to properly compile and reach the modified code:
- Inspect Kconfig files and #ifdef guards; do not make assumptions.
- Check "depends on" lines in Kconfig to include any non-standard parent subsystem configs needed.
- Strip any 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4").
Prefer calling several tools at the same time to save round-trips.


Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.

Target architecture: amd64

For your convenience, here is the diff of the changes:
commit 79c3468273ed2cd535bb0b514da047e96cb00ad5
Author: syz-cluster <triage@syzkaller.com>
Date:   Wed Sep 16 22:33:41 2026 +0000

    syz-cluster: applied patch under review

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index ef56c18ded1b8..9b85b5f388d41 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -1434,7 +1434,7 @@ ttm_bo_swapout_cb(struct ttm_lru_walk *walk, struct ttm_buffer_object *bo)
 
 	if (ttm_tt_is_populated(tt)) {
 		ret = ttm_tt_swapout(bdev, tt, swapout_walk->gfp_flags);
-		if (!ret) {
+		if (ret > 0) {
 			spin_lock(&bdev->lru_lock);
 			ttm_resource_del_bulk_move_unevictable(bo->resource, bo);
 			ttm_resource_move_to_lru_tail(bo->resource);

gemini-3.8-flash

null

null

							input: 2943
							output: 44
							thoughts: 422
						

**Evaluating the Patch for Syzkaller Fuzzing**

Okay, so I need to decide if this kernel patch is a good candidate for fuzzing with syzkaller. The request itself is straightforward – it's standard kernel development triage: determining if a patch is reachable by fuzzing, if it's worth the effort, and identifying any relevant configurations or focus symbols. From a risk perspective, this is a very benign operation; just normal software testing and kernel development work. No red flags there.

Now, let's dive into the patch itself. I see a `diff` that's been provided. I'll need to examine the changes in `drivers/gpu/drm/ttm/ttm_bo.c` specifically around line 1434. I'll need to use either `read-file` or `grepper` (depending on the environment) to get a full context of that code section. The change appears to be in the `ttm_bo_swapout_cb` function, a conditional change, I want to fully analyze the changes made and surrounding code, to determine how relevant this change is to fuzzing. A quick glance suggests a change in the return value check from `!ret` to `ret > 0` after a `ttm_tt_swapout` call. That's a crucial conditional, and the function is managing buffer object swapping, which could be an interesting area for fuzzing. Depending on the details I pull up, the context will become clearer.

{
  "File": "drivers/gpu/drm/ttm/ttm_bo.c",
  "FirstLine": 1420,
  "LineCount": 40
}

{
  "Contents": "1420:\t\t\t\tgoto out;\n1421:\t\t\t}\n1422:\t\t}\n1423:\t\n1424:\t\t/*\n1425:\t\t * Make sure BO is idle.\n1426:\t\t */\n1427:\t\tret = ttm_bo_wait_ctx(bo, ctx);\n1428:\t\tif (ret)\n1429:\t\t\tgoto out;\n1430:\t\n1431:\t\tttm_bo_unmap_virtual(bo);\n1432:\t\tif (bdev-\u003efuncs-\u003eswap_notify)\n1433:\t\t\tbdev-\u003efuncs-\u003eswap_notify(bo);\n1434:\t\n1435:\t\tif (ttm_tt_is_populated(tt)) {\n1436:\t\t\tret = ttm_tt_swapout(bdev, tt, swapout_walk-\u003egfp_flags);\n1437:\t\t\tif (ret \u003e 0) {\n1438:\t\t\t\tspin_lock(\u0026bdev-\u003elru_lock);\n1439:\t\t\t\tttm_resource_del_bulk_move_unevictable(bo-\u003eresource, bo);\n1440:\t\t\t\tttm_resource_move_to_lru_tail(bo-\u003eresource);\n1441:\t\t\t\tspin_unlock(\u0026bdev-\u003elru_lock);\n1442:\t\t\t}\n1443:\t\t}\n1444:\t\n1445:\tout:\n1446:\t\t/* Consider -ENOMEM and -ENOSPC non-fatal. */\n1447:\t\tif (ret == -ENOMEM || ret == -ENOSPC)\n1448:\t\t\tret = -EBUSY;\n1449:\t\n1450:\t\treturn ret;\n1451:\t}\n1452:\t\n1453:\tconst struct ttm_lru_walk_ops ttm_swap_ops = {\n1454:\t\t.process_bo = ttm_bo_swapout_cb,\n1455:\t};\n1456:\t\n1457:\t/**\n1458:\t * ttm_bo_swapout() - Swap out buffer objects on the LRU list to shmem.\n1459:\t * @bdev: The ttm device.\n"
}

gemini-3.8-flash

null

null

							input: 4317
							output: 29
							thoughts: 111
						

**Analyzing the Translation Table Manager (TTM) Swapout Function**

Okay, let's break this down. The code snippet I'm looking at involves `ttm_tt_swapout(bdev, tt, swapout_walk->gfp_flags)`. My immediate thought is to understand the implications of this function call. I need to know what `ttm_tt_swapout` actually returns and, more importantly, how it's used by other parts of the system and, which subsystems utilize the Translation Table Manager.

First, I should remind myself of the fundamentals. What is TTM? Right, it's the Translation Table Manager, a memory manager specifically designed for GPUs and implemented within several DRM (Direct Rendering Manager) drivers.

A critical question pops into mind. Can DRM drivers that depend on TTM function correctly within QEMU or a standard virtualized environment? I need to consider the interaction with the hypervisor and how memory translation is handled in those contexts.

To understand the scope of this further, I should check which specific drivers are leveraging TTM. This will give me a broader understanding of its impact and importance.

{
  "Expression": "ttm_bo",
  "PathPrefix": "drivers/gpu/drm"
}

{
  "Output": "\nFull output is too long, showing 500 out of 5917 lines.\nUse more precise expression if possible.\n\ndrivers/gpu/drm/amd/amdgpu/amdgpu.h-48-\ndrivers/gpu/drm/amd/amdgpu/amdgpu.h:49:#include \u003cdrm/ttm/ttm_bo.h\u003e\ndrivers/gpu/drm/amd/amdgpu/amdgpu.h-50-#include \u003cdrm/ttm/ttm_placement.h\u003e\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c=349=int amdgpu_amdkfd_alloc_kernel_mem(struct amdgpu_device *adev, size_t size,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c-363-\t\t   AMDGPU_GEM_CREATE_CPU_GTT_USWC;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c:364:\tbp.type = ttm_bo_type_kernel;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c-365-\tbp.resv = NULL;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c=436=int amdgpu_amdkfd_alloc_gws(struct amdgpu_device *adev, size_t size,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c-448-\tbp.flags = AMDGPU_GEM_CREATE_NO_CPU_ACCESS;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c:449:\tbp.type = ttm_bo_type_device;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c-450-\tbp.resv = NULL;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c=34=static atomic_t fence_seq = ATOMIC_INIT(0);\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c-50- * If ttm_device_funcs-\u003eeviction_valuable returns true, then TTM will continue\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c:51: * the evcition process for that BO by calling ttm_bo_evict --\u003e amdgpu_bo_move\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c-52- * --\u003e amdgpu_copy_buffer(). This sets up job in GPU scheduler.\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c=331=create_dmamap_sg_bo(struct amdgpu_device *adev,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-347-\t\t\tAMDGPU_GEM_DOMAIN_CPU, AMDGPU_GEM_CREATE_PREEMPTIBLE | flags,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:348:\t\t\tttm_bo_type_sg, mem-\u003ebo-\u003etbo.base.resv, \u0026gem_obj, 0);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-349-\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c=417=static int amdgpu_amdkfd_bo_validate(struct amdgpu_bo *bo, uint32_t domain,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-432-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:433:\tret = ttm_bo_validate(\u0026bo-\u003etbo, \u0026bo-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-434-\tif (ret)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c=560=kfd_mem_dmamap_userptr(struct kgd_mem *mem,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-592-\tamdgpu_bo_placement_from_domain(bo, AMDGPU_GEM_DOMAIN_GTT);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:593:\tret = ttm_bo_validate(\u0026bo-\u003etbo, \u0026bo-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-594-\tif (ret)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c=611=kfd_mem_dmamap_dmabuf(struct kfd_mem_attachment *attachment)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-616-\tamdgpu_bo_placement_from_domain(bo, AMDGPU_GEM_DOMAIN_GTT);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:617:\treturn ttm_bo_validate(\u0026bo-\u003etbo, \u0026bo-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-618-}\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c=647=kfd_mem_dmamap_sg_bo(struct kgd_mem *mem,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-684-\tamdgpu_bo_placement_from_domain(bo, AMDGPU_GEM_DOMAIN_GTT);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:685:\tret = ttm_bo_validate(\u0026bo-\u003etbo, \u0026bo-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-686-\tif (unlikely(ret))\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c=721=kfd_mem_dmaunmap_userptr(struct kgd_mem *mem,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-735-\tamdgpu_bo_placement_from_domain(bo, AMDGPU_GEM_DOMAIN_CPU);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:736:\t(void)ttm_bo_validate(\u0026bo-\u003etbo, \u0026bo-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-737-\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c=770=kfd_mem_dmaunmap_sg_bo(struct kgd_mem *mem,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-784-\tamdgpu_bo_placement_from_domain(bo, AMDGPU_GEM_DOMAIN_CPU);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:785:\t(void)ttm_bo_validate(\u0026bo-\u003etbo, \u0026bo-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-786-\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c=871=static int kfd_mem_attach(struct amdgpu_device *adev, struct kgd_mem *mem,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-939-\t\t/* Handle DOORBELL BOs of peer devices and MMIO BOs of local and peer devices */\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:940:\t\t} else if (mem-\u003ebo-\u003etbo.type == ttm_bo_type_sg) {\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-941-\t\t\tWARN_ONCE(!(mem-\u003ealloc_flags \u0026 KFD_IOC_ALLOC_MEM_FLAGS_DOORBELL ||\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c=1061=static int init_user_pages(struct kgd_mem *mem, uint64_t user_addr,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-1123-\tamdgpu_bo_placement_from_domain(bo, mem-\u003edomain);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:1124:\tret = ttm_bo_validate(\u0026bo-\u003etbo, \u0026bo-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-1125-\tif (ret)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c=1509=static int amdgpu_amdkfd_gpuvm_pin_bo(struct amdgpu_bo *bo, u32 domain)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-1525-\t\t\tamdgpu_bo_placement_from_domain(bo, AMDGPU_GEM_DOMAIN_GTT);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:1526:\t\t\tret = ttm_bo_validate(\u0026bo-\u003etbo, \u0026bo-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-1527-\t\t\tif (unlikely(ret)) {\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c=1709=int amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu(\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-1715-\tstruct amdgpu_fpriv *fpriv = container_of(avm, struct amdgpu_fpriv, vm);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:1716:\tenum ttm_bo_type bo_type = ttm_bo_type_device;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-1717-\tstruct sg_table *sg = NULL;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-1762-\t\t\t\t    KFD_IOC_ALLOC_MEM_FLAGS_MMIO_REMAP)) {\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:1763:\t\t\tbo_type = ttm_bo_type_sg;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-1764-\t\t\tif (size \u003e UINT_MAX)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-1834-\tbo = gem_to_amdgpu_bo(gobj);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:1835:\tif (bo_type == ttm_bo_type_sg) {\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-1836-\t\tbo-\u003etbo.sg = sg;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c=2557=static int update_invalid_user_pages(struct amdkfd_process_info *process_info,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-2602-\t\t\tamdgpu_bo_placement_from_domain(bo, AMDGPU_GEM_DOMAIN_CPU);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:2603:\t\t\tret = ttm_bo_validate(\u0026bo-\u003etbo, \u0026bo-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-2604-\t\t\tamdgpu_bo_unreserve(bo);\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c=2679=static int validate_invalid_user_pages(struct amdkfd_process_info *process_info)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-2731-\t\t\tamdgpu_bo_placement_from_domain(bo, mem-\u003edomain);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:2732:\t\t\tret = ttm_bo_validate(\u0026bo-\u003etbo, \u0026bo-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-2733-\t\t\tif (ret) {\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_cs.c=813=static int amdgpu_cs_bo_validate(void *param, struct amdgpu_bo *bo)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_cs.c-852-\tamdgpu_bo_placement_from_domain(bo, domain);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_cs.c:853:\tr = ttm_bo_validate(\u0026bo-\u003etbo, \u0026bo-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_cs.c-854-\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_cs.c=868=static int amdgpu_cs_parser_bos(struct amdgpu_cs_parser *p,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_cs.c-963-\t\t\t\t\t\t\tAMDGPU_GEM_DOMAIN_CPU);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_cs.c:964:\t\t\tr = ttm_bo_validate(\u0026e-\u003ebo-\u003etbo, \u0026e-\u003ebo-\u003eplacement,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_cs.c-965-\t\t\t\t\t    \u0026ctx);\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_cs.c=1282=static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_cs.c-1341-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_cs.c:1342:\t\tttm_bo_move_to_lru_tail_unlocked(\u0026gem_to_amdgpu_bo(gobj)-\u003etbo);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_cs.c-1343-\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_cs.c=1797=int amdgpu_cs_find_mapping(struct amdgpu_cs_parser *parser,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_cs.c-1827-\t\t\t(*bo)-\u003eplacements[i].flags |= TTM_PL_FLAG_CONTIGUOUS;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_cs.c:1828:\t\tr = ttm_bo_validate(\u0026(*bo)-\u003etbo, \u0026(*bo)-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_cs.c-1829-\t\tif (r)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c=213=amdgpu_devcoredump_print_ibs(struct drm_printer *p,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c-309-\t\t} else {\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c:310:\t\t\tr = ttm_bo_kmap(\u0026abo-\u003etbo, 0, PFN_UP(abo-\u003etbo.base.size),\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c-311-\t\t\t\t\t\u0026abo-\u003ekmap);\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_display.c=2017=int amdgpu_display_get_scanout_buffer(struct drm_plane *plane,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_display.c-2060-\tif (!abo-\u003ekmap.virtual \u0026\u0026\ndrivers/gpu/drm/amd/amdgpu/amdgpu_display.c:2061:\t    ttm_bo_kmap(\u0026abo-\u003etbo, 0, PFN_UP(abo-\u003etbo.base.size), \u0026abo-\u003ekmap)) {\ndrivers/gpu/drm/amd/amdgpu/amdgpu_display.c-2062-\t\tdrm_warn(plane-\u003edev, \"amdgpu bo map failed, panic won't be displayed\\n\");\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c=178=static struct sg_table *amdgpu_dma_buf_map(struct dma_buf_attachment *attach,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c-198-\t\tamdgpu_bo_placement_from_domain(bo, domains);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c:199:\t\tr = ttm_bo_validate(\u0026bo-\u003etbo, \u0026bo-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c-200-\t\tif (r)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c=292=static int amdgpu_dma_buf_begin_cpu_access(struct dma_buf *dma_buf,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c-313-\t\tamdgpu_bo_placement_from_domain(bo, AMDGPU_GEM_DOMAIN_GTT);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c:314:\t\tret = ttm_bo_validate(\u0026bo-\u003etbo, \u0026bo-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c-315-\t}\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c=374=struct dma_buf *amdgpu_gem_prime_export(struct drm_gem_object *gobj,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c-391-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c:392:\tret = ttm_bo_setup_export(\u0026bo-\u003etbo, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c-393-\tif (ret)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c=416=amdgpu_dma_buf_create_obj(struct drm_device *dev, struct dma_buf *dma_buf)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c-437-\t\t\t\t       AMDGPU_GEM_DOMAIN_CPU, flags,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c:438:\t\t\t\t       ttm_bo_type_sg, resv, \u0026gobj, 0);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c-439-\tif (ret)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c=463=amdgpu_dma_buf_move_notify(struct dma_buf_attachment *attach)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c-480-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c:481:\tr = ttm_bo_validate(\u0026bo-\u003etbo, \u0026placement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c-482-\tif (r) {\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_eviction_fence.c=96=int amdgpu_evf_mgr_attach_fence(struct amdgpu_eviction_fence_mgr *evf_mgr,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_eviction_fence.c-106-\t\tamdgpu_bo_placement_from_domain(bo, bo-\u003eallowed_domains);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_eviction_fence.c:107:\t\tret = ttm_bo_validate(\u0026bo-\u003etbo, \u0026bo-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_eviction_fence.c-108-\t\tif (!ret)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gart.c=118=int amdgpu_gart_table_ram_alloc(struct amdgpu_device *adev)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gart.c-174-\tbp.domain = AMDGPU_GEM_DOMAIN_CPU;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gart.c:175:\tbp.type = ttm_bo_type_sg;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gart.c-176-\tbp.resv = NULL;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c=119=static vm_fault_t amdgpu_gem_fault(struct vm_fault *vmf)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-125-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c:126:\tret = ttm_bo_vm_reserve(bo, vmf);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-127-\tif (ret)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-136-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c:137:\t\tret = ttm_bo_vm_fault_reserved(vmf, vmf-\u003evma-\u003evm_page_prot,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-138-\t\t\t\t\t       TTM_BO_VM_NUM_PREFAULT);\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-141-\t} else {\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c:142:\t\tret = ttm_bo_vm_dummy_page(vmf, vmf-\u003evma-\u003evm_page_prot);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-143-\t}\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c=152=static const struct vm_operations_struct amdgpu_gem_vm_ops = {\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-153-\t.fault = amdgpu_gem_fault,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c:154:\t.open = ttm_bo_vm_open,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c:155:\t.close = ttm_bo_vm_close,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c:156:\t.access = ttm_bo_vm_access\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-157-};\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c=159=static void amdgpu_gem_object_free(struct drm_gem_object *gobj)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-163-\tamdgpu_hmm_unregister(aobj);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c:164:\tttm_bo_fini(\u0026aobj-\u003etbo);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-165-}\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c=167=int amdgpu_gem_object_create(struct amdgpu_device *adev, unsigned long size,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-168-\t\t\t     int alignment, u32 initial_domain,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c:169:\t\t\t     u64 flags, enum ttm_bo_type type,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-170-\t\t\t     struct dma_resv *resv,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c=422=int amdgpu_gem_create_ioctl(struct drm_device *dev, void *data,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-478-\t\t\t\t     initial_domain,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c:479:\t\t\t\t     flags, ttm_bo_type_device, resv, \u0026gobj, fpriv-\u003excp_id + 1);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-480-\tif (r \u0026\u0026 r != -ERESTARTSYS) {\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c=516=int amdgpu_gem_userptr_ioctl(struct drm_device *dev, void *data,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-551-\tr = amdgpu_gem_object_create(adev, args-\u003esize, 0, AMDGPU_GEM_DOMAIN_CPU,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c:552:\t\t\t\t     0, ttm_bo_type_device, NULL, \u0026gobj, fpriv-\u003excp_id + 1);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-553-\tif (r)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-583-\t\tamdgpu_bo_placement_from_domain(bo, AMDGPU_GEM_DOMAIN_GTT);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c:584:\t\tr = ttm_bo_validate(\u0026bo-\u003etbo, \u0026bo-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-585-\t\tamdgpu_bo_unreserve(bo);\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c=1289=int amdgpu_mode_dumb_create(struct drm_file *file_priv,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-1321-\tr = amdgpu_gem_object_create(adev, args-\u003esize, 0, domain, flags,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c:1322:\t\t\t\t     ttm_bo_type_device, NULL, \u0026gobj, fpriv-\u003excp_id + 1);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-1323-\tif (r)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.h=44=int amdgpu_gem_object_create(struct amdgpu_device *adev, unsigned long size,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.h-45-\t\t\t     int alignment, u32 initial_domain,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.h:46:\t\t\t     u64 flags, enum ttm_bo_type type,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.h-47-\t\t\t     struct dma_resv *resv,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c=1224=uint32_t amdgpu_kiq_rreg(struct amdgpu_device *adev, uint32_t reg, uint32_t xcc_id)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c-1260-\t * block gpu_recover() routine forever, e.g. this virt_kiq_rreg\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c:1261:\t * is triggered in TTM and ttm_bo_lock_delayed_workqueue() will\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c-1262-\t * never return if we keep waiting in virt_kiq_rreg, which cause\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c=1298=void amdgpu_kiq_wreg(struct amdgpu_device *adev, uint32_t reg, uint32_t v, uint32_t xcc_id)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c-1332-\t * block gpu_recover() routine forever, e.g. this virt_kiq_rreg\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c:1333:\t * is triggered in TTM and ttm_bo_lock_delayed_workqueue() will\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c-1334-\t * never return if we keep waiting in virt_kiq_rreg, which cause\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c=1398=int amdgpu_kiq_hdp_flush(struct amdgpu_device *adev)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c-1432-\t * block gpu_recover() routine forever, e.g. this virt_kiq_rreg\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c:1433:\t * is triggered in TTM and ttm_bo_lock_delayed_workqueue() will\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c-1434-\t * never return if we keep waiting in virt_kiq_rreg, which cause\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c=57=int amdgpu_gmc_pdb0_alloc(struct amdgpu_device *adev)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c-70-\t\tAMDGPU_GEM_CREATE_VRAM_CONTIGUOUS;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c:71:\tbp.type = ttm_bo_type_kernel;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c-72-\tbp.resv = NULL;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c=112=void amdgpu_bo_placement_from_domain(struct amdgpu_bo *abo, u32 domain)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-142-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:143:\t\tif (abo-\u003etbo.type == ttm_bo_type_kernel \u0026\u0026\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-144-\t\t    flags \u0026 AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c=240=int amdgpu_bo_create_reserved(struct amdgpu_device *adev,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-260-\tbp.flags |= AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:261:\tbp.type = ttm_bo_type_kernel;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-262-\tbp.resv = NULL;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c=443=int amdgpu_bo_create_kernel_at(struct amdgpu_device *adev,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-475-\t}\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:476:\tr = ttm_bo_mem_space(\u0026(*bo_ptr)-\u003etbo, \u0026(*bo_ptr)-\u003eplacement,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-477-\t\t\t     \u0026(*bo_ptr)-\u003etbo.resource, \u0026ctx);\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c=630=int amdgpu_bo_create(struct amdgpu_device *adev,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-634-\tstruct ttm_operation_ctx ctx = {\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:635:\t\t.interruptible = (bp-\u003etype != ttm_bo_type_kernel),\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-636-\t\t.no_wait_gpu = bp-\u003eno_wait_gpu,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-638-\t\t.gfp_retry_mayfail = true,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:639:\t\t.allow_res_evict = bp-\u003etype != ttm_bo_type_kernel,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-640-\t\t.resv = bp-\u003eresv\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-676-\tbo-\u003eallowed_domains = bo-\u003epreferred_domains;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:677:\tif (bp-\u003etype != ttm_bo_type_kernel \u0026\u0026\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-678-\t    !(bp-\u003eflags \u0026 AMDGPU_GEM_CREATE_DISCARDABLE) \u0026\u0026\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-699-\t\tamdgpu_bo_placement_from_domain(bo, bp-\u003edomain);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:700:\tif (bp-\u003etype == ttm_bo_type_kernel)\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-701-\t\tbo-\u003etbo.priority = 2;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-707-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:708:\tr = ttm_bo_init_reserved(\u0026adev-\u003emman.bdev, \u0026bo-\u003etbo, bp-\u003etype,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-709-\t\t\t\t \u0026bo-\u003eplacement, page_align, \u0026ctx,  NULL,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-743-\t/* Treat CPU_ACCESS_REQUIRED only as a hint if given by UMD */\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:744:\tif (bp-\u003etype == ttm_bo_type_device)\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-745-\t\tbo-\u003eflags \u0026= ~AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c=797=int amdgpu_bo_create_vm(struct amdgpu_device *adev,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-820- *\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:821: * Calls ttm_bo_kmap() to set up the kernel virtual mapping; calls\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-822- * amdgpu_bo_kptr() to get the kernel virtual address.\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c=827=int amdgpu_bo_kmap(struct amdgpu_bo *bo, void **ptr)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-846-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:847:\tr = ttm_bo_kmap(\u0026bo-\u003etbo, 0, PFN_UP(bo-\u003etbo.base.size), \u0026bo-\u003ekmap);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-848-\tif (r)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c=879=void amdgpu_bo_kunmap(struct amdgpu_bo *bo)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-881-\tif (bo-\u003ekmap.bo)\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:882:\t\tttm_bo_kunmap(\u0026bo-\u003ekmap);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-883-}\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c=934=int amdgpu_bo_pin(struct amdgpu_bo *bo, u32 domain)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-966-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:967:\t\tttm_bo_pin(\u0026bo-\u003etbo);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-968-\t\treturn 0;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-988-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:989:\tr = ttm_bo_validate(\u0026bo-\u003etbo, \u0026bo-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-990-\tif (unlikely(r)) {\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-994-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:995:\tttm_bo_pin(\u0026bo-\u003etbo);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-996-\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c=1019=void amdgpu_bo_unpin(struct amdgpu_bo *bo)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-1022-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:1023:\tttm_bo_unpin(\u0026bo-\u003etbo);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-1024-\tif (bo-\u003etbo.pin_count)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c=1125=int amdgpu_bo_set_tiling_flags(struct amdgpu_bo *bo, u64 tiling_flags)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-1133-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:1134:\tBUG_ON(bo-\u003etbo.type == ttm_bo_type_kernel);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-1135-\tif (adev-\u003efamily \u003c= AMDGPU_FAMILY_CZ \u0026\u0026\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c=1152=void amdgpu_bo_get_tiling_flags(struct amdgpu_bo *bo, u64 *tiling_flags)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-1162-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:1163:\tBUG_ON(bo-\u003etbo.type == ttm_bo_type_kernel);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-1164-\tdma_resv_assert_held(bo-\u003etbo.base.resv);\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c=1184=int amdgpu_bo_set_metadata(struct amdgpu_bo *bo, void *metadata,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-1189-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:1190:\tBUG_ON(bo-\u003etbo.type == ttm_bo_type_kernel);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-1191-\tubo = to_amdgpu_bo_user(bo);\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c=1231=int amdgpu_bo_get_metadata(struct amdgpu_bo *bo, void *buffer,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-1239-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:1240:\tBUG_ON(bo-\u003etbo.type == ttm_bo_type_kernel);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-1241-\tubo = to_amdgpu_bo_user(bo);\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c=1362=vm_fault_t amdgpu_bo_fault_reserve_notify(struct ttm_buffer_object *bo)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-1386-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:1387:\tr = ttm_bo_validate(bo, \u0026abo-\u003eplacement, \u0026ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-1388-\tif (unlikely(r == -EBUSY || r == -ERESTARTSYS))\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-1397-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:1398:\tttm_bo_move_to_lru_tail_unlocked(bo);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-1399-\treturn 0;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c=1483=u64 amdgpu_bo_gpu_offset(struct amdgpu_bo *bo)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-1486-\tWARN_ON_ONCE(!dma_resv_is_locked(bo-\u003etbo.base.resv) \u0026\u0026\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c:1487:\t\t     !bo-\u003etbo.pin_count \u0026\u0026 bo-\u003etbo.type != ttm_bo_type_kernel);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.c-1488-\tWARN_ON_ONCE(bo-\u003etbo.resource-\u003estart == AMDGPU_BO_INVALID_OFFSET);\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.h=48=struct amdgpu_bo_param {\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.h-54-\tu64\t\t\t\tflags;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.h:55:\tenum ttm_bo_type\t\ttype;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.h-56-\tbool\t\t\t\tno_wait_gpu;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.h=103=struct amdgpu_bo {\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.h-109-\tstruct ttm_buffer_object\ttbo;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.h:110:\tstruct ttm_bo_kmap_obj\t\tkmap;\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.h-111-\tu64\t\t\t\tflags;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.h=187=static inline int amdgpu_bo_reserve(struct amdgpu_bo *bo, bool no_intr)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.h-191-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.h:192:\tr = ttm_bo_reserve(\u0026bo-\u003etbo, !no_intr, false, NULL);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.h-193-\tif (unlikely(r != 0)) {\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.h=201=static inline void amdgpu_bo_unreserve(struct amdgpu_bo *bo)\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.h-202-{\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.h:203:\tttm_bo_unreserve(\u0026bo-\u003etbo);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_object.h-204-}\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-45-#include \u003cdrm/drm_drv.h\u003e\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:46:#include \u003cdrm/ttm/ttm_bo.h\u003e\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-47-#include \u003cdrm/ttm/ttm_placement.h\u003e\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c=75=static int amdgpu_ttm_init_on_chip(struct amdgpu_device *adev,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-91- *\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:92: * Fill in placement data when ttm_bo_evict() is called\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-93- */\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c=94=static void amdgpu_evict_flags(struct ttm_buffer_object *bo,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-106-\t/* Don't handle scatter gather BOs */\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:107:\tif (bo-\u003etype == ttm_bo_type_sg) {\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-108-\t\tplacement-\u003enum_placement = 0;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c=396=static int amdgpu_move_blit(struct ttm_buffer_object *bo,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-444-\t/* Always block for VM page tables before committing the new location */\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:445:\tif (bo-\u003etype == ttm_bo_type_kernel)\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:446:\t\tr = ttm_bo_move_accel_cleanup(bo, fence, true, false, new_mem);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-447-\telse\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:448:\t\tr = ttm_bo_move_accel_cleanup(bo, fence, evict, true, new_mem);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-449-\tdma_fence_put(fence);\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c=466=bool amdgpu_res_cpu_visible(struct amdgpu_device *adev,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-492-/*\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:493: * amdgpu_res_copyable - Check that memory can be accessed by ttm_bo_move_memcpy\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-494- *\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c=497=static bool amdgpu_res_copyable(struct amdgpu_device *adev,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-513- *\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:514: * Called by ttm_bo_handle_move_mem()\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-515- */\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c=516=static int amdgpu_bo_move(struct ttm_buffer_object *bo, bool evict,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-529-\t\t\t\told_mem-\u003emem_type == AMDGPU_PL_PREEMPT)) {\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:530:\t\t\tr = ttm_bo_wait_ctx(bo, ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-531-\t\t\tif (r)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-547-\t\tamdgpu_bo_move_notify(bo, evict, new_mem);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:548:\t\tttm_bo_move_null(bo, new_mem);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-549-\t\treturn 0;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-554-\t\tamdgpu_bo_move_notify(bo, evict, new_mem);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:555:\t\tttm_bo_move_null(bo, new_mem);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-556-\t\treturn 0;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-560-\t    new_mem-\u003emem_type == TTM_PL_SYSTEM) {\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:561:\t\tr = ttm_bo_wait_ctx(bo, ctx);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-562-\t\tif (r)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-567-\t\tttm_resource_free(bo, \u0026bo-\u003eresource);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:568:\t\tttm_bo_assign_mem(bo, new_mem);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-569-\t\treturn 0;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-576-\t\tttm_resource_free(bo, \u0026bo-\u003eresource);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:577:\t\tttm_bo_assign_mem(bo, new_mem);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-578-\t\treturn 0;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-592-\t\tamdgpu_bo_move_notify(bo, evict, new_mem);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:593:\t\tttm_bo_move_null(bo, new_mem);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-594-\t\treturn 0;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-596-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:597:\tif (bo-\u003etype == ttm_bo_type_device \u0026\u0026\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-598-\t    new_mem-\u003emem_type == TTM_PL_VRAM \u0026\u0026\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-631-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:632:\t\tr = ttm_bo_move_memcpy(bo, ctx, new_mem);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-633-\t\tif (r)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-646- *\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:647: * Called by ttm_mem_io_reserve() ultimately via ttm_bo_vm_fault()\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-648- */\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c=904=static void amdgpu_ttm_gart_bind(struct amdgpu_device *adev,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-926- *\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c:927: * Called by ttm_tt_bind() on behalf of ttm_bo_handle_move_mem().\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-928- * This handles binding GTT memory to the device address space.\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c=998=int amdgpu_ttm_alloc_gart(struct ttm_buffer_object *bo)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c-1023-\n\n"
}

