AI Trajectory

null

{
  "EnableConfigs": [
    "MEMORY_HOTPLUG",
    "MEMORY_HOTREMOVE",
    "INTEL_TDX_HOST",
    "VIRTIO_MEM"
  ],
  "FocusSymbols": [
    "memblock_bsearch_start",
    "memblock_add_range",
    "memblock_isolate_range",
    "memblock_add_node",
    "memblock_remove_range",
    "memblock_remove",
    "memblock_phys_free"
  ],
  "KMSANReasoning": "The patch optimizes region lookup in early boot memblock management (mm/memblock.c) by introducing memblock_bsearch_start() and for_each_memblock_type_from(). The changes operate exclusively on existing, initialized memblock regions and internal indices. Potential bugs in this logic (such as index calculation errors or array out-of-bounds access) would be caught by KASAN and standard assertion/bounds checking. The patch does not introduce or expose uninitialized memory, does not copy kernel data to user space, and does not alter padding/uninitialized field initialization, making dedicated KMSAN fuzzing unnecessary.",
  "NeedsKMSAN": false,
  "Reasoning": "The patch modifies the memory block management subsystem (mm/memblock.c), introducing binary search (memblock_bsearch_start) to find candidate regions in memblock_add_range and memblock_isolate_range. This affects core memory management and region splitting/merging algorithms reachable at runtime during memory hotplug and hotremove when memblock metadata is retained (CONFIG_ARCH_KEEP_MEMBLOCK). Fuzzing is warranted to test region manipulation logic and boundaries.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit f6f0e825bfc8372d55dd8b0bf8b1501c090fd441\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Sat Sep 5 00:53:12 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/mm/memblock.c b/mm/memblock.c\nindex 9ce86349a29fa..88940474b0203 100644\n--- a/mm/memblock.c\n+++ b/mm/memblock.c\n@@ -160,6 +160,11 @@ static __refdata struct memblock_type *memblock_memory = \u0026memblock.memory;\n \t     i \u003c memblock_type-\u003ecnt;\t\t\t\t\t\\\n \t     i++, rgn = \u0026memblock_type-\u003eregions[i])\n \n+#define for_each_memblock_type_from(i, memblock_type, rgn, start)\t\\\n+\tfor (i = (start), rgn = \u0026memblock_type-\u003eregions[i];\t\t\\\n+\t     i \u003c memblock_type-\u003ecnt;\t\t\t\t\t\\\n+\t     i++, rgn = \u0026memblock_type-\u003eregions[i])\n+\n #define memblock_dbg(fmt, ...)\t\t\t\t\t\t\\\n \tdo {\t\t\t\t\t\t\t\t\\\n \t\tif (memblock_debug)\t\t\t\t\t\\\n@@ -591,6 +596,33 @@ static void __init_memblock memblock_insert_region(struct memblock_type *type,\n \ttype-\u003etotal_size += size;\n }\n \n+/**\n+ * memblock_bsearch_start - Find the first region index where rend \u003e base\n+ * @type: memblock type to search\n+ * @base: base physical address of the candidate range\n+ *\n+ * Returns the first region index that could potentially overlap @base.\n+ */\n+static int __init_memblock memblock_bsearch_start(struct memblock_type *type,\n+\t\t\t\t\t\t  phys_addr_t base)\n+{\n+\tint mid, low = 0;\n+\tint high = type-\u003ecnt;\n+\n+\tif (type-\u003ecnt \u0026\u0026 base \u003e= type-\u003eregions[type-\u003ecnt - 1].base +\n+\t\t\t\t type-\u003eregions[type-\u003ecnt - 1].size)\n+\t\treturn type-\u003ecnt;\n+\n+\twhile (low \u003c high) {\n+\t\tmid = (low + high) / 2;\n+\t\tif (type-\u003eregions[mid].base + type-\u003eregions[mid].size \u003c= base)\n+\t\t\tlow = mid + 1;\n+\t\telse\n+\t\t\thigh = mid;\n+\t}\n+\treturn low;\n+}\n+\n /**\n  * memblock_add_range - add new memblock region\n  * @type: memblock type to add new region into\n@@ -651,7 +683,8 @@ static int __init_memblock memblock_add_range(struct memblock_type *type,\n \tbase = obase;\n \tnr_new = 0;\n \n-\tfor_each_memblock_type(idx, type, rgn) {\n+\tfor_each_memblock_type_from(idx, type, rgn,\n+\t\t\t\t    memblock_bsearch_start(type, base)) {\n \t\tphys_addr_t rbase = rgn-\u003ebase;\n \t\tphys_addr_t rend = rbase + rgn-\u003esize;\n \n@@ -827,7 +860,8 @@ static int __init_memblock memblock_isolate_range(struct memblock_type *type,\n \t\tif (memblock_double_array(type, base, size) \u003c 0)\n \t\t\treturn -ENOMEM;\n \n-\tfor_each_memblock_type(idx, type, rgn) {\n+\tfor_each_memblock_type_from(idx, type, rgn,\n+\t\t\t\t    memblock_bsearch_start(type, base)) {\n \t\tphys_addr_t rbase = rgn-\u003ebase;\n \t\tphys_addr_t rend = rbase + rgn-\u003esize;\n \n"
}

core

null

{
  "EnableConfigs": [
    "MEMORY_HOTPLUG",
    "MEMORY_HOTREMOVE",
    "INTEL_TDX_HOST",
    "VIRTIO_MEM"
  ],
  "FocusSymbols": [
    "memblock_bsearch_start",
    "memblock_add_range",
    "memblock_isolate_range",
    "memblock_add_node",
    "memblock_remove_range",
    "memblock_remove",
    "memblock_phys_free"
  ],
  "Reasoning": "The patch modifies the memory block management subsystem (mm/memblock.c), introducing binary search (memblock_bsearch_start) to find candidate regions in memblock_add_range and memblock_isolate_range. This affects core memory management and region splitting/merging algorithms reachable at runtime during memory hotplug and hotremove when memblock metadata is retained (CONFIG_ARCH_KEEP_MEMBLOCK). Fuzzing is warranted to test region manipulation logic and boundaries.",
  "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 f6f0e825bfc8372d55dd8b0bf8b1501c090fd441
Author: syz-cluster <triage@syzkaller.com>
Date:   Sat Sep 5 00:53:12 2026 +0000

    syz-cluster: applied patch under review

diff --git a/mm/memblock.c b/mm/memblock.c
index 9ce86349a29fa..88940474b0203 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -160,6 +160,11 @@ static __refdata struct memblock_type *memblock_memory = &memblock.memory;
 	     i < memblock_type->cnt;					\
 	     i++, rgn = &memblock_type->regions[i])
 
+#define for_each_memblock_type_from(i, memblock_type, rgn, start)	\
+	for (i = (start), rgn = &memblock_type->regions[i];		\
+	     i < memblock_type->cnt;					\
+	     i++, rgn = &memblock_type->regions[i])
+
 #define memblock_dbg(fmt, ...)						\
 	do {								\
 		if (memblock_debug)					\
@@ -591,6 +596,33 @@ static void __init_memblock memblock_insert_region(struct memblock_type *type,
 	type->total_size += size;
 }
 
+/**
+ * memblock_bsearch_start - Find the first region index where rend > base
+ * @type: memblock type to search
+ * @base: base physical address of the candidate range
+ *
+ * Returns the first region index that could potentially overlap @base.
+ */
+static int __init_memblock memblock_bsearch_start(struct memblock_type *type,
+						  phys_addr_t base)
+{
+	int mid, low = 0;
+	int high = type->cnt;
+
+	if (type->cnt && base >= type->regions[type->cnt - 1].base +
+				 type->regions[type->cnt - 1].size)
+		return type->cnt;
+
+	while (low < high) {
+		mid = (low + high) / 2;
+		if (type->regions[mid].base + type->regions[mid].size <= base)
+			low = mid + 1;
+		else
+			high = mid;
+	}
+	return low;
+}
+
 /**
  * memblock_add_range - add new memblock region
  * @type: memblock type to add new region into
@@ -651,7 +683,8 @@ static int __init_memblock memblock_add_range(struct memblock_type *type,
 	base = obase;
 	nr_new = 0;
 
-	for_each_memblock_type(idx, type, rgn) {
+	for_each_memblock_type_from(idx, type, rgn,
+				    memblock_bsearch_start(type, base)) {
 		phys_addr_t rbase = rgn->base;
 		phys_addr_t rend = rbase + rgn->size;
 
@@ -827,7 +860,8 @@ static int __init_memblock memblock_isolate_range(struct memblock_type *type,
 		if (memblock_double_array(type, base, size) < 0)
 			return -ENOMEM;
 
-	for_each_memblock_type(idx, type, rgn) {
+	for_each_memblock_type_from(idx, type, rgn,
+				    memblock_bsearch_start(type, base)) {
 		phys_addr_t rbase = rgn->base;
 		phys_addr_t rend = rbase + rgn->size;
 

gemini-3.7-flash

null

null

							input: 3588
							output: 35
							thoughts: 201
						

**Analyzing the Patch for Fuzzing Potential**

Okay, let's dive into this patch and figure out if it's even worth our time fuzzing, and if so, how to best approach it. What configurations are going to be necessary? And what are our key focus symbols?

First, I'll take a look at the modified file, `mm/memblock.c`. Hmm, I see these functions have been touched: `for_each_memblock_type_from`, `memblock_bsearch_start`, `memblock_add_range`, and `memblock_isolate_range`. That `__init_memblock` prefix... wait a minute! Are these functions only used during early boot, the init phase, or is there a possibility that `memblock` code is accessible at runtime, perhaps for something like memory hotplug?

I need to confirm whether `memblock_add_range`, `memblock_isolate_range`, or other `memblock_*` functions are called later, in the main runtime of the kernel. I'll need to check `mm/memblock.c` and trace those calls. Time to break out `grepper` or `read-file` and get digging.

{
  "Expression": "memblock_add_range|memblock_isolate_range",
  "PathPrefix": "mm/"
}

{
  "Output": "mm/memblock.c=606=static int __init_memblock memblock_bsearch_start(struct memblock_type *type,\n--\nmm/memblock.c-626-/**\nmm/memblock.c:627: * memblock_add_range - add new memblock region\nmm/memblock.c-628- * @type: memblock type to add new region into\n--\nmm/memblock.c-641- */\nmm/memblock.c:642:static int __init_memblock memblock_add_range(struct memblock_type *type,\nmm/memblock.c-643-\t\t\t\tphys_addr_t base, phys_addr_t size,\n--\nmm/memblock.c-756- * Add new memblock region [@base, @base + @size) to the \"memory\"\nmm/memblock.c:757: * type. See memblock_add_range() description for mode details\nmm/memblock.c-758- *\n--\nmm/memblock.c=762=int __init_memblock memblock_add_node(phys_addr_t base, phys_addr_t size,\n--\nmm/memblock.c-769-\nmm/memblock.c:770:\treturn memblock_add_range(\u0026memblock.memory, base, size, nid, flags);\nmm/memblock.c-771-}\n--\nmm/memblock.c-778- * Add new memblock region [@base, @base + @size) to the \"memory\"\nmm/memblock.c:779: * type. See memblock_add_range() description for mode details\nmm/memblock.c-780- *\n--\nmm/memblock.c=784=int __init_memblock memblock_add(phys_addr_t base, phys_addr_t size)\n--\nmm/memblock.c-790-\nmm/memblock.c:791:\treturn memblock_add_range(\u0026memblock.memory, base, size, MAX_NUMNODES, 0);\nmm/memblock.c-792-}\n--\nmm/memblock.c=805=bool __init_memblock memblock_validate_numa_coverage(unsigned long threshold_bytes)\n--\nmm/memblock.c-828-/**\nmm/memblock.c:829: * memblock_isolate_range - isolate given range into disjoint memblocks\nmm/memblock.c-830- * @type: memblock type to isolate range for\n--\nmm/memblock.c-844- */\nmm/memblock.c:845:static int __init_memblock memblock_isolate_range(struct memblock_type *type,\nmm/memblock.c-846-\t\t\t\t\tphys_addr_t base, phys_addr_t size,\n--\nmm/memblock.c=906=static int __init_memblock memblock_remove_range(struct memblock_type *type,\n--\nmm/memblock.c-911-\nmm/memblock.c:912:\tret = memblock_isolate_range(type, base, size, \u0026start_rgn, \u0026end_rgn);\nmm/memblock.c-913-\tif (ret)\n--\nmm/memblock.c=1041=int __init_memblock __memblock_reserve(phys_addr_t base, phys_addr_t size,\n--\nmm/memblock.c-1048-\nmm/memblock.c:1049:\treturn memblock_add_range(\u0026memblock.reserved, base, size, nid, flags);\nmm/memblock.c-1050-}\n--\nmm/memblock.c=1053=int __init_memblock memblock_physmem_add(phys_addr_t base, phys_addr_t size)\n--\nmm/memblock.c-1059-\nmm/memblock.c:1060:\treturn memblock_add_range(\u0026physmem, base, size, MAX_NUMNODES, 0);\nmm/memblock.c-1061-}\n--\nmm/memblock.c=1076=static int __init_memblock memblock_setclr_flag(struct memblock_type *type,\n--\nmm/memblock.c-1080-\nmm/memblock.c:1081:\tret = memblock_isolate_range(type, base, size, \u0026start_rgn, \u0026end_rgn);\nmm/memblock.c-1082-\tif (ret)\n--\nmm/memblock.c=1523=int __init_memblock memblock_set_node(phys_addr_t base, phys_addr_t size,\n--\nmm/memblock.c-1529-\nmm/memblock.c:1530:\tret = memblock_isolate_range(type, base, size, \u0026start_rgn, \u0026end_rgn);\nmm/memblock.c-1531-\tif (ret)\n--\nmm/memblock.c=2053=void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size)\n--\nmm/memblock.c-2065-\nmm/memblock.c:2066:\tret = memblock_isolate_range(\u0026memblock.memory, base, size,\nmm/memblock.c-2067-\t\t\t\t\t\t\u0026start_rgn, \u0026end_rgn);\n"
}

gemini-3.7-flash

null

null

							input: 5464
							output: 21
							thoughts: 28
						

Here's my thought process, as requested:

**Investigating the Definition of `__init_memblock`**

Okay, so I need to understand what's going on with `__init_memblock`. My first step, naturally, is to determine where and how it's defined. Given that I'm likely dealing with low-level memory management code, I'll assume it's part of the kernel or a related library. So, I need to find the source code, and since I'm trying to figure out how it's defined, I'll reach for `grep`. A simple `grep` for the exact string `__init_memblock` should be a good starting point. I can quickly scan the results to see the file and definition. That should quickly tell me what I need to know about this function.

{
  "Expression": "#define __init_memblock"
}

{
  "Output": "include/linux/memblock.h=114=extern struct memblock memblock;\n--\ninclude/linux/memblock.h-116-#ifndef CONFIG_ARCH_KEEP_MEMBLOCK\ninclude/linux/memblock.h:117:#define __init_memblock __meminit\ninclude/linux/memblock.h-118-#define __initdata_memblock __meminitdata\ninclude/linux/memblock.h=119=void memblock_discard(void);\ninclude/linux/memblock.h-120-#else\ninclude/linux/memblock.h:121:#define __init_memblock\ninclude/linux/memblock.h-122-#define __initdata_memblock\n"
}

gemini-3.7-flash

null

null

							input: 5875
							output: 33
							thoughts: 95
						

**Analyzing Memory Initialization in the Kernel**

Okay, so I'm diving into this memory initialization process, trying to understand how it all fits together. First things first: `__meminit` – that's either the same as `__init`, or it's retained if memory hotplug is enabled, which makes sense. I have to make sure I grasp the relationship correctly. Now, a key question comes to mind: how crucial is the memblock mechanism in the grand scheme of things? Specifically, is `memblock` still relevant during runtime when memory hotplug is involved? Or is its role limited to the boot process? Is it discarded later, or does it serve some purpose throughout the system's life? This is a critical point that needs clarification.

To get a clearer picture, my next step is to perform a detailed audit of the kernel source code. I need to pinpoint every instance where the `memblock_add`, `memblock_add_range`, and other `memblock` functions are invoked. This will illuminate exactly how `memblock` is utilized, which in turn will give me a comprehensive understanding of its role in both the initial boot sequence and any memory hotplug operations that might be taking place.