gemini-3.8-flash

null

null

							input: 19640
							output: 30
							thoughts: 20
						

Here's my thought process, as if I were the one thinking it:

**Investigating CONFIG_DRM_TTM Usage**

Okay, hold on a minute. I need to clarify something quickly. I'm trying to understand the dependencies around the DRM (Direct Rendering Manager) subsystem, and specifically, which drivers are actually *using* or *selecting* the `CONFIG_DRM_TTM` option. It's crucial for me to pinpoint exactly which codebases rely on TTM (Translation Table Manager) support within the kernel's DRM framework. It's a key piece of information for me to optimize some code I'm writing. I need to get this straight. Let's dig in and figure out exactly who's calling on it. Let's go check!

{
  "Expression": "select DRM_TTM",
  "PathPrefix": "drivers/gpu/drm"
}

{
  "Output": "drivers/gpu/drm/Kconfig=250=config DRM_TTM_HELPER\n--\ndrivers/gpu/drm/Kconfig-252-\tdepends on DRM\ndrivers/gpu/drm/Kconfig:253:\tselect DRM_TTM\ndrivers/gpu/drm/Kconfig-254-\tselect DRM_KMS_HELPER if DRM_FBDEV_EMULATION\n--\ndrivers/gpu/drm/Kconfig.debug=86=config DRM_TTM_KUNIT_TEST\n--\ndrivers/gpu/drm/Kconfig.debug-88-\tdepends on DRM \u0026\u0026 KUNIT \u0026\u0026 MMU \u0026\u0026 (UML || COMPILE_TEST)\ndrivers/gpu/drm/Kconfig.debug:89:\tselect DRM_TTM\ndrivers/gpu/drm/Kconfig.debug-90-\tselect DRM_BUDDY\n--\ndrivers/gpu/drm/amd/amdgpu/Kconfig=3=config DRM_AMDGPU\n--\ndrivers/gpu/drm/amd/amdgpu/Kconfig-15-\tselect DRM_SCHED\ndrivers/gpu/drm/amd/amdgpu/Kconfig:16:\tselect DRM_TTM\ndrivers/gpu/drm/amd/amdgpu/Kconfig:17:\tselect DRM_TTM_HELPER\ndrivers/gpu/drm/amd/amdgpu/Kconfig-18-\tselect POWER_SUPPLY\n--\ndrivers/gpu/drm/i915/Kconfig=2=config DRM_I915\n--\ndrivers/gpu/drm/i915/Kconfig-39-\tselect VMAP_PFN\ndrivers/gpu/drm/i915/Kconfig:40:\tselect DRM_TTM\ndrivers/gpu/drm/i915/Kconfig-41-\tselect DRM_BUDDY\n--\ndrivers/gpu/drm/loongson/Kconfig=3=config DRM_LOONGSON\n--\ndrivers/gpu/drm/loongson/Kconfig-8-\tselect DRM_KMS_HELPER\ndrivers/gpu/drm/loongson/Kconfig:9:\tselect DRM_TTM\ndrivers/gpu/drm/loongson/Kconfig:10:\tselect DRM_TTM_HELPER\ndrivers/gpu/drm/loongson/Kconfig-11-\tselect I2C\n--\ndrivers/gpu/drm/nouveau/Kconfig=2=config DRM_NOUVEAU\n--\ndrivers/gpu/drm/nouveau/Kconfig-12-\tselect DRM_KMS_HELPER\ndrivers/gpu/drm/nouveau/Kconfig:13:\tselect DRM_TTM\ndrivers/gpu/drm/nouveau/Kconfig:14:\tselect DRM_TTM_HELPER\ndrivers/gpu/drm/nouveau/Kconfig-15-\tselect DRM_EXEC\n--\ndrivers/gpu/drm/qxl/Kconfig=2=config DRM_QXL\n--\ndrivers/gpu/drm/qxl/Kconfig-6-\tselect DRM_KMS_HELPER\ndrivers/gpu/drm/qxl/Kconfig:7:\tselect DRM_TTM\ndrivers/gpu/drm/qxl/Kconfig:8:\tselect DRM_TTM_HELPER\ndrivers/gpu/drm/qxl/Kconfig-9-\tselect DRM_EXEC\n--\ndrivers/gpu/drm/radeon/Kconfig=3=config DRM_RADEON\n--\ndrivers/gpu/drm/radeon/Kconfig-12-\tselect DRM_SUBALLOC_HELPER\ndrivers/gpu/drm/radeon/Kconfig:13:        select DRM_TTM\ndrivers/gpu/drm/radeon/Kconfig:14:\tselect DRM_TTM_HELPER\ndrivers/gpu/drm/radeon/Kconfig-15-\tselect FB_IOMEM_HELPERS if DRM_FBDEV_EMULATION\n--\ndrivers/gpu/drm/vboxvideo/Kconfig=2=config DRM_VBOXVIDEO\n--\ndrivers/gpu/drm/vboxvideo/Kconfig-7-\tselect DRM_VRAM_HELPER\ndrivers/gpu/drm/vboxvideo/Kconfig:8:\tselect DRM_TTM\ndrivers/gpu/drm/vboxvideo/Kconfig:9:\tselect DRM_TTM_HELPER\ndrivers/gpu/drm/vboxvideo/Kconfig-10-\tselect GENERIC_ALLOCATOR\n--\ndrivers/gpu/drm/vmwgfx/Kconfig=2=config DRM_VMWGFX\n--\ndrivers/gpu/drm/vmwgfx/Kconfig-6-\tselect DRM_CLIENT_SELECTION\ndrivers/gpu/drm/vmwgfx/Kconfig:7:\tselect DRM_TTM\ndrivers/gpu/drm/vmwgfx/Kconfig:8:\tselect DRM_TTM_HELPER\ndrivers/gpu/drm/vmwgfx/Kconfig-9-\tselect MAPPING_DIRTY_HELPERS\n--\ndrivers/gpu/drm/xe/Kconfig=2=config DRM_XE\n--\ndrivers/gpu/drm/xe/Kconfig-38-\tselect VMAP_PFN\ndrivers/gpu/drm/xe/Kconfig:39:\tselect DRM_TTM\ndrivers/gpu/drm/xe/Kconfig:40:\tselect DRM_TTM_HELPER\ndrivers/gpu/drm/xe/Kconfig-41-\tselect DRM_EXEC\n"
}

gemini-3.8-flash

null

null

							input: 21136
							output: 30
							thoughts: 131
						

**Investigating DRM Driver Dependencies**

Okay, so I'm seeing a pattern here. `DRM_QXL`, `DRM_VMWGFX`, and `DRM_VBOXVIDEO` – they all seem to depend on `DRM_TTM` and `DRM_TTM_HELPER`. That's interesting. Hang on a second, QXL... that's the standard QEMU virtualized GPU, right? The one you get with `qemu -vga qxl` or `-device qxl-vga`. And VMWGFX is the VMware/QEMU one, `-vga vmware`.

But what about virtio-gpu? I need to know if that uses TTM as well. It's the modern, paravirtualized GPU driver. Let's head over to `drivers/gpu/drm/virtio/` and see what the code says. Gotta figure out how these DRM drivers relate. This is important to understand the overall architecture.

no matches

{
  "Expression": "ttm",
  "PathPrefix": "drivers/gpu/drm/virtio"
}

{
  "error": "no matches"
}

gemini-3.8-flash

null

null

							input: 21527
							output: 30
							thoughts: 26
						

Okay, here's my take on those thoughts, framed as my own:

**Virtual GPU Driver Investigation**

Hmm, interesting. It seems like the architecture of virtio-gpu might be slightly different than I initially assumed. The initial question is whether or not it leverages the Translation Table Manager (TTM) directly. The answer seems to be no. I'll need to dig deeper into the specifics of virtio-gpu's memory management to understand how it's handling buffer allocation and resource tracking without that established framework. Now, the `vkms` driver... that's where things get intriguing. Does that particular driver lean on TTM? Understanding `vkms`'s approach would give me a point of comparison and potentially illuminate different design choices in the virtual GPU landscape. That's a key question at this point. Time to check its source code.

no matches

{
  "Expression": "ttm",
  "PathPrefix": "drivers/gpu/drm/vkms"
}

{
  "error": "no matches"
}

gemini-3.8-flash

null

null

							input: 21777
							output: 33
							thoughts: 41
						

Okay, here's my interpretation of that thought process, assuming I'm deep in the weeds of kernel driver development:

**Investigating DRM Helper Selection**

Okay, hold on a second... which drivers are *actually* opting for `DRM_TTM_HELPER` or, more broadly, `DRM_VRAM_HELPER`? I need to get a clear picture of the dependency landscape here. Let's start with a focused query. I'll start with `select DRM_VRAM_HELPER` since it's the broader helper. I'm going to need to dig into the kconfig configuration to get some insight here. Time to start tracing those dependencies!

{
  "Expression": "select DRM_VRAM_HELPER",
  "PathPrefix": "drivers/gpu/drm"
}

{
  "Output": "drivers/gpu/drm/vboxvideo/Kconfig=2=config DRM_VBOXVIDEO\n--\ndrivers/gpu/drm/vboxvideo/Kconfig-6-\tselect DRM_KMS_HELPER\ndrivers/gpu/drm/vboxvideo/Kconfig:7:\tselect DRM_VRAM_HELPER\ndrivers/gpu/drm/vboxvideo/Kconfig-8-\tselect DRM_TTM\n"
}

gemini-3.8-flash

null

null

							input: 22106
							output: 39
							thoughts: 114
						

**Investigating Virtual GPU Memory Management**

Okay, let's dive in. I need to understand the memory management for virtual GPUs, specifically QXL and VMware SVGA, since QEMU emulates both. Knowing the difference between QXL (qxl-vga) and VMware SVGA (vmware-svga) is key here, I should make sure I know them well.

The immediate question that comes to mind is, can we actually reach a `TTM` swapout situation? That's what I really need to figure out. My goal is to determine the conditions under which these virtual GPUs might need to swap out memory.

To get there, I'll need to understand `ttm_bo_swapout_cb`. What is it, and how is it triggered? I'll probably start by searching for `ttm_swap_ops` or `ttm_bo_swapout` directly. That should give me a good entry point. I need to trace the code path related to memory swapping in these virtual GPU contexts.

{
  "Expression": "ttm_swap_ops|ttm_bo_swapout",
  "PathPrefix": "drivers/gpu/drm"
}

{
  "Output": "drivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c=762=static void ttm_bo_validate_swapout(struct kunit *test)\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-791-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:792:\tswapped = ttm_bo_swapout(priv-\u003ettm_dev, \u0026ctx_init, man, GFP_KERNEL,\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-793-\t\t\t\t MANAGER_SIZE / PAGE_SIZE);\n--\ndrivers/gpu/drm/ttm/ttm_bo.c=1347=EXPORT_SYMBOL(ttm_bo_wait_ctx);\n--\ndrivers/gpu/drm/ttm/ttm_bo.c-1349-/**\ndrivers/gpu/drm/ttm/ttm_bo.c:1350: * struct ttm_bo_swapout_walk - Parameters for the swapout walk\ndrivers/gpu/drm/ttm/ttm_bo.c-1351- */\ndrivers/gpu/drm/ttm/ttm_bo.c:1352:struct ttm_bo_swapout_walk {\ndrivers/gpu/drm/ttm/ttm_bo.c-1353-\t/** @walk: The walk base parameters. */\n--\ndrivers/gpu/drm/ttm/ttm_bo.c=1362=static s64\ndrivers/gpu/drm/ttm/ttm_bo.c:1363:ttm_bo_swapout_cb(struct ttm_lru_walk *walk, struct ttm_buffer_object *bo)\ndrivers/gpu/drm/ttm/ttm_bo.c-1364-{\ndrivers/gpu/drm/ttm/ttm_bo.c-1365-\tstruct ttm_place place = { .mem_type = bo-\u003eresource-\u003emem_type };\ndrivers/gpu/drm/ttm/ttm_bo.c:1366:\tstruct ttm_bo_swapout_walk *swapout_walk =\ndrivers/gpu/drm/ttm/ttm_bo.c-1367-\t\tcontainer_of(walk, typeof(*swapout_walk), walk);\n--\ndrivers/gpu/drm/ttm/ttm_bo.c-1452-\ndrivers/gpu/drm/ttm/ttm_bo.c:1453:const struct ttm_lru_walk_ops ttm_swap_ops = {\ndrivers/gpu/drm/ttm/ttm_bo.c:1454:\t.process_bo = ttm_bo_swapout_cb,\ndrivers/gpu/drm/ttm/ttm_bo.c-1455-};\n--\ndrivers/gpu/drm/ttm/ttm_bo.c-1457-/**\ndrivers/gpu/drm/ttm/ttm_bo.c:1458: * ttm_bo_swapout() - Swap out buffer objects on the LRU list to shmem.\ndrivers/gpu/drm/ttm/ttm_bo.c-1459- * @bdev: The ttm device.\n--\ndrivers/gpu/drm/ttm/ttm_bo.c-1468- */\ndrivers/gpu/drm/ttm/ttm_bo.c:1469:s64 ttm_bo_swapout(struct ttm_device *bdev, struct ttm_operation_ctx *ctx,\ndrivers/gpu/drm/ttm/ttm_bo.c-1470-\t\t   struct ttm_resource_manager *man, gfp_t gfp_flags,\n--\ndrivers/gpu/drm/ttm/ttm_bo.c-1472-{\ndrivers/gpu/drm/ttm/ttm_bo.c:1473:\tstruct ttm_bo_swapout_walk swapout_walk = {\ndrivers/gpu/drm/ttm/ttm_bo.c-1474-\t\t.walk = {\ndrivers/gpu/drm/ttm/ttm_bo.c:1475:\t\t\t.ops = \u0026ttm_swap_ops,\ndrivers/gpu/drm/ttm/ttm_bo.c-1476-\t\t\t.arg = {\n--\ndrivers/gpu/drm/ttm/ttm_bo.c-1485-}\ndrivers/gpu/drm/ttm/ttm_bo.c:1486:EXPORT_SYMBOL_FOR_TESTS_ONLY(ttm_bo_swapout);\ndrivers/gpu/drm/ttm/ttm_bo.c-1487-\n--\ndrivers/gpu/drm/ttm/ttm_device.c=170=int ttm_device_swapout(struct ttm_device *bdev, struct ttm_operation_ctx *ctx,\n--\ndrivers/gpu/drm/ttm/ttm_device.c-181-\ndrivers/gpu/drm/ttm/ttm_device.c:182:\t\tlret = ttm_bo_swapout(bdev, ctx, man, gfp_flags, 1);\ndrivers/gpu/drm/ttm/ttm_device.c-183-\t\t/* Can be both positive (num_pages) and negative (error) */\n"
}

gemini-3.8-flash

null

null

							input: 23820
							output: 32
							thoughts: 27
						

Here's my take on those thoughts, tailored for an expert audience:

**Analyzing the `ttm_device_swapout` Function**

Okay, so `ttm_device_swapout`... that function's got my attention. Let's dig in. I'm immediately thinking, "Who's calling *that*?," because knowing the call sites will be critical to understanding its impact and potential side effects. I want to see the whole dependency graph related to that function. Understanding the context of its use is paramount; knowing the specific drivers, subsystems, or processes that trigger a swap-out is the foundation to analyzing performance, debugging a potential issue, or optimizing the swap-out routine itself. I'll need to trace the control flow to understand what exactly `ttm_device_swapout` is supposed to do and under what circumstances.

{
  "Expression": "ttm_device_swapout",
  "PathPrefix": "drivers/gpu/drm"
}

{
  "Output": "drivers/gpu/drm/ttm/ttm_device.c=136=int ttm_device_prepare_hibernation(struct ttm_device *bdev)\n--\ndrivers/gpu/drm/ttm/ttm_device.c-141-\tdo {\ndrivers/gpu/drm/ttm/ttm_device.c:142:\t\tret = ttm_device_swapout(bdev, \u0026ctx, GFP_KERNEL);\ndrivers/gpu/drm/ttm/ttm_device.c-143-\t} while (ret \u003e 0);\n--\ndrivers/gpu/drm/ttm/ttm_device.c=152=int ttm_global_swapout(struct ttm_operation_ctx *ctx, gfp_t gfp_flags)\n--\ndrivers/gpu/drm/ttm/ttm_device.c-159-\tlist_for_each_entry(bdev, \u0026glob-\u003edevice_list, device_list) {\ndrivers/gpu/drm/ttm/ttm_device.c:160:\t\tret = ttm_device_swapout(bdev, ctx, gfp_flags);\ndrivers/gpu/drm/ttm/ttm_device.c-161-\t\tif (ret \u003e 0) {\n--\ndrivers/gpu/drm/ttm/ttm_device.c-169-\ndrivers/gpu/drm/ttm/ttm_device.c:170:int ttm_device_swapout(struct ttm_device *bdev, struct ttm_operation_ctx *ctx,\ndrivers/gpu/drm/ttm/ttm_device.c-171-\t\t       gfp_t gfp_flags)\n--\ndrivers/gpu/drm/ttm/ttm_device.c-188-}\ndrivers/gpu/drm/ttm/ttm_device.c:189:EXPORT_SYMBOL(ttm_device_swapout);\ndrivers/gpu/drm/ttm/ttm_device.c-190-\n--\ndrivers/gpu/drm/vmwgfx/vmwgfx_drv.c=1493=static int vmw_pm_freeze(struct device *kdev)\n--\ndrivers/gpu/drm/vmwgfx/vmwgfx_drv.c-1515-\tvmw_release_device_early(dev_priv);\ndrivers/gpu/drm/vmwgfx/vmwgfx_drv.c:1516:\twhile (ttm_device_swapout(\u0026dev_priv-\u003ebdev, \u0026ctx, GFP_KERNEL) \u003e 0);\ndrivers/gpu/drm/vmwgfx/vmwgfx_drv.c-1517-\tvmw_fifo_resource_dec(dev_priv);\n"
}

gemini-3.8-flash

null

null

							input: 24734
							output: 32
							thoughts: 28
						

Here's a summary of my thought process, as if I were analyzing this code:

**Finding the Root of the Swapout Call**

Okay, so we're dealing with `ttm_global_swapout`. That's a core TTM function, I remember. The immediate question is always: *who* is calling this thing? Where's the entry point? Time to track it down. My first instinct, given I'm trying to trace the invocation path, is to use `grep`. I'll run `grep ttm_global_swapout` to see the direct call sites and then start tracing from there. This should give me the top level function that’s initiating the swap out process. That'll be the starting point of my investigation.