{
  "Expression": "memblock_add\\(|memblock_add_node\\(|memblock_reserve\\("
}

{
  "Output": "\nFull output is too long, showing 500 out of 1758 lines.\nUse more precise expression if possible.\n\nDocumentation/admin-guide/ramoops.rst=134=You can specify either RAM memory or peripheral devices' memory. However, when\nDocumentation/admin-guide/ramoops.rst:135:specifying RAM, be sure to reserve the memory by issuing memblock_reserve()\nDocumentation/admin-guide/ramoops.rst-136-very early in the architecture code, e.g.::\n--\nDocumentation/admin-guide/ramoops.rst-139-\nDocumentation/admin-guide/ramoops.rst:140:\tmemblock_reserve(ramoops_data.mem_address, ramoops_data.mem_size);\nDocumentation/admin-guide/ramoops.rst-141-\n--\narch/alpha/kernel/core_irongate.c=202=albacore_init_arch(void)\n--\narch/alpha/kernel/core_irongate.c-241-#endif\narch/alpha/kernel/core_irongate.c:242:\t\tmemblock_reserve(pci_mem, memtop - pci_mem);\narch/alpha/kernel/core_irongate.c-243-\t\tprintk(\"irongate_init_arch: temporarily reserving \"\n--\narch/alpha/kernel/setup.c=286=setup_memory(void *kernel_end)\n--\narch/alpha/kernel/setup.c-307-\narch/alpha/kernel/setup.c:308:\t\tmemblock_add(PFN_PHYS(cluster-\u003estart_pfn),\narch/alpha/kernel/setup.c-309-\t\t\t     cluster-\u003enumpages \u003c\u003c PAGE_SHIFT);\n--\narch/alpha/kernel/setup.c-314-\t\tif (cluster-\u003eusage \u0026 3)\narch/alpha/kernel/setup.c:315:\t\t\tmemblock_reserve(PFN_PHYS(cluster-\u003estart_pfn),\narch/alpha/kernel/setup.c-316-\t\t\t\t         cluster-\u003enumpages \u003c\u003c PAGE_SHIFT);\n--\narch/alpha/kernel/setup.c-346-\tkernel_size = virt_to_phys(kernel_end) - KERNEL_START_PHYS;\narch/alpha/kernel/setup.c:347:\tmemblock_reserve(KERNEL_START_PHYS, kernel_size);\narch/alpha/kernel/setup.c-348-\n--\narch/alpha/kernel/setup.c-362-\t\t} else {\narch/alpha/kernel/setup.c:363:\t\t\tmemblock_reserve(virt_to_phys((void *)initrd_start),\narch/alpha/kernel/setup.c-364-\t\t\t\t\tINITRD_SIZE);\n--\narch/arc/mm/init.c=51=void __init early_init_dt_add_memory_arch(u64 base, u64 size)\n--\narch/arc/mm/init.c-60-\t\tin_use = 1;\narch/arc/mm/init.c:61:\t\tmemblock_add_node(base, size, 0, MEMBLOCK_NONE);\narch/arc/mm/init.c-62-\t} else {\n--\narch/arc/mm/init.c-66-\t\tin_use = 1;\narch/arc/mm/init.c:67:\t\tmemblock_add_node(base, size, 1, MEMBLOCK_NONE);\narch/arc/mm/init.c:68:\t\tmemblock_reserve(base, size);\narch/arc/mm/init.c-69-#endif\n--\narch/arc/mm/init.c=101=void __init setup_arch_memory(void)\n--\narch/arc/mm/init.c-123-\narch/arc/mm/init.c:124:\tmemblock_reserve(CONFIG_LINUX_LINK_BASE,\narch/arc/mm/init.c-125-\t\t\t __pa(_end) - CONFIG_LINUX_LINK_BASE);\n--\narch/arc/mm/init.c-128-\tif (phys_initrd_size) {\narch/arc/mm/init.c:129:\t\tmemblock_reserve(phys_initrd_start, phys_initrd_size);\narch/arc/mm/init.c-130-\t\tinitrd_start = (unsigned long)__va(phys_initrd_start);\n--\narch/arm/kernel/setup.c=760=int __init arm_add_memory(u64 start, u64 size)\n--\narch/arm/kernel/setup.c-816-\narch/arm/kernel/setup.c:817:\tmemblock_add(start, size);\narch/arm/kernel/setup.c-818-\treturn 0;\n--\narch/arm/kernel/setup.c=1096=void __init setup_arch(char **cmdline_p)\n--\narch/arm/kernel/setup.c-1107-\t\tif (mdesc)\narch/arm/kernel/setup.c:1108:\t\t\tmemblock_reserve(__atags_pointer,\narch/arm/kernel/setup.c-1109-\t\t\t\t\t fdt_totalsize(atags_vaddr));\n--\narch/arm/mach-hisi/platmcpm.c=265=static int __init hip04_smp_init(void)\n--\narch/arm/mach-hisi/platmcpm.c-287-\narch/arm/mach-hisi/platmcpm.c:288:\tret = memblock_reserve(hip04_boot_method[0], hip04_boot_method[1]);\narch/arm/mach-hisi/platmcpm.c-289-\tif (ret)\n--\narch/arm/mach-mvebu/board-v7.c=66=static int __init mvebu_scan_mem(unsigned long node, const char *uname,\n--\narch/arm/mach-mvebu/board-v7.c-91-\narch/arm/mach-mvebu/board-v7.c:92:\t\tmemblock_reserve(base, MVEBU_DDR_TRAINING_AREA_SZ);\narch/arm/mach-mvebu/board-v7.c-93-\t}\n--\narch/arm/mach-mvebu/board-v7.c-97-\narch/arm/mach-mvebu/board-v7.c:98:static void __init mvebu_memblock_reserve(void)\narch/arm/mach-mvebu/board-v7.c-99-{\n--\narch/arm/mach-mvebu/board-v7.c-102-#else\narch/arm/mach-mvebu/board-v7.c:103:static void __init mvebu_memblock_reserve(void) {}\narch/arm/mach-mvebu/board-v7.c-104-#endif\n--\narch/arm/mach-pxa/spitz.c=1134=static void __init spitz_fixup(struct tag *tags, char **cmdline)\n--\narch/arm/mach-pxa/spitz.c-1136-\tsharpsl_save_param();\narch/arm/mach-pxa/spitz.c:1137:\tmemblock_add(0xa0000000, SZ_64M);\narch/arm/mach-pxa/spitz.c-1138-}\n--\narch/arm/mach-versatile/integrator.c=91=void __init integrator_reserve(void)\narch/arm/mach-versatile/integrator.c-92-{\narch/arm/mach-versatile/integrator.c:93:\tmemblock_reserve(PHYS_OFFSET, __pa(swapper_pg_dir) - PHYS_OFFSET);\narch/arm/mach-versatile/integrator.c-94-}\n--\narch/arm/mach-zynq/common.c=52=static void __init zynq_memory_init(void)\n--\narch/arm/mach-zynq/common.c-54-\tif (!__pa(PAGE_OFFSET))\narch/arm/mach-zynq/common.c:55:\t\tmemblock_reserve(__pa(PAGE_OFFSET), 0x80000);\narch/arm/mach-zynq/common.c-56-}\n--\narch/arm/mm/init.c=180=void __init arm_memblock_init(const struct machine_desc *mdesc)\n--\narch/arm/mm/init.c-182-\t/* Register the kernel text, kernel data and initrd with memblock. */\narch/arm/mm/init.c:183:\tmemblock_reserve(__pa(KERNEL_START), KERNEL_END - KERNEL_START);\narch/arm/mm/init.c-184-\n--\narch/arm/mm/init.c-186-\narch/arm/mm/init.c:187:\tarm_mm_memblock_reserve();\narch/arm/mm/init.c-188-\n--\narch/arm/mm/mm.h=89=void __init bootmem_init(void);\narch/arm/mm/mm.h:90:void arm_mm_memblock_reserve(void);\narch/arm/mm/mm.h-91-#ifdef CONFIG_CMA_AREAS\n--\narch/arm/mm/mmu.c=1273=static __init void prepare_page_table(void)\n--\narch/arm/mm/mmu.c-1334- */\narch/arm/mm/mmu.c:1335:void __init arm_mm_memblock_reserve(void)\narch/arm/mm/mmu.c-1336-{\n--\narch/arm/mm/mmu.c-1340-\t */\narch/arm/mm/mmu.c:1341:\tmemblock_reserve(__pa(swapper_pg_dir), SWAPPER_PG_DIR_SIZE);\narch/arm/mm/mmu.c-1342-\n--\narch/arm/mm/mmu.c-1347-\t */\narch/arm/mm/mmu.c:1348:\tmemblock_reserve(PHYS_OFFSET, __pa(swapper_pg_dir) - PHYS_OFFSET);\narch/arm/mm/mmu.c-1349-#endif\n--\narch/arm/mm/nommu.c=63=unsigned long setup_vectors_base(void)\n--\narch/arm/mm/nommu.c-81-\narch/arm/mm/nommu.c:82:void __init arm_mm_memblock_reserve(void)\narch/arm/mm/nommu.c-83-{\n--\narch/arm/mm/nommu.c-90-\t */\narch/arm/mm/nommu.c:91:\tmemblock_reserve(vectors_base, 2 * PAGE_SIZE);\narch/arm/mm/nommu.c-92-#else /* ifndef CONFIG_CPU_V7M */\n--\narch/arm/mm/nommu.c-101-\t */\narch/arm/mm/nommu.c:102:\tmemblock_reserve(0, 1);\narch/arm/mm/nommu.c-103-}\n--\narch/arm64/kernel/machine_kexec.c=235=void crash_post_resume(void)\n--\narch/arm64/kernel/machine_kexec.c-247- * Note that all the pages in crash dump kernel memory have been initially\narch/arm64/kernel/machine_kexec.c:248: * marked as Reserved as memory was allocated via memblock_reserve().\narch/arm64/kernel/machine_kexec.c-249- *\n--\narch/arm64/kernel/setup.c=170=static void __init setup_machine_fdt(phys_addr_t dt_phys)\n--\narch/arm64/kernel/setup.c-176-\tif (dt_virt)\narch/arm64/kernel/setup.c:177:\t\tmemblock_reserve(dt_phys, size);\narch/arm64/kernel/setup.c-178-\n--\narch/arm64/mm/init.c=196=void __init arm64_memblock_init(void)\n--\narch/arm64/mm/init.c-256-\t\tmemblock_mem_limit_remove_map(memory_limit);\narch/arm64/mm/init.c:257:\t\tmemblock_add(__pa_symbol(_text), (resource_size_t)(_end - _text));\narch/arm64/mm/init.c-258-\t}\n--\narch/arm64/mm/init.c-282-\t\t} else {\narch/arm64/mm/init.c:283:\t\t\tmemblock_add(base, size);\narch/arm64/mm/init.c-284-\t\t\tmemblock_clear_nomap(base, size);\narch/arm64/mm/init.c:285:\t\t\tmemblock_reserve(base, size);\narch/arm64/mm/init.c-286-\t\t}\n--\narch/arm64/mm/init.c-292-\t */\narch/arm64/mm/init.c:293:\tmemblock_reserve(__pa_symbol(_text), _end - _text);\narch/arm64/mm/init.c-294-\tif (IS_ENABLED(CONFIG_BLK_DEV_INITRD) \u0026\u0026 phys_initrd_size) {\n--\narch/csky/kernel/setup.c=16=static void __init setup_initrd(void)\n--\narch/csky/kernel/setup.c-37-\narch/csky/kernel/setup.c:38:\tmemblock_reserve(__pa(initrd_start), size);\narch/csky/kernel/setup.c-39-\n--\narch/csky/kernel/setup.c=62=static void __init csky_memblock_init(void)\n--\narch/csky/kernel/setup.c-67-\narch/csky/kernel/setup.c:68:\tmemblock_reserve(__pa(_start), _end - _start);\narch/csky/kernel/setup.c-69-\n--\narch/hexagon/mm/init.c=104=void __init setup_arch_memory(void)\n--\narch/hexagon/mm/init.c-123-\narch/hexagon/mm/init.c:124:\tmemblock_add(PHYS_OFFSET,\narch/hexagon/mm/init.c-125-\t\t     (bootmem_lastpg - ARCH_PFN_OFFSET) \u003c\u003c PAGE_SHIFT);\n--\narch/hexagon/mm/init.c-127-\t/* Reserve kernel text/data/bss */\narch/hexagon/mm/init.c:128:\tmemblock_reserve(PHYS_OFFSET,\narch/hexagon/mm/init.c-129-\t\t\t (bootmem_startpg - ARCH_PFN_OFFSET) \u003c\u003c PAGE_SHIFT);\n--\narch/hexagon/mm/init.c-135-\tmin_low_pfn = ARCH_PFN_OFFSET;\narch/hexagon/mm/init.c:136:\tmemblock_reserve(PFN_PHYS(max_low_pfn), DMA_RESERVED_BYTES);\narch/hexagon/mm/init.c-137-\n--\narch/loongarch/kernel/acpi.c=378=void __init arch_reserve_mem_area(acpi_physical_address addr, size_t size)\narch/loongarch/kernel/acpi.c-379-{\narch/loongarch/kernel/acpi.c:380:\tmemblock_reserve(addr, size);\narch/loongarch/kernel/acpi.c-381-}\n--\narch/loongarch/kernel/efi.c=82=static void __init init_primary_display(void)\n--\narch/loongarch/kernel/efi.c-97-\narch/loongarch/kernel/efi.c:98:\tmemblock_reserve(__screen_info_lfb_base(\u0026sysfb_primary_display.screen),\narch/loongarch/kernel/efi.c-99-\t\t\t sysfb_primary_display.screen.lfb_size);\n--\narch/loongarch/kernel/efi.c=102=void __init efi_init(void)\n--\narch/loongarch/kernel/efi.c-158-\t\t */\narch/loongarch/kernel/efi.c:159:\t\tmemblock_reserve((phys_addr_t)boot_memmap, sizeof(*tbl) + data.size);\narch/loongarch/kernel/efi.c-160-\t\tset_bit(EFI_PRESERVE_BS_REGIONS, \u0026efi.flags);\n--\narch/loongarch/kernel/mem.c=13=void __init memblock_init(void)\n--\narch/loongarch/kernel/mem.c-31-\t\tcase EFI_CONVENTIONAL_MEMORY:\narch/loongarch/kernel/mem.c:32:\t\t\tmemblock_add(mem_start, mem_size);\narch/loongarch/kernel/mem.c-33-\t\t\tbreak;\n--\narch/loongarch/kernel/mem.c-36-\t\tcase EFI_ACPI_RECLAIM_MEMORY:\narch/loongarch/kernel/mem.c:37:\t\t\tmemblock_add(mem_start, mem_size);\narch/loongarch/kernel/mem.c-38-\t\t\tfallthrough;\n--\narch/loongarch/kernel/mem.c-43-\t\tcase EFI_MEMORY_MAPPED_IO_PORT_SPACE:\narch/loongarch/kernel/mem.c:44:\t\t\tmemblock_reserve(mem_start, mem_size);\narch/loongarch/kernel/mem.c-45-\t\t\tbreak;\n--\narch/loongarch/kernel/mem.c-53-\t/* Reserve the first 2MB */\narch/loongarch/kernel/mem.c:54:\tmemblock_reserve(PHYS_OFFSET, 0x200000);\narch/loongarch/kernel/mem.c-55-\narch/loongarch/kernel/mem.c-56-\t/* Reserve the kernel text/data/bss */\narch/loongarch/kernel/mem.c:57:\tmemblock_reserve(__pa_symbol(\u0026_text),\narch/loongarch/kernel/mem.c-58-\t\t\t __pa_symbol(\u0026_end) - __pa_symbol(\u0026_text));\n--\narch/loongarch/kernel/setup.c=191=static int __init early_parse_mem(char *p)\n--\narch/loongarch/kernel/setup.c-221-\tif (!IS_ENABLED(CONFIG_NUMA))\narch/loongarch/kernel/setup.c:222:\t\tmemblock_add(start, size);\narch/loongarch/kernel/setup.c-223-\telse\narch/loongarch/kernel/setup.c:224:\t\tmemblock_add_node(start, size, pa_to_nid(start), MEMBLOCK_NONE);\narch/loongarch/kernel/setup.c-225-\n--\narch/loongarch/kernel/setup.c=230=static void __init arch_reserve_vmcore(void)\n--\narch/loongarch/kernel/setup.c-257-\narch/loongarch/kernel/setup.c:258:\tmemblock_reserve(elfcorehdr_addr, elfcorehdr_size);\narch/loongarch/kernel/setup.c-259-\n--\narch/loongarch/kernel/setup.c=380=static void __init check_kernel_sections_mem(void)\n--\narch/loongarch/kernel/setup.c-386-\t\tpr_info(\"Kernel sections are not in the memory maps\\n\");\narch/loongarch/kernel/setup.c:387:\t\tmemblock_add(start, size);\narch/loongarch/kernel/setup.c-388-\t}\n--\narch/m68k/kernel/setup_mm.c=206=void __init setup_arch(char **cmdline_p)\n--\narch/m68k/kernel/setup_mm.c-330-\tif (IS_ENABLED(CONFIG_BLK_DEV_INITRD) \u0026\u0026 m68k_ramdisk.size)\narch/m68k/kernel/setup_mm.c:331:\t\tmemblock_reserve(m68k_ramdisk.addr, m68k_ramdisk.size);\narch/m68k/kernel/setup_mm.c-332-\n--\narch/m68k/kernel/setup_no.c=82=void __init setup_arch(char **cmdline_p)\n--\narch/m68k/kernel/setup_no.c-142-\narch/m68k/kernel/setup_no.c:143:\tmemblock_add(_rambase, memory_end - _rambase);\narch/m68k/kernel/setup_no.c:144:\tmemblock_reserve(_rambase, memory_start - _rambase);\narch/m68k/kernel/setup_no.c-145-\n--\narch/m68k/kernel/setup_no.c-159-\t\t\t(initrd_end \u003c memory_end))\narch/m68k/kernel/setup_no.c:160:\t\tmemblock_reserve(initrd_start, initrd_end - initrd_start);\narch/m68k/kernel/setup_no.c-161-#endif /* if defined(CONFIG_BLK_DEV_INITRD) */\n--\narch/m68k/mm/mcfmmu.c=148=void __init cf_bootmem_alloc(void)\n--\narch/m68k/mm/mcfmmu.c-155-\narch/m68k/mm/mcfmmu.c:156:\tmemblock_add_node(m68k_memory[0].addr, m68k_memory[0].size, 0,\narch/m68k/mm/mcfmmu.c-157-\t\t\t  MEMBLOCK_NONE);\n--\narch/m68k/mm/mcfmmu.c-168-\t/* Reserve kernel text/data/bss */\narch/m68k/mm/mcfmmu.c:169:\tmemblock_reserve(_rambase, memstart - _rambase);\narch/m68k/mm/mcfmmu.c-170-\n--\narch/m68k/mm/motorola.c=430=void __init paging_init(void)\n--\narch/m68k/mm/motorola.c-451-\tmax_addr = min_addr + m68k_memory[0].size - 1;\narch/m68k/mm/motorola.c:452:\tmemblock_add_node(m68k_memory[0].addr, m68k_memory[0].size, 0,\narch/m68k/mm/motorola.c-453-\t\t\t  MEMBLOCK_NONE);\n--\narch/m68k/mm/motorola.c-463-\t\t}\narch/m68k/mm/motorola.c:464:\t\tmemblock_add_node(m68k_memory[i].addr, m68k_memory[i].size, i,\narch/m68k/mm/motorola.c-465-\t\t\t\t  MEMBLOCK_NONE);\n--\narch/m68k/mm/motorola.c-482-\t/* Reserve kernel text/data/bss and the memory allocated in head.S */\narch/m68k/mm/motorola.c:483:\tmemblock_reserve(m68k_memory[0].addr, availmem - m68k_memory[0].addr);\narch/m68k/mm/motorola.c-484-\n--\narch/microblaze/mm/init.c=165=asmlinkage void __init mmu_init(void)\n--\narch/microblaze/mm/init.c-198-\tksize = PAGE_ALIGN(((u32)_end - (u32)CONFIG_KERNEL_START));\narch/microblaze/mm/init.c:199:\tmemblock_reserve(kstart, ksize);\narch/microblaze/mm/init.c-200-\n--\narch/microblaze/mm/init.c-205-\t\tsize = initrd_end - initrd_start;\narch/microblaze/mm/init.c:206:\t\tmemblock_reserve(__virt_to_phys(initrd_start), size);\narch/microblaze/mm/init.c-207-\t}\n--\narch/mips/alchemy/common/prom.c=83=void __init prom_init(void)\n--\narch/mips/alchemy/common/prom.c-97-\narch/mips/alchemy/common/prom.c:98:\tmemblock_add(0, memsize);\narch/mips/alchemy/common/prom.c-99-}\n--\narch/mips/ath25/ar2315.c=255=void __init ar2315_plat_mem_setup(void)\n--\narch/mips/ath25/ar2315.c-269-\tmemsize \u003c\u003c= 3;\narch/mips/ath25/ar2315.c:270:\tmemblock_add(0, memsize);\narch/mips/ath25/ar2315.c-271-\tiounmap(sdram_base);\n--\narch/mips/ath25/ar5312.c=351=void __init ar5312_plat_mem_setup(void)\n--\narch/mips/ath25/ar5312.c-365-\tmemsize \u003c\u003c= 20;\narch/mips/ath25/ar5312.c:366:\tmemblock_add(0, memsize);\narch/mips/ath25/ar5312.c-367-\tiounmap(sdram_base);\n--\narch/mips/bcm47xx/prom.c=58=static __init void prom_init_mem(void)\n--\narch/mips/bcm47xx/prom.c-102-\t\tmem -= 0x1000;\narch/mips/bcm47xx/prom.c:103:\tmemblock_add(0, mem);\narch/mips/bcm47xx/prom.c-104-}\n--\narch/mips/bcm63xx/setup.c=155=void __init plat_mem_setup(void)\narch/mips/bcm63xx/setup.c-156-{\narch/mips/bcm63xx/setup.c:157:\tmemblock_add(0, bcm63xx_get_memory_size());\narch/mips/bcm63xx/setup.c-158-\n--\narch/mips/cavium-octeon/setup.c=928=static __init void memory_exclude_page(u64 addr, u64 *mem, u64 *size)\n--\narch/mips/cavium-octeon/setup.c-931-\t\tu64 inc = addr - *mem;\narch/mips/cavium-octeon/setup.c:932:\t\tmemblock_add(*mem, inc);\narch/mips/cavium-octeon/setup.c-933-\t\t*mem += inc;\n--\narch/mips/cavium-octeon/setup.c=967=void __init plat_mem_setup(void)\n--\narch/mips/cavium-octeon/setup.c-991-#ifdef CONFIG_CRASH_DUMP\narch/mips/cavium-octeon/setup.c:992:\tmemblock_add(reserve_low_mem, max_memory);\narch/mips/cavium-octeon/setup.c-993-\ttotal += max_memory;\n--\narch/mips/cavium-octeon/setup.c-996-\tif (crashk_size \u003e 0) {\narch/mips/cavium-octeon/setup.c:997:\t\tmemblock_add(crashk_base, crashk_size);\narch/mips/cavium-octeon/setup.c-998-\t\tcrashk_end = crashk_base + crashk_size;\n--\narch/mips/cavium-octeon/setup.c-1037-\t\t\t\t/* region is fully in */\narch/mips/cavium-octeon/setup.c:1038:\t\t\t\tmemblock_add(memory, crashk_base - memory);\narch/mips/cavium-octeon/setup.c-1039-\t\t\t\ttotal += crashk_base - memory;\narch/mips/cavium-octeon/setup.c:1040:\t\t\t\tmemblock_add(crashk_end, end - crashk_end);\narch/mips/cavium-octeon/setup.c-1041-\t\t\t\ttotal += end - crashk_end;\n--\narch/mips/cavium-octeon/setup.c-1067-#endif\narch/mips/cavium-octeon/setup.c:1068:\t\t\tmemblock_add(memory, mem_alloc_size);\narch/mips/cavium-octeon/setup.c-1069-\t\t\ttotal += mem_alloc_size;\n--\narch/mips/cobalt/setup.c=97=void __init prom_init(void)\n--\narch/mips/cobalt/setup.c-112-\narch/mips/cobalt/setup.c:113:\tmemblock_add(0, memsz);\narch/mips/cobalt/setup.c-114-\n--\narch/mips/dec/prom/memory.c=30=static __init void pmax_setup_memory_region(void)\n--\narch/mips/dec/prom/memory.c-51-\narch/mips/dec/prom/memory.c:52:\tmemblock_add(0, (unsigned long)memory_page - CKSEG1 - CHUNK_SIZE);\narch/mips/dec/prom/memory.c-53-}\n--\narch/mips/dec/prom/memory.c=59=static __init void rex_setup_memory_region(void)\n--\narch/mips/dec/prom/memory.c-76-\t\telse {\narch/mips/dec/prom/memory.c:77:\t\t\tmemblock_add(mem_start, mem_size);\narch/mips/dec/prom/memory.c-78-\t\t\tmem_start += mem_size + (8 * bm-\u003epagesize);\n--\narch/mips/dec/prom/memory.c-82-\tif (mem_size)\narch/mips/dec/prom/memory.c:83:\t\tmemblock_add(mem_start, mem_size);\narch/mips/dec/prom/memory.c-84-}\n--\narch/mips/dec/setup.c=137=void __init plat_mem_setup(void)\n--\narch/mips/dec/setup.c-150-\t/* Stay away from the firmware working memory area for now. */\narch/mips/dec/setup.c:151:\tmemblock_reserve(PHYS_OFFSET, __pa_symbol(\u0026_text) - PHYS_OFFSET);\narch/mips/dec/setup.c-152-}\n--\narch/mips/fw/arc/memory.c=123=void __weak __init prom_meminit(void)\n--\narch/mips/fw/arc/memory.c-153-\narch/mips/fw/arc/memory.c:154:\t\tmemblock_add(base, size);\narch/mips/fw/arc/memory.c-155-\narch/mips/fw/arc/memory.c-156-\t\tif (type == mem_reserved)\narch/mips/fw/arc/memory.c:157:\t\t\tmemblock_reserve(base, size);\narch/mips/fw/arc/memory.c-158-\narch/mips/fw/arc/memory.c-159-\t\tif (type == mem_prom_used) {\narch/mips/fw/arc/memory.c:160:\t\t\tmemblock_reserve(base, size);\narch/mips/fw/arc/memory.c-161-\t\t\tif (nr_prom_mem \u003e= 5) {\n--\narch/mips/fw/sni/sniprom.c=100=static void __init sni_mem_init(void)\n--\narch/mips/fw/sni/sniprom.c-130-\t\t\tmemconf[i].size, memconf[i].base);\narch/mips/fw/sni/sniprom.c:131:\t\tmemblock_add(memconf[i].base, memconf[i].size);\narch/mips/fw/sni/sniprom.c-132-\t}\n--\narch/mips/kernel/setup.c=98=void __init detect_memory_region(phys_addr_t start, phys_addr_t sz_min, phys_addr_t sz_max)\n--\narch/mips/kernel/setup.c-113-\narch/mips/kernel/setup.c:114:\tmemblock_add(start, size);\narch/mips/kernel/setup.c-115-}\n--\narch/mips/kernel/setup.c=215=static void __init finalize_initrd(void)\n--\narch/mips/kernel/setup.c-229-\narch/mips/kernel/setup.c:230:\tmemblock_reserve(__pa(initrd_start), size);\narch/mips/kernel/setup.c-231-\tinitrd_below_start_ok = 1;\n--\narch/mips/kernel/setup.c=267=static void __init bootmem_init(void)\n--\narch/mips/kernel/setup.c-284-\t/* Reserve memory occupied by kernel. */\narch/mips/kernel/setup.c:285:\tmemblock_reserve(__pa_symbol(\u0026_text),\narch/mips/kernel/setup.c-286-\t\t\t__pa_symbol(\u0026_end) - __pa_symbol(\u0026_text));\n--\narch/mips/kernel/setup.c-296-\tif (ramstart \u003e PHYS_OFFSET)\narch/mips/kernel/setup.c:297:\t\tmemblock_reserve(PHYS_OFFSET, ramstart - PHYS_OFFSET);\narch/mips/kernel/setup.c-298-\n--\narch/mips/kernel/setup.c=346=static int __init early_parse_mem(char *p)\n--\narch/mips/kernel/setup.c-370-\tif (IS_ENABLED(CONFIG_NUMA))\narch/mips/kernel/setup.c:371:\t\tmemblock_add_node(start, size, pa_to_nid(start), MEMBLOCK_NONE);\narch/mips/kernel/setup.c-372-\telse\narch/mips/kernel/setup.c:373:\t\tmemblock_add(start, size);\narch/mips/kernel/setup.c-374-\n--\narch/mips/kernel/setup.c=379=static int __init early_parse_memmap(char *p)\n--\narch/mips/kernel/setup.c-398-\t\tstart_at = memparse(p+1, \u0026p);\narch/mips/kernel/setup.c:399:\t\tmemblock_add(start_at, mem_size);\narch/mips/kernel/setup.c-400-\t} else if (*p == '#') {\n--\narch/mips/kernel/setup.c-404-\t\tstart_at = memparse(p+1, \u0026p);\narch/mips/kernel/setup.c:405:\t\tmemblock_add(start_at, mem_size);\narch/mips/kernel/setup.c:406:\t\tmemblock_reserve(start_at, mem_size);\narch/mips/kernel/setup.c-407-\t} else {\n--\narch/mips/kernel/setup.c=420=static void __init mips_reserve_vmcore(void)\n--\narch/mips/kernel/setup.c-442-\narch/mips/kernel/setup.c:443:\tmemblock_reserve(elfcorehdr_addr, elfcorehdr_size);\narch/mips/kernel/setup.c-444-#endif\n--\narch/mips/kernel/setup.c=508=static void __init check_kernel_sections_mem(void)\n--\narch/mips/kernel/setup.c-514-\t\tpr_info(\"Kernel sections are not in the memory maps\\n\");\narch/mips/kernel/setup.c:515:\t\tmemblock_add(start, size);\narch/mips/kernel/setup.c-516-\t}\n--\narch/mips/kernel/setup.c=633=static void __init arch_mem_init(char **cmdline_p)\n--\narch/mips/kernel/setup.c-676-\t/* Reserve for hibernation. */\narch/mips/kernel/setup.c:677:\tmemblock_reserve(__pa_symbol(\u0026__nosave_begin),\narch/mips/kernel/setup.c-678-\t\t__pa_symbol(\u0026__nosave_end) - __pa_symbol(\u0026__nosave_begin));\n--\narch/mips/kernel/traps.c=2010=void reserve_exception_space(phys_addr_t addr, unsigned long size)\n--\narch/mips/kernel/traps.c-2017-\tif (smp_processor_id() == 0)\narch/mips/kernel/traps.c:2018:\t\tmemblock_reserve(addr, size);\narch/mips/kernel/traps.c-2019-}\n--\narch/mips/loongson2ef/common/mem.c=18=void __init prom_init_memory(void)\narch/mips/loongson2ef/common/mem.c-19-{\narch/mips/loongson2ef/common/mem.c:20:\tmemblock_add(0x0, (memsize \u003c\u003c 20));\narch/mips/loongson2ef/common/mem.c-21-\n--\narch/mips/loongson2ef/common/mem.c-40-\tif (highmemsize \u003e 0)\narch/mips/loongson2ef/common/mem.c:41:\t\tmemblock_add(LOONGSON_HIGHMEM_START, highmemsize \u003c\u003c 20);\narch/mips/loongson2ef/common/mem.c-42-#endif /* !CONFIG_64BIT */\n--\narch/mips/loongson64/init.c=50=void __init szmem(unsigned int node)\n--\narch/mips/loongson64/init.c-81-\t\t\t\t(u32)node_id, mem_type, \u0026mem_start, \u0026mem_size);\narch/mips/loongson64/init.c:82:\t\t\tmemblock_add_node(mem_start, mem_size, node,\narch/mips/loongson64/init.c-83-\t\t\t\t\t  MEMBLOCK_NONE);\n--\narch/mips/loongson64/init.c-91-\t\t\t\t(u32)node_id, mem_type, \u0026mem_start, \u0026mem_size);\narch/mips/loongson64/init.c:92:\t\t\tmemblock_reserve(mem_start, mem_size);\narch/mips/loongson64/init.c-93-\t\t\tbreak;\n--\narch/mips/loongson64/init.c-104-\tif (loongson_sysconf.vgabios_addr)\narch/mips/loongson64/init.c:105:\t\tmemblock_reserve(virt_to_phys((void *)loongson_sysconf.vgabios_addr),\narch/mips/loongson64/init.c-106-\t\t\t\tSZ_256K);\n--\narch/mips/loongson64/numa.c=82=static void __init node_mem_init(unsigned int node)\n--\narch/mips/loongson64/numa.c-110-\t\t/* Reserve the kernel text/data/bss */\narch/mips/loongson64/numa.c:111:\t\tmemblock_reserve(kernel_start_pfn \u003c\u003c PAGE_SHIFT,\n\n"
}

gemini-3.7-flash

null

null

							input: 16653
							output: 47
							thoughts: 50
						

Okay, let's dive into this. Here's how I'd approach understanding the memory block situation on x86/amd64:

**Investigating memblock on x86/amd64**

Alright, I need to get a clear picture of how `memblock` is utilized on x86/amd64. My immediate thought is to start with a grep within the `arch/x86/` directory. That's the most logical place to begin, focusing on the core architectural implementation. I'll zero in on the functions `memblock_add` and `memblock_reserve`. These are the key functions, as `memblock_add` should be responsible for adding available memory ranges to the memblock list, while `memblock_reserve` is what is used to reserve ranges and prevent the kernel from using them. By searching for these, I should be able to quickly identify where memory regions are being managed, which drivers are using it, how it interacts with the BIOS or firmware, and get an overview of the boot process memory map on x86. I'll pay close attention to the contexts in which these functions are called, and the data structures they operate on, as that will give me clues about how the system's memory is initially set up and how it evolves as the kernel boots.

{
  "Expression": "memblock_add|memblock_reserve|memblock_isolate_range|memblock_remove",
  "PathPrefix": "arch/x86/"
}

{
  "Output": "arch/x86/kernel/check.c=92=void __init setup_bios_corruption_check(void)\n--\narch/x86/kernel/check.c-123-\narch/x86/kernel/check.c:124:\t\tmemblock_reserve(start, end - start);\narch/x86/kernel/check.c-125-\t\tscan_areas[num_scan_areas].addr = start;\n--\narch/x86/kernel/e820.c=1288=__init void e820__memblock_setup(void)\n--\narch/x86/kernel/e820.c-1341-\t\tif (entry-\u003etype == E820_TYPE_SOFT_RESERVED)\narch/x86/kernel/e820.c:1342:\t\t\tmemblock_reserve(entry-\u003eaddr, entry-\u003esize);\narch/x86/kernel/e820.c-1343-\n--\narch/x86/kernel/e820.c-1346-\narch/x86/kernel/e820.c:1347:\t\tmemblock_add(entry-\u003eaddr, entry-\u003esize);\narch/x86/kernel/e820.c-1348-\t}\n--\narch/x86/kernel/e820.c-1373-\tif (IS_ENABLED(CONFIG_X86_32))\narch/x86/kernel/e820.c:1374:\t\tmemblock_remove(PFN_PHYS(max_pfn), -1);\narch/x86/kernel/e820.c-1375-\n--\narch/x86/kernel/ebda.c=56=void __init reserve_bios_regions(void)\n--\narch/x86/kernel/ebda.c-96-\t/* Reserve all memory between bios_start and the 1MB mark: */\narch/x86/kernel/ebda.c:97:\tmemblock_reserve(bios_start, 0x100000 - bios_start);\narch/x86/kernel/ebda.c-98-}\n--\narch/x86/kernel/mpparse.c=552=static void __init smp_reserve_memory(struct mpf_intel *mpf)\narch/x86/kernel/mpparse.c-553-{\narch/x86/kernel/mpparse.c:554:\tmemblock_reserve(mpf-\u003ephysptr, get_mpc_size(mpf-\u003ephysptr));\narch/x86/kernel/mpparse.c-555-}\n--\narch/x86/kernel/mpparse.c=557=static int __init smp_scan_config(unsigned long base, unsigned long length)\n--\narch/x86/kernel/mpparse.c-582-\narch/x86/kernel/mpparse.c:583:\t\t\tmemblock_reserve(base, sizeof(*mpf));\narch/x86/kernel/mpparse.c-584-\t\t\tif (mpf-\u003ephysptr)\n--\narch/x86/kernel/setup.c=283=static void __init reserve_brk(void)\n--\narch/x86/kernel/setup.c-285-\tif (_brk_end \u003e _brk_start)\narch/x86/kernel/setup.c:286:\t\tmemblock_reserve_kern(__pa_symbol(_brk_start),\narch/x86/kernel/setup.c-287-\t\t\t\t      _brk_end - _brk_start);\n--\narch/x86/kernel/setup.c=349=static void __init early_reserve_initrd(void)\n--\narch/x86/kernel/setup.c-359-\narch/x86/kernel/setup.c:360:\tmemblock_reserve_kern(ramdisk_image, ramdisk_end - ramdisk_image);\narch/x86/kernel/setup.c-361-}\n--\narch/x86/kernel/setup.c=401=static void __init add_early_ima_buffer(u64 phys_addr)\n--\narch/x86/kernel/setup.c-412-\tif (data-\u003esize) {\narch/x86/kernel/setup.c:413:\t\tmemblock_reserve_kern(data-\u003eaddr, data-\u003esize);\narch/x86/kernel/setup.c-414-\t\tima_kexec_buffer_phys = data-\u003eaddr;\n--\narch/x86/kernel/setup.c=569=static void __init memblock_x86_reserve_range_setup_data(void)\n--\narch/x86/kernel/setup.c-586-\narch/x86/kernel/setup.c:587:\t\tmemblock_reserve_kern(pa_data, sizeof(*data) + data-\u003elen);\narch/x86/kernel/setup.c-588-\n--\narch/x86/kernel/setup.c-600-\t\t\tif (indirect-\u003etype != SETUP_INDIRECT)\narch/x86/kernel/setup.c:601:\t\t\t\tmemblock_reserve_kern(indirect-\u003eaddr, indirect-\u003elen);\narch/x86/kernel/setup.c-602-\t\t}\n--\narch/x86/kernel/setup.c=719=static void __init trim_snb_memory(void)\n--\narch/x86/kernel/setup.c-746-\tfor (i = 0; i \u003c ARRAY_SIZE(bad_pages); i++) {\narch/x86/kernel/setup.c:747:\t\tif (memblock_reserve(bad_pages[i], PAGE_SIZE))\narch/x86/kernel/setup.c-748-\t\t\tprintk(KERN_WARNING \"failed to reserve 0x%08lx\\n\",\n--\narch/x86/kernel/setup.c=797=static void __init early_reserve_memory(void)\n--\narch/x86/kernel/setup.c-802-\t * __end_of_kernel_reserve symbol must be explicitly reserved with a\narch/x86/kernel/setup.c:803:\t * separate memblock_reserve() or they will be discarded.\narch/x86/kernel/setup.c-804-\t */\narch/x86/kernel/setup.c:805:\tmemblock_reserve_kern(__pa_symbol(_text),\narch/x86/kernel/setup.c-806-\t\t\t      (unsigned long)__end_of_kernel_reserve - (unsigned long)_text);\n--\narch/x86/kernel/setup.c-818-\t */\narch/x86/kernel/setup.c:819:\tmemblock_reserve(0, SZ_64K);\narch/x86/kernel/setup.c-820-\n--\narch/x86/kernel/vmlinux.lds.S=130=SECTIONS\n--\narch/x86/kernel/vmlinux.lds.S-375-\t * automatically reserved in setup_arch(). Anything after here must be\narch/x86/kernel/vmlinux.lds.S:376:\t * explicitly reserved using memblock_reserve() or it will be discarded\narch/x86/kernel/vmlinux.lds.S-377-\t * and treated as available memory.\n--\narch/x86/platform/efi/efi.c=192=int __init efi_memblock_x86_reserve_range(void)\n--\narch/x86/platform/efi/efi.c-226-\narch/x86/platform/efi/efi.c:227:\tmemblock_reserve(pmap, efi.memmap.nr_map * efi.memmap.desc_size);\narch/x86/platform/efi/efi.c-228-\tset_bit(EFI_PRESERVE_BS_REGIONS, \u0026efi.flags);\n--\narch/x86/platform/efi/quirks.c=324=void __init efi_reserve_boot_services(void)\n--\narch/x86/platform/efi/quirks.c-342-\t\t/*\narch/x86/platform/efi/quirks.c:343:\t\t * Because the following memblock_reserve() is paired\narch/x86/platform/efi/quirks.c-344-\t\t * with free_reserved_area() for this region in\n--\narch/x86/platform/efi/quirks.c-356-\t\tif (!already_reserved) {\narch/x86/platform/efi/quirks.c:357:\t\t\tmemblock_reserve(start, size);\narch/x86/platform/efi/quirks.c-358-\n--\narch/x86/realmode/init.c=47=void __init reserve_real_mode(void)\n--\narch/x86/realmode/init.c-66-\t */\narch/x86/realmode/init.c:67:\tmemblock_reserve(0, SZ_1M);\narch/x86/realmode/init.c-68-\n--\narch/x86/virt/svm/sev.c=161=static void __init __snp_fixup_e820_tables(u64 pa)\n--\narch/x86/virt/svm/sev.c-187-\t\tif (!memblock_is_region_reserved(pa, PMD_SIZE))\narch/x86/virt/svm/sev.c:188:\t\t\tmemblock_reserve(pa, PMD_SIZE);\narch/x86/virt/svm/sev.c-189-\t}\n--\narch/x86/xen/enlighten.c=415=void __init xen_add_extra_mem(unsigned long start_pfn, unsigned long n_pfns)\n--\narch/x86/xen/enlighten.c-439-\narch/x86/xen/enlighten.c:440:\tmemblock_reserve(PFN_PHYS(start_pfn), PFN_PHYS(n_pfns));\narch/x86/xen/enlighten.c-441-}\n--\narch/x86/xen/enlighten_hvm.c=50=static void __init reserve_shared_info(void)\n--\narch/x86/xen/enlighten_hvm.c-69-\narch/x86/xen/enlighten_hvm.c:70:\tmemblock_reserve(pa, PAGE_SIZE);\narch/x86/xen/enlighten_hvm.c-71-\tHYPERVISOR_shared_info = early_memremap(pa, PAGE_SIZE);\n--\narch/x86/xen/mmu_pv.c=1768=void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)\n--\narch/x86/xen/mmu_pv.c-1891-\txen_pt_size = (pt_end - pt_base) * PAGE_SIZE;\narch/x86/xen/mmu_pv.c:1892:\tmemblock_reserve(xen_pt_base, xen_pt_size);\narch/x86/xen/mmu_pv.c-1893-\n--\narch/x86/xen/mmu_pv.c=2076=void __init xen_reserve_special_pages(void)\n--\narch/x86/xen/mmu_pv.c-2079-\narch/x86/xen/mmu_pv.c:2080:\tmemblock_reserve(__pa(xen_start_info), PAGE_SIZE);\narch/x86/xen/mmu_pv.c-2081-\tif (xen_start_info-\u003estore_mfn) {\narch/x86/xen/mmu_pv.c-2082-\t\tpaddr = PFN_PHYS(mfn_to_pfn(xen_start_info-\u003estore_mfn));\narch/x86/xen/mmu_pv.c:2083:\t\tmemblock_reserve(paddr, PAGE_SIZE);\narch/x86/xen/mmu_pv.c-2084-\t}\n--\narch/x86/xen/mmu_pv.c-2086-\t\tpaddr = PFN_PHYS(mfn_to_pfn(xen_start_info-\u003econsole.domU.mfn));\narch/x86/xen/mmu_pv.c:2087:\t\tmemblock_reserve(paddr, PAGE_SIZE);\narch/x86/xen/mmu_pv.c-2088-\t}\n--\narch/x86/xen/setup.c=83=static void __init xen_del_extra_mem(unsigned long start_pfn,\n--\narch/x86/xen/setup.c-109-\t\t\txen_extra_mem[i].n_pfns = start_pfn - start_r;\narch/x86/xen/setup.c:110:\t\t\t/* Calling memblock_reserve() again is okay. */\narch/x86/xen/setup.c-111-\t\t\txen_add_extra_mem(start_pfn + n_pfns, start_r + size_r -\n--\narch/x86/xen/setup.c=601=phys_addr_t __init xen_find_free_area(phys_addr_t size)\n--\narch/x86/xen/setup.c-618-\t\tif (addr \u003e= start + size) {\narch/x86/xen/setup.c:619:\t\t\tmemblock_reserve(start, size);\narch/x86/xen/setup.c-620-\t\t\treturn start;\n--\narch/x86/xen/setup.c=770=static void __init xen_reserve_xen_mfnlist(void)\n--\narch/x86/xen/setup.c-782-\narch/x86/xen/setup.c:783:\tmemblock_reserve(start, size);\narch/x86/xen/setup.c-784-\tif (!xen_is_e820_reserved(start, size))\n"
}