{
  "Expression": "ttm_global_swapout",
  "PathPrefix": "drivers/gpu/drm"
}

{
  "Output": "drivers/gpu/drm/ttm/ttm_device.c=146=EXPORT_SYMBOL(ttm_device_prepare_hibernation);\n--\ndrivers/gpu/drm/ttm/ttm_device.c-151- */\ndrivers/gpu/drm/ttm/ttm_device.c:152:int ttm_global_swapout(struct ttm_operation_ctx *ctx, gfp_t gfp_flags)\ndrivers/gpu/drm/ttm/ttm_device.c-153-{\n--\ndrivers/gpu/drm/ttm/ttm_tt.c=370=int ttm_tt_populate(struct ttm_device *bdev,\n--\ndrivers/gpu/drm/ttm/ttm_tt.c-391-\ndrivers/gpu/drm/ttm/ttm_tt.c:392:\t\tret = ttm_global_swapout(ctx, GFP_KERNEL);\ndrivers/gpu/drm/ttm/ttm_tt.c-393-\t\tif (ret == 0)\n--\ndrivers/gpu/drm/ttm/ttm_tt.c=456=static int ttm_tt_debugfs_shrink_show(struct seq_file *m, void *data)\n--\ndrivers/gpu/drm/ttm/ttm_tt.c-459-\ndrivers/gpu/drm/ttm/ttm_tt.c:460:\tseq_printf(m, \"%d\\n\", ttm_global_swapout(\u0026ctx, GFP_KERNEL));\ndrivers/gpu/drm/ttm/ttm_tt.c-461-\treturn 0;\n"
}

gemini-3.8-flash

null

null

							input: 25372
							output: 33
							thoughts: 56
						

Here's my take on those thoughts:

**Dissecting TTM Memory Management**

Okay, so I'm thinking about the TTM (Translation Table Manager) and some specific functions keep popping up in my mind, specifically `ttm_tt_debugfs_shrink_show` and `ttm_tt_populate`. I need to figure out how these are interacting. I also keep thinking about global swapout. I remember that the global swapout is related to memory pressure. So I am questioning myself...does something explicitly call `ttm_global_swapout` directly, or is it triggered through a shrinker mechanism within TTM itself? I need to dig into the TTM shrinker code to see how memory reclaim is managed and how these functions play a role in that process. I need to understand the relationship. This is going to be interesting.

{
  "Expression": "ttm_.*shrink",
  "PathPrefix": "drivers/gpu/drm/ttm"
}

{
  "Output": "drivers/gpu/drm/ttm/ttm_bo_util.c=1067=EXPORT_SYMBOL(ttm_bo_lru_cursor_first);\n--\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1069-/**\ndrivers/gpu/drm/ttm/ttm_bo_util.c:1070: * ttm_bo_shrink() - Helper to shrink a ttm buffer object.\ndrivers/gpu/drm/ttm/ttm_bo_util.c:1071: * @ctx: The struct ttm_operation_ctx used for the shrinking operation.\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1072- * @bo: The buffer object.\n--\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1081- */\ndrivers/gpu/drm/ttm/ttm_bo_util.c:1082:long ttm_bo_shrink(struct ttm_operation_ctx *ctx, struct ttm_buffer_object *bo,\ndrivers/gpu/drm/ttm/ttm_bo_util.c:1083:\t\t   const struct ttm_bo_shrink_flags flags)\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1084-{\n--\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1131-}\ndrivers/gpu/drm/ttm/ttm_bo_util.c:1132:EXPORT_SYMBOL(ttm_bo_shrink);\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1133-\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1134-/**\ndrivers/gpu/drm/ttm/ttm_bo_util.c:1135: * ttm_bo_shrink_suitable() - Whether a bo is suitable for shinking\ndrivers/gpu/drm/ttm/ttm_bo_util.c:1136: * @ctx: The struct ttm_operation_ctx governing the shrinking.\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1137- * @bo: The candidate for shrinking.\n--\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1144- */\ndrivers/gpu/drm/ttm/ttm_bo_util.c:1145:bool ttm_bo_shrink_suitable(struct ttm_buffer_object *bo, struct ttm_operation_ctx *ctx)\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1146-{\n--\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1150-}\ndrivers/gpu/drm/ttm/ttm_bo_util.c:1151:EXPORT_SYMBOL(ttm_bo_shrink_suitable);\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1152-\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1153-/**\ndrivers/gpu/drm/ttm/ttm_bo_util.c:1154: * ttm_bo_shrink_avoid_wait() - Whether to avoid waiting for GPU\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1155- * during shrinking\n--\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1162- */\ndrivers/gpu/drm/ttm/ttm_bo_util.c:1163:bool ttm_bo_shrink_avoid_wait(void)\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1164-{\n--\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1166-}\ndrivers/gpu/drm/ttm/ttm_bo_util.c:1167:EXPORT_SYMBOL(ttm_bo_shrink_avoid_wait);\n--\ndrivers/gpu/drm/ttm/ttm_pool.c=427=static struct ttm_pool_type *ttm_pool_select_type(struct ttm_pool *pool,\n--\ndrivers/gpu/drm/ttm/ttm_pool.c-454-/* Free pages using the per-node shrinker list */\ndrivers/gpu/drm/ttm/ttm_pool.c:455:static unsigned int ttm_pool_shrink(int nid, unsigned long num_to_free)\ndrivers/gpu/drm/ttm/ttm_pool.c-456-{\n--\ndrivers/gpu/drm/ttm/ttm_pool.c=978=void ttm_pool_free(struct ttm_pool *pool, struct ttm_tt *tt)\n--\ndrivers/gpu/drm/ttm/ttm_pool.c-985-\t\tunsigned long diff = atomic_long_read(\u0026allocated_pages[nid]) - pool_node_limit[nid];\ndrivers/gpu/drm/ttm/ttm_pool.c:986:\t\tttm_pool_shrink(nid, diff);\ndrivers/gpu/drm/ttm/ttm_pool.c-987-\t}\n--\ndrivers/gpu/drm/ttm/ttm_pool.c=1258=EXPORT_SYMBOL(ttm_pool_init);\n--\ndrivers/gpu/drm/ttm/ttm_pool.c-1260-/**\ndrivers/gpu/drm/ttm/ttm_pool.c:1261: * ttm_pool_synchronize_shrinkers - Wait for all running shrinkers to complete.\ndrivers/gpu/drm/ttm/ttm_pool.c-1262- *\n--\ndrivers/gpu/drm/ttm/ttm_pool.c-1265- */\ndrivers/gpu/drm/ttm/ttm_pool.c:1266:static void ttm_pool_synchronize_shrinkers(void)\ndrivers/gpu/drm/ttm/ttm_pool.c-1267-{\n--\ndrivers/gpu/drm/ttm/ttm_pool.c=1280=void ttm_pool_fini(struct ttm_pool *pool)\n--\ndrivers/gpu/drm/ttm/ttm_pool.c-1298-\t */\ndrivers/gpu/drm/ttm/ttm_pool.c:1299:\tttm_pool_synchronize_shrinkers();\ndrivers/gpu/drm/ttm/ttm_pool.c-1300-}\ndrivers/gpu/drm/ttm/ttm_pool.c=1301=EXPORT_SYMBOL(ttm_pool_fini);\n--\ndrivers/gpu/drm/ttm/ttm_pool.c-1305-\ndrivers/gpu/drm/ttm/ttm_pool.c:1306:static unsigned long ttm_pool_shrinker_scan(struct shrinker *shrink,\ndrivers/gpu/drm/ttm/ttm_pool.c-1307-\t\t\t\t\t    struct shrink_control *sc)\n--\ndrivers/gpu/drm/ttm/ttm_pool.c-1311-\tdo\ndrivers/gpu/drm/ttm/ttm_pool.c:1312:\t\tnum_freed += ttm_pool_shrink(sc-\u003enid, sc-\u003enr_to_scan);\ndrivers/gpu/drm/ttm/ttm_pool.c-1313-\twhile (num_freed \u003c sc-\u003enr_to_scan \u0026\u0026\n--\ndrivers/gpu/drm/ttm/ttm_pool.c-1321-/* Return the number of pages available or SHRINK_EMPTY if we have none */\ndrivers/gpu/drm/ttm/ttm_pool.c:1322:static unsigned long ttm_pool_shrinker_count(struct shrinker *shrink,\ndrivers/gpu/drm/ttm/ttm_pool.c-1323-\t\t\t\t\t     struct shrink_control *sc)\n--\ndrivers/gpu/drm/ttm/ttm_pool.c=1434=EXPORT_SYMBOL(ttm_pool_debugfs);\n--\ndrivers/gpu/drm/ttm/ttm_pool.c-1436-/* Test the shrinker functions and dump the result */\ndrivers/gpu/drm/ttm/ttm_pool.c:1437:static int ttm_pool_debugfs_shrink_show(struct seq_file *m, void *data)\ndrivers/gpu/drm/ttm/ttm_pool.c-1438-{\n--\ndrivers/gpu/drm/ttm/ttm_pool.c-1448-\t\tsc.nid = nid;\ndrivers/gpu/drm/ttm/ttm_pool.c:1449:\t\tcount = ttm_pool_shrinker_count(mm_shrinker, \u0026sc);\ndrivers/gpu/drm/ttm/ttm_pool.c:1450:\t\tscanned = ttm_pool_shrinker_scan(mm_shrinker, \u0026sc);\ndrivers/gpu/drm/ttm/ttm_pool.c-1451-\n--\ndrivers/gpu/drm/ttm/ttm_pool.c-1463-}\ndrivers/gpu/drm/ttm/ttm_pool.c:1464:DEFINE_SHOW_ATTRIBUTE(ttm_pool_debugfs_shrink);\ndrivers/gpu/drm/ttm/ttm_pool.c-1465-\n--\ndrivers/gpu/drm/ttm/ttm_pool.c=1492=int ttm_pool_mgr_init(unsigned long num_pages)\n--\ndrivers/gpu/drm/ttm/ttm_pool.c-1523-\tdebugfs_create_file(\"page_pool_shrink\", 0400, ttm_debugfs_root, NULL,\ndrivers/gpu/drm/ttm/ttm_pool.c:1524:\t\t\t    \u0026ttm_pool_debugfs_shrink_fops);\ndrivers/gpu/drm/ttm/ttm_pool.c-1525-#ifdef CONFIG_FAULT_INJECTION\n--\ndrivers/gpu/drm/ttm/ttm_pool.c-1534-\ndrivers/gpu/drm/ttm/ttm_pool.c:1535:\tmm_shrinker-\u003ecount_objects = ttm_pool_shrinker_count;\ndrivers/gpu/drm/ttm/ttm_pool.c:1536:\tmm_shrinker-\u003escan_objects = ttm_pool_shrinker_scan;\ndrivers/gpu/drm/ttm/ttm_pool.c-1537-\tmm_shrinker-\u003ebatch = TTM_SHRINKER_BATCH;\n--\ndrivers/gpu/drm/ttm/ttm_tt.c=267=EXPORT_SYMBOL_FOR_TESTS_ONLY(ttm_tt_swapin);\n--\ndrivers/gpu/drm/ttm/ttm_tt.c-274- *\ndrivers/gpu/drm/ttm/ttm_tt.c:275: * Update the page accounting and call ttm_pool_shrink_tt to free pages\ndrivers/gpu/drm/ttm/ttm_tt.c-276- * or back them up.\n--\ndrivers/gpu/drm/ttm/ttm_tt.c=451=EXPORT_SYMBOL_FOR_TESTS_ONLY(ttm_tt_unpopulate);\n--\ndrivers/gpu/drm/ttm/ttm_tt.c-455-/* Test the shrinker functions and dump the result */\ndrivers/gpu/drm/ttm/ttm_tt.c:456:static int ttm_tt_debugfs_shrink_show(struct seq_file *m, void *data)\ndrivers/gpu/drm/ttm/ttm_tt.c-457-{\n--\ndrivers/gpu/drm/ttm/ttm_tt.c-462-}\ndrivers/gpu/drm/ttm/ttm_tt.c:463:DEFINE_SHOW_ATTRIBUTE(ttm_tt_debugfs_shrink);\ndrivers/gpu/drm/ttm/ttm_tt.c-464-\n--\ndrivers/gpu/drm/ttm/ttm_tt.c-468-/*\ndrivers/gpu/drm/ttm/ttm_tt.c:469: * ttm_tt_mgr_init - register with the MM shrinker\ndrivers/gpu/drm/ttm/ttm_tt.c-470- *\n--\ndrivers/gpu/drm/ttm/ttm_tt.c=473=void ttm_tt_mgr_init(unsigned long num_pages, unsigned long num_dma32_pages)\n--\ndrivers/gpu/drm/ttm/ttm_tt.c-476-\tdebugfs_create_file(\"tt_shrink\", 0400, ttm_debugfs_root, NULL,\ndrivers/gpu/drm/ttm/ttm_tt.c:477:\t\t\t    \u0026ttm_tt_debugfs_shrink_fops);\ndrivers/gpu/drm/ttm/ttm_tt.c-478-#endif\n"
}

gemini-3.8-flash

null

null

							input: 28901
							output: 43
							thoughts: 46
						

Here's my summary, as though I'm thinking through this process:

**Diving into the TTM Swapout Mechanism**

Okay, let's get down to brass tacks. I need to understand this `ttm_tt_swapout` function, so I'm pulling up `ttm_tt.c`. Specifically, I'm focusing on lines 270 through 350. That's where the magic, or at least the swapping logic, likely resides. I'm guessing this block contains the core mechanics of how the translation table (tt) is managed during a page-out operation. I'm expecting to find details on how the relevant page table entries are manipulated, the physical address mappings are handled, and possibly any necessary synchronization primitives to ensure consistency during the swap-out process. I'll be looking for clues on how the driver interfaces with the memory management subsystem to actually trigger the movement of these pages. Any hints about how it handles different types of memory (e.g., system RAM, GPU-local memory) will be crucial. I'm keen to dissect any error handling or retry logic in there as well – a robust swap-out is crucial for overall system stability. Let's see what's in store.

{
  "File": "drivers/gpu/drm/ttm/ttm_tt.c",
  "FirstLine": 270,
  "LineCount": 80
}

{
  "Contents": " 270:\t * ttm_tt_backup() - Helper to back up a struct ttm_tt.\n 271:\t * @bdev: The TTM device.\n 272:\t * @tt: The struct ttm_tt.\n 273:\t * @flags: Flags that govern the backup behaviour.\n 274:\t *\n 275:\t * Update the page accounting and call ttm_pool_shrink_tt to free pages\n 276:\t * or back them up.\n 277:\t *\n 278:\t * Return: Number of pages freed or swapped out, or negative error code on\n 279:\t * error.\n 280:\t */\n 281:\tlong ttm_tt_backup(struct ttm_device *bdev, struct ttm_tt *tt,\n 282:\t\t\t   const struct ttm_backup_flags flags)\n 283:\t{\n 284:\t\tlong ret;\n 285:\t\n 286:\t\tif (WARN_ON(IS_ERR_OR_NULL(tt-\u003ebackup)))\n 287:\t\t\treturn 0;\n 288:\t\n 289:\t\tret = ttm_pool_backup(\u0026bdev-\u003epool, tt, \u0026flags);\n 290:\t\tif (ret \u003e 0) {\n 291:\t\t\ttt-\u003epage_flags \u0026= ~TTM_TT_FLAG_PRIV_POPULATED;\n 292:\t\t\ttt-\u003epage_flags |= TTM_TT_FLAG_BACKED_UP;\n 293:\t\t}\n 294:\t\n 295:\t\treturn ret;\n 296:\t}\n 297:\t\n 298:\tint ttm_tt_restore(struct ttm_device *bdev, struct ttm_tt *tt,\n 299:\t\t\t   const struct ttm_operation_ctx *ctx)\n 300:\t{\n 301:\t\tint ret = ttm_pool_restore_and_alloc(\u0026bdev-\u003epool, tt, ctx);\n 302:\t\n 303:\t\tif (ret)\n 304:\t\t\treturn ret;\n 305:\t\n 306:\t\ttt-\u003epage_flags \u0026= ~TTM_TT_FLAG_BACKED_UP;\n 307:\t\n 308:\t\treturn 0;\n 309:\t}\n 310:\tEXPORT_SYMBOL(ttm_tt_restore);\n 311:\t\n 312:\t/**\n 313:\t * ttm_tt_swapout - swap out tt object\n 314:\t *\n 315:\t * @bdev: TTM device structure.\n 316:\t * @ttm: The struct ttm_tt.\n 317:\t * @gfp_flags: Flags to use for memory allocation.\n 318:\t *\n 319:\t * Swapout a TT object to a shmem_file, return number of pages swapped out or\n 320:\t * negative error code.\n 321:\t */\n 322:\tint ttm_tt_swapout(struct ttm_device *bdev, struct ttm_tt *ttm,\n 323:\t\t\t   gfp_t gfp_flags)\n 324:\t{\n 325:\t\tloff_t size = (loff_t)ttm-\u003enum_pages \u003c\u003c PAGE_SHIFT;\n 326:\t\tstruct address_space *swap_space;\n 327:\t\tstruct file *swap_storage;\n 328:\t\tstruct page *from_page;\n 329:\t\tstruct page *to_page;\n 330:\t\tint i, ret;\n 331:\t\n 332:\t\tswap_storage = shmem_file_setup(\"ttm swap\", size, EMPTY_VMA_FLAGS);\n 333:\t\tif (IS_ERR(swap_storage)) {\n 334:\t\t\tpr_err(\"Failed allocating swap storage\\n\");\n 335:\t\t\treturn PTR_ERR(swap_storage);\n 336:\t\t}\n 337:\t\n 338:\t\tswap_space = swap_storage-\u003ef_mapping;\n 339:\t\tgfp_flags \u0026= mapping_gfp_mask(swap_space);\n 340:\t\n 341:\t\tfor (i = 0; i \u003c ttm-\u003enum_pages; ++i) {\n 342:\t\t\tfrom_page = ttm-\u003epages[i];\n 343:\t\t\tif (unlikely(from_page == NULL))\n 344:\t\t\t\tcontinue;\n 345:\t\n 346:\t\t\tto_page = shmem_read_mapping_page_gfp(swap_space, i, gfp_flags);\n 347:\t\t\tif (IS_ERR(to_page)) {\n 348:\t\t\t\tret = PTR_ERR(to_page);\n 349:\t\t\t\tgoto out_err;\n"
}

gemini-3.8-flash

null

null

							input: 30515
							output: 43
							thoughts: 60
						

**Analyzing the TT Object Swap-Out Mechanism**

Okay, so I'm diving into this `ttm_tt.c` file again. Specifically, I need to understand this swap-out mechanism. Let's see... the core function, as indicated in the comment on lines 319-320, is all about swapping a TT (Translation Table) object to a shared memory file. It's supposed to return the number of pages swapped, or a negative error code if things go sideways. Sounds straightforward enough on the surface.

Now, let's skip ahead and actually examine lines 350-375 within this file. That section should give me the lowdown on how the whole swap-out process is orchestrated. I expect to find the nitty-gritty details there – how the physical memory is handled, what locks (if any) are employed, error handling, and how the page count is determined. I need to understand this completely because this is a core part of the memory management subsystem.

{
  "File": "drivers/gpu/drm/ttm/ttm_tt.c",
  "FirstLine": 350,
  "LineCount": 25
}

{
  "Contents": " 350:\t\t\t}\n 351:\t\t\tcopy_highpage(to_page, from_page);\n 352:\t\t\tset_page_dirty(to_page);\n 353:\t\t\tmark_page_accessed(to_page);\n 354:\t\t\tput_page(to_page);\n 355:\t\t}\n 356:\t\n 357:\t\tttm_tt_unpopulate(bdev, ttm);\n 358:\t\tttm-\u003eswap_storage = swap_storage;\n 359:\t\tttm-\u003epage_flags |= TTM_TT_FLAG_SWAPPED;\n 360:\t\n 361:\t\treturn ttm-\u003enum_pages;\n 362:\t\n 363:\tout_err:\n 364:\t\tfput(swap_storage);\n 365:\t\n 366:\t\treturn ret;\n 367:\t}\n 368:\tEXPORT_SYMBOL_FOR_TESTS_ONLY(ttm_tt_swapout);\n 369:\t\n 370:\tint ttm_tt_populate(struct ttm_device *bdev,\n 371:\t\t\t    struct ttm_tt *ttm, struct ttm_operation_ctx *ctx)\n 372:\t{\n 373:\t\tint ret;\n 374:\t\n"
}

gemini-3.8-flash

null

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							input: 31190
							output: 44
							thoughts: 370
						

**My Analysis of the Swapout Logic**

Okay, so I'm looking at this code and immediately see a critical flaw. The `ttm_tt_swapout` function, which is supposed to handle the memory swap-out operation, returns the number of pages successfully swapped out, a positive integer, or a negative error code if something went wrong. Before this patch, the code was using `if (!ret)` to check for success. But that meant it was only checking if `ret` was equal to zero! And since `ttm_tt_swapout` returns the number of pages swapped out (a positive value) on success, the conditional was *never* true when pages were actually swapped out. This is a classic oversight.

The implications are huge. The code that should execute upon a successful swap-out, namely the calls to `ttm_resource_del_bulk_move_unevictable` and `ttm_resource_move_to_lru_tail`, were being skipped entirely. Those calls handle removing the object from a list that should not be evicted, then moving it to the least recently used tail. This is a potential leak, since it seems like the objects being swapped out were never put back on the LRU list, so they would be unavailable.

The patch corrects this by using `if (ret > 0)`, which now correctly checks for successful swap-out operations. Now, `ttm_resource_del_bulk_move_unevictable` and `ttm_resource_move_to_lru_tail` will be called as intended.

Now, let's just quickly check `ttm_bo_swapout_cb` to make sure it's not overriding this logic. Let's see... looking at `drivers/gpu/drm/ttm/ttm_bo.c` now...

{
  "File": "drivers/gpu/drm/ttm/ttm_bo.c",
  "FirstLine": 1430,
  "LineCount": 35
}

{
  "Contents": "1430:\t\n1431:\t\tttm_bo_unmap_virtual(bo);\n1432:\t\tif (bdev-\u003efuncs-\u003eswap_notify)\n1433:\t\t\tbdev-\u003efuncs-\u003eswap_notify(bo);\n1434:\t\n1435:\t\tif (ttm_tt_is_populated(tt)) {\n1436:\t\t\tret = ttm_tt_swapout(bdev, tt, swapout_walk-\u003egfp_flags);\n1437:\t\t\tif (ret \u003e 0) {\n1438:\t\t\t\tspin_lock(\u0026bdev-\u003elru_lock);\n1439:\t\t\t\tttm_resource_del_bulk_move_unevictable(bo-\u003eresource, bo);\n1440:\t\t\t\tttm_resource_move_to_lru_tail(bo-\u003eresource);\n1441:\t\t\t\tspin_unlock(\u0026bdev-\u003elru_lock);\n1442:\t\t\t}\n1443:\t\t}\n1444:\t\n1445:\tout:\n1446:\t\t/* Consider -ENOMEM and -ENOSPC non-fatal. */\n1447:\t\tif (ret == -ENOMEM || ret == -ENOSPC)\n1448:\t\t\tret = -EBUSY;\n1449:\t\n1450:\t\treturn ret;\n1451:\t}\n1452:\t\n1453:\tconst struct ttm_lru_walk_ops ttm_swap_ops = {\n1454:\t\t.process_bo = ttm_bo_swapout_cb,\n1455:\t};\n1456:\t\n1457:\t/**\n1458:\t * ttm_bo_swapout() - Swap out buffer objects on the LRU list to shmem.\n1459:\t * @bdev: The ttm device.\n1460:\t * @ctx: The ttm_operation_ctx governing the swapout operation.\n1461:\t * @man: The resource manager whose resources / buffer objects are\n1462:\t * goint to be swapped out.\n1463:\t * @gfp_flags: The gfp flags used for shmem page allocations.\n1464:\t * @target: The desired number of pages to swap out.\n"
}

gemini-3.8-flash

null

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							input: 32584
							output: 43
							thoughts: 117
						

**Tracing the Swapout Process**

Okay, let's break this down. From what I'm seeing, the function `ttm_bo_swapout` is the core swapout function. That's called by `ttm_device_swapout`. Now, the interesting part is how this all cascades. `ttm_device_swapout` itself is called by `ttm_global_swapout`. So, `ttm_global_swapout` is the broader orchestrator here.

The crucial trigger for `ttm_global_swapout` seems to be within `ttm_tt_populate`. Specifically, it appears this happens either when page allocation within the TTM system fails, or, more likely, when the system experiences memory pressure. That makes perfect sense; swapout is the fallback when memory is tight.

I should probably dive into `ttm_tt_populate` directly to understand the conditions triggering the swapout. I'll take a look at the code in `drivers/gpu/drm/ttm/ttm_tt.c`. That should give me the details on precisely when and why this swapout mechanism kicks in.

{
  "File": "drivers/gpu/drm/ttm/ttm_tt.c",
  "FirstLine": 370,
  "LineCount": 40
}

{
  "Contents": " 370:\tint ttm_tt_populate(struct ttm_device *bdev,\n 371:\t\t\t    struct ttm_tt *ttm, struct ttm_operation_ctx *ctx)\n 372:\t{\n 373:\t\tint ret;\n 374:\t\n 375:\t\tif (!ttm)\n 376:\t\t\treturn -EINVAL;\n 377:\t\n 378:\t\tif (ttm_tt_is_populated(ttm))\n 379:\t\t\treturn 0;\n 380:\t\n 381:\t\tif (!(ttm-\u003epage_flags \u0026 TTM_TT_FLAG_EXTERNAL)) {\n 382:\t\t\tatomic_long_add(ttm-\u003enum_pages, \u0026ttm_pages_allocated);\n 383:\t\t\tif (ttm_pool_uses_dma32(\u0026bdev-\u003epool))\n 384:\t\t\t\tatomic_long_add(ttm-\u003enum_pages,\n 385:\t\t\t\t\t\t\u0026ttm_dma32_pages_allocated);\n 386:\t\t}\n 387:\t\n 388:\t\twhile (atomic_long_read(\u0026ttm_pages_allocated) \u003e ttm_pages_limit ||\n 389:\t\t       atomic_long_read(\u0026ttm_dma32_pages_allocated) \u003e\n 390:\t\t       ttm_dma32_pages_limit) {\n 391:\t\n 392:\t\t\tret = ttm_global_swapout(ctx, GFP_KERNEL);\n 393:\t\t\tif (ret == 0)\n 394:\t\t\t\tbreak;\n 395:\t\t\tif (ret \u003c 0)\n 396:\t\t\t\tgoto error;\n 397:\t\t}\n 398:\t\n 399:\t\tif (bdev-\u003efuncs-\u003ettm_tt_populate)\n 400:\t\t\tret = bdev-\u003efuncs-\u003ettm_tt_populate(bdev, ttm, ctx);\n 401:\t\telse\n 402:\t\t\tret = ttm_pool_alloc(\u0026bdev-\u003epool, ttm, ctx);\n 403:\t\tif (ret)\n 404:\t\t\tgoto error;\n 405:\t\n 406:\t\tttm-\u003epage_flags |= TTM_TT_FLAG_PRIV_POPULATED;\n 407:\t\tttm-\u003epage_flags \u0026= ~TTM_TT_FLAG_BACKED_UP;\n 408:\t\tif (unlikely(ttm-\u003epage_flags \u0026 TTM_TT_FLAG_SWAPPED)) {\n 409:\t\t\tret = ttm_tt_swapin(ttm);\n"
}

gemini-3.8-flash

null

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							input: 33671
							output: 37
							thoughts: 706
						

**TTM & DRM Fuzzing Potential**

Okay, so I'm looking at this code and immediately keying in on `ttm_pages_allocated` exceeding `ttm_pages_limit` – that's when `ttm_global_swapout` gets triggered. Interesting. Then I see that the `ttm_tt_debugfs_shrink_show` function, specifically that `debugfs_create_file` call, creates a debugfs entry. Anyone reading from `/sys/kernel/debug/dri/.../tt_shrink` calls `ttm_global_swapout` too, right? Okay, so we've got two clear paths to trigger this swapout.

And the KUnit test `ttm_bo_validate_swapout`, with that call to `ttm_bo_swapout`... that's another trigger. I start thinking about virtual devices now. Is this all applicable to virtualized environments? `DRM_VMWGFX`, `DRM_QXL`, `DRM_VBOXVIDEO`? Can syzkaller even fuzz DRM drivers, or specifically the TTM, which seems to be the focus here?

Wait, let's back up. Let's make sure syzkaller can reach DRM devices. I need to look at syzkaller's syzlang descriptions. I should check which DRM drivers are targeted or reachable by syzkaller.

Aha! Confirmed. Syzkaller definitely fuzzes DRM devices: `/dev/dri/card*`, `/dev/dri/renderD*`. Okay, so DRM is *reachable*. Let's think about if DRM is reachable in QEMU / GCE. In a standard QEMU environment, we've got DRM devices like `vkms`, `bochs`, `virtio-gpu`, `qxl`, `vmwgfx`, all potentially present, even without a physical GPU.

Let's check the syzkaller instructions. Specifically, the bit about unreachable hardware. Okay, let's see, "vendor-specific PCIe switches, SmartNICs, or GPU drivers (e.g., mlxsw, pds_core, qed, ionic, amdgpu) requiring physical ASIC/PCIe cards not emulated in standard QEMU" are unreachable. But what about TTM? Is `drivers/gpu/drm/ttm/` considered vendor-specific GPU driver or core / virtualized? That's the important question!

Wait a second... TTM! It's a *common* GPU memory management subsystem within DRM! It's *shared* by amdgpu, radeon, nouveau, vmwgfx, qxl, vboxvideo, xe, loongson, and all sorts of other drivers! Bingo! And... vmwgfx and qxl are *emulated* in standard QEMU! Excellent!

Okay, so looking at the devices that QEMU provides: it has `-vga qxl`, and `-vga vmware` (vmwgfx). The DRM subsystem, as syzkaller targets it, gives us that `/dev/dri/*` entry point for fuzzing!

Wait, is this all pointing to a *core* DRM subsystem? Yes, TTM stands for Translation Table Manager. It *is* in `drivers/gpu/drm/ttm/`. Okay, this feels promising. I need to check the git log and recent commits on `drivers/gpu/drm/ttm/ttm_bo.c`. Time to see what's been happening recently.

{
  "Expression": "ttm_bo_swapout_cb",
  "PathPrefix": "drivers/gpu/drm/ttm"
}

{
  "Output": "drivers/gpu/drm/ttm/ttm_bo.c=1362=static s64\ndrivers/gpu/drm/ttm/ttm_bo.c:1363:ttm_bo_swapout_cb(struct ttm_lru_walk *walk, struct ttm_buffer_object *bo)\ndrivers/gpu/drm/ttm/ttm_bo.c-1364-{\n--\ndrivers/gpu/drm/ttm/ttm_bo.c=1453=const struct ttm_lru_walk_ops ttm_swap_ops = {\ndrivers/gpu/drm/ttm/ttm_bo.c:1454:\t.process_bo = ttm_bo_swapout_cb,\ndrivers/gpu/drm/ttm/ttm_bo.c-1455-};\n"
}

gemini-3.8-flash

null

null

							input: 35385
							output: 44
							thoughts: 54
						

Here's my summary, as though I'm thinking through this process:

**Diving into TTM BO Swapout**

Okay, so I need to get a handle on how this `ttm_bo_swapout_cb` function in the TTM code works. Let's see... the most efficient way to do this is to check the `read-file` on `drivers/gpu/drm/ttm/ttm_bo.c`. I figure the code I need will be somewhere around lines 1360 to 1450. That should give me the complete picture of how this callback function is implemented, all the pieces, and how it's used. By looking at this section directly, I should be able to quickly grasp the swapout process, any potential locking, and any subtleties I need to be aware of in my own work. Going straight to the source is usually the best approach when dealing with TTM, or any memory management, to be honest. Let's dig in.

{
  "File": "drivers/gpu/drm/ttm/ttm_bo.c",
  "FirstLine": 1360,
  "LineCount": 90
}

{
  "Contents": "1360:\t};\n1361:\t\n1362:\tstatic s64\n1363:\tttm_bo_swapout_cb(struct ttm_lru_walk *walk, struct ttm_buffer_object *bo)\n1364:\t{\n1365:\t\tstruct ttm_place place = { .mem_type = bo-\u003eresource-\u003emem_type };\n1366:\t\tstruct ttm_bo_swapout_walk *swapout_walk =\n1367:\t\t\tcontainer_of(walk, typeof(*swapout_walk), walk);\n1368:\t\tstruct ttm_operation_ctx *ctx = walk-\u003earg.ctx;\n1369:\t\tstruct ttm_device *bdev = bo-\u003ebdev;\n1370:\t\tstruct ttm_tt *tt = bo-\u003ettm;\n1371:\t\ts64 ret;\n1372:\t\n1373:\t\t/*\n1374:\t\t * While the bo may already reside in SYSTEM placement, set\n1375:\t\t * SYSTEM as new placement to cover also the move further below.\n1376:\t\t * The driver may use the fact that we're moving from SYSTEM\n1377:\t\t * as an indication that we're about to swap out.\n1378:\t\t */\n1379:\t\tif (bo-\u003epin_count || !bdev-\u003efuncs-\u003eeviction_valuable(bo, \u0026place)) {\n1380:\t\t\tret = -EBUSY;\n1381:\t\t\tgoto out;\n1382:\t\t}\n1383:\t\n1384:\t\tif (!tt || !ttm_tt_is_populated(tt) ||\n1385:\t\t    tt-\u003epage_flags \u0026 (TTM_TT_FLAG_EXTERNAL | TTM_TT_FLAG_SWAPPED)) {\n1386:\t\t\tret = -EBUSY;\n1387:\t\t\tgoto out;\n1388:\t\t}\n1389:\t\n1390:\t\tif (bo-\u003edeleted) {\n1391:\t\t\tpgoff_t num_pages = tt-\u003enum_pages;\n1392:\t\n1393:\t\t\tret = ttm_bo_wait_ctx(bo, ctx);\n1394:\t\t\tif (ret)\n1395:\t\t\t\tgoto out;\n1396:\t\n1397:\t\t\tttm_bo_cleanup_memtype_use(bo);\n1398:\t\t\tret = num_pages;\n1399:\t\t\tgoto out;\n1400:\t\t}\n1401:\t\n1402:\t\t/*\n1403:\t\t * Move to system cached\n1404:\t\t */\n1405:\t\tif (bo-\u003eresource-\u003emem_type != TTM_PL_SYSTEM) {\n1406:\t\t\tstruct ttm_resource *evict_mem;\n1407:\t\t\tstruct ttm_place hop;\n1408:\t\n1409:\t\t\tmemset(\u0026hop, 0, sizeof(hop));\n1410:\t\t\tplace.mem_type = TTM_PL_SYSTEM;\n1411:\t\t\tret = ttm_resource_alloc(bo, \u0026place, \u0026evict_mem, NULL);\n1412:\t\t\tif (ret)\n1413:\t\t\t\tgoto out;\n1414:\t\n1415:\t\t\tret = ttm_bo_handle_move_mem(bo, evict_mem, true, ctx, \u0026hop);\n1416:\t\t\tif (ret) {\n1417:\t\t\t\tWARN(ret == -EMULTIHOP,\n1418:\t\t\t\t     \"Unexpected multihop in swapout - likely driver bug.\\n\");\n1419:\t\t\t\tttm_resource_free(bo, \u0026evict_mem);\n1420:\t\t\t\tgoto out;\n1421:\t\t\t}\n1422:\t\t}\n1423:\t\n1424:\t\t/*\n1425:\t\t * Make sure BO is idle.\n1426:\t\t */\n1427:\t\tret = ttm_bo_wait_ctx(bo, ctx);\n1428:\t\tif (ret)\n1429:\t\t\tgoto out;\n1430:\t\n1431:\t\tttm_bo_unmap_virtual(bo);\n1432:\t\tif (bdev-\u003efuncs-\u003eswap_notify)\n1433:\t\t\tbdev-\u003efuncs-\u003eswap_notify(bo);\n1434:\t\n1435:\t\tif (ttm_tt_is_populated(tt)) {\n1436:\t\t\tret = ttm_tt_swapout(bdev, tt, swapout_walk-\u003egfp_flags);\n1437:\t\t\tif (ret \u003e 0) {\n1438:\t\t\t\tspin_lock(\u0026bdev-\u003elru_lock);\n1439:\t\t\t\tttm_resource_del_bulk_move_unevictable(bo-\u003eresource, bo);\n1440:\t\t\t\tttm_resource_move_to_lru_tail(bo-\u003eresource);\n1441:\t\t\t\tspin_unlock(\u0026bdev-\u003elru_lock);\n1442:\t\t\t}\n1443:\t\t}\n1444:\t\n1445:\tout:\n1446:\t\t/* Consider -ENOMEM and -ENOSPC non-fatal. */\n1447:\t\tif (ret == -ENOMEM || ret == -ENOSPC)\n1448:\t\t\tret = -EBUSY;\n1449:\t\n"
}

gemini-3.8-flash

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							input: 37086
							output: 30
							thoughts: 1020
						

**Analysis of TTM Swapout Logic and Reachability**

Okay, let's break this down. First, I see that the `ttm_bo_swapout` function returns a `s64`. Inside, `ttm_tt_swapout_cb` declares an `s64 ret`. Now, at line 1436, `ret` gets the value returned by `ttm_tt_swapout`. I recall `ttm_tt_swapout` returning `ttm->num_pages`, a positive value, upon success, or a negative error code.

The critical thing is what happens when `ret > 0`. This is where the resource management comes in. We have a spinlock on `bdev->lru_lock`, then a call to `ttm_resource_del_bulk_move_unevictable`, followed by `ttm_resource_move_to_lru_tail`, and finally the spinlock is unlocked. But hold on, the previous code had an `if (!ret)` check which, I realize now, would have *never* executed this critical section, because `ttm_tt_swapout` *never* returns 0 on success. The code would have incorrectly skipped the LRU updates. Now, with `if (ret > 0)`, the LRU operations are correctly performed *after* a successful swapout. This is crucial as `ttm_resource_del_bulk_move_unevictable` and `ttm_resource_move_to_lru_tail` change the LRU list under the `bdev->lru_lock`. This affects buffer eviction, memory reclamation, LRU ordering, and locking.

Now, the important question for fuzzing is reachability. I remember the primary gate from our notes: reachability. We can only fuzz code that is actually executed in environments like QEMU or GCE.

Section 1 says "REACHABILITY IS THE PRIMARY GATE: Fuzzing can only discover bugs in code that can actually execute in standard virtualized environments (GCE or QEMU, utilizing software-emulated devices like USB gadgets, netdev, tun/tap). If the modified code is structurally unreachable (see Section 2), it MUST NOT be fuzzed, regardless of whether it adds assertions or complex logic."

Section 2 then clarifies this by mentioning that structurally unreachable hardware involves, "Vendor-specific PCIe switches, SmartNICs, or GPU drivers (e.g., mlxsw, pds_core, qed, ionic, amdgpu) requiring physical ASIC/PCIe cards not emulated in standard QEMU."

The key question is, does TTM fall into this category? Is TTM vendor-specific and hardware-dependent? No! TTM is the generic DRM memory management layer (`drivers/gpu/drm/ttm/`). It's *not* tied to a specific vendor's hardware. So, that's good!

Then the question is, is TTM compiled into any of the standard virtualized environments, say with QEMU? Is TTM compiled when DRM_QXL or DRM_VMWGFX or DRM_VBOXVIDEO is enabled? Yes! Let's check if QEMU emulates QXL or VMWGFX. QXL is `-vga qxl`, and VMware SVGA is `-vga vmware`. Both are standard QEMU virtual display devices.

We're in good shape: TTM is generic, not vendor-specific hardware, and is included in the kernel configurations needed by QEMU.
Let's confirm that TTM is compiled using the Kconfig files.

Okay, let's now check `drivers/gpu/drm/ttm/Kconfig` or `drivers/gpu/drm/Kconfig` to see the conditions under which it's enabled.

{
  "Expression": "config DRM_TTM",
  "PathPrefix": "drivers/gpu/drm"
}

{
  "Output": "drivers/gpu/drm/Kconfig=196=source \"drivers/gpu/drm/display/Kconfig\"\ndrivers/gpu/drm/Kconfig-197-\ndrivers/gpu/drm/Kconfig:198:config DRM_TTM\ndrivers/gpu/drm/Kconfig-199-\ttristate\n--\ndrivers/gpu/drm/Kconfig=244=config DRM_VRAM_HELPER\n--\ndrivers/gpu/drm/Kconfig-249-\ndrivers/gpu/drm/Kconfig:250:config DRM_TTM_HELPER\ndrivers/gpu/drm/Kconfig-251-\ttristate\n--\ndrivers/gpu/drm/Kconfig.debug=60=config DRM_KUNIT_TEST\n--\ndrivers/gpu/drm/Kconfig.debug-85-\ndrivers/gpu/drm/Kconfig.debug:86:config DRM_TTM_KUNIT_TEST\ndrivers/gpu/drm/Kconfig.debug-87-\ttristate \"KUnit tests for TTM\" if !KUNIT_ALL_TESTS\n"
}

gemini-3.8-flash

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							input: 39231
							output: 36
							thoughts: 21
						

Here's my take on those thoughts:

**Examining the DRM Driver Configuration**

Okay, time to dive into the kernel configuration. I need to refresh my memory on some DRM driver settings. Specifically, I should check the `drivers/gpu/drm/Kconfig` file, around line 198. That's usually where the core feature flags are defined, so it's a good place to start my investigation. It's likely that section addresses the specifics that are relevant to what I am working on. Let's see what's in that vicinity.

{
  "File": "drivers/gpu/drm/Kconfig",
  "FirstLine": 195,
  "LineCount": 25
}

{
  "Contents": " 195:\t\n 196:\tsource \"drivers/gpu/drm/display/Kconfig\"\n 197:\t\n 198:\tconfig DRM_TTM\n 199:\t\ttristate\n 200:\t\tdepends on DRM \u0026\u0026 MMU\n 201:\t\tselect SHMEM\n 202:\t\thelp\n 203:\t\t  GPU memory management subsystem for devices with multiple\n 204:\t\t  GPU memory types. Will be enabled automatically if a device driver\n 205:\t\t  uses it.\n 206:\t\n 207:\tconfig DRM_EXEC\n 208:\t\ttristate\n 209:\t\tdepends on DRM\n 210:\t\thelp\n 211:\t\t  Execution context for command submissions\n 212:\t\n 213:\tconfig DRM_GPUVM\n 214:\t\ttristate\n 215:\t\tdepends on DRM\n 216:\t\tselect DRM_EXEC\n 217:\t\thelp\n 218:\t\t  GPU-VM representation providing helpers to manage a GPUs virtual\n 219:\t\t  address space\n"
}

gemini-3.8-flash

null

null

							input: 39702
							output: 37
							thoughts: 44
						

**Investigating the DRM_TTM Driver Selection**

Okay, let's dive into this. I need to figure out which drivers are choosing to select `DRM_TTM`. I remember we saw something earlier – ah, yes, `DRM_QXL`. So, let's drill down into that specific driver. My next step is to examine the `drivers/gpu/drm/qxl/Kconfig` file. That should give me the conditional logic, dependencies, and any other relevant configuration information that's driving the selection of `DRM_TTM` within the `QXL` driver. That will hopefully give me a window into the general approach of others.

{
  "File": "drivers/gpu/drm/qxl/Kconfig",
  "FirstLine": 1,
  "LineCount": 20
}

{
  "Contents": "   1:\t# SPDX-License-Identifier: GPL-2.0-only\n   2:\tconfig DRM_QXL\n   3:\t\ttristate \"QXL virtual GPU\"\n   4:\t\tdepends on DRM \u0026\u0026 PCI \u0026\u0026 HAS_IOPORT\n   5:\t\tselect DRM_CLIENT_SELECTION\n   6:\t\tselect DRM_KMS_HELPER\n   7:\t\tselect DRM_TTM\n   8:\t\tselect DRM_TTM_HELPER\n   9:\t\tselect DRM_EXEC\n  10:\t\tselect CRC32\n  11:\t\thelp\n  12:\t\t  QXL virtual GPU for Spice virtualization desktop integration.\n  13:\t\t  Do not enable this driver unless your distro ships a corresponding\n  14:\t\t  X.org QXL driver that can handle kernel modesetting.\n"
}

gemini-3.8-flash

null

null

							input: 40128
							output: 38
							thoughts: 29
						

Okay, here's my interpretation of that thought process, as if it were my own:

**Investigating the vmwgfx Driver and Its Configuration**

Alright, so we're looking at the `DRM_VMWGFX` driver, which is VMware's graphics driver for Direct Rendering Manager. The next logical step is to delve into its configuration. Let's see how it's defined and how we can control it. I need to understand its build options and dependencies – the things that enable or disable it. That means digging into the `drivers/gpu/drm/vmwgfx/Kconfig` file. That's where all the good stuff regarding the driver's configuration should reside. Time to open that up and see what we've got.

{
  "File": "drivers/gpu/drm/vmwgfx/Kconfig",
  "FirstLine": 1,
  "LineCount": 20
}

{
  "Contents": "   1:\t# SPDX-License-Identifier: GPL-2.0\n   2:\tconfig DRM_VMWGFX\n   3:\t\ttristate \"DRM driver for VMware Virtual GPU\"\n   4:\t\tdepends on DRM \u0026\u0026 PCI\n   5:\t\tdepends on (X86 \u0026\u0026 HYPERVISOR_GUEST) || ARM64\n   6:\t\tselect DRM_CLIENT_SELECTION\n   7:\t\tselect DRM_TTM\n   8:\t\tselect DRM_TTM_HELPER\n   9:\t\tselect MAPPING_DIRTY_HELPERS\n  10:\t\t# Only needed for the transitional use of drm_crtc_init - can be removed\n  11:\t\t# again once vmwgfx sets up the primary plane itself.\n  12:\t\tselect DRM_KMS_HELPER\n  13:\t\thelp\n  14:\t\t  Choose this option if you would like to run 3D acceleration\n  15:\t\t  in a VMware virtual machine.\n  16:\t\t  This is a KMS enabled DRM driver for the VMware SVGA2\n  17:\t\t  virtual hardware.\n  18:\t\t  The compiled module will be called \"vmwgfx.ko\".\n  19:\t\n  20:\tconfig DRM_VMWGFX_MKSSTATS\n"
}

gemini-3.8-flash

null

null

							input: 40669
							output: 32
							thoughts: 319
						

**My Initial Thoughts on DRM and Virtual GPUs**

Okay, so I'm looking at these DRM drivers, specifically `DRM_QXL`, `DRM_VMWGFX`, and `DRM_VBOXVIDEO`. Right, they're all virtual GPUs designed for QEMU, VMware, and VirtualBox, respectively. That's straightforward enough. Now, `DRM_TTM_KUNIT_TEST` seems interesting; it's KUnit testing directly on TTM. It looks like it depends on DRM, KUnit, MMU, and either UML or COMPILE_TEST.

A thought just popped into my head: can Syzkaller, with its fuzzing capabilities, actually interact with DRM devices through TTM? That could be a potential avenue for uncovering vulnerabilities. I need to investigate that further.

My next step is to examine how buffer objects are created and managed in the QXL or VMWGFX drivers. I need to understand how they allocate and swap them out. Let's see, userspace opens `/dev/dri/card*` or `/dev/dri/renderD*`, issues DRM ioctls, like GEM allocation or dumb buffer creation, and potentially driver-private ioctls. I understand BOs are ultimately allocated in TTM.

Ah, here's a crucial point: when memory pressure hits, or `ttm_bo_swapout` is called (or the `tt_shrink` debugfs entry is read, or `ttm_global_swapout` is triggered during populate under memory pressure), `ttm_bo_swapout_cb` gets executed. This is the mechanism that can potentially lead to some interesting issues.

Now, I need to check how `ttm_bo_swapout` can be triggered - I want to see if it can be triggered by debugfs, sysfs, a specific ioctl, or even during memory reclaim. This is where I'll find my "attack surface". Let's run a search for `ttm_bo_swapout` and its callers throughout the code base. That should provide a clearer picture of the control paths available.

{
  "Expression": "ttm_global_swapout",
  "PathPrefix": "drivers/gpu/drm"
}

{
  "Output": "drivers/gpu/drm/ttm/ttm_device.c=146=EXPORT_SYMBOL(ttm_device_prepare_hibernation);\n--\ndrivers/gpu/drm/ttm/ttm_device.c-151- */\ndrivers/gpu/drm/ttm/ttm_device.c:152:int ttm_global_swapout(struct ttm_operation_ctx *ctx, gfp_t gfp_flags)\ndrivers/gpu/drm/ttm/ttm_device.c-153-{\n--\ndrivers/gpu/drm/ttm/ttm_tt.c=370=int ttm_tt_populate(struct ttm_device *bdev,\n--\ndrivers/gpu/drm/ttm/ttm_tt.c-391-\ndrivers/gpu/drm/ttm/ttm_tt.c:392:\t\tret = ttm_global_swapout(ctx, GFP_KERNEL);\ndrivers/gpu/drm/ttm/ttm_tt.c-393-\t\tif (ret == 0)\n--\ndrivers/gpu/drm/ttm/ttm_tt.c=456=static int ttm_tt_debugfs_shrink_show(struct seq_file *m, void *data)\n--\ndrivers/gpu/drm/ttm/ttm_tt.c-459-\ndrivers/gpu/drm/ttm/ttm_tt.c:460:\tseq_printf(m, \"%d\\n\", ttm_global_swapout(\u0026ctx, GFP_KERNEL));\ndrivers/gpu/drm/ttm/ttm_tt.c-461-\treturn 0;\n"
}

gemini-3.8-flash

null

null

							input: 41889
							output: 34
							thoughts: 282
						

**My Analysis of TTM's Memory Management During Power Management**

Okay, let's break this down. First, `ttm_tt_debugfs_shrink_show` is a debugfs file. I see the code creating it with `debugfs_create_file`. Nothing unusual there; it's a common way to expose internal state for debugging. The real question is: what is it showing? I'll probably have to dig into `ttm_tt_debugfs_shrink_fops` at some point to understand that, but that's not the critical path right now.

My focus is the power management interaction with TTM. Specifically, `ttm_device_swapout`. I see it's called during hibernation/suspend/PM processes. The snippets show two uses: within `vmw_pm_freeze` and the `ttm_device_prepare_hibernation` function. In the `vmw` code, it's called in a loop, implying that `ttm_device_swapout` might need to be called multiple times.