gemini-3.7-flash

null

null

							input: 20670
							output: 20
							thoughts: 39
						

Okay, let's dive into this.

**Investigating `CONFIG_ARCH_KEEP_MEMBLOCK` Usage**

Alright, I need to get a handle on `CONFIG_ARCH_KEEP_MEMBLOCK`. My first thought is, which architectures are even bothering to define `ARCH_KEEP_MEMBLOCK`? That's the core question here. To figure this out, the obvious move is to use `grep`. I'll fire up a grep command to search the codebase for every instance of `ARCH_KEEP_MEMBLOCK`. That should give me a solid list of the architectures I need to look at more closely. From there, I can start to understand why those particular architectures need this configuration option and what it signifies in their context.

{
  "Expression": "ARCH_KEEP_MEMBLOCK"
}

{
  "Output": "arch/arm/Kconfig=2=config ARM\n--\narch/arm/Kconfig-35-\tselect ARCH_HAS_GCOV_PROFILE_ALL\narch/arm/Kconfig:36:\tselect ARCH_KEEP_MEMBLOCK\narch/arm/Kconfig-37-\tselect ARCH_HAS_UBSAN\n--\narch/arm64/Kconfig=2=config ARM64\n--\narch/arm64/Kconfig-63-\tselect ARCH_HAVE_TRACE_MMIO_ACCESS\narch/arm64/Kconfig:64:\tselect ARCH_KEEP_MEMBLOCK\narch/arm64/Kconfig-65-\tselect ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE\n--\narch/loongarch/Kconfig=2=config LOONGARCH\n--\narch/loongarch/Kconfig-58-\tselect ARCH_INLINE_SPIN_UNLOCK_IRQRESTORE if !PREEMPTION\narch/loongarch/Kconfig:59:\tselect ARCH_KEEP_MEMBLOCK\narch/loongarch/Kconfig-60-\tselect ARCH_MIGHT_HAVE_PC_PARPORT\n--\narch/mips/Kconfig=2=config MIPS\n--\narch/mips/Kconfig-21-\tselect ARCH_HAS_GCOV_PROFILE_ALL\narch/mips/Kconfig:22:\tselect ARCH_KEEP_MEMBLOCK\narch/mips/Kconfig-23-\tselect ARCH_USE_BUILTIN_BSWAP\n--\narch/powerpc/Kconfig=118=config PPC\n--\narch/powerpc/Kconfig-163-\tselect ARCH_HAVE_EXTRA_ELF_NOTES        if SPU_BASE\narch/powerpc/Kconfig:164:\tselect ARCH_KEEP_MEMBLOCK\narch/powerpc/Kconfig-165-\tselect ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE\tif PPC_RADIX_MMU\n--\narch/riscv/Kconfig=13=config RISCV\n--\narch/riscv/Kconfig-60-\tselect ARCH_HAVE_NMI_SAFE_CMPXCHG\narch/riscv/Kconfig:61:\tselect ARCH_KEEP_MEMBLOCK if ACPI || KEXEC\narch/riscv/Kconfig-62-\tselect ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE\tif 64BIT \u0026\u0026 MMU\n--\narch/x86/Kconfig=1865=config INTEL_TDX_HOST\n--\narch/x86/Kconfig-1870-\tdepends on X86_X2APIC\narch/x86/Kconfig:1871:\tselect ARCH_KEEP_MEMBLOCK\narch/x86/Kconfig-1872-\tdepends on CONTIG_ALLOC\n--\ndrivers/firmware/efi/efi.c=1073=static int efi_mem_reserve_iomem(phys_addr_t addr, u64 size)\n--\ndrivers/firmware/efi/efi.c-1095-\t */\ndrivers/firmware/efi/efi.c:1096:\tif (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK) \u0026\u0026 !ret)\ndrivers/firmware/efi/efi.c-1097-\t\tmemblock_reserve(addr, size);\n--\ninclude/linux/memblock.h=114=extern struct memblock memblock;\ninclude/linux/memblock.h-115-\ninclude/linux/memblock.h:116:#ifndef CONFIG_ARCH_KEEP_MEMBLOCK\ninclude/linux/memblock.h-117-#define __init_memblock __meminit\n--\nkernel/kexec_file.c=560=static int locate_mem_hole_callback(struct resource *res, void *arg)\n--\nkernel/kexec_file.c-586-\nkernel/kexec_file.c:587:#ifdef CONFIG_ARCH_KEEP_MEMBLOCK\nkernel/kexec_file.c-588-static int kexec_walk_memblock(struct kexec_buf *kbuf,\n--\nkernel/kexec_file.c=716=int kexec_locate_mem_hole(struct kexec_buf *kbuf)\n--\nkernel/kexec_file.c-738-\nkernel/kexec_file.c:739:\tif (!IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))\nkernel/kexec_file.c-740-\t\tret = kexec_walk_resources(kbuf, locate_mem_hole_callback);\n--\nmm/Kconfig=482=config MEMBLOCK_KHO_SCRATCH\n--\nmm/Kconfig-487-# Also, memblocks are updated with memory hot(un)plug.\nmm/Kconfig:488:config ARCH_KEEP_MEMBLOCK\nmm/Kconfig-489-\tbool\n--\nmm/memblock.c-100- *\nmm/memblock.c:101: * Unless an architecture enables %CONFIG_ARCH_KEEP_MEMBLOCK, the\nmm/memblock.c-102- * memblock data structures (except \"physmem\") will be discarded after the\n--\nmm/memblock.c=369=static void __init_memblock memblock_remove_region(struct memblock_type *type, unsigned long r)\n--\nmm/memblock.c-385-\nmm/memblock.c:386:#ifndef CONFIG_ARCH_KEEP_MEMBLOCK\nmm/memblock.c-387-/**\n--\nmm/memblock.c=966=unsigned long free_reserved_area(void *start, void *end, int poison, const char *s)\n--\nmm/memblock.c-984-\nmm/memblock.c:985:\tif (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) {\nmm/memblock.c-986-\t\tif (start_pa \u003c end_pa)\n--\nmm/memblock.c=1022=int __init_memblock memblock_phys_free(phys_addr_t base, phys_addr_t size)\n--\nmm/memblock.c-1031-\nmm/memblock.c:1032:\tif (!slab_is_available() || IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))\nmm/memblock.c-1033-\t\tret = memblock_remove_range(\u0026memblock.reserved, base, size);\n--\nmm/memblock.c=2911=__setup(\"reserve_mem=\", reserve_mem);\n--\nmm/memblock.c-2913-#ifdef CONFIG_DEBUG_FS\nmm/memblock.c:2914:#ifdef CONFIG_ARCH_KEEP_MEMBLOCK\nmm/memblock.c-2915-static const char * const flagname[] = {\n--\nmm/memblock.c=2975=static inline void memblock_debugfs_expose_arrays(struct dentry *root) { }\nmm/memblock.c-2976-\nmm/memblock.c:2977:#endif /* CONFIG_ARCH_KEEP_MEMBLOCK */\nmm/memblock.c-2978-\n--\nmm/memblock.c=2999=static int __init memblock_init_debugfs(void)\n--\nmm/memblock.c-3002-\nmm/memblock.c:3003:\tif (!IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK) \u0026\u0026 !reserved_mem_count)\nmm/memblock.c-3004-\t\treturn 0;\n--\nmm/memory_hotplug.c=1530=static int __add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags,\n--\nmm/memory_hotplug.c-1560-\nmm/memory_hotplug.c:1561:\tif (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) {\nmm/memory_hotplug.c-1562-\t\tif (res-\u003eflags \u0026 IORESOURCE_SYSRAM_DRIVER_MANAGED)\n--\nmm/memory_hotplug.c-1631-error_memblock_remove:\nmm/memory_hotplug.c:1632:\tif (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))\nmm/memory_hotplug.c-1633-\t\tmemblock_remove(start, size);\n--\nmm/memory_hotplug.c=2293=static int try_remove_memory(u64 start, u64 size)\n--\nmm/memory_hotplug.c-2333-\nmm/memory_hotplug.c:2334:\tif (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))\nmm/memory_hotplug.c-2335-\t\tmemblock_remove(start, size);\n"
}

gemini-3.7-flash

null

null

							input: 23061
							output: 31
							thoughts: 69
						

**Analyzing Memory Hotplug in the Kernel**

Okay, let's dive into this. My initial thought process is to trace the memory hotplug mechanism, specifically within `mm/memory_hotplug.c`. I immediately notice that `memblock_add_node` and `memblock_remove` are key functions being utilized, and their operation seems contingent on `IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)`. This is a crucial conditional, as it dictates whether the system maintains a persistent `memblock` representation. Given my expertise, I already have a mental map of how these components interact, but I want to refresh my memory on the precise implementation, especially how these functions are being employed in hotplug scenarios. My focus will be around line 1560 within `mm/memory_hotplug.c`, as that's where I assume the most pertinent logic will reside in terms of adding and removing memory blocks during hotplug operations. Let's see what the code reveals.