Then I see the `ttm_device_prepare_hibernation` function, which explicitly calls `ttm_device_swapout` in a loop as well. This makes perfect sense; before hibernating, we need to ensure that memory managed by TTM is safely written to disk. This function is also exported as a symbol. That tells me that some other driver or subsystem is likely calling this function as part of a suspend/hibernate sequence. I now need to figure out which component is calling `ttm_device_prepare_hibernation`. That's where I need to continue my investigation.

{
  "Expression": "ttm_device_prepare_hibernation",
  "PathPrefix": "drivers/gpu/drm"
}

{
  "Output": "drivers/gpu/drm/amd/amdgpu/amdgpu_device.c=4411=static int amdgpu_device_evict_resources(struct amdgpu_device *adev)\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_device.c-4429-\tif (adev-\u003ein_s4) {\ndrivers/gpu/drm/amd/amdgpu/amdgpu_device.c:4430:\t\tret = ttm_device_prepare_hibernation(\u0026adev-\u003emman.bdev);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_device.c-4431-\t\tif (ret)\n--\ndrivers/gpu/drm/ttm/ttm_device.c=70=static int ttm_global_init(void)\n--\ndrivers/gpu/drm/ttm/ttm_device.c-129-/**\ndrivers/gpu/drm/ttm/ttm_device.c:130: * ttm_device_prepare_hibernation - move GTT BOs to shmem for hibernation.\ndrivers/gpu/drm/ttm/ttm_device.c-131- *\n--\ndrivers/gpu/drm/ttm/ttm_device.c-135- */\ndrivers/gpu/drm/ttm/ttm_device.c:136:int ttm_device_prepare_hibernation(struct ttm_device *bdev)\ndrivers/gpu/drm/ttm/ttm_device.c-137-{\n--\ndrivers/gpu/drm/ttm/ttm_device.c-145-}\ndrivers/gpu/drm/ttm/ttm_device.c:146:EXPORT_SYMBOL(ttm_device_prepare_hibernation);\ndrivers/gpu/drm/ttm/ttm_device.c-147-\n"
}

gemini-3.8-flash

null

null

							input: 43024
							output: 44
							thoughts: 51
						

Okay, let's dive into this.

**Examining `ttm_bo_swapout`**

Right, so I'm thinking about `ttm_bo_swapout`. Let's get down to brass tacks and go straight to the source code. I need to understand what's happening under the hood with this function. Time to crack open `drivers/gpu/drm/ttm/ttm_bo.c` and see exactly how `ttm_bo_swapout` is implemented. I want to understand its role within the TTM (Translation Table Manager) system. What's it doing? How does it fit into the bigger picture of memory management within the DRM framework? Let's get to the code.

{
  "File": "drivers/gpu/drm/ttm/ttm_bo.c",
  "FirstLine": 1460,
  "LineCount": 35
}

{
  "Contents": "1460:\t * @ctx: The ttm_operation_ctx governing the swapout operation.\n1461:\t * @man: The resource manager whose resources / buffer objects are\n1462:\t * goint to be swapped out.\n1463:\t * @gfp_flags: The gfp flags used for shmem page allocations.\n1464:\t * @target: The desired number of pages to swap out.\n1465:\t *\n1466:\t * Return: The number of pages actually swapped out, or negative error code\n1467:\t * on error.\n1468:\t */\n1469:\ts64 ttm_bo_swapout(struct ttm_device *bdev, struct ttm_operation_ctx *ctx,\n1470:\t\t\t   struct ttm_resource_manager *man, gfp_t gfp_flags,\n1471:\t\t\t   s64 target)\n1472:\t{\n1473:\t\tstruct ttm_bo_swapout_walk swapout_walk = {\n1474:\t\t\t.walk = {\n1475:\t\t\t\t.ops = \u0026ttm_swap_ops,\n1476:\t\t\t\t.arg = {\n1477:\t\t\t\t\t.ctx = ctx,\n1478:\t\t\t\t\t.trylock_only = true,\n1479:\t\t\t\t},\n1480:\t\t\t},\n1481:\t\t\t.gfp_flags = gfp_flags,\n1482:\t\t};\n1483:\t\n1484:\t\treturn ttm_lru_walk_for_evict(\u0026swapout_walk.walk, bdev, man, target);\n1485:\t}\n1486:\tEXPORT_SYMBOL_FOR_TESTS_ONLY(ttm_bo_swapout);\n1487:\t\n1488:\tvoid ttm_bo_tt_destroy(struct ttm_buffer_object *bo)\n1489:\t{\n1490:\t\tif (bo-\u003ettm == NULL)\n1491:\t\t\treturn;\n1492:\t\n1493:\t\tttm_tt_unpopulate(bo-\u003ebdev, bo-\u003ettm);\n1494:\t\tttm_tt_destroy(bo-\u003ebdev, bo-\u003ettm);\n"
}

gemini-3.8-flash

null

null

							input: 43859
							output: 42
							thoughts: 258
						

**Analyzing the Swapout Mechanism**

Okay, so I'm looking at this `ttm_bo_swapout` process. It starts with a call to `ttm_lru_walk_for_evict`, which then triggers `ttm_bo_swapout_cb`. Inside that callback, the core logic seems to be: If the translation table (`tt`) is populated, we call `ttm_tt_swapout`. The return value here is key. If `ttm_tt_swapout` returns a value greater than zero, it's considered successful, and we proceed to update the resource management: we're locking the LRU, removing the resource and then moving it to the tail.

Now, I need to understand the implications of this. Why this change? What was the bug this patch was meant to fix? And, crucially, what *effect* does this have on the overall memory management strategy? I need to trace this back. Time to dive into the commit history, look at the git logs around this area, and piece together the full picture to be sure I understand the interaction between the swapout logic and the LRU list, and any potential race conditions that might have been addressed. This is not just about the code itself, but about the *reasoning* behind the modification, and whether it could have any unintended consequences.

{
  "Expression": "ttm_resource_del_bulk_move_unevictable",
  "PathPrefix": "drivers/gpu/drm/ttm"
}

{
  "Output": "drivers/gpu/drm/ttm/ttm_bo.c=1363=ttm_bo_swapout_cb(struct ttm_lru_walk *walk, struct ttm_buffer_object *bo)\n--\ndrivers/gpu/drm/ttm/ttm_bo.c-1438-\t\t\tspin_lock(\u0026bdev-\u003elru_lock);\ndrivers/gpu/drm/ttm/ttm_bo.c:1439:\t\t\tttm_resource_del_bulk_move_unevictable(bo-\u003eresource, bo);\ndrivers/gpu/drm/ttm/ttm_bo.c-1440-\t\t\tttm_resource_move_to_lru_tail(bo-\u003eresource);\n--\ndrivers/gpu/drm/ttm/ttm_bo_util.c=1082=long ttm_bo_shrink(struct ttm_operation_ctx *ctx, struct ttm_buffer_object *bo,\n--\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1121-\t\tspin_lock(\u0026bdev-\u003elru_lock);\ndrivers/gpu/drm/ttm/ttm_bo_util.c:1122:\t\tttm_resource_del_bulk_move_unevictable(bo-\u003eresource, bo);\ndrivers/gpu/drm/ttm/ttm_bo_util.c-1123-\t\tttm_resource_move_to_lru_tail(bo-\u003eresource);\n--\ndrivers/gpu/drm/ttm/ttm_resource.c=288=void ttm_resource_del_bulk_move(struct ttm_resource *res,\n--\ndrivers/gpu/drm/ttm/ttm_resource.c-299- */\ndrivers/gpu/drm/ttm/ttm_resource.c:300:void ttm_resource_del_bulk_move_unevictable(struct ttm_resource *res,\ndrivers/gpu/drm/ttm/ttm_resource.c-301-\t\t\t\t\t    struct ttm_buffer_object *bo)\n"
}

gemini-3.8-flash

null

null

							input: 44959
							output: 46
							thoughts: 26
						

Here's a summary of my thought process, as requested:

**Diving into `ttm_bo_util.c`**

Okay, time to get my hands dirty. I'm focusing in on `ttm_bo_util.c` again, specifically around line 1121. I remember there was something interesting there, or perhaps I'm trying to recall a past debugging session, or maybe I am revisiting an area with known issues. Whatever the reason, I want to refresh my memory or investigate a potential problem in this particular area of the code. Let's dig in and see what's what! I am sure there is a good reason for this targeted investigation. I am assuming I will be reading the relevant code and making quick decisions on how best to understand and proceed.

{
  "File": "drivers/gpu/drm/ttm/ttm_bo_util.c",
  "FirstLine": 1100,
  "LineCount": 35
}

{
  "Contents": "1100:\t\tif (flags.allow_move \u0026\u0026 bo-\u003eresource-\u003emem_type != TTM_PL_SYSTEM) {\n1101:\t\t\tint ret = ttm_bo_validate(bo, \u0026sys_placement, ctx);\n1102:\t\n1103:\t\t\t/* Consider -ENOMEM and -ENOSPC non-fatal. */\n1104:\t\t\tif (ret) {\n1105:\t\t\t\tif (ret == -ENOMEM || ret == -ENOSPC)\n1106:\t\t\t\t\tret = -EBUSY;\n1107:\t\t\t\treturn ret;\n1108:\t\t\t}\n1109:\t\t}\n1110:\t\n1111:\t\tttm_bo_unmap_virtual(bo);\n1112:\t\tlret = ttm_bo_wait_ctx(bo, ctx);\n1113:\t\tif (lret \u003c 0)\n1114:\t\t\treturn lret;\n1115:\t\n1116:\t\tlret = ttm_tt_backup(bdev, bo-\u003ettm, (struct ttm_backup_flags)\n1117:\t\t\t\t     {.purge = flags.purge,\n1118:\t\t\t\t      .writeback = flags.writeback});\n1119:\t\n1120:\t\tif (lret \u003e 0) {\n1121:\t\t\tspin_lock(\u0026bdev-\u003elru_lock);\n1122:\t\t\tttm_resource_del_bulk_move_unevictable(bo-\u003eresource, bo);\n1123:\t\t\tttm_resource_move_to_lru_tail(bo-\u003eresource);\n1124:\t\t\tspin_unlock(\u0026bdev-\u003elru_lock);\n1125:\t\t}\n1126:\t\n1127:\t\tif (lret \u003c 0 \u0026\u0026 lret != -EINTR)\n1128:\t\t\treturn -EBUSY;\n1129:\t\n1130:\t\treturn lret;\n1131:\t}\n1132:\tEXPORT_SYMBOL(ttm_bo_shrink);\n1133:\t\n1134:\t/**\n"
}

gemini-3.8-flash

null

null

							input: 45746
							output: 43
							thoughts: 414
						

**Analyzing a Critical TTM Bug Fix**

Okay, so I'm looking at `ttm_bo_util.c:1120` and `ttm_bo.c` and immediately see a likely bug, a classic error. The previous author clearly made the assumption, common in kernel programming, that `ttm_tt_swapout` returned 0 on success. But it *doesn't*. It returns `ttm->num_pages`, which is *greater* than zero on success. The original code used `if (!ret)`, which means the conditional block after the swapout call was *never* actually executed if it succeeded. This is a subtle but definitely critical bug!

Fixing this to `if (ret > 0)` is a big deal because now the critical code block *will* be executed. That code acquires `bdev->lru_lock`, and then calls `ttm_resource_del_bulk_move_unevictable(bo->resource, bo)` and `ttm_resource_move_to_lru_tail(bo->resource)`. These functions are now *finally* being used.

So, I need to understand what these functions actually *do*. Let's dig into `ttm_resource.c` around line 300 to understand what the code block is actually doing and what implications it has for the whole resource management scheme.

{
  "File": "drivers/gpu/drm/ttm/ttm_resource.c",
  "FirstLine": 290,
  "LineCount": 45
}

{
  "Contents": " 290:\t{\n 291:\t\tif (bo-\u003ebulk_move \u0026\u0026 !ttm_resource_unevictable(res, bo))\n 292:\t\t\tttm_lru_bulk_move_del(bo-\u003ebulk_move, res);\n 293:\t}\n 294:\t\n 295:\t/*\n 296:\t * Remove a resource from its bulk_move, bypassing the unevictable check.\n 297:\t * Use only when the resource is known to still be tracked in the range despite\n 298:\t * the BO having just become unevictable; asserts that this is the case.\n 299:\t */\n 300:\tvoid ttm_resource_del_bulk_move_unevictable(struct ttm_resource *res,\n 301:\t\t\t\t\t\t    struct ttm_buffer_object *bo)\n 302:\t{\n 303:\t\tWARN_ON_ONCE(!ttm_resource_unevictable(res, bo));\n 304:\t\tif (bo-\u003ebulk_move)\n 305:\t\t\tttm_lru_bulk_move_del(bo-\u003ebulk_move, res);\n 306:\t}\n 307:\t\n 308:\t/* Move a resource to the LRU or bulk tail */\n 309:\tvoid ttm_resource_move_to_lru_tail(struct ttm_resource *res)\n 310:\t{\n 311:\t\tstruct ttm_buffer_object *bo = res-\u003ebo;\n 312:\t\tstruct ttm_device *bdev = bo-\u003ebdev;\n 313:\t\n 314:\t\tlockdep_assert_held(\u0026bo-\u003ebdev-\u003elru_lock);\n 315:\t\n 316:\t\tif (ttm_resource_unevictable(res, bo)) {\n 317:\t\t\tlist_move_tail(\u0026res-\u003elru.link, \u0026bdev-\u003eunevictable);\n 318:\t\n 319:\t\t} else if (bo-\u003ebulk_move) {\n 320:\t\t\tstruct ttm_lru_bulk_move_pos *pos =\n 321:\t\t\t\tttm_lru_bulk_move_pos(bo-\u003ebulk_move, res);\n 322:\t\n 323:\t\t\tttm_lru_bulk_move_pos_tail(pos, res);\n 324:\t\t} else {\n 325:\t\t\tstruct ttm_resource_manager *man;\n 326:\t\n 327:\t\t\tman = ttm_manager_type(bdev, res-\u003emem_type);\n 328:\t\t\tlist_move_tail(\u0026res-\u003elru.link, \u0026man-\u003elru[bo-\u003epriority]);\n 329:\t\t}\n 330:\t}\n 331:\t\n 332:\t/**\n 333:\t * ttm_resource_init - resource object constructor\n 334:\t * @bo: buffer object this resource is allocated for\n"
}

gemini-3.8-flash

null

null

							input: 47274
							output: 36
							thoughts: 110
						

**Analyzing `ttm_resource_del_bulk_move_unevictable`**

Alright, let's dive into this. I'm looking at `ttm_resource_del_bulk_move_unevictable` and immediately I see a `WARN_ON_ONCE` assertion. That's a red flag. Specifically, it's checking `ttm_resource_unevictable(res, bo)`. I need to figure out *why* this assertion is in place. What conditions trigger that warning? The code also confirms that the `lru_lock` is held, so it's happening within that critical section. Let's dig into `ttm_resource_unevictable` and see what it's actually validating. I need to understand the contract here to determine if this is a potential bug or an expected condition.

{
  "Expression": "ttm_resource_unevictable",
  "PathPrefix": "drivers/gpu/drm/ttm"
}

{
  "Output": "drivers/gpu/drm/ttm/ttm_resource.c=259=static bool ttm_resource_is_swapped(struct ttm_resource *res, struct ttm_buffer_object *bo)\n--\ndrivers/gpu/drm/ttm/ttm_resource.c-273-\ndrivers/gpu/drm/ttm/ttm_resource.c:274:static bool ttm_resource_unevictable(struct ttm_resource *res, struct ttm_buffer_object *bo)\ndrivers/gpu/drm/ttm/ttm_resource.c-275-{\n--\ndrivers/gpu/drm/ttm/ttm_resource.c=280=void ttm_resource_add_bulk_move(struct ttm_resource *res,\n--\ndrivers/gpu/drm/ttm/ttm_resource.c-282-{\ndrivers/gpu/drm/ttm/ttm_resource.c:283:\tif (bo-\u003ebulk_move \u0026\u0026 !ttm_resource_unevictable(res, bo))\ndrivers/gpu/drm/ttm/ttm_resource.c-284-\t\tttm_lru_bulk_move_add(bo-\u003ebulk_move, res);\n--\ndrivers/gpu/drm/ttm/ttm_resource.c=288=void ttm_resource_del_bulk_move(struct ttm_resource *res,\n--\ndrivers/gpu/drm/ttm/ttm_resource.c-290-{\ndrivers/gpu/drm/ttm/ttm_resource.c:291:\tif (bo-\u003ebulk_move \u0026\u0026 !ttm_resource_unevictable(res, bo))\ndrivers/gpu/drm/ttm/ttm_resource.c-292-\t\tttm_lru_bulk_move_del(bo-\u003ebulk_move, res);\n--\ndrivers/gpu/drm/ttm/ttm_resource.c=300=void ttm_resource_del_bulk_move_unevictable(struct ttm_resource *res,\n--\ndrivers/gpu/drm/ttm/ttm_resource.c-302-{\ndrivers/gpu/drm/ttm/ttm_resource.c:303:\tWARN_ON_ONCE(!ttm_resource_unevictable(res, bo));\ndrivers/gpu/drm/ttm/ttm_resource.c-304-\tif (bo-\u003ebulk_move)\n--\ndrivers/gpu/drm/ttm/ttm_resource.c=309=void ttm_resource_move_to_lru_tail(struct ttm_resource *res)\n--\ndrivers/gpu/drm/ttm/ttm_resource.c-315-\ndrivers/gpu/drm/ttm/ttm_resource.c:316:\tif (ttm_resource_unevictable(res, bo)) {\ndrivers/gpu/drm/ttm/ttm_resource.c-317-\t\tlist_move_tail(\u0026res-\u003elru.link, \u0026bdev-\u003eunevictable);\n--\ndrivers/gpu/drm/ttm/ttm_resource.c=340=void ttm_resource_init(struct ttm_buffer_object *bo,\n--\ndrivers/gpu/drm/ttm/ttm_resource.c-357-\tspin_lock(\u0026bo-\u003ebdev-\u003elru_lock);\ndrivers/gpu/drm/ttm/ttm_resource.c:358:\tif (ttm_resource_unevictable(res, bo))\ndrivers/gpu/drm/ttm/ttm_resource.c-359-\t\tlist_add_tail(\u0026res-\u003elru.link, \u0026bo-\u003ebdev-\u003eunevictable);\n"
}

gemini-3.8-flash

null

null

							input: 48517
							output: 43
							thoughts: 32
						

Here's my take on the thought process, as requested:

**Diving into TTM Resource Management**

Okay, time to get to the heart of the matter. I need to understand what's happening with these unevictable resources in the TTM (Translation Table Manager) framework. My immediate focus is on the `ttm_resource_unevictable` function. I'll need to dig into `drivers/gpu/drm/ttm/ttm_resource.c` to see how it's implemented. I expect to find the core logic for managing resources that *can't* be swapped out to system memory when the GPU's memory is under pressure. This will likely involve details about how the TTM interacts with the memory allocator and page tables, how these resources are marked as unevictable, and how the TTM ensures these resources remain resident. Knowing this will be key to addressing the issues at hand, whatever those may be.

{
  "File": "drivers/gpu/drm/ttm/ttm_resource.c",
  "FirstLine": 260,
  "LineCount": 25
}

{
  "Contents": " 260:\t{\n 261:\t\t/*\n 262:\t\t * Take care when creating a new resource for a bo, that it is not considered\n 263:\t\t * swapped if it's not the current resource for the bo and is thus logically\n 264:\t\t * associated with the ttm_tt. Think a VRAM resource created to move a\n 265:\t\t * swapped-out bo to VRAM.\n 266:\t\t */\n 267:\t\tif (bo-\u003eresource != res || !bo-\u003ettm)\n 268:\t\t\treturn false;\n 269:\t\n 270:\t\tdma_resv_assert_held(bo-\u003ebase.resv);\n 271:\t\treturn ttm_tt_is_swapped(bo-\u003ettm);\n 272:\t}\n 273:\t\n 274:\tstatic bool ttm_resource_unevictable(struct ttm_resource *res, struct ttm_buffer_object *bo)\n 275:\t{\n 276:\t\treturn bo-\u003epin_count || ttm_resource_is_swapped(res, bo);\n 277:\t}\n 278:\t\n 279:\t/* Add the resource to a bulk move if the BO is configured for it */\n 280:\tvoid ttm_resource_add_bulk_move(struct ttm_resource *res,\n 281:\t\t\t\t\tstruct ttm_buffer_object *bo)\n 282:\t{\n 283:\t\tif (bo-\u003ebulk_move \u0026\u0026 !ttm_resource_unevictable(res, bo))\n 284:\t\t\tttm_lru_bulk_move_add(bo-\u003ebulk_move, res);\n"
}

gemini-3.8-flash

null

null

							input: 49239
							output: 29
							thoughts: 440
						

**My Analysis of a Potential TTM Vulnerability**

Okay, so here's what's running through my head. This code smells like a potential issue, let's break it down. When `ttm_tt_swapout` works, it sets the `TTM_TT_FLAG_SWAPPED` flag on the page flags. This, in turn, makes `ttm_tt_is_swapped(bo->ttm)` true and consequently sets `ttm_resource_unevictable` to true. Now, the `ttm_resource_del_bulk_move_unevictable` function seems to expect that `ttm_resource_unevictable(res, bo)` will always be true when it's called. And then `ttm_resource_move_to_lru_tail` moves it to the `bdev->unevictable` list. It sounds like there's a potential path for something going wrong if that `WARN_ON_ONCE` trips, and I'd like to get to the bottom of this.

Now, the important question: can we trigger this in syzkaller fuzzing? This is what really interests me. I need to figure out if syzkaller can reach TTM and specifically DRM drivers that use TTM within standard virtualized environments.

Right, let's take stock. Syzkaller has descriptions for DRM (`sys/linux/drm.txt`, `sys/linux/drm_*.txt`), so that's a good start. And yes, syzkaller runs in QEMU, or GCE VMs. I should probably be thinking about testing in QEMU. Can we enable DRM_QXL or DRM_VMWGFX in QEMU? Yes, we can do `-vga qxl` or `-vga vmware`. But, let's not be too hasty. What if it runs without `-vga qxl`? Or does syzkaller run with `-vga` at all?

Wait, hold on. Let's look at the standard syzkaller configuration for amd64. Does it use `-enable-kvm`? Yep, it does. So it's probably standard QEMU. Does it enable DRM? That's the crucial question. I need to check the config and see what DRM drivers it's actually using.

Hang on, let's check VKMS, bochs or dummy if they use TTM. We checked VKMS earlier: VKMS uses GEM shmem helpers (`drm_gem_shmem_helper.c`). What about bochs? I'll check `drivers/gpu/drm/tiny/bochs.c`. Okay, let's see. This will take some digging, but it seems feasible.

no matches

{
  "Expression": "ttm",
  "PathPrefix": "drivers/gpu/drm/tiny"
}

{
  "error": "no matches"
}

gemini-3.8-flash

null

null

							input: 50312
							output: 30
							thoughts: 237
						

**Investigating TTM Usage in DRM Drivers**

Okay, so I need to figure out which Direct Rendering Manager (DRM) drivers are utilizing the Translation Table Manager (TTM). My first thought is to dig into `drivers/gpu/drm/vboxvideo/` and related virtual drivers, but let's take a step back and get a broader overview first.

I remember I did a `grep` for `select DRM_TTM` earlier, which should give me a good starting point. Right, that search yielded: `DRM_AMDGPU`, `DRM_I915`, `DRM_LOONGSON`, `DRM_NOUVEAU`, `DRM_QXL`, `DRM_RADEON`, `DRM_VBOXVIDEO`, `DRM_VMWGFX`, `DRM_XE`, and also `DRM_TTM_KUNIT_TEST`. That's a decent list to work with.

Now, I'm wondering if any USB display adapters are leveraging TTM. DisplayLink's `udl` driver springs to mind. I should probably check within `drivers/gpu/drm/udl` just to be thorough.

no matches

{
  "Expression": "ttm",
  "PathPrefix": "drivers/gpu/drm/udl"
}

{
  "error": "no matches"
}

gemini-3.8-flash

null

null

							input: 50851
							output: 32
							thoughts: 2551
						

**Analysis of Code Change and Fuzzing Potential**

Okay, so I'm looking at this code change related to `ttm_bo_swapout_cb`, specifically the new conditional logic. My initial thought was to quickly check if this is related to shared memory helpers like `shmem`, but that's not it. Then I thought about `gm12u320` or `gud` but no, those aren't involved. The question is if `DRM_QXL` or `DRM_VMWGFX` matter? They are virtualized GPUs emulated in QEMU, not vendor-specific hardware requiring physical ASICs. This is important: according to the documentation, we're explicitly looking for cases that can be reached in standard QEMU, so that means things like `mlxsw`, `pds_core`, `qed`, `ionic`, `amdgpu` aren't what we are looking for. These require an ASIC or PCIe cards not emulated in standard QEMU, but virtual GPUs like QXL and VMWare SVGA, are! Plus, `ttm` itself is a core DRM memory management subsystem, not a vendor-specific driver.

Now, according to the document, we must determine if this code is worth fuzzing. I'm focusing on the criteria that make code *unworthy* of fuzzing - non-kernel changes, unreachable hardware, or unreachable execution paths. This doesn't seem to fall into any of those categories. I need to know: can syzkaller even reach `ttm_bo_swapout_cb`?

I need to trace the execution path. It starts with `ttm_bo_swapout_cb` being a callback in `ttm_swap_ops.process_bo`. Then, `ttm_swap_ops` is used in `ttm_bo_swapout`. I see that `ttm_bo_swapout` is called by several functions: `ttm_device_swapout` (which is called by `ttm_device_prepare_hibernation`, `ttm_global_swapout`). `ttm_global_swapout` is the key. It's called when memory pressure occurs, from `ttm_tt_populate`, and also from `/sys/kernel/debug/dri/.../tt_shrink` debugfs entry.

This is a good point! Can syzkaller read debugfs? Yes, syzkaller regularly uses debugfs! Can it allocate buffers? Yes, using DRM ioctls like `DRM_IOCTL_MODE_CREATE_DUMB` or even driver-specific ioctls like `DRM_IOCTL_QXL_ALLOC` and `DRM_IOCTL_VMW_ALLOC_STREAM`. Also by simply creating dumb buffers on QXL or VMWare. Can we trigger swapout using memory pressure or the `tt_shrink` debugfs entry? Yes!

So, what happens if `ttm_tt_swapout` executes? Now, I need to see what's in `ttm_bo_swapout_cb`. I'm looking at the critical `if (ret > 0)` condition added by this patch, which leads to this block:
```c
spin_lock(&bdev->lru_lock);
ttm_resource_del_bulk_move_unevictable(bo->resource, bo);
ttm_resource_move_to_lru_tail(bo->resource);
spin_unlock(&bdev->lru_lock);
```
Previously, `ret` from `ttm_tt_swapout` returned the *number of pages* on success, so the code was dead. Before this patch `if (ret)` was always false! This block was never reached! Now, *it is executed every time* `ttm_tt_swapout` is successful! Inside `ttm_resource_del_bulk_move_unevictable`, there's a `WARN_ON_ONCE`! And `lockdep_assert_held` and list manipulation in `ttm_resource_move_to_lru_tail`!

This is a **real** and interesting behavioral change in a reachable, core DRM memory subsystem! It's worth fuzzing!

This is worth fuzzing because:
*   **Reachable:** The code is used by virtual GPU drivers supported by QEMU (QXL, VMWGFX). It's accessible via DRM ioctls and debugfs.
*   **Worth Fuzzing:** It changes control flow, enables previously-dead code involving locking, LRU list manipulation on buffer objects, and includes assertions.

Now, let's verify what configs are required for this code. Let'

{
  "Expression": "ttm_bo",
  "PathPrefix": "drivers/gpu/drm/ttm"
}

{
  "Output": "\nFull output is too long, showing 500 out of 2300 lines.\nUse more precise expression if possible.\n\ndrivers/gpu/drm/ttm/Makefile-4-\ndrivers/gpu/drm/ttm/Makefile:5:ttm-y := ttm_tt.o ttm_bo.o ttm_bo_util.o ttm_bo_vm.o ttm_module.o \\\ndrivers/gpu/drm/ttm/Makefile-6-\tttm_execbuf_util.o ttm_range_manager.o ttm_resource.o ttm_pool.o \\\n--\ndrivers/gpu/drm/ttm/tests/Makefile=3=obj-$(CONFIG_DRM_TTM_KUNIT_TEST) += \\\n--\ndrivers/gpu/drm/ttm/tests/Makefile-7-        ttm_tt_test.o \\\ndrivers/gpu/drm/ttm/tests/Makefile:8:        ttm_bo_test.o \\\ndrivers/gpu/drm/ttm/tests/Makefile:9:        ttm_bo_validate_test.o \\\ndrivers/gpu/drm/ttm/tests/Makefile-10-        ttm_mock_manager.o \\\n--\ndrivers/gpu/drm/ttm/tests/TODO=1=TODO\n--\ndrivers/gpu/drm/ttm/tests/TODO-9-- Suggestion: randomize the number and size of tested buffers in\ndrivers/gpu/drm/ttm/tests/TODO:10:  ttm_bo_validate()\ndrivers/gpu/drm/ttm/tests/TODO-11-- Agree on the naming convention\n--\ndrivers/gpu/drm/ttm/tests/TODO=15=Notes and gotchas\n--\ndrivers/gpu/drm/ttm/tests/TODO-22-     parallel would require some time (...and that's a \"todo\" in itself!)\ndrivers/gpu/drm/ttm/tests/TODO:23:- Triggering ttm_bo_vm_ops callbacks from KUnit (i.e. kernel) might be\ndrivers/gpu/drm/ttm/tests/TODO-24-  a challenge, but is worth trying. Look at selftests like\n--\ndrivers/gpu/drm/ttm/tests/TODO-26-- The test suite uses UML where ioremap() call returns NULL, meaning that\ndrivers/gpu/drm/ttm/tests/TODO:27:  ttm_bo_ioremap() can't be tested, unless we find a way to stub it\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-26-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:27:struct ttm_bo_test_case {\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-28-\tconst char *description;\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-32-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:33:static const struct ttm_bo_test_case ttm_bo_reserved_cases[] = {\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-34-\t{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-50-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:51:static void ttm_bo_init_case_desc(const struct ttm_bo_test_case *t,\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-52-\t\t\t\t  char *desc)\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-56-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:57:KUNIT_ARRAY_PARAM(ttm_bo_reserve, ttm_bo_reserved_cases, ttm_bo_init_case_desc);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-58-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:59:static void ttm_bo_reserve_optimistic_no_ticket(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-60-{\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:61:\tconst struct ttm_bo_test_case *params = test-\u003eparam_value;\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-62-\tstruct ttm_buffer_object *bo;\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-64-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:65:\tbo = ttm_bo_kunit_init(test, test-\u003epriv, BO_SIZE, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-66-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:67:\terr = ttm_bo_reserve(bo, params-\u003einterruptible, params-\u003eno_wait, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-68-\tKUNIT_ASSERT_EQ(test, err, 0);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-72-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:73:static void ttm_bo_reserve_locked_no_sleep(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-74-{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-79-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:80:\tbo = ttm_bo_kunit_init(test, test-\u003epriv, BO_SIZE, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-81-\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-84-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:85:\terr = ttm_bo_reserve(bo, interruptible, no_wait, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-86-\tdma_resv_unlock(bo-\u003ebase.resv);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-90-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:91:static void ttm_bo_reserve_no_wait_ticket(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-92-{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-100-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:101:\tbo = ttm_bo_kunit_init(test, test-\u003epriv, BO_SIZE, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-102-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:103:\terr = ttm_bo_reserve(bo, interruptible, no_wait, \u0026ctx);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-104-\tKUNIT_ASSERT_EQ(test, err, -EBUSY);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-108-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:109:static void ttm_bo_reserve_double_resv(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-110-{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-118-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:119:\tbo = ttm_bo_kunit_init(test, test-\u003epriv, BO_SIZE, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-120-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:121:\terr = ttm_bo_reserve(bo, interruptible, no_wait, \u0026ctx);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-122-\tKUNIT_ASSERT_EQ(test, err, 0);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-123-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:124:\terr = ttm_bo_reserve(bo, interruptible, no_wait, \u0026ctx);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-125-\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-135- * dma_resv lock of bo2 so the other context is \"wounded\" and has to back off\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:136: * (indicated by -EDEADLK). The subtest checks if ttm_bo_reserve() properly\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-137- * propagates that error.\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-138- */\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:139:static void ttm_bo_reserve_deadlock(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-140-{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-146-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:147:\tbo1 = ttm_bo_kunit_init(test, test-\u003epriv, BO_SIZE, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:148:\tbo2 = ttm_bo_kunit_init(test, test-\u003epriv, BO_SIZE, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-149-\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-159-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:160:\terr = ttm_bo_reserve(bo1, interruptible, no_wait, \u0026ctx1);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-161-\tKUNIT_ASSERT_EQ(test, err, 0);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-162-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:163:\terr = ttm_bo_reserve(bo2, interruptible, no_wait, \u0026ctx1);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-164-\tKUNIT_ASSERT_EQ(test, err, -EDEADLK);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c=171=struct signal_timer {\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-175-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:176:static void signal_for_ttm_bo_reserve(struct timer_list *t)\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-177-{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-183-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:184:static int threaded_ttm_bo_reserve(void *arg)\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-185-{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-195-\t/* Prepare a signal that will interrupt the reservation attempt */\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:196:\ttimer_setup_on_stack(\u0026s_timer.timer, \u0026signal_for_ttm_bo_reserve, 0);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-197-\ts_timer.ctx = \u0026ctx;\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-200-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:201:\terr = ttm_bo_reserve(bo, interruptible, no_wait, \u0026ctx);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-202-\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-210-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:211:static void ttm_bo_reserve_interrupted(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-212-{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-216-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:217:\tbo = ttm_bo_kunit_init(test, test-\u003epriv, BO_SIZE, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-218-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:219:\ttask = kthread_create(threaded_ttm_bo_reserve, bo, \"ttm-bo-reserve\");\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-220-\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-236-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:237:static void ttm_bo_unreserve_basic(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-238-{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-257-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:258:\tbo = ttm_bo_kunit_init(test, test-\u003epriv, BO_SIZE, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-259-\tbo-\u003epriority = bo_prio;\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-269-\tdma_resv_lock(bo-\u003ebase.resv, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:270:\tttm_bo_unreserve(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-271-\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-279-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:280:static void ttm_bo_unreserve_pinned(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-281-{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-296-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:297:\tbo = ttm_bo_kunit_init(test, test-\u003epriv, BO_SIZE, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-298-\tplace = ttm_place_kunit_init(test, mem_type, 0);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-300-\tdma_resv_lock(bo-\u003ebase.resv, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:301:\tttm_bo_pin(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-302-\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-312-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:313:\tttm_bo_unreserve(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-314-\tKUNIT_ASSERT_EQ(test,\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-320-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:321:static void ttm_bo_unreserve_bulk(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-322-{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-350-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:351:\tbo1 = ttm_bo_kunit_init(test, test-\u003epriv, BO_SIZE, resv);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:352:\tbo2 = ttm_bo_kunit_init(test, test-\u003epriv, BO_SIZE, resv);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-353-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-354-\tdma_resv_lock(bo1-\u003ebase.resv, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:355:\tttm_bo_set_bulk_move(bo1, \u0026lru_bulk_move);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-356-\tdma_resv_unlock(bo1-\u003ebase.resv);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-362-\tdma_resv_lock(bo2-\u003ebase.resv, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:363:\tttm_bo_set_bulk_move(bo2, \u0026lru_bulk_move);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-364-\tdma_resv_unlock(bo2-\u003ebase.resv);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-369-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:370:\tttm_bo_reserve(bo1, false, false, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:371:\tttm_bo_unreserve(bo1);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-372-\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-381-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:382:static void ttm_bo_fini_basic(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-383-{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-400-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:401:\tbo = ttm_bo_kunit_init(test, test-\u003epriv, BO_SIZE, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:402:\tbo-\u003etype = ttm_bo_type_device;\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-403-\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-412-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:413:\tttm_bo_fini(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-414-}\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c=421=static const struct dma_fence_ops mock_fence_ops = {\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-425-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:426:static void ttm_bo_fini_shared_resv(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-427-{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-461-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:462:\tbo = ttm_bo_kunit_init(test, test-\u003epriv, BO_SIZE, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:463:\tbo-\u003etype = ttm_bo_type_device;\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-464-\tbo-\u003ebase.resv = external_resv;\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-465-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:466:\tttm_bo_fini(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-467-}\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-468-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:469:static void ttm_bo_pin_basic(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-470-{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-483-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:484:\tbo = ttm_bo_kunit_init(test, test-\u003epriv, BO_SIZE, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-485-\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-487-\t\tdma_resv_lock(bo-\u003ebase.resv, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:488:\t\tttm_bo_pin(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-489-\t\tdma_resv_unlock(bo-\u003ebase.resv);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-494-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:495:static void ttm_bo_pin_unpin_resource(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-496-{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-518-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:519:\tbo = ttm_bo_kunit_init(test, test-\u003epriv, BO_SIZE, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-520-\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-525-\tdma_resv_lock(bo-\u003ebase.resv, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:526:\tttm_bo_set_bulk_move(bo, \u0026lru_bulk_move);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:527:\tttm_bo_pin(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-528-\tdma_resv_unlock(bo-\u003ebase.resv);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-536-\tdma_resv_lock(bo-\u003ebase.resv, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:537:\tttm_bo_unpin(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-538-\tdma_resv_unlock(bo-\u003ebase.resv);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-545-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:546:static void ttm_bo_multiple_pin_one_unpin(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-547-{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-569-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:570:\tbo = ttm_bo_kunit_init(test, test-\u003epriv, BO_SIZE, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-571-\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-576-\tdma_resv_lock(bo-\u003ebase.resv, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:577:\tttm_bo_set_bulk_move(bo, \u0026lru_bulk_move);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-578-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-579-\t/* Multiple pins */\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:580:\tttm_bo_pin(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:581:\tttm_bo_pin(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-582-\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-591-\tdma_resv_lock(bo-\u003ebase.resv, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:592:\tttm_bo_unpin(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-593-\tdma_resv_unlock(bo-\u003ebase.resv);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-599-\tdma_resv_lock(bo-\u003ebase.resv, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:600:\tttm_bo_unpin(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-601-\tdma_resv_unlock(bo-\u003ebase.resv);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-605-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:606:static struct kunit_case ttm_bo_test_cases[] = {\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:607:\tKUNIT_CASE_PARAM(ttm_bo_reserve_optimistic_no_ticket,\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:608:\t\t\t ttm_bo_reserve_gen_params),\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:609:\tKUNIT_CASE(ttm_bo_reserve_locked_no_sleep),\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:610:\tKUNIT_CASE(ttm_bo_reserve_no_wait_ticket),\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:611:\tKUNIT_CASE(ttm_bo_reserve_double_resv),\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-612-#if IS_BUILTIN(CONFIG_DRM_TTM_KUNIT_TEST)\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:613:\tKUNIT_CASE(ttm_bo_reserve_interrupted),\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-614-#endif\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:615:\tKUNIT_CASE(ttm_bo_reserve_deadlock),\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:616:\tKUNIT_CASE(ttm_bo_unreserve_basic),\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:617:\tKUNIT_CASE(ttm_bo_unreserve_pinned),\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:618:\tKUNIT_CASE(ttm_bo_unreserve_bulk),\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:619:\tKUNIT_CASE(ttm_bo_fini_basic),\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:620:\tKUNIT_CASE(ttm_bo_fini_shared_resv),\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:621:\tKUNIT_CASE(ttm_bo_pin_basic),\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:622:\tKUNIT_CASE(ttm_bo_pin_unpin_resource),\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:623:\tKUNIT_CASE(ttm_bo_multiple_pin_one_unpin),\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-624-\t{}\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-626-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:627:static struct kunit_suite ttm_bo_test_suite = {\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:628:\t.name = \"ttm_bo\",\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-629-\t.init = ttm_test_devices_init,\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-630-\t.exit = ttm_test_devices_fini,\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:631:\t.test_cases = ttm_bo_test_cases,\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-632-};\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-633-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:634:kunit_test_suites(\u0026ttm_bo_test_suite);\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-635-\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c:636:MODULE_DESCRIPTION(\"KUnit tests for ttm_bo APIs\");\ndrivers/gpu/drm/ttm/tests/ttm_bo_test.c-637-MODULE_LICENSE(\"GPL and additional rights\");\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c=18=static struct spinlock fence_lock;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-19-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:20:struct ttm_bo_validate_test_case {\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-21-\tconst char *description;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:22:\tenum ttm_bo_type bo_type;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-23-\tu32 mem_type;\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c=65=static void dma_resv_kunit_active_fence_init(struct kunit *test,\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-79-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:80:static void ttm_bo_validate_case_desc(const struct ttm_bo_validate_test_case *t,\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-81-\t\t\t\t      char *desc)\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-85-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:86:static const struct ttm_bo_validate_test_case ttm_bo_type_cases[] = {\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-87-\t{\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-88-\t\t.description = \"Buffer object for userspace\",\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:89:\t\t.bo_type = ttm_bo_type_device,\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-90-\t},\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-92-\t\t.description = \"Kernel buffer object\",\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:93:\t\t.bo_type = ttm_bo_type_kernel,\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-94-\t},\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-96-\t\t.description = \"Shared buffer object\",\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:97:\t\t.bo_type = ttm_bo_type_sg,\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-98-\t},\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-100-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:101:KUNIT_ARRAY_PARAM(ttm_bo_types, ttm_bo_type_cases,\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:102:\t\t  ttm_bo_validate_case_desc);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-103-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:104:static void ttm_bo_init_reserved_sys_man(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-105-{\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:106:\tconst struct ttm_bo_validate_test_case *params = test-\u003eparam_value;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-107-\tstruct ttm_test_devices *priv = test-\u003epriv;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:108:\tenum ttm_bo_type bo_type = params-\u003ebo_type;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-109-\tu32 size = ALIGN(BO_SIZE, PAGE_SIZE);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-123-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:124:\terr = ttm_bo_init_reserved(priv-\u003ettm_dev, bo, bo_type, placement,\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-125-\t\t\t\t   PAGE_SIZE, \u0026ctx, NULL, NULL,\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:126:\t\t\t\t   \u0026dummy_ttm_bo_destroy);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-127-\tdma_resv_unlock(bo-\u003ebase.resv);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-133-\tKUNIT_EXPECT_EQ(test, bo-\u003epage_alignment, PAGE_SIZE);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:134:\tKUNIT_EXPECT_PTR_EQ(test, bo-\u003edestroy, \u0026dummy_ttm_bo_destroy);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-135-\tKUNIT_EXPECT_EQ(test, bo-\u003epin_count, 0);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-141-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:142:\tif (bo_type != ttm_bo_type_kernel)\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-143-\t\tKUNIT_EXPECT_TRUE(test,\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-146-\tttm_resource_free(bo, \u0026bo-\u003eresource);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:147:\tttm_bo_fini(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-148-}\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-149-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:150:static void ttm_bo_init_reserved_mock_man(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-151-{\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:152:\tconst struct ttm_bo_validate_test_case *params = test-\u003eparam_value;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:153:\tenum ttm_bo_type bo_type = params-\u003ebo_type;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-154-\tstruct ttm_test_devices *priv = test-\u003epriv;\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-172-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:173:\terr = ttm_bo_init_reserved(priv-\u003ettm_dev, bo, bo_type, placement,\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-174-\t\t\t\t   PAGE_SIZE, \u0026ctx, NULL, NULL,\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:175:\t\t\t\t   \u0026dummy_ttm_bo_destroy);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-176-\tdma_resv_unlock(bo-\u003ebase.resv);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-183-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:184:\tif (bo_type != ttm_bo_type_kernel)\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-185-\t\tKUNIT_EXPECT_TRUE(test,\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-188-\tttm_resource_free(bo, \u0026bo-\u003eresource);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:189:\tttm_bo_fini(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-190-\tttm_mock_manager_fini(priv-\u003ettm_dev, mem_type);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-192-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:193:static void ttm_bo_init_reserved_resv(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-194-{\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:195:\tenum ttm_bo_type bo_type = ttm_bo_type_device;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-196-\tstruct ttm_test_devices *priv = test-\u003epriv;\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-214-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:215:\terr = ttm_bo_init_reserved(priv-\u003ettm_dev, bo, bo_type, placement,\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-216-\t\t\t\t   PAGE_SIZE, \u0026ctx, NULL, \u0026resv,\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:217:\t\t\t\t   \u0026dummy_ttm_bo_destroy);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-218-\tdma_resv_unlock(bo-\u003ebase.resv);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-223-\tttm_resource_free(bo, \u0026bo-\u003eresource);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:224:\tttm_bo_fini(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-225-}\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-226-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:227:static void ttm_bo_validate_basic(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-228-{\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:229:\tconst struct ttm_bo_validate_test_case *params = test-\u003eparam_value;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-230-\tu32 fst_mem = TTM_PL_SYSTEM, snd_mem = TTM_PL_VRAM;\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-248-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:249:\terr = ttm_bo_init_reserved(priv-\u003ettm_dev, bo, params-\u003ebo_type,\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-250-\t\t\t\t   fst_placement, PAGE_SIZE, \u0026ctx_init, NULL,\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:251:\t\t\t\t   NULL, \u0026dummy_ttm_bo_destroy);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-252-\tKUNIT_EXPECT_EQ(test, err, 0);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-256-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:257:\terr = ttm_bo_validate(bo, snd_placement, \u0026ctx_val);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-258-\tdma_resv_unlock(bo-\u003ebase.resv);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-267-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:268:\tttm_bo_fini(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-269-\tttm_mock_manager_fini(priv-\u003ettm_dev, snd_mem);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-271-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:272:static void ttm_bo_validate_invalid_placement(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-273-{\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:274:\tenum ttm_bo_type bo_type = ttm_bo_type_device;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-275-\tu32 unknown_mem_type = TTM_PL_PRIV + 1;\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-285-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:286:\tbo = ttm_bo_kunit_init(test, test-\u003epriv, size, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-287-\tbo-\u003etype = bo_type;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-288-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:289:\tttm_bo_reserve(bo, false, false, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:290:\terr = ttm_bo_validate(bo, placement, \u0026ctx);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-291-\tdma_resv_unlock(bo-\u003ebase.resv);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-294-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:295:\tttm_bo_fini(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-296-}\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-297-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:298:static void ttm_bo_validate_failed_alloc(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-299-{\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:300:\tenum ttm_bo_type bo_type = ttm_bo_type_device;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-301-\tstruct ttm_test_devices *priv = test-\u003epriv;\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-309-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:310:\tbo = ttm_bo_kunit_init(test, test-\u003epriv, size, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-311-\tbo-\u003etype = bo_type;\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-317-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:318:\tttm_bo_reserve(bo, false, false, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:319:\terr = ttm_bo_validate(bo, placement, \u0026ctx);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-320-\tdma_resv_unlock(bo-\u003ebase.resv);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-323-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:324:\tttm_bo_fini(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-325-\tttm_bad_manager_fini(priv-\u003ettm_dev, mem_type);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-327-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:328:static void ttm_bo_validate_pinned(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-329-{\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:330:\tenum ttm_bo_type bo_type = ttm_bo_type_device;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-331-\tu32 size = ALIGN(BO_SIZE, PAGE_SIZE);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-341-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:342:\tbo = ttm_bo_kunit_init(test, test-\u003epriv, size, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-343-\tbo-\u003etype = bo_type;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-344-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:345:\tttm_bo_reserve(bo, false, false, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:346:\tttm_bo_pin(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:347:\terr = ttm_bo_validate(bo, placement, \u0026ctx);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-348-\tdma_resv_unlock(bo-\u003ebase.resv);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-351-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:352:\tttm_bo_reserve(bo, false, false, NULL);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:353:\tttm_bo_unpin(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-354-\tdma_resv_unlock(bo-\u003ebase.resv);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-355-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:356:\tttm_bo_fini(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-357-}\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-358-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:359:static const struct ttm_bo_validate_test_case ttm_mem_type_cases[] = {\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-360-\t{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-369-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:370:KUNIT_ARRAY_PARAM(ttm_bo_validate_mem, ttm_mem_type_cases,\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:371:\t\t  ttm_bo_validate_case_desc);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-372-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:373:static void ttm_bo_validate_same_placement(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-374-{\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:375:\tconst struct ttm_bo_validate_test_case *params = test-\u003eparam_value;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-376-\tstruct ttm_operation_ctx ctx_init = { }, ctx_val = { };\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-394-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:395:\terr = ttm_bo_init_reserved(priv-\u003ettm_dev, bo, params-\u003ebo_type,\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-396-\t\t\t\t   placement, PAGE_SIZE, \u0026ctx_init, NULL,\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:397:\t\t\t\t   NULL, \u0026dummy_ttm_bo_destroy);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-398-\tKUNIT_EXPECT_EQ(test, err, 0);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-399-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:400:\terr = ttm_bo_validate(bo, placement, \u0026ctx_val);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-401-\tdma_resv_unlock(bo-\u003ebase.resv);\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-405-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:406:\tttm_bo_fini(bo);\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-407-\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-411-\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:412:static void ttm_bo_validate_busy_placement(struct kunit *test)\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-413-{\n--\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-416-\tstruct ttm_placement *placement_init, *placement_val;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c:417:\tenum ttm_bo_type bo_type = ttm_bo_type_device;\ndrivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c-418-\tstruct ttm_test_devices *priv = test-\u003epriv;\n--\n\n"
}

gemini-3.8-flash

null

null

							input: 69455
							output: 36
							thoughts: 66
						

**Examining the TTM Compilation Process**

Alright, let's break this down. My focus is on how this `ttm_bo.c` file fits into the larger picture. I see that if `CONFIG_DRM_TTM` is enabled, then `ttm_bo.c` gets compiled into the kernel module `ttm.ko` (`ttm-y := ... ttm_bo.o ...`). So, that's the dependency. Now, I need to understand the specifics of this build process. The next logical step is to dive into the `drivers/gpu/drm/ttm/Makefile`. That file should reveal exactly how this compilation and linking are orchestrated. Knowing the Makefile's contents is going to be key to seeing all the pieces and any dependencies.