{
  "Expression": "memblock_",
  "PathPrefix": "mm/memory_hotplug.c"
}

{
  "Output": "mm/memory_hotplug.c=1418=static void remove_memory_blocks_and_altmaps(u64 start, u64 size)\nmm/memory_hotplug.c-1419-{\nmm/memory_hotplug.c:1420:\tunsigned long memblock_size = memory_block_size_bytes();\nmm/memory_hotplug.c-1421-\tu64 cur_start;\n--\nmm/memory_hotplug.c-1427-\tfor (cur_start = start; cur_start \u003c start + size;\nmm/memory_hotplug.c:1428:\t     cur_start += memblock_size) {\nmm/memory_hotplug.c-1429-\t\tstruct vmem_altmap *altmap = NULL;\n--\nmm/memory_hotplug.c-1439-\nmm/memory_hotplug.c:1440:\t\tremove_memory_block_devices(cur_start, memblock_size);\nmm/memory_hotplug.c:1441:\t\tarch_remove_memory(cur_start, memblock_size, altmap, NULL);\nmm/memory_hotplug.c-1442-\t\taltmap_free(altmap);\n--\nmm/memory_hotplug.c=1446=static int create_altmaps_and_memory_blocks(int nid, struct memory_group *group,\n--\nmm/memory_hotplug.c-1448-{\nmm/memory_hotplug.c:1449:\tunsigned long memblock_size = memory_block_size_bytes();\nmm/memory_hotplug.c-1450-\tu64 cur_start;\n--\nmm/memory_hotplug.c-1453-\tfor (cur_start = start; cur_start \u003c start + size;\nmm/memory_hotplug.c:1454:\t     cur_start += memblock_size) {\nmm/memory_hotplug.c-1455-\t\tstruct mhp_params params = { .pgprot =\n--\nmm/memory_hotplug.c-1458-\t\t\t.base_pfn = PHYS_PFN(cur_start),\nmm/memory_hotplug.c:1459:\t\t\t.end_pfn = PHYS_PFN(cur_start + memblock_size - 1),\nmm/memory_hotplug.c-1460-\t\t};\n--\nmm/memory_hotplug.c-1470-\t\t/* call arch's memory hotadd */\nmm/memory_hotplug.c:1471:\t\tret = arch_add_memory(nid, cur_start, memblock_size, \u0026params);\nmm/memory_hotplug.c-1472-\t\tif (ret \u003c 0) {\n--\nmm/memory_hotplug.c-1477-\t\t/* create memory block devices after memory was added */\nmm/memory_hotplug.c:1478:\t\tret = create_memory_block_devices(cur_start, memblock_size, nid,\nmm/memory_hotplug.c-1479-\t\t\t\t\t\t  params.altmap, group);\nmm/memory_hotplug.c-1480-\t\tif (ret) {\nmm/memory_hotplug.c:1481:\t\t\tarch_remove_memory(cur_start, memblock_size, params.altmap, NULL);\nmm/memory_hotplug.c-1482-\t\t\taltmap_free(params.altmap);\n--\nmm/memory_hotplug.c-1493-\nmm/memory_hotplug.c:1494:static int check_no_memblock_for_node_cb(struct memory_block *mem, void *arg)\nmm/memory_hotplug.c-1495-{\n--\nmm/memory_hotplug.c=1507=static bool node_is_memoryless(int nid)\n--\nmm/memory_hotplug.c-1520-\t */\nmm/memory_hotplug.c:1521:\treturn !for_each_memory_block(\u0026nid, check_no_memblock_for_node_cb);\nmm/memory_hotplug.c-1522-}\n--\nmm/memory_hotplug.c=1530=static int __add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags,\n--\nmm/memory_hotplug.c-1533-\tstruct mhp_params params = { .pgprot = pgprot_mhp(PAGE_KERNEL) };\nmm/memory_hotplug.c:1534:\tenum memblock_flags memblock_flags = MEMBLOCK_NONE;\nmm/memory_hotplug.c-1535-\tstruct memory_group *group = NULL;\n--\nmm/memory_hotplug.c-1562-\t\tif (res-\u003eflags \u0026 IORESOURCE_SYSRAM_DRIVER_MANAGED)\nmm/memory_hotplug.c:1563:\t\t\tmemblock_flags = MEMBLOCK_DRIVER_MANAGED;\nmm/memory_hotplug.c:1564:\t\tret = memblock_add_node(start, size, nid, memblock_flags);\nmm/memory_hotplug.c-1565-\t\tif (ret)\n--\nmm/memory_hotplug.c-1570-\tif (ret \u003c 0)\nmm/memory_hotplug.c:1571:\t\tgoto error_memblock_remove;\nmm/memory_hotplug.c-1572-\tif (ret) {\n--\nmm/memory_hotplug.c-1576-\t\t\tnode_set_offline(nid);\nmm/memory_hotplug.c:1577:\t\t\tgoto error_memblock_remove;\nmm/memory_hotplug.c-1578-\t\t}\n--\nmm/memory_hotplug.c-1630-\t}\nmm/memory_hotplug.c:1631:error_memblock_remove:\nmm/memory_hotplug.c-1632-\tif (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))\nmm/memory_hotplug.c:1633:\t\tmemblock_remove(start, size);\nmm/memory_hotplug.c-1634-error_mem_hotplug_end:\n--\nmm/memory_hotplug.c=1985=int offline_pages(unsigned long start_pfn, unsigned long nr_pages,\n--\nmm/memory_hotplug.c-2202-\nmm/memory_hotplug.c:2203:static int check_memblock_offlined_cb(struct memory_block *mem, void *arg)\nmm/memory_hotplug.c-2204-{\n--\nmm/memory_hotplug.c=2293=static int try_remove_memory(u64 start, u64 size)\n--\nmm/memory_hotplug.c-2307-\t */\nmm/memory_hotplug.c:2308:\trc = walk_memory_blocks(start, size, \u0026nid, check_memblock_offlined_cb);\nmm/memory_hotplug.c-2309-\tif (rc)\n--\nmm/memory_hotplug.c-2334-\tif (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))\nmm/memory_hotplug.c:2335:\t\tmemblock_remove(start, size);\nmm/memory_hotplug.c-2336-\n"
}

gemini-3.7-flash

null

null

							input: 25229
							output: 32
							thoughts: 231
						

**Investigating Kernel Memory Block Retention**

Okay, so I'm trying to figure out the conditions under which `ARCH_KEEP_MEMBLOCK` is enabled, specifically on amd64. My initial thought was that perhaps `CONFIG_INTEL_TDX_HOST` or something similar was responsible, but I need to make sure I haven't missed anything. I can't just jump to a conclusion.

Right, so, what other configurations select or relate to keeping the memory block around? I need a more comprehensive view. I had already used `grep` earlier for `ARCH_KEEP_MEMBLOCK` across the Kconfig files, but let's recap the findings to be certain.

Okay, here's what I've got: `ARCH_KEEP_MEMBLOCK` is selected by ARM, ARM64, LOONGARCH, MIPS, PPC, and RISCV, but RISCV has a conditional based on `ACPI` or `KEXEC`. On x86, `INTEL_TDX_HOST` selects it. Alright.

But what about other related configurations? Like if `MEMBLOCK_KHO_SCRATCH` is enabled? I have to go through all of the possibilities. Is there anything else I'm missing? I should really check `mm/Kconfig` around line 482 because that's where a lot of this type of configuration lives. I need to be methodical here.

{
  "File": "mm/Kconfig",
  "FirstLine": 475,
  "LineCount": 30
}

{
  "Contents": " 475:\t\tbool\n 476:\t\n 477:\tconfig HAVE_GUP_FAST\n 478:\t\tdepends on MMU\n 479:\t\tbool\n 480:\t\n 481:\t# Enable memblock support for scratch memory which is needed for kexec handover\n 482:\tconfig MEMBLOCK_KHO_SCRATCH\n 483:\t\tbool\n 484:\t\n 485:\t# Don't discard allocated memory used to track \"memory\" and \"reserved\" memblocks\n 486:\t# after early boot, so it can still be used to test for validity of memory.\n 487:\t# Also, memblocks are updated with memory hot(un)plug.\n 488:\tconfig ARCH_KEEP_MEMBLOCK\n 489:\t\tbool\n 490:\t\n 491:\t# Keep arch NUMA mapping infrastructure post-init.\n 492:\tconfig NUMA_KEEP_MEMINFO\n 493:\t\tbool\n 494:\t\n 495:\tconfig MEMORY_ISOLATION\n 496:\t\tbool\n 497:\t\n 498:\t# IORESOURCE_SYSTEM_RAM regions in the kernel resource tree that are marked\n 499:\t# IORESOURCE_EXCLUSIVE cannot be mapped to user space, for example, via\n 500:\t# /dev/mem.\n 501:\tconfig EXCLUSIVE_SYSTEM_RAM\n 502:\t\tdef_bool y\n 503:\t\tdepends on !DEVMEM || STRICT_DEVMEM\n 504:\t\n"
}

gemini-3.7-flash

null

null

							input: 26207
							output: 34
							thoughts: 141
						

**Investigating Memory Hotplug Fuzzing Potential**

Okay, hold on a second! Can syzkaller or anything running in userspace actually trigger memory hotplug operations or other related kernel paths at runtime? That's the key question. And, can syzkaller even be used to fuzz the boot code? No, I'm pretty sure it's designed to focus on live kernel states, hitting it through syscalls and perhaps virtual devices or sysfs. So, back to the initial question: is there a way for userspace to manipulate memory hotplug, adding or removing memory through sysfs, dax, or anything else?

Right, let's dig into the kernel source. Looking at `mm/memory_hotplug.c`, I see `__add_memory_resource` is a crucial function. Aha! I see it's called by: `add_memory`, `add_memory_resource`, and `add_memory_driver_managed`. Now the investigation begins... where are *those* functions called from? That's the trail I need to follow. Time to start tracing those calls and see if a viable fuzzing target can be identified.

{
  "Expression": "add_memory\\(|add_memory_resource\\(|add_memory_driver_managed\\("
}

{
  "Output": "Documentation/core-api/memory-hotplug.rst=173=memory faster than expected:\n--\nDocumentation/core-api/memory-hotplug.rst-176-  mem_hotplug_lock\nDocumentation/core-api/memory-hotplug.rst:177:- add_memory_resource() will first take the mem_hotplug_lock, followed by\nDocumentation/core-api/memory-hotplug.rst-178-  the device_lock() (while creating the devices, during bus_add_device()).\n--\nDocumentation/translations/zh_CN/core-api/memory-hotplug.rst=87=NOTIFY_STOP停止对通知队列的进一步处理。\n--\nDocumentation/translations/zh_CN/core-api/memory-hotplug.rst-105-\nDocumentation/translations/zh_CN/core-api/memory-hotplug.rst:106:- add_memory_resource()将首先使用mem_hotplug_lock，然后是device_lock()（在创\nDocumentation/translations/zh_CN/core-api/memory-hotplug.rst-107-  建设备时，在bus_add_device()期间）。\n--\narch/arm/include/asm/setup.h=20=static const struct tagtable __tagtable_##fn __tag = { tag, fn }\narch/arm/include/asm/setup.h-21-\narch/arm/include/asm/setup.h:22:extern int arm_add_memory(u64 start, u64 size);\narch/arm/include/asm/setup.h-23-extern __printf(1, 2) void early_print(const char *str, ...);\n--\narch/arm/kernel/atags_parse.c=65=static int __init parse_tag_mem32(const struct tag *tag)\narch/arm/kernel/atags_parse.c-66-{\narch/arm/kernel/atags_parse.c:67:\treturn arm_add_memory(tag-\u003eu.mem.start, tag-\u003eu.mem.size);\narch/arm/kernel/atags_parse.c-68-}\n--\narch/arm/kernel/setup.c=746=void __init dump_machine_table(void)\n--\narch/arm/kernel/setup.c-759-\narch/arm/kernel/setup.c:760:int __init arm_add_memory(u64 start, u64 size)\narch/arm/kernel/setup.c-761-{\n--\narch/arm/kernel/setup.c=826=static int __init early_mem(char *p)\n--\narch/arm/kernel/setup.c-848-\narch/arm/kernel/setup.c:849:\tarm_add_memory(start, size);\narch/arm/kernel/setup.c-850-\n--\narch/arm64/mm/mmu.c=1975=struct range arch_get_mappable_range(void)\n--\narch/arm64/mm/mmu.c-2006-\narch/arm64/mm/mmu.c:2007:int arch_add_memory(int nid, u64 start, u64 size,\narch/arm64/mm/mmu.c-2008-\t\t    struct mhp_params *params)\n--\narch/loongarch/mm/init.c=64=void __init fixrange_init(unsigned long start, unsigned long end, pgd_t *pgd_base)\n--\narch/loongarch/mm/init.c-106-#ifdef CONFIG_MEMORY_HOTPLUG\narch/loongarch/mm/init.c:107:int arch_add_memory(int nid, u64 start, u64 size, struct mhp_params *params)\narch/loongarch/mm/init.c-108-{\n--\narch/powerpc/mm/mem.c=129=int __ref add_pages(int nid, unsigned long start_pfn, unsigned long nr_pages,\n--\narch/powerpc/mm/mem.c-144-\narch/powerpc/mm/mem.c:145:int __ref arch_add_memory(int nid, u64 start, u64 size,\narch/powerpc/mm/mem.c-146-\t\t\t  struct mhp_params *params)\n--\narch/powerpc/platforms/pseries/hotplug-memory.c=564=static int dlpar_add_lmb(struct drmem_lmb *lmb)\n--\narch/powerpc/platforms/pseries/hotplug-memory.c-586-\t/* Add the memory */\narch/powerpc/platforms/pseries/hotplug-memory.c:587:\trc = __add_memory(nid, lmb-\u003ebase_addr, block_sz, MHP_MEMMAP_ON_MEMORY);\narch/powerpc/platforms/pseries/hotplug-memory.c-588-\tif (rc) {\n--\narch/riscv/mm/init.c=1712=struct range arch_get_mappable_range(void)\n--\narch/riscv/mm/init.c-1720-\narch/riscv/mm/init.c:1721:int __ref arch_add_memory(int nid, u64 start, u64 size, struct mhp_params *params)\narch/riscv/mm/init.c-1722-{\n--\narch/s390/mm/init.c=271=device_initcall(s390_cma_mem_init);\n--\narch/s390/mm/init.c-274-\narch/s390/mm/init.c:275:int arch_add_memory(int nid, u64 start, u64 size,\narch/s390/mm/init.c-276-\t\t    struct mhp_params *params)\n--\narch/x86/mm/init_64.c=963=int add_pages(int nid, unsigned long start_pfn, unsigned long nr_pages,\n--\narch/x86/mm/init_64.c-990-\narch/x86/mm/init_64.c:991:int arch_add_memory(int nid, u64 start, u64 size,\narch/x86/mm/init_64.c-992-\t\t    struct mhp_params *params)\n--\ndrivers/acpi/acpi_memhotplug.c=168=static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)\n--\ndrivers/acpi/acpi_memhotplug.c-212-\t\tmhp_flags |= MHP_MEMMAP_ON_MEMORY;\ndrivers/acpi/acpi_memhotplug.c:213:\t\tresult = __add_memory(mgid, info-\u003estart_addr, info-\u003elength,\ndrivers/acpi/acpi_memhotplug.c-214-\t\t\t\t      mhp_flags);\n--\ndrivers/acpi/acpi_memhotplug.c-216-\t\t/*\ndrivers/acpi/acpi_memhotplug.c:217:\t\t * If the memory block has been used by the kernel, add_memory()\ndrivers/acpi/acpi_memhotplug.c:218:\t\t * returns -EEXIST. If add_memory() returns the other error, it\ndrivers/acpi/acpi_memhotplug.c-219-\t\t * means that this memory block is not used by the kernel.\n--\ndrivers/acpi/acpi_memhotplug.c-232-\t\t/*\ndrivers/acpi/acpi_memhotplug.c:233:\t\t * Add num_enable even if add_memory() returns -EEXIST, so the\ndrivers/acpi/acpi_memhotplug.c-234-\t\t * device is bound to this driver.\n--\ndrivers/acpi/scan.c=2820=void __init acpi_scan_init(void)\n--\ndrivers/acpi/scan.c-2860-\t/*\ndrivers/acpi/scan.c:2861:\t * Although we call __add_memory() that is documented to require the\ndrivers/acpi/scan.c-2862-\t * device_hotplug_lock, it is not necessary here because this is an\n--\ndrivers/base/memory.c=572=static ssize_t probe_store(struct device *dev, struct device_attribute *attr,\n--\ndrivers/base/memory.c-590-\tnid = memory_add_physaddr_to_nid(phys_addr);\ndrivers/base/memory.c:591:\tret = __add_memory(nid, phys_addr,\ndrivers/base/memory.c-592-\t\t\t   MIN_MEMORY_BLOCK_SIZE * sections_per_block,\n--\ndrivers/dax/Kconfig=73=config DEV_DAX_KMEM\n--\ndrivers/dax/Kconfig-76-\tdepends on DEV_DAX\ndrivers/dax/Kconfig:77:\tdepends on MEMORY_HOTPLUG # for add_memory() and friends\ndrivers/dax/Kconfig-78-\thelp\n--\ndrivers/dax/kmem.c-25-\ndrivers/dax/kmem.c:26:/* Memory resource name used for add_memory_driver_managed(). */\ndrivers/dax/kmem.c-27-static const char *kmem_name;\n--\ndrivers/dax/kmem.c=87=static int dax_kmem_do_hotplug(struct dev_dax *dev_dax,\n--\ndrivers/dax/kmem.c-126-\t\t */\ndrivers/dax/kmem.c:127:\t\trc = __add_memory_driver_managed(data-\u003emgid, range.start,\ndrivers/dax/kmem.c-128-\t\t\t\trange_len(\u0026range), kmem_name, mhp_flags,\n--\ndrivers/dax/kmem.c=163=static int dax_kmem_init_resources(struct dev_dax *dev_dax,\n--\ndrivers/dax/kmem.c-197-\t\t * Set flags appropriate for System RAM.  Leave ..._BUSY clear\ndrivers/dax/kmem.c:198:\t\t * so that add_memory() can add a child resource.  Do not\ndrivers/dax/kmem.c-199-\t\t * inherit flags from the parent since it may set new flags\ndrivers/dax/kmem.c:200:\t\t * unknown to us that will break add_memory() later.\ndrivers/dax/kmem.c-201-\t\t */\n--\ndrivers/firmware/qcom/qcom_tzmem.c=185=static void qcom_tzmem_cleanup_area(struct qcom_tzmem_area *area)\n--\ndrivers/firmware/qcom/qcom_tzmem.c-194-\ndrivers/firmware/qcom/qcom_tzmem.c:195:static int qcom_tzmem_pool_add_memory(struct qcom_tzmem_pool *pool,\ndrivers/firmware/qcom/qcom_tzmem.c-196-\t\t\t\t      size_t size, gfp_t gfp)\n--\ndrivers/firmware/qcom/qcom_tzmem.c=245=qcom_tzmem_pool_new(const struct qcom_tzmem_pool_config *config)\n--\ndrivers/firmware/qcom/qcom_tzmem.c-282-\tif (config-\u003einitial_size) {\ndrivers/firmware/qcom/qcom_tzmem.c:283:\t\tret = qcom_tzmem_pool_add_memory(pool, config-\u003einitial_size,\ndrivers/firmware/qcom/qcom_tzmem.c-284-\t\t\t\t\t\t GFP_KERNEL);\n--\ndrivers/firmware/qcom/qcom_tzmem.c=375=static bool qcom_tzmem_try_grow_pool(struct qcom_tzmem_pool *pool,\n--\ndrivers/firmware/qcom/qcom_tzmem.c-392-\ndrivers/firmware/qcom/qcom_tzmem.c:393:\treturn !qcom_tzmem_pool_add_memory(pool, requested, gfp);\ndrivers/firmware/qcom/qcom_tzmem.c-394-}\n--\ndrivers/hv/hv_balloon.c=708=static void hv_mem_hot_add(unsigned long start, unsigned long size,\n--\ndrivers/hv/hv_balloon.c-730-\t\tnid = memory_add_physaddr_to_nid(PFN_PHYS(start_pfn));\ndrivers/hv/hv_balloon.c:731:\t\tret = add_memory(nid, PFN_PHYS((start_pfn)),\ndrivers/hv/hv_balloon.c-732-\t\t\t\t HA_BYTES_IN_CHUNK, MHP_MERGE_RESOURCE);\n--\ndrivers/hv/hv_balloon.c=1692=static int hot_add_enabled(void)\n--\ndrivers/hv/hv_balloon.c-1698-\t * DM_MEM_HOT_ADD_REQUEST doesn't have the NUMA node information for\ndrivers/hv/hv_balloon.c:1699:\t * add_memory().\ndrivers/hv/hv_balloon.c-1700-\t */\n--\ndrivers/hv/hv_balloon.c=1930=static int balloon_probe(struct hv_device *dev,\n--\ndrivers/hv/hv_balloon.c-1941-\t * Hot-add must operate in chunks that are of size equal to the\ndrivers/hv/hv_balloon.c:1942:\t * memory block size because that's what the core add_memory()\ndrivers/hv/hv_balloon.c-1943-\t * interface requires. The Hyper-V interface requires that the memory\n--\ndrivers/s390/char/sclp_mem.c=189=static ssize_t sclp_config_mem_store(struct kobject *kobj, struct kobj_attribute *attr,\n--\ndrivers/s390/char/sclp_mem.c-222-\t\t * Set entire memory block CMMA state to nodat. Later, when\ndrivers/s390/char/sclp_mem.c:223:\t\t * page tables pages are allocated via __add_memory(), those\ndrivers/s390/char/sclp_mem.c-224-\t\t * regions are marked __arch_set_page_dat().\n--\ndrivers/s390/char/sclp_mem.c-226-\t\t__arch_set_page_nodat((void *)__va(addr), block_size \u003e\u003e PAGE_SHIFT);\ndrivers/s390/char/sclp_mem.c:227:\t\trc = __add_memory(0, addr, block_size,\ndrivers/s390/char/sclp_mem.c-228-\t\t\t\t  sclp_mem-\u003ememmap_on_memory ?\n--\ndrivers/virtio/virtio_mem.c=67=enum virtio_mem_sbm_mb_state {\n--\ndrivers/virtio/virtio_mem.c-69-\tVIRTIO_MEM_SBM_MB_UNUSED = 0,\ndrivers/virtio/virtio_mem.c:70:\t/* (Partially) plugged, not added to Linux. Error on add_memory(). */\ndrivers/virtio/virtio_mem.c-71-\tVIRTIO_MEM_SBM_MB_PLUGGED,\n--\ndrivers/virtio/virtio_mem.c=90=enum virtio_mem_bbm_bb_state {\n--\ndrivers/virtio/virtio_mem.c-92-\tVIRTIO_MEM_BBM_BB_UNUSED = 0,\ndrivers/virtio/virtio_mem.c:93:\t/* Plugged, not added to Linux. Error on add_memory(). */\ndrivers/virtio/virtio_mem.c-94-\tVIRTIO_MEM_BBM_BB_PLUGGED,\n--\ndrivers/virtio/virtio_mem.c=102=struct virtio_mem {\n--\ndrivers/virtio/virtio_mem.c-142-\t * Copy of \"System RAM (virtio_mem)\" to be used for\ndrivers/virtio/virtio_mem.c:143:\t * add_memory_driver_managed().\ndrivers/virtio/virtio_mem.c-144-\t */\n--\ndrivers/virtio/virtio_mem.c=588=static int virtio_mem_sbm_sb_states_prepare_next_mb(struct virtio_mem *vm)\n--\ndrivers/virtio/virtio_mem.c-619- */\ndrivers/virtio/virtio_mem.c:620:static bool virtio_mem_could_add_memory(struct virtio_mem *vm, uint64_t size)\ndrivers/virtio/virtio_mem.c-621-{\n--\ndrivers/virtio/virtio_mem.c-635- */\ndrivers/virtio/virtio_mem.c:636:static int virtio_mem_add_memory(struct virtio_mem *vm, uint64_t addr,\ndrivers/virtio/virtio_mem.c-637-\t\t\t\t uint64_t size)\n--\ndrivers/virtio/virtio_mem.c-655-\tatomic64_add(size, \u0026vm-\u003eoffline_size);\ndrivers/virtio/virtio_mem.c:656:\trc = add_memory_driver_managed(vm-\u003emgid, addr, size, vm-\u003eresource_name,\ndrivers/virtio/virtio_mem.c-657-\t\t\t\t       MHP_MERGE_RESOURCE | MHP_NID_IS_MGID);\n--\ndrivers/virtio/virtio_mem.c-669-/*\ndrivers/virtio/virtio_mem.c:670: * See virtio_mem_add_memory(): Try adding a single Linux memory block.\ndrivers/virtio/virtio_mem.c-671- */\ndrivers/virtio/virtio_mem.c=672=static int virtio_mem_sbm_add_mb(struct virtio_mem *vm, unsigned long mb_id)\n--\ndrivers/virtio/virtio_mem.c-676-\ndrivers/virtio/virtio_mem.c:677:\treturn virtio_mem_add_memory(vm, addr, size);\ndrivers/virtio/virtio_mem.c-678-}\n--\ndrivers/virtio/virtio_mem.c-680-/*\ndrivers/virtio/virtio_mem.c:681: * See virtio_mem_add_memory(): Try adding a big block.\ndrivers/virtio/virtio_mem.c-682- */\ndrivers/virtio/virtio_mem.c=683=static int virtio_mem_bbm_add_bb(struct virtio_mem *vm, unsigned long bb_id)\n--\ndrivers/virtio/virtio_mem.c-687-\ndrivers/virtio/virtio_mem.c:688:\treturn virtio_mem_add_memory(vm, addr, size);\ndrivers/virtio/virtio_mem.c-689-}\n--\ndrivers/virtio/virtio_mem.c=974=static void virtio_mem_bbm_notify_cancel_offline(struct virtio_mem *vm,\n--\ndrivers/virtio/virtio_mem.c-985-/*\ndrivers/virtio/virtio_mem.c:986: * This callback will either be called synchronously from add_memory() or\ndrivers/virtio/virtio_mem.c-987- * asynchronously (e.g., triggered via user space). We have to be careful\ndrivers/virtio/virtio_mem.c:988: * with locking when calling add_memory().\ndrivers/virtio/virtio_mem.c-989- */\ndrivers/virtio/virtio_mem.c=990=static int virtio_mem_memory_notifier_cb(struct notifier_block *nb,\n--\ndrivers/virtio/virtio_mem.c-1087-\t\tif (!atomic_read(\u0026vm-\u003ewq_active) \u0026\u0026\ndrivers/virtio/virtio_mem.c:1088:\t\t    virtio_mem_could_add_memory(vm, vm-\u003eoffline_threshold / 2))\ndrivers/virtio/virtio_mem.c-1089-\t\t\tvirtio_mem_retry(vm);\n--\ndrivers/virtio/virtio_mem.c=1760=static int virtio_mem_sbm_plug_request(struct virtio_mem *vm, uint64_t diff)\n--\ndrivers/virtio/virtio_mem.c-1793-\tvirtio_mem_sbm_for_each_mb(vm, mb_id, VIRTIO_MEM_SBM_MB_UNUSED) {\ndrivers/virtio/virtio_mem.c:1794:\t\tif (!virtio_mem_could_add_memory(vm, memory_block_size_bytes()))\ndrivers/virtio/virtio_mem.c-1795-\t\t\treturn -ENOSPC;\n--\ndrivers/virtio/virtio_mem.c-1804-\twhile (nb_sb) {\ndrivers/virtio/virtio_mem.c:1805:\t\tif (!virtio_mem_could_add_memory(vm, memory_block_size_bytes()))\ndrivers/virtio/virtio_mem.c-1806-\t\t\treturn -ENOSPC;\n--\ndrivers/virtio/virtio_mem.c=1878=static int virtio_mem_bbm_plug_request(struct virtio_mem *vm, uint64_t diff)\n--\ndrivers/virtio/virtio_mem.c-1888-\tvirtio_mem_bbm_for_each_bb(vm, bb_id, VIRTIO_MEM_BBM_BB_UNUSED) {\ndrivers/virtio/virtio_mem.c:1889:\t\tif (!virtio_mem_could_add_memory(vm, vm-\u003ebbm.bb_size))\ndrivers/virtio/virtio_mem.c-1890-\t\t\treturn -ENOSPC;\n--\ndrivers/virtio/virtio_mem.c-1901-\twhile (nb_bb) {\ndrivers/virtio/virtio_mem.c:1902:\t\tif (!virtio_mem_could_add_memory(vm, vm-\u003ebbm.bb_size))\ndrivers/virtio/virtio_mem.c-1903-\t\t\treturn -ENOSPC;\n--\ndrivers/virtio/virtio_mem.c=2879=static int virtio_mem_create_resource(struct virtio_mem *vm)\n--\ndrivers/virtio/virtio_mem.c-2901-\ndrivers/virtio/virtio_mem.c:2902:\t/* The memory is not actually busy - make add_memory() work. */\ndrivers/virtio/virtio_mem.c-2903-\tvm-\u003eparent_resource-\u003eflags \u0026= ~IORESOURCE_BUSY;\n--\ndrivers/xen/balloon.c=264=static enum bp_state reserve_additional_memory(void)\n--\ndrivers/xen/balloon.c-296-        /*\ndrivers/xen/balloon.c:297:         * add_memory() will build page tables for the new memory so\ndrivers/xen/balloon.c-298-         * the p2m must contain invalid entries so the correct\n--\ndrivers/xen/balloon.c-318-\t/*\ndrivers/xen/balloon.c:319:\t * add_memory_resource() will call online_pages() which in its turn\ndrivers/xen/balloon.c-320-\t * will call xen_online_page() callback causing deadlock if we don't\n--\ndrivers/xen/balloon.c-324-\tmutex_unlock(\u0026balloon_mutex);\ndrivers/xen/balloon.c:325:\t/* add_memory_resource() requires the device_hotplug lock */\ndrivers/xen/balloon.c-326-\tlock_device_hotplug();\ndrivers/xen/balloon.c:327:\trc = add_memory_resource(nid, resource, MHP_MERGE_RESOURCE);\ndrivers/xen/balloon.c-328-\tunlock_device_hotplug();\n--\ninclude/linux/memory_hotplug.h=32=struct page *pfn_to_online_page(unsigned long pfn);\ninclude/linux/memory_hotplug.h-33-\ninclude/linux/memory_hotplug.h:34:/* Flags for add_memory() and friends to specify memory hotplug details. */\ninclude/linux/memory_hotplug.h-35-typedef int __bitwise mhp_t;\n--\ninclude/linux/memory_hotplug.h-40- * Allow merging of the added System RAM resource with adjacent,\ninclude/linux/memory_hotplug.h:41: * mergeable resources. After a successful call to add_memory_resource()\ninclude/linux/memory_hotplug.h-42- * with this flag set, the resource pointer must no longer be used as it\n--\ninclude/linux/memory_hotplug.h=123=extern int try_online_node(int nid);\ninclude/linux/memory_hotplug.h-124-\ninclude/linux/memory_hotplug.h:125:extern int arch_add_memory(int nid, u64 start, u64 size,\ninclude/linux/memory_hotplug.h-126-\t\t\t   struct mhp_params *params);\n--\ninclude/linux/memory_hotplug.h=301=int __ref free_area_init_core_hotplug(struct pglist_data *pgdat);\ninclude/linux/memory_hotplug.h:302:extern int __add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags);\ninclude/linux/memory_hotplug.h:303:extern int add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags);\ninclude/linux/memory_hotplug.h:304:extern int add_memory_resource(int nid, struct resource *resource,\ninclude/linux/memory_hotplug.h-305-\t\t\t       mhp_t mhp_flags);\ninclude/linux/memory_hotplug.h:306:int __add_memory_driver_managed(int nid, u64 start, u64 size,\ninclude/linux/memory_hotplug.h-307-\t\t\t\tconst char *resource_name, mhp_t mhp_flags,\ninclude/linux/memory_hotplug.h-308-\t\t\t\tenum mmop online_type);\ninclude/linux/memory_hotplug.h:309:extern int add_memory_driver_managed(int nid, u64 start, u64 size,\ninclude/linux/memory_hotplug.h-310-\t\t\t\t     const char *resource_name,\n--\nmm/memory_hotplug.c=322=static int check_pfn_span(unsigned long pfn, unsigned long nr_pages)\n--\nmm/memory_hotplug.c-328-\t * online, so this check should only fire for direct\nmm/memory_hotplug.c:329:\t * arch_{add,remove}_memory() users outside of add_memory_resource().\nmm/memory_hotplug.c-330-\t */\n--\nmm/memory_hotplug.c=1446=static int create_altmaps_and_memory_blocks(int nid, struct memory_group *group,\n--\nmm/memory_hotplug.c-1470-\t\t/* call arch's memory hotadd */\nmm/memory_hotplug.c:1471:\t\tret = arch_add_memory(nid, cur_start, memblock_size, \u0026params);\nmm/memory_hotplug.c-1472-\t\tif (ret \u003c 0) {\n--\nmm/memory_hotplug.c=1507=static bool node_is_memoryless(int nid)\n--\nmm/memory_hotplug.c-1529- */\nmm/memory_hotplug.c:1530:static int __add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags,\nmm/memory_hotplug.c-1531-\t\t\t\t enum mmop online_type)\n--\nmm/memory_hotplug.c-1590-\t} else {\nmm/memory_hotplug.c:1591:\t\tret = arch_add_memory(nid, start, size, \u0026params);\nmm/memory_hotplug.c-1592-\t\tif (ret \u003c 0)\n--\nmm/memory_hotplug.c-1638-\nmm/memory_hotplug.c:1639:int add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)\nmm/memory_hotplug.c-1640-{\nmm/memory_hotplug.c:1641:\treturn __add_memory_resource(nid, res, mhp_flags,\nmm/memory_hotplug.c-1642-\t\t\t\t     mhp_get_default_online_type());\n--\nmm/memory_hotplug.c-1644-\nmm/memory_hotplug.c:1645:/* requires device_hotplug_lock, see __add_memory_resource() */\nmm/memory_hotplug.c:1646:int __add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags)\nmm/memory_hotplug.c-1647-{\n--\nmm/memory_hotplug.c-1654-\nmm/memory_hotplug.c:1655:\tret = add_memory_resource(nid, res, mhp_flags);\nmm/memory_hotplug.c-1656-\tif (ret \u003c 0)\n--\nmm/memory_hotplug.c-1660-\nmm/memory_hotplug.c:1661:int add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags)\nmm/memory_hotplug.c-1662-{\n--\nmm/memory_hotplug.c-1665-\tlock_device_hotplug();\nmm/memory_hotplug.c:1666:\trc = __add_memory(nid, start, size, mhp_flags);\nmm/memory_hotplug.c-1667-\tunlock_device_hotplug();\n--\nmm/memory_hotplug.c=1671=EXPORT_SYMBOL_GPL(add_memory);\n--\nmm/memory_hotplug.c-1704- */\nmm/memory_hotplug.c:1705:int __add_memory_driver_managed(int nid, u64 start, u64 size,\nmm/memory_hotplug.c-1706-\t\tconst char *resource_name, mhp_t mhp_flags,\n--\nmm/memory_hotplug.c-1727-\nmm/memory_hotplug.c:1728:\trc = __add_memory_resource(nid, res, mhp_flags, online_type);\nmm/memory_hotplug.c-1729-\tif (rc \u003c 0)\n--\nmm/memory_hotplug.c=1736=EXPORT_SYMBOL_FOR_MODULES(__add_memory_driver_managed, \"kmem\");\n--\nmm/memory_hotplug.c-1752- */\nmm/memory_hotplug.c:1753:int add_memory_driver_managed(int nid, u64 start, u64 size,\nmm/memory_hotplug.c-1754-\t\t\t      const char *resource_name, mhp_t mhp_flags)\nmm/memory_hotplug.c-1755-{\nmm/memory_hotplug.c:1756:\treturn __add_memory_driver_managed(nid, start, size, resource_name,\nmm/memory_hotplug.c-1757-\t\t\tmhp_flags,\n--\nmm/memremap.c=144=static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params,\n--\nmm/memremap.c-203-\t * over the device memory is un-accessible thus we do not want to\nmm/memremap.c:204:\t * create a linear mapping for the memory like arch_add_memory()\nmm/memremap.c-205-\t * would do.\n--\nmm/memremap.c-208-\t * the CPU, we do want the linear mapping and thus use\nmm/memremap.c:209:\t * arch_add_memory().\nmm/memremap.c-210-\t */\n--\nmm/memremap.c-220-\nmm/memremap.c:221:\t\terror = arch_add_memory(nid, range-\u003estart, range_len(range),\nmm/memremap.c-222-\t\t\t\t\tparams);\n"
}