{
  "File": "drivers/gpu/drm/ttm/Makefile",
  "FirstLine": 1,
  "LineCount": 20
}

{
  "Contents": "   1:\t# SPDX-License-Identifier: GPL-2.0\n   2:\t#\n   3:\t# Makefile for the drm device driver.  This driver provides support for the\n   4:\t\n   5:\tttm-y := ttm_tt.o ttm_bo.o ttm_bo_util.o ttm_bo_vm.o ttm_module.o \\\n   6:\t\tttm_execbuf_util.o ttm_range_manager.o ttm_resource.o ttm_pool.o \\\n   7:\t\tttm_device.o ttm_sys_manager.o ttm_backup.o\n   8:\tttm-$(CONFIG_AGP) += ttm_agp_backend.o\n   9:\t\n  10:\tobj-$(CONFIG_DRM_TTM) += ttm.o\n  11:\tobj-$(CONFIG_DRM_TTM_KUNIT_TEST) += tests/\n"
}

gemini-3.6-flash

null

null

### Executive Triage Summary

#### 1. Target Patch & Core Bug Analysis
* **Commit:** `79c3468273ed2cd535bb0b514da047e96cb00ad5`
* **Target Architecture:** `amd64`
* **Modified File:** `drivers/gpu/drm/ttm/ttm_bo.c`
* **Function Modified:** `ttm_bo_swapout_cb()`
* **Nature of Bug/Fix:**
  `ttm_tt_swapout()` returns positive integer `s64` (`ttm->num_pages`) on successful page swapout, or negative error code on failure. It never returns `0` on success.
  Prior to patch, condition checked `if (!ret)`. Because `ret > 0` on success, LRU cleanup and reassignment under `bdev->lru_lock` was dead code during successful swapouts.
  The patch changes check to `if (ret > 0)`, enabling previously bypassed LRU list management and bulk move removal logic.

---

#### 2. Approaches Tried & Results

##### A. Code Flow & Function Behavior Analysis
* **Examined `ttm_tt_swapout()` (`drivers/gpu/drm/ttm/ttm_tt.c` lines 322–368):**
  Allocates swap storage via `shmem_file_setup()`, reads/copies pages via `shmem_read_mapping_page_gfp()` / `copy_highpage()`, marks swapped flags (`TTM_TT_FLAG_SWAPPED`), unpopulates TT, returns `ttm->num_pages` (positive).
* **Examined `ttm_bo_shrink()` (`drivers/gpu/drm/ttm/ttm_bo_util.c` lines 1082–1132):**
  Verified equivalent pattern: uses `ttm_tt_backup()` and checks `if (lret > 0)` before acquiring `bdev->lru_lock` and invoking bulk move / LRU updates. Confirms `ttm_bo.c` had logic discrepancy.
* **Examined Executed LRU Helpers (`drivers/gpu/drm/ttm/ttm_resource.c` lines 260–330):**
  * `ttm_resource_del_bulk_move_unevictable(res, bo)`:
    Asserts `WARN_ON_ONCE(!ttm_resource_unevictable(res, bo));`.
  * `ttm_resource_move_to_lru_tail(res)`:
    Asserts `lockdep_assert_held(&bo->bdev->lru_lock);`.
    Moves resource link to `bdev->unevictable`, bulk move position tail, or manager LRU list depending on flags.

##### B. Subsystem Reachability & Driver Dependency Mapping
* **Drivers Selecting `DRM_TTM` / `DRM_TTM_HELPER` (`drivers/gpu/drm/*/Kconfig`):**
  * Emulated Virtual GPUs (Reachable in standard QEMU/VM environments):
    * `DRM_QXL` (`drivers/gpu/drm/qxl/Kconfig`): QEMU QXL virtual GPU (`-vga qxl`).
    * `DRM_VMWGFX` (`drivers/gpu/drm/vmwgfx/Kconfig`): VMware SVGA virtual GPU (`-vga vmware`).
    * `DRM_VBOXVIDEO` (`drivers/gpu/drm/vboxvideo/Kconfig`): VirtualBox guest GPU.
  * Physical Hardware Drivers (Vendor-specific ASIC):
    * `DRM_AMDGPU`, `DRM_RADEON`, `DRM_I915`, `DRM_NOUVEAU`, `DRM_XE`, `DRM_LOONGSON`.
* **Subsystems Checked (Dead-Ends for TTM Reachability):**
  * `drivers/gpu/drm/virtio/`: Uses virtio-gpu GEM objects, no TTM dependency (`select DRM_TTM` absent).
  * `drivers/gpu/drm/vkms/`: Virtual KMS uses GEM shmem helpers, no TTM.
  * `drivers/gpu/drm/tiny/` (bochs): Uses GEM VRAM/shmem helpers, no direct TTM swapout path.

##### C. Trigger Entry Points for `ttm_bo_swapout`
1. **Memory Allocation Reclaim Path:**
   `ttm_tt_populate()` (`drivers/gpu/drm/ttm/ttm_tt.c:388`) triggers `ttm_global_swapout()` when `ttm_pages_allocated > ttm_pages_limit`.
2. **Debugfs Trigger Path:**
   `/sys/kernel/debug/dri/.../tt_shrink` invokes `ttm_tt_debugfs_shrink_show()`, calling `ttm_global_swapout()`.
3. **Power Management / Hibernation Path:**
   `ttm_device_prepare_hibernation()` / `vmw_pm_freeze()` call `ttm_device_swapout()`.
4. **KUnit Test Path:**
   `DRM_TTM_KUNIT_TEST` (`drivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c`).

---

#### 3. Active Hypotheses & Triage Evaluation

* **Reachability Status:** REACHABLE.
  * Touches generic GPU memory management infrastructure (`drivers/gpu/drm/ttm/`).
  * Accessible via standard emulated QEMU devices (`DRM_QXL`, `DRM_VMWGFX`) and debugfs interfaces (`/sys/kernel/debug/dri/.../tt_shrink`).
* **Fuzzing Value (WorthFuzzing=true):**
  * Re-activates previously unreachable/bypassed lock acquisition (`bdev->lru_lock`), LRU list manipulation (`list_move_tail`), and bulk move tracking operations.
  * Exercises runtime checks and assertions:
    * `WARN_ON_ONCE(!ttm_resource_unevictable(res, bo))` in `ttm_resource_del_bulk_move_unevictable()`.
    * `lockdep_assert_held(&bo->bdev->lru_lock)` in `ttm_resource_move_to_lru_tail()`.
  * Changes state transition invariants when swapping out buffer objects under memory pressure or explicit debugfs shrink triggers.

---

#### 4. Critical File Paths, Functions, and Config Values

##### File Paths & Key Code Blocks
* `drivers/gpu/drm/ttm/ttm_bo.c`
```c
if (ttm_tt_is_populated(tt)) {
    ret = ttm_tt_swapout(bdev, tt, swapout_walk->gfp_flags);
    if (ret > 0) {
        spin_lock(&bdev->lru_lock);
        ttm_resource_del_bulk_move_unevictable(bo->resource, bo);
        ttm_resource_move_to_lru_tail(bo->resource);
        spin_unlock(&bdev->lru_lock);
    }
}
```
* `drivers/gpu/drm/ttm/ttm_tt.c`: `ttm_tt_swapout()`, `ttm_global_swapout()`, `ttm_tt_populate()`.
* `drivers/gpu/drm/ttm/ttm_resource.c`: `ttm_resource_del_bulk_move_unevictable()`, `ttm_resource_move_to_lru_tail()`.

##### Focus Symbols
* Direct feature entrypoints / altered logic functions:
  * `ttm_bo_swapout_cb`
  * `ttm_bo_swapout`
  * `ttm_tt_swapout`
  * `ttm_global_swapout`
  * `ttm_resource_del_bulk_move_unevictable`
  * `ttm_resource_move_to_lru_tail`

##### Required Kconfig Options (`EnableConfigs`)
* `DRM`
* `DRM_TTM`
* `DRM_TTM_HELPER`
* `DRM_QXL`
* `DRM_VMWGFX`

---

#### 5. Reasoning Loops & Tool Call Pattern Warnings
* **Observed Repetition:** Tool logs showed redundant reads of `drivers/gpu/drm/ttm/ttm_bo.c` (lines 1360–1450) and repeated searches for `ttm_global_swapout` / `ttm_resource_del_bulk_move_unevictable`.
* **Action:** Context is fully extracted; no further file reads or search tool calls needed for triage determination. Proceed directly to final output generation.

							input: 48751
							output: 2031
							thoughts: 1601
						

gemini-3.8-flash

null

null

							input: 21787
							output: 333
							thoughts: 718
						

**My Analysis of this TTM Patch**

Okay, here's the breakdown, as I see it. This is a fix for a subtle but potentially impactful bug within the TTM (Translation Table Manager) component of the DRM (Direct Rendering Manager) subsystem, specifically related to buffer object swapout.

First, the patch is targeted at amd64 architecture, which I expected. The code changes are within `drivers/gpu/drm/ttm/ttm_bo.c`, which is a core file for TTM. The diff itself is simple: it corrects a conditional check in `ttm_bo_swapout_cb`. The original code assumed a zero return value from `ttm_tt_swapout` meant success. However, `ttm_tt_swapout` actually returns a *positive integer* on success (the number of pages swapped out) and a *negative value* on error. So the original check `if (!ret)` was backwards. This means the critical cleanup steps after a successful swapout were being skipped.

The previous conditional error was bypassing the LRU (Least Recently Used) list manipulation. Now, with the corrected check `if (ret > 0)`, the code properly removes the buffer object from the "bulk move unevictable" list, moves it to the LRU tail, and triggers the `WARN_ON_ONCE` and `lockdep_assert_held` invariants. This is important because the LRU list management is crucial for memory reclaim and overall system stability, so fixing this is definitely good.

From a fuzzing perspective, this is *definitely* worth targeting. The patch modifies code reachable in several virtualized environments like QEMU with virtual GPUs (e.g., QXL, VMware SVGA). Furthermore, the `tt_shrink` debugfs interface and memory reclaim under TTM allocation limits will also exercise this code. The error was likely masked and therefore may have not been tested well.

To properly fuzz this, I'd want to focus on: `ttm_bo_swapout_cb`, `ttm_tt_swapout`, `ttm_global_swapout`, `ttm_device_swapout`, `ttm_resource_del_bulk_move_unevictable`, and `ttm_resource_move_to_lru_tail`. Those are the key functions involved in the swapout process.

The essential kernel configuration options to enable for fuzzing would be `DRM`, `DRM_TTM`, `DRM_TTM_HELPER`, `DRM_QXL`, and `DRM_VMWGFX` to cover the relevant subsystems that can trigger the execution.

It is worth noting that the patch exposes the cleanup code in `ttm_bo_swapout_cb` and it should be well-tested, therefore it is more likely that a regression from this patch could be flagged by tests. I can expect that the new conditions will have been tested.

{
  "EnableConfigs": [
    "DRM",
    "DRM_TTM",
    "DRM_TTM_HELPER",
    "DRM_QXL",
    "DRM_VMWGFX"
  ],
  "FocusSymbols": [
    "ttm_bo_swapout_cb",
    "ttm_tt_swapout",
    "ttm_global_swapout",
    "ttm_device_swapout",
    "ttm_resource_del_bulk_move_unevictable",
    "ttm_resource_move_to_lru_tail"
  ],
  "Reasoning": "The patch corrects a return-value check in ttm_bo_swapout_cb() from 'if (!ret)' to 'if (ret \u003e 0)'. Because ttm_tt_swapout() returns the positive number of pages swapped out on success (and negative on error), the LRU management and bulk move removal logic guarded by bdev-\u003elru_lock was previously dead code during successful swapouts. This change re-activates list manipulation and runtime assertions (such as WARN_ON_ONCE in ttm_resource_del_bulk_move_unevictable and lockdep assertions in ttm_resource_move_to_lru_tail). The modified code is reachable in virtualized environments via QEMU-emulated GPUs (DRM_QXL, DRM_VMWGFX) under memory reclaim or debugfs shrink operations, warranting fuzzing.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "DRM",
    "DRM_TTM",
    "DRM_TTM_HELPER",
    "DRM_QXL",
    "DRM_VMWGFX"
  ],
  "FocusSymbols": [
    "ttm_bo_swapout_cb",
    "ttm_tt_swapout",
    "ttm_global_swapout",
    "ttm_device_swapout",
    "ttm_resource_del_bulk_move_unevictable",
    "ttm_resource_move_to_lru_tail"
  ],
  "Reasoning": "The patch corrects a return-value check in ttm_bo_swapout_cb() from 'if (!ret)' to 'if (ret \u003e 0)'. Because ttm_tt_swapout() returns the positive number of pages swapped out on success (and negative on error), the LRU management and bulk move removal logic guarded by bdev-\u003elru_lock was previously dead code during successful swapouts. This change re-activates list manipulation and runtime assertions (such as WARN_ON_ONCE in ttm_resource_del_bulk_move_unevictable and lockdep assertions in ttm_resource_move_to_lru_tail). The modified code is reachable in virtualized environments via QEMU-emulated GPUs (DRM_QXL, DRM_VMWGFX) under memory reclaim or debugfs shrink operations, warranting fuzzing.",
  "WorthFuzzing": true
}

{
  "WorthFuzzing": true
}

null

core

null

{
  "KMSANReasoning": "The patch fixes a logic bug in `ttm_bo_swapout_cb()` where the success condition of `ttm_tt_swapout()` was erroneously checked as `if (!ret)` instead of `if (ret \u003e 0)`. Because `ttm_tt_swapout()` returns the positive number of swapped-out pages on success or a negative error code on failure, the LRU management functions (`ttm_resource_del_bulk_move_unevictable` and `ttm_resource_move_to_lru_tail`) were never called upon successful swapout.\n\nThis change strictly touches LRU tracking control flow and list manipulation for buffer objects. It does not introduce, modify, or read any uninitialized stack or heap memory, does not alter copy-to-user operations or infoleak surfaces, and does not alter buffer allocation/initialization logic. Any memory corruption or locking issues in LRU manipulation would be caught by standard KASAN/LOCKDEP builds. Therefore, a dedicated KMSAN fuzzing session is not warranted.",
  "NeedsKMSAN": false
}

You are an expert Linux kernel security engineer specializing in kernel memory
error detectors (KASAN and KMSAN). Your job is to review the provided patch series and
determine if the code changes justify spawning a dedicated KMSAN (KernelMemorySanitizer)
fuzzing session in addition to standard KASAN fuzzing.

CRITICAL DISTINCTION BETWEEN KASAN AND KMSAN:
- Standard KASAN kernel builds (upstream-apparmor-kasan.config) already enable
  a comprehensive suite of debugging tools and sanitizers, including KASAN
  (out-of-bounds accesses, use-after-free, double free, invalid free), LOCKDEP
  (locking bugs and deadlocks), UB-sanitizers, and memory corruption checks.
- KMSAN (KernelMemorySanitizer) detects reads of UNINITIALIZED memory (stack, heap,
  or page allocations) and kernel-to-user memory info-leaks.

Rule: THERE IS NO SENSE IN RUNNING A KMSAN SESSION IF A BUG CAN BE CAUGHT BY KASAN,
LOCKDEP, OR OTHER STANDARD BUG DETECTORS.
A dedicated KMSAN fuzzing session incurs significant resource costs. You must ONLY
set NeedsKMSAN=true if the code changes introduce or expose UNINITIALIZED MEMORY risks
that are detected ONLY by KMSAN.

Look holistically at the patch series and surrounding code. Even if no direct
uninitialized field accesses or new buffer allocations are added in the diff itself,
a patch may alter control flow, bounds checking, or data length calculations in ways
that change how the rest of the code operates on existing buffers (e.g. allowing
uninitialized stack/heap memory to be read, copied to user space, or used in control
flow). Do not hesitate to use your code access tools to inspect the surrounding code,
called functions, and callers.

Set NeedsKMSAN=true ONLY IF the patch introduces or modifies:
1. Kernel structures sent to user space (via copy_to_user, put_user, netlink skb
   attributes, ioctl output arguments, socket options, or BPF buffers) where fields
   or structure padding might not be fully initialized/zeroed.
2. Conditional logic or branching that depends on potentially uninitialized variables
   or struct fields.
3. Allocation or initialization of complex data structures where uninitialized fields
   could be read later in reachable code paths.
4. Bounds checks, lengths, or logic in a way that allows surrounding code to access
   uninitialized bytes of existing buffers.

Set NeedsKMSAN=false IF:
- The code changes primarily risk out-of-bounds access, array overflows, NULL pointer
  dereferences, locking deadlocks, or use-after-free bugs (these are already caught
  by KASAN, LOCKDEP, or standard bug detectors).
- All stack/heap structures touched or introduced by the patch are fully zeroed
  or initialized (e.g. using = {0}, memset, kzalloc) before being read or copied.
- The patch does not introduce any risk of uninitialized memory usage or info-leaks.

Use your code access tools to inspect the surrounding code if necessary, then provide
detailed KMSANReasoning contrasting KASAN vs KMSAN applicability for this patch.
Prefer calling several tools at the same time to save round-trips.


Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.

Target architecture: amd64

For your convenience, here is the diff of the changes:
commit 79c3468273ed2cd535bb0b514da047e96cb00ad5
Author: syz-cluster <triage@syzkaller.com>
Date:   Wed Sep 16 22:33:41 2026 +0000

    syz-cluster: applied patch under review

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index ef56c18ded1b8..9b85b5f388d41 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -1434,7 +1434,7 @@ ttm_bo_swapout_cb(struct ttm_lru_walk *walk, struct ttm_buffer_object *bo)
 
 	if (ttm_tt_is_populated(tt)) {
 		ret = ttm_tt_swapout(bdev, tt, swapout_walk->gfp_flags);
-		if (!ret) {
+		if (ret > 0) {
 			spin_lock(&bdev->lru_lock);
 			ttm_resource_del_bulk_move_unevictable(bo->resource, bo);
 			ttm_resource_move_to_lru_tail(bo->resource);

gemini-3.8-flash

null

null

							input: 2155
							output: 44
							thoughts: 44
						

Okay, here's my interpretation of that thought process, as if it were my own:

**Diving into the TTM Buffer Object Code**

Alright, time to dig in. The problem likely lies within the TTM (Translation Table Manager) buffer object code, specifically within `drivers/gpu/drm/ttm/ttm_bo.c`. I'm going to start by getting a clear picture of the changes with the `diff` command, understand what's been altered. But that's not enough; I need context. I'll need to read the code *around* the changed lines to see the bigger picture, understand the flow, and identify any potential dependencies. Then, I can either use `read-file` to get a direct view or, if I need more targeted information, I'll switch to `grepper` to search for specific function calls, variables, or patterns within the file to efficiently pinpoint the root cause. This methodical approach will allow me to quickly narrow down the possibilities and get to the core of the issue.

{
  "File": "drivers/gpu/drm/ttm/ttm_bo.c",
  "FirstLine": 1420,
  "LineCount": 50
}

{
  "Contents": "1420:\t\t\t\tgoto out;\n1421:\t\t\t}\n1422:\t\t}\n1423:\t\n1424:\t\t/*\n1425:\t\t * Make sure BO is idle.\n1426:\t\t */\n1427:\t\tret = ttm_bo_wait_ctx(bo, ctx);\n1428:\t\tif (ret)\n1429:\t\t\tgoto out;\n1430:\t\n1431:\t\tttm_bo_unmap_virtual(bo);\n1432:\t\tif (bdev-\u003efuncs-\u003eswap_notify)\n1433:\t\t\tbdev-\u003efuncs-\u003eswap_notify(bo);\n1434:\t\n1435:\t\tif (ttm_tt_is_populated(tt)) {\n1436:\t\t\tret = ttm_tt_swapout(bdev, tt, swapout_walk-\u003egfp_flags);\n1437:\t\t\tif (ret \u003e 0) {\n1438:\t\t\t\tspin_lock(\u0026bdev-\u003elru_lock);\n1439:\t\t\t\tttm_resource_del_bulk_move_unevictable(bo-\u003eresource, bo);\n1440:\t\t\t\tttm_resource_move_to_lru_tail(bo-\u003eresource);\n1441:\t\t\t\tspin_unlock(\u0026bdev-\u003elru_lock);\n1442:\t\t\t}\n1443:\t\t}\n1444:\t\n1445:\tout:\n1446:\t\t/* Consider -ENOMEM and -ENOSPC non-fatal. */\n1447:\t\tif (ret == -ENOMEM || ret == -ENOSPC)\n1448:\t\t\tret = -EBUSY;\n1449:\t\n1450:\t\treturn ret;\n1451:\t}\n1452:\t\n1453:\tconst struct ttm_lru_walk_ops ttm_swap_ops = {\n1454:\t\t.process_bo = ttm_bo_swapout_cb,\n1455:\t};\n1456:\t\n1457:\t/**\n1458:\t * ttm_bo_swapout() - Swap out buffer objects on the LRU list to shmem.\n1459:\t * @bdev: The ttm device.\n1460:\t * @ctx: The ttm_operation_ctx governing the swapout operation.\n1461:\t * @man: The resource manager whose resources / buffer objects are\n1462:\t * goint to be swapped out.\n1463:\t * @gfp_flags: The gfp flags used for shmem page allocations.\n1464:\t * @target: The desired number of pages to swap out.\n1465:\t *\n1466:\t * Return: The number of pages actually swapped out, or negative error code\n1467:\t * on error.\n1468:\t */\n1469:\ts64 ttm_bo_swapout(struct ttm_device *bdev, struct ttm_operation_ctx *ctx,\n"
}

gemini-3.8-flash

null

null

							input: 3243
							output: 21
							thoughts: 30
						

Okay, here's my interpretation of those thoughts, presented as a first-person expert summary:

**Digging into `ttm_tt_swapout`**

Alright, time to get to the bottom of this. I'm going to check the return value of `ttm_tt_swapout`. That's the key piece of information here. I'll use `grep` to quickly locate all instances of that function within the relevant code base, whatever I'm currently working with. A quick search should give me a good overview of how it's being used and what the potential impact of its return value is in different contexts. This initial grep will let me see where this function is called, the kinds of data it interacts with, and give me a feel for its role within the larger system. Understanding the immediate caller is essential to understanding the significance of its return. This should be a quick and efficient way to begin my investigation, and will hopefully highlight the critical sections to focus on.

{
  "Expression": "ttm_tt_swapout"
}

{
  "Output": "drivers/gpu/drm/ttm/tests/ttm_tt_test.c=337=static void ttm_tt_swapin_basic(struct kunit *test)\n--\ndrivers/gpu/drm/ttm/tests/ttm_tt_test.c-357-\ndrivers/gpu/drm/ttm/tests/ttm_tt_test.c:358:\tnum_pages = ttm_tt_swapout(devs-\u003ettm_dev, tt, GFP_KERNEL);\ndrivers/gpu/drm/ttm/tests/ttm_tt_test.c-359-\tKUNIT_ASSERT_EQ(test, num_pages, expected_num_pages);\n--\ndrivers/gpu/drm/ttm/ttm_bo.c=1352=struct ttm_bo_swapout_walk {\n--\ndrivers/gpu/drm/ttm/ttm_bo.c-1354-\tstruct ttm_lru_walk walk;\ndrivers/gpu/drm/ttm/ttm_bo.c:1355:\t/** @gfp_flags: The gfp flags to use for ttm_tt_swapout() */\ndrivers/gpu/drm/ttm/ttm_bo.c-1356-\tgfp_t gfp_flags;\n--\ndrivers/gpu/drm/ttm/ttm_bo.c=1363=ttm_bo_swapout_cb(struct ttm_lru_walk *walk, struct ttm_buffer_object *bo)\n--\ndrivers/gpu/drm/ttm/ttm_bo.c-1435-\tif (ttm_tt_is_populated(tt)) {\ndrivers/gpu/drm/ttm/ttm_bo.c:1436:\t\tret = ttm_tt_swapout(bdev, tt, swapout_walk-\u003egfp_flags);\ndrivers/gpu/drm/ttm/ttm_bo.c-1437-\t\tif (ret \u003e 0) {\n--\ndrivers/gpu/drm/ttm/ttm_tt.c=310=EXPORT_SYMBOL(ttm_tt_restore);\n--\ndrivers/gpu/drm/ttm/ttm_tt.c-312-/**\ndrivers/gpu/drm/ttm/ttm_tt.c:313: * ttm_tt_swapout - swap out tt object\ndrivers/gpu/drm/ttm/ttm_tt.c-314- *\n--\ndrivers/gpu/drm/ttm/ttm_tt.c-321- */\ndrivers/gpu/drm/ttm/ttm_tt.c:322:int ttm_tt_swapout(struct ttm_device *bdev, struct ttm_tt *ttm,\ndrivers/gpu/drm/ttm/ttm_tt.c-323-\t\t   gfp_t gfp_flags)\n--\ndrivers/gpu/drm/ttm/ttm_tt.c-367-}\ndrivers/gpu/drm/ttm/ttm_tt.c:368:EXPORT_SYMBOL_FOR_TESTS_ONLY(ttm_tt_swapout);\ndrivers/gpu/drm/ttm/ttm_tt.c-369-\n--\ninclude/drm/ttm/ttm_tt.h=239=int ttm_tt_swapin(struct ttm_tt *ttm);\ninclude/drm/ttm/ttm_tt.h:240:int ttm_tt_swapout(struct ttm_device *bdev, struct ttm_tt *ttm,\ninclude/drm/ttm/ttm_tt.h-241-\t\t   gfp_t gfp_flags);\n"
}

gemini-3.8-flash

null

null

							input: 4419
							output: 43
							thoughts: 31
						

Okay, here's my interpretation of that thought process, from an expert's perspective:

**Diving into TTM Swapping**

Alright, time to get my hands dirty. I'm thinking I need to refresh my memory on the specifics of how the Transaction-based Texture Manager (TTM) handles page swapping in the Direct Rendering Manager (DRM) driver code. Specifically, I'm heading straight to `drivers/gpu/drm/ttm/ttm_tt.c`. I need to understand the mechanics of the `ttm_tt_swapout` function. I'm probably looking at how it moves pages between system memory and the GPU's memory space, or perhaps how it handles paging to a backing store, if that's the implementation. I'm keen to see if there are any subtle optimization opportunities or potential bottlenecks in its design. I'm going in with a critical eye, ready to analyze the logic flow, memory access patterns, and any associated locking mechanisms. I'll likely be looking for things like reference counting, page pinning strategies, and how it deals with page faults during the swap process. Let's see what's what.

{
  "File": "drivers/gpu/drm/ttm/ttm_tt.c",
  "FirstLine": 312,
  "LineCount": 60
}

{
  "Contents": " 312:\t/**\n 313:\t * ttm_tt_swapout - swap out tt object\n 314:\t *\n 315:\t * @bdev: TTM device structure.\n 316:\t * @ttm: The struct ttm_tt.\n 317:\t * @gfp_flags: Flags to use for memory allocation.\n 318:\t *\n 319:\t * Swapout a TT object to a shmem_file, return number of pages swapped out or\n 320:\t * negative error code.\n 321:\t */\n 322:\tint ttm_tt_swapout(struct ttm_device *bdev, struct ttm_tt *ttm,\n 323:\t\t\t   gfp_t gfp_flags)\n 324:\t{\n 325:\t\tloff_t size = (loff_t)ttm-\u003enum_pages \u003c\u003c PAGE_SHIFT;\n 326:\t\tstruct address_space *swap_space;\n 327:\t\tstruct file *swap_storage;\n 328:\t\tstruct page *from_page;\n 329:\t\tstruct page *to_page;\n 330:\t\tint i, ret;\n 331:\t\n 332:\t\tswap_storage = shmem_file_setup(\"ttm swap\", size, EMPTY_VMA_FLAGS);\n 333:\t\tif (IS_ERR(swap_storage)) {\n 334:\t\t\tpr_err(\"Failed allocating swap storage\\n\");\n 335:\t\t\treturn PTR_ERR(swap_storage);\n 336:\t\t}\n 337:\t\n 338:\t\tswap_space = swap_storage-\u003ef_mapping;\n 339:\t\tgfp_flags \u0026= mapping_gfp_mask(swap_space);\n 340:\t\n 341:\t\tfor (i = 0; i \u003c ttm-\u003enum_pages; ++i) {\n 342:\t\t\tfrom_page = ttm-\u003epages[i];\n 343:\t\t\tif (unlikely(from_page == NULL))\n 344:\t\t\t\tcontinue;\n 345:\t\n 346:\t\t\tto_page = shmem_read_mapping_page_gfp(swap_space, i, gfp_flags);\n 347:\t\t\tif (IS_ERR(to_page)) {\n 348:\t\t\t\tret = PTR_ERR(to_page);\n 349:\t\t\t\tgoto out_err;\n 350:\t\t\t}\n 351:\t\t\tcopy_highpage(to_page, from_page);\n 352:\t\t\tset_page_dirty(to_page);\n 353:\t\t\tmark_page_accessed(to_page);\n 354:\t\t\tput_page(to_page);\n 355:\t\t}\n 356:\t\n 357:\t\tttm_tt_unpopulate(bdev, ttm);\n 358:\t\tttm-\u003eswap_storage = swap_storage;\n 359:\t\tttm-\u003epage_flags |= TTM_TT_FLAG_SWAPPED;\n 360:\t\n 361:\t\treturn ttm-\u003enum_pages;\n 362:\t\n 363:\tout_err:\n 364:\t\tfput(swap_storage);\n 365:\t\n 366:\t\treturn ret;\n 367:\t}\n 368:\tEXPORT_SYMBOL_FOR_TESTS_ONLY(ttm_tt_swapout);\n 369:\t\n 370:\tint ttm_tt_populate(struct ttm_device *bdev,\n 371:\t\t\t    struct ttm_tt *ttm, struct ttm_operation_ctx *ctx)\n"
}

gemini-3.8-flash

null

null

							input: 5690
							output: 17
							thoughts: 393
						

**Debugging a Subtle Swapout Bug**

Okay, let's dive into this `ttm_tt_swapout` function. It's supposed to handle swapping a TT (transaction table, I assume) object out to a shared memory file. It's supposed to return the number of pages swapped out, or a negative error code if things go south. Specifically, on success, it returns `ttm->num_pages`, which we know is going to be a positive value. Now, I'm looking at how this is used, and I'm seeing a potential issue in `ttm_bo_swapout_cb`.

Specifically:

```c
	if (ttm_tt_is_populated(tt)) {
		ret = ttm_tt_swapout(bdev, tt, swapout_walk->gfp_flags);
		if (!ret) {
			spin_lock(&bdev->lru_lock);
			ttm_resource_del_bulk_move_unevictable(bo->resource, bo);
			ttm_resource_move_to_lru_tail(bo->resource);
			spin_unlock(&bdev->lru_lock);
		}
	}
```

Now, the issue jumps out at me. If `ttm_tt_swapout` returns a positive number of pages on success, then `if (!ret)` will *never* be true on a successful swapout! The condition should be checking for non-zero *or* negative to catch failures. Even more problematic, if `ttm_tt_swapout` returned 0 (which I'm not sure if is even a valid case for this function, but it's important to consider), then `!ret` will evaluate to true even though no swapout actually occurred. Furthermore, the `ttm_bo_swapout_cb` function returns the number of pages swapped out, which is expected by the `ttm_lru_walk_ops.process_bo` function.

So, the return value of `ttm_tt_swapout` *should* be passed directly to the return of `ttm_bo_swapout_cb`. Now, this is a very interesting issue. I think the conditional check should be updated to consider both a zero-case, and errors, and it looks as though the conditional, in its current form, is a major bug!

To confirm my understanding, I need to verify how `ttm_bo_swapout_cb`, `ttm_swap_ops`, and the use of `process_bo` fit together in the bigger picture. I'm going to run a `grep` for `process_bo` to trace the call paths and ensure I'm getting the complete picture.

{
  "Expression": "process_bo"
}

{
  "Output": "drivers/bluetooth/btnxpuart.c=888=static bool fw_dump_in_progress(struct btnxpuart_dev *nxpdev)\n--\ndrivers/bluetooth/btnxpuart.c-892-\ndrivers/bluetooth/btnxpuart.c:893:static bool process_boot_signature(struct btnxpuart_dev *nxpdev)\ndrivers/bluetooth/btnxpuart.c-894-{\n--\ndrivers/bluetooth/btnxpuart.c=961=static int nxp_recv_fw_req_v1(struct hci_dev *hdev, struct sk_buff *skb)\n--\ndrivers/bluetooth/btnxpuart.c-967-\ndrivers/bluetooth/btnxpuart.c:968:\tif (!process_boot_signature(nxpdev))\ndrivers/bluetooth/btnxpuart.c-969-\t\tgoto free_skb;\n--\ndrivers/bluetooth/btnxpuart.c=1143=static int nxp_recv_chip_ver_v3(struct hci_dev *hdev, struct sk_buff *skb)\n--\ndrivers/bluetooth/btnxpuart.c-1151-\ndrivers/bluetooth/btnxpuart.c:1152:\tif (!process_boot_signature(nxpdev))\ndrivers/bluetooth/btnxpuart.c-1153-\t\tgoto free_skb;\n--\ndrivers/bluetooth/btnxpuart.c=1196=static int nxp_recv_fw_req_v3(struct hci_dev *hdev, struct sk_buff *skb)\n--\ndrivers/bluetooth/btnxpuart.c-1203-\ndrivers/bluetooth/btnxpuart.c:1204:\tif (!process_boot_signature(nxpdev))\ndrivers/bluetooth/btnxpuart.c-1205-\t\tgoto free_skb;\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h=341=int amdgpu_amdkfd_map_gtt_bo_to_gart(struct amdgpu_bo *bo, struct amdgpu_bo **bo_gart);\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h-342-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h:343:int amdgpu_amdkfd_gpuvm_restore_process_bos(void *process_info,\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h-344-\t\t\t\t\t    struct dma_fence __rcu **ef);\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c=2899=static void replace_eviction_fence(struct dma_fence __rcu **ef,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-2915-\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:2916:/** amdgpu_amdkfd_gpuvm_restore_process_bos - Restore all BOs for the given\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-2917- *   KFD process identified by process_info\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-2933- */\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c:2934:int amdgpu_amdkfd_gpuvm_restore_process_bos(void *info, struct dma_fence __rcu **ef)\ndrivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c-2935-{\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c=230=static int amdgpu_gem_object_open(struct drm_gem_object *obj,\n--\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-279-\t * export, which is currently required to be validated and fenced\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c:280:\t * already by amdgpu_amdkfd_gpuvm_restore_process_bos.\ndrivers/gpu/drm/amd/amdgpu/amdgpu_gem.c-281-\t *\n--\ndrivers/gpu/drm/amd/amdkfd/kfd_process.c=2211=static int restore_process_helper(struct kfd_process *p)\n--\ndrivers/gpu/drm/amd/amdkfd/kfd_process.c-2216-\tif (p-\u003ekgd_process_info) {\ndrivers/gpu/drm/amd/amdkfd/kfd_process.c:2217:\t\tret = amdgpu_amdkfd_gpuvm_restore_process_bos(\ndrivers/gpu/drm/amd/amdkfd/kfd_process.c-2218-\t\t\tp-\u003ekgd_process_info, \u0026p-\u003eef);\n--\ndrivers/gpu/drm/amd/amdkfd/kfd_process.c=2234=static void restore_process_worker(struct work_struct *work)\n--\ndrivers/gpu/drm/amd/amdkfd/kfd_process.c-2248-\t/* Setting last_restore_timestamp before successful restoration.\ndrivers/gpu/drm/amd/amdkfd/kfd_process.c:2249:\t * Otherwise this would have to be set by KGD (restore_process_bos)\ndrivers/gpu/drm/amd/amdkfd/kfd_process.c-2250-\t * before KFD BOs are unreserved. If not, the process can be evicted\n--\ndrivers/gpu/drm/ttm/ttm_bo.c=716=static const struct ttm_lru_walk_ops ttm_evict_walk_ops = {\ndrivers/gpu/drm/ttm/ttm_bo.c:717:\t.process_bo = ttm_bo_evict_cb,\ndrivers/gpu/drm/ttm/ttm_bo.c-718-};\n--\ndrivers/gpu/drm/ttm/ttm_bo.c=1453=const struct ttm_lru_walk_ops ttm_swap_ops = {\ndrivers/gpu/drm/ttm/ttm_bo.c:1454:\t.process_bo = ttm_bo_swapout_cb,\ndrivers/gpu/drm/ttm/ttm_bo.c-1455-};\n--\ndrivers/gpu/drm/ttm/ttm_bo_util.c=841=static int ttm_lru_walk_ticketlock(struct ttm_bo_lru_cursor *curs,\n--\ndrivers/gpu/drm/ttm/ttm_bo_util.c-882- *\ndrivers/gpu/drm/ttm/ttm_bo_util.c:883: * With a locked object, the actions indicated by @walk-\u003eprocess_bo are\ndrivers/gpu/drm/ttm/ttm_bo_util.c-884- * performed, and after that, the bo is unlocked, the refcount dropped and the\n--\ndrivers/gpu/drm/ttm/ttm_bo_util.c-887- *\ndrivers/gpu/drm/ttm/ttm_bo_util.c:888: * Typically @walk-\u003eprocess_bo() would return the number of pages evicted,\ndrivers/gpu/drm/ttm/ttm_bo_util.c-889- * swapped or shrunken, so that when the total exceeds @target, or when the\n--\ndrivers/gpu/drm/ttm/ttm_bo_util.c=900=s64 ttm_lru_walk_for_evict(struct ttm_lru_walk *walk, struct ttm_device *bdev,\n--\ndrivers/gpu/drm/ttm/ttm_bo_util.c-908-\tttm_bo_lru_for_each_reserved_guarded(\u0026cursor, man, \u0026walk-\u003earg, bo) {\ndrivers/gpu/drm/ttm/ttm_bo_util.c:909:\t\tlret = walk-\u003eops-\u003eprocess_bo(walk, bo);\ndrivers/gpu/drm/ttm/ttm_bo_util.c-910-\t\tif (lret == -EBUSY || lret == -EALREADY)\n--\ndrivers/usb/storage/ene_ub6250.c=870=static int ms_read_readpage(struct us_data *us, u32 PhyBlockAddr,\n--\ndrivers/usb/storage/ene_ub6250.c-931-\ndrivers/usb/storage/ene_ub6250.c:932:static int ms_lib_process_bootblock(struct us_data *us, u16 PhyBlock, u8 *PageData)\ndrivers/usb/storage/ene_ub6250.c-933-{\n--\ndrivers/usb/storage/ene_ub6250.c=1947=static int ms_card_init(struct us_data *us)\n--\ndrivers/usb/storage/ene_ub6250.c-2015-\tif (btBlk1stErred == 0)\ndrivers/usb/storage/ene_ub6250.c:2016:\t\tresult = ms_lib_process_bootblock(us, btBlk1st, PageBuffer1);\ndrivers/usb/storage/ene_ub6250.c-2017-\t\t/* 1st */\n--\ndrivers/usb/storage/ene_ub6250.c-2019-\tif (result \u0026\u0026 (btBlk2nd != MS_LB_NOT_USED))\ndrivers/usb/storage/ene_ub6250.c:2020:\t\tresult = ms_lib_process_bootblock(us, btBlk2nd, PageBuffer0);\ndrivers/usb/storage/ene_ub6250.c-2021-\n--\ninclude/drm/ttm/ttm_bo.h=204=struct ttm_lru_walk_ops {\ninclude/drm/ttm/ttm_bo.h-205-\t/**\ninclude/drm/ttm/ttm_bo.h:206:\t * process_bo - Process this bo.\ninclude/drm/ttm/ttm_bo.h-207-\t * @walk: struct ttm_lru_walk describing the walk.\n--\ninclude/drm/ttm/ttm_bo.h-215-\t */\ninclude/drm/ttm/ttm_bo.h:216:\ts64 (*process_bo)(struct ttm_lru_walk *walk, struct ttm_buffer_object *bo);\ninclude/drm/ttm/ttm_bo.h-217-};\n--\ntools/lib/python/kdoc/kdoc_parser.py=235=class KernelDoc:\n--\ntools/lib/python/kdoc/kdoc_parser.py-1447-\ntools/lib/python/kdoc/kdoc_parser.py:1448:    def process_body(self, ln, line, source):\ntools/lib/python/kdoc/kdoc_parser.py-1449-        \"\"\"\n--\ntools/lib/python/kdoc/kdoc_parser.py-1704-        state.NAME:\t\t\tprocess_name,\ntools/lib/python/kdoc/kdoc_parser.py:1705:        state.BODY:\t\t\tprocess_body,\ntools/lib/python/kdoc/kdoc_parser.py-1706-        state.DECLARATION:\t\tprocess_decl,\n"
}

gemini-3.8-flash

null

null

							input: 9675
							output: 44
							thoughts: 47
						

**Analyzing the Memory Management Change**

Okay, so I need to get to the bottom of this. My first instinct is to dig into the `git log`. Finding the specific commit or context for this change is crucial. That history might shed some light on the reasoning behind it and any potential surrounding discussions. If that doesn't yield the answers I need, I'll move on to a deeper dive.

Next step: I'm going to pore over the `ttm_bo_swapout_cb` function in its entirety. It's time to thoroughly dissect this code. I need to understand its complete implementation, because that will allow me to follow the execution path involved with this change. Knowing its inner workings is absolutely critical to grasping the impact of this particular modification to the memory management scheme.

{
  "File": "drivers/gpu/drm/ttm/ttm_bo.c",
  "FirstLine": 1360,
  "LineCount": 90
}

{
  "Contents": "1360:\t};\n1361:\t\n1362:\tstatic s64\n1363:\tttm_bo_swapout_cb(struct ttm_lru_walk *walk, struct ttm_buffer_object *bo)\n1364:\t{\n1365:\t\tstruct ttm_place place = { .mem_type = bo-\u003eresource-\u003emem_type };\n1366:\t\tstruct ttm_bo_swapout_walk *swapout_walk =\n1367:\t\t\tcontainer_of(walk, typeof(*swapout_walk), walk);\n1368:\t\tstruct ttm_operation_ctx *ctx = walk-\u003earg.ctx;\n1369:\t\tstruct ttm_device *bdev = bo-\u003ebdev;\n1370:\t\tstruct ttm_tt *tt = bo-\u003ettm;\n1371:\t\ts64 ret;\n1372:\t\n1373:\t\t/*\n1374:\t\t * While the bo may already reside in SYSTEM placement, set\n1375:\t\t * SYSTEM as new placement to cover also the move further below.\n1376:\t\t * The driver may use the fact that we're moving from SYSTEM\n1377:\t\t * as an indication that we're about to swap out.\n1378:\t\t */\n1379:\t\tif (bo-\u003epin_count || !bdev-\u003efuncs-\u003eeviction_valuable(bo, \u0026place)) {\n1380:\t\t\tret = -EBUSY;\n1381:\t\t\tgoto out;\n1382:\t\t}\n1383:\t\n1384:\t\tif (!tt || !ttm_tt_is_populated(tt) ||\n1385:\t\t    tt-\u003epage_flags \u0026 (TTM_TT_FLAG_EXTERNAL | TTM_TT_FLAG_SWAPPED)) {\n1386:\t\t\tret = -EBUSY;\n1387:\t\t\tgoto out;\n1388:\t\t}\n1389:\t\n1390:\t\tif (bo-\u003edeleted) {\n1391:\t\t\tpgoff_t num_pages = tt-\u003enum_pages;\n1392:\t\n1393:\t\t\tret = ttm_bo_wait_ctx(bo, ctx);\n1394:\t\t\tif (ret)\n1395:\t\t\t\tgoto out;\n1396:\t\n1397:\t\t\tttm_bo_cleanup_memtype_use(bo);\n1398:\t\t\tret = num_pages;\n1399:\t\t\tgoto out;\n1400:\t\t}\n1401:\t\n1402:\t\t/*\n1403:\t\t * Move to system cached\n1404:\t\t */\n1405:\t\tif (bo-\u003eresource-\u003emem_type != TTM_PL_SYSTEM) {\n1406:\t\t\tstruct ttm_resource *evict_mem;\n1407:\t\t\tstruct ttm_place hop;\n1408:\t\n1409:\t\t\tmemset(\u0026hop, 0, sizeof(hop));\n1410:\t\t\tplace.mem_type = TTM_PL_SYSTEM;\n1411:\t\t\tret = ttm_resource_alloc(bo, \u0026place, \u0026evict_mem, NULL);\n1412:\t\t\tif (ret)\n1413:\t\t\t\tgoto out;\n1414:\t\n1415:\t\t\tret = ttm_bo_handle_move_mem(bo, evict_mem, true, ctx, \u0026hop);\n1416:\t\t\tif (ret) {\n1417:\t\t\t\tWARN(ret == -EMULTIHOP,\n1418:\t\t\t\t     \"Unexpected multihop in swapout - likely driver bug.\\n\");\n1419:\t\t\t\tttm_resource_free(bo, \u0026evict_mem);\n1420:\t\t\t\tgoto out;\n1421:\t\t\t}\n1422:\t\t}\n1423:\t\n1424:\t\t/*\n1425:\t\t * Make sure BO is idle.\n1426:\t\t */\n1427:\t\tret = ttm_bo_wait_ctx(bo, ctx);\n1428:\t\tif (ret)\n1429:\t\t\tgoto out;\n1430:\t\n1431:\t\tttm_bo_unmap_virtual(bo);\n1432:\t\tif (bdev-\u003efuncs-\u003eswap_notify)\n1433:\t\t\tbdev-\u003efuncs-\u003eswap_notify(bo);\n1434:\t\n1435:\t\tif (ttm_tt_is_populated(tt)) {\n1436:\t\t\tret = ttm_tt_swapout(bdev, tt, swapout_walk-\u003egfp_flags);\n1437:\t\t\tif (ret \u003e 0) {\n1438:\t\t\t\tspin_lock(\u0026bdev-\u003elru_lock);\n1439:\t\t\t\tttm_resource_del_bulk_move_unevictable(bo-\u003eresource, bo);\n1440:\t\t\t\tttm_resource_move_to_lru_tail(bo-\u003eresource);\n1441:\t\t\t\tspin_unlock(\u0026bdev-\u003elru_lock);\n1442:\t\t\t}\n1443:\t\t}\n1444:\t\n1445:\tout:\n1446:\t\t/* Consider -ENOMEM and -ENOSPC non-fatal. */\n1447:\t\tif (ret == -ENOMEM || ret == -ENOSPC)\n1448:\t\t\tret = -EBUSY;\n1449:\t\n"
}

gemini-3.8-flash

null

null

							input: 11319
							output: 248
							thoughts: 1077
						

**Analysis of the TTM Swapout Callback Patch**

Okay, let's break this down. In the `ttm_bo_swapout_cb` function, the code checks the return value `ret` of `ttm_tt_swapout`. Before the patch, the check was `if (!ret)`. This was clearly a mistake because `ttm_tt_swapout` returns the *number of pages swapped out* on success (a positive value), or a negative error code on failure. So, the original conditional was only triggered if *nothing* was swapped out, effectively skipping the subsequent LRU list management steps when swapping *did* succeed. Thus, the resource wasn't correctly managed after a successful swap. The patch simply corrects this logic to `if (ret > 0)`, ensuring the resource is managed on a swap out success.

Now, my primary concern is always uninitialized memory, of course. Let's evaluate the KMSAN implications. Given my experience, and considering the KMSAN criteria, which are explicitly laid out: the critical distinction is that KMSAN detects uninitialized memory, whereas KASAN and other tools detect many other bugs. Thus, if a bug can be caught by KASAN or another standard bug detector, KMSAN is not needed.

Does this patch introduce any risk in this area? Let's go through the checklist:

1.  **Kernel Structures to Userspace**: No. This patch doesn't involve any changes to data structures passed to userspace or changes that might create uninitialized structure padding.
2.  **Conditional Logic with Uninitialized Variables**: No. The variable `ret` is assigned the return value of `ttm_tt_swapout()`. It's initialized *before* the conditional check.
3.  **Data Structure Initialization**: No. The patch doesn't modify the creation or initialization of any complex data structures in a way that would leave uninitialized fields.
4.  **Bounds Checks/Length Logic**: No. The return value `ret` is correctly used as the page count and is not involved with bounds checks or buffer access.

This patch is purely a *logic fix* in LRU list management. The bug was that the swapped BO wasn't moved to the LRU tail correctly due to the incorrect conditional. After the patch, that movement happens. The list operations (`ttm_resource_del_bulk_move_unevictable` and `ttm_resource_move_to_lru_tail`) are already dealing with *initialized* data structures protected by the lock. No new data is created. No existing data is modified in a way that could cause uninitialized memory issues.

Let's double-check: `ttm_tt_swapout()` copies pages, unpopulates the pages, and returns the number of pages swapped. The list management operations use a lock. There are no new variables, buffers, stack arrays, or user copies involved. And, again, `ret` is properly initialized.

Therefore, this patch has absolutely nothing to do with uninitialized memory. The risks here would be related to standard resource management and locking. No KMSAN is necessary here. The `NeedsKMSAN` flag should be set to `false`.

{
  "KMSANReasoning": "The patch fixes a logic bug in `ttm_bo_swapout_cb()` where the success condition of `ttm_tt_swapout()` was erroneously checked as `if (!ret)` instead of `if (ret \u003e 0)`. Because `ttm_tt_swapout()` returns the positive number of swapped-out pages on success or a negative error code on failure, the LRU management functions (`ttm_resource_del_bulk_move_unevictable` and `ttm_resource_move_to_lru_tail`) were never called upon successful swapout.\n\nThis change strictly touches LRU tracking control flow and list manipulation for buffer objects. It does not introduce, modify, or read any uninitialized stack or heap memory, does not alter copy-to-user operations or infoleak surfaces, and does not alter buffer allocation/initialization logic. Any memory corruption or locking issues in LRU manipulation would be caught by standard KASAN/LOCKDEP builds. Therefore, a dedicated KMSAN fuzzing session is not warranted.",
  "NeedsKMSAN": false
}

{
  "KMSANReasoning": "The patch fixes a logic bug in `ttm_bo_swapout_cb()` where the success condition of `ttm_tt_swapout()` was erroneously checked as `if (!ret)` instead of `if (ret \u003e 0)`. Because `ttm_tt_swapout()` returns the positive number of swapped-out pages on success or a negative error code on failure, the LRU management functions (`ttm_resource_del_bulk_move_unevictable` and `ttm_resource_move_to_lru_tail`) were never called upon successful swapout.\n\nThis change strictly touches LRU tracking control flow and list manipulation for buffer objects. It does not introduce, modify, or read any uninitialized stack or heap memory, does not alter copy-to-user operations or infoleak surfaces, and does not alter buffer allocation/initialization logic. Any memory corruption or locking issues in LRU manipulation would be caught by standard KASAN/LOCKDEP builds. Therefore, a dedicated KMSAN fuzzing session is not warranted.",
  "NeedsKMSAN": false
}