gemini-3.7-flash

null

null

							input: 34954
							output: 35
							thoughts: 88
						

**Analyzing the Memory Probe Mechanism**

Okay, let's break this down. My initial thought is to trace how the system handles memory probing. I see that `drivers/base/memory.c` has a function called `probe_store`. This function is likely the handler for writes to `/sys/devices/system/memory/probe`. It seems straightforward: the function `probe_store` receives the write operation and then calls `__add_memory(nid, phys_addr, ...)`.

But wait a minute... A red flag! My expert instincts are kicking in. I need to clarify something. Is this `drivers/base/memory.c:probe_store` accessible from userspace? I need to know if an unprivileged process can trigger this function. It would be a serious security concern if so. Time to dive back into `drivers/base/memory.c` and confirm exactly how this probe mechanism is exposed. I'm going to carefully review the code to understand its security implications.

{
  "File": "drivers/base/memory.c",
  "FirstLine": 565,
  "LineCount": 40
}

{
  "Contents": " 565:\t/*\n 566:\t * Some architectures will have custom drivers to do this, and\n 567:\t * will not need to do it from userspace.  The fake hot-add code\n 568:\t * as well as ppc64 will do all of their discovery in userspace\n 569:\t * and will require this interface.\n 570:\t */\n 571:\t#ifdef CONFIG_ARCH_MEMORY_PROBE\n 572:\tstatic ssize_t probe_store(struct device *dev, struct device_attribute *attr,\n 573:\t\t\t\t   const char *buf, size_t count)\n 574:\t{\n 575:\t\tu64 phys_addr;\n 576:\t\tint nid, ret;\n 577:\t\tunsigned long pages_per_block = PAGES_PER_SECTION * sections_per_block;\n 578:\t\n 579:\t\tret = kstrtoull(buf, 0, \u0026phys_addr);\n 580:\t\tif (ret)\n 581:\t\t\treturn ret;\n 582:\t\n 583:\t\tif (phys_addr \u0026 ((pages_per_block \u003c\u003c PAGE_SHIFT) - 1))\n 584:\t\t\treturn -EINVAL;\n 585:\t\n 586:\t\tret = lock_device_hotplug_sysfs();\n 587:\t\tif (ret)\n 588:\t\t\treturn ret;\n 589:\t\n 590:\t\tnid = memory_add_physaddr_to_nid(phys_addr);\n 591:\t\tret = __add_memory(nid, phys_addr,\n 592:\t\t\t\t   MIN_MEMORY_BLOCK_SIZE * sections_per_block,\n 593:\t\t\t\t   MHP_NONE);\n 594:\t\n 595:\t\tif (ret)\n 596:\t\t\tgoto out;\n 597:\t\n 598:\t\tret = count;\n 599:\tout:\n 600:\t\tunlock_device_hotplug();\n 601:\t\treturn ret;\n 602:\t}\n 603:\t\n 604:\tstatic DEVICE_ATTR_WO(probe);\n"
}

gemini-3.7-flash

null

null

							input: 35863
							output: 34
							thoughts: 1019
						

**Analyzing the `memblock.c` Patch**

Okay, let's dive into this patch for `memblock.c`. I need to understand exactly what's changed and the implications for memory management. First, I'm noting the addition of a new macro, `for_each_memblock_type_from`. This looks like a variation of the existing `for_each_memblock_type` macro, with a key difference: it allows specifying a starting index, `start`. My initial thought is that this probably introduces more targeted iteration, likely for performance or when we *know* a starting point that we can optimize from.

Now, let me zoom in on the functions using this new macro, specifically `memblock_add_range` and `memblock_isolate_range`. Looking at the surrounding code and the changes, I see that this new macro is being used in these two functions in place of the original `for_each_memblock_type` macro. The key is in the parameters. The "from" index appears to be coming from a new function called `memblock_bsearch_start`. It looks like it's a binary search implementation.

So, the code now looks like it is using a binary search to find a suitable starting index for adding a memory range. I can see that `memblock_bsearch_start` calculates an index that is the first region where the potential overlap base address starts. This is a significant optimization! Instead of iterating through *all* existing memblock regions, the code now uses `memblock_bsearch_start` to narrow the search, effectively reducing the number of iterations required, especially when dealing with large memblock lists. This should improve performance when adding or isolating memory regions, which can be critical during early boot stages or memory hotplug operations.

Okay, let me confirm my hypothesis by reading further into the source. I need to fully understand the logic here: how `memblock_bsearch_start` is used, and how it impacts the overall memory block management. I need to make sure I haven't missed a nuance.

{
  "File": "mm/memblock.c",
  "FirstLine": 630,
  "LineCount": 80
}

{
  "Contents": " 630:\t * @size: size of the new region\n 631:\t * @nid: nid of the new region\n 632:\t * @flags: flags of the new region\n 633:\t *\n 634:\t * Add new memblock region [@base, @base + @size) into @type.  The new region\n 635:\t * is allowed to overlap with existing ones - overlaps don't affect already\n 636:\t * existing regions.  @type is guaranteed to be minimal (all neighbouring\n 637:\t * compatible regions are merged) after the addition.\n 638:\t *\n 639:\t * Return:\n 640:\t * 0 on success, -errno on failure.\n 641:\t */\n 642:\tstatic int __init_memblock memblock_add_range(struct memblock_type *type,\n 643:\t\t\t\t\tphys_addr_t base, phys_addr_t size,\n 644:\t\t\t\t\tint nid, enum memblock_flags flags)\n 645:\t{\n 646:\t\tbool insert = false;\n 647:\t\tphys_addr_t obase = base;\n 648:\t\tphys_addr_t end = base + memblock_cap_size(base, \u0026size);\n 649:\t\tint idx, nr_new, start_rgn = -1, end_rgn;\n 650:\t\tstruct memblock_region *rgn;\n 651:\t\n 652:\t\tif (!size)\n 653:\t\t\treturn 0;\n 654:\t\n 655:\t\t/* special case for empty array */\n 656:\t\tif (type-\u003eregions[0].size == 0) {\n 657:\t\t\tWARN_ON(type-\u003ecnt != 0 || type-\u003etotal_size);\n 658:\t\t\ttype-\u003eregions[0].base = base;\n 659:\t\t\ttype-\u003eregions[0].size = size;\n 660:\t\t\ttype-\u003eregions[0].flags = flags;\n 661:\t\t\tmemblock_set_region_node(\u0026type-\u003eregions[0], nid);\n 662:\t\t\ttype-\u003etotal_size = size;\n 663:\t\t\ttype-\u003ecnt = 1;\n 664:\t\t\treturn 0;\n 665:\t\t}\n 666:\t\n 667:\t\t/*\n 668:\t\t * The worst case is when new range overlaps all existing regions,\n 669:\t\t * then we'll need type-\u003ecnt + 1 empty regions in @type. So if\n 670:\t\t * type-\u003ecnt * 2 + 1 is less than or equal to type-\u003emax, we know\n 671:\t\t * that there is enough empty regions in @type, and we can insert\n 672:\t\t * regions directly.\n 673:\t\t */\n 674:\t\tif (type-\u003ecnt * 2 + 1 \u003c= type-\u003emax)\n 675:\t\t\tinsert = true;\n 676:\t\n 677:\trepeat:\n 678:\t\t/*\n 679:\t\t * The following is executed twice.  Once with %false @insert and\n 680:\t\t * then with %true.  The first counts the number of regions needed\n 681:\t\t * to accommodate the new area.  The second actually inserts them.\n 682:\t\t */\n 683:\t\tbase = obase;\n 684:\t\tnr_new = 0;\n 685:\t\n 686:\t\tfor_each_memblock_type_from(idx, type, rgn,\n 687:\t\t\t\t\t    memblock_bsearch_start(type, base)) {\n 688:\t\t\tphys_addr_t rbase = rgn-\u003ebase;\n 689:\t\t\tphys_addr_t rend = rbase + rgn-\u003esize;\n 690:\t\n 691:\t\t\tif (rbase \u003e= end)\n 692:\t\t\t\tbreak;\n 693:\t\t\tif (rend \u003c= base)\n 694:\t\t\t\tcontinue;\n 695:\t\t\t/*\n 696:\t\t\t * @rgn overlaps.  If it separates the lower part of new\n 697:\t\t\t * area, insert that portion.\n 698:\t\t\t */\n 699:\t\t\tif (rbase \u003e base) {\n 700:\t#ifdef CONFIG_NUMA\n 701:\t\t\t\tWARN_ON(nid != memblock_get_region_node(rgn));\n 702:\t#endif\n 703:\t\t\t\tWARN_ON(flags != MEMBLOCK_NONE \u0026\u0026 flags != rgn-\u003eflags);\n 704:\t\t\t\tnr_new++;\n 705:\t\t\t\tif (insert) {\n 706:\t\t\t\t\tif (start_rgn == -1)\n 707:\t\t\t\t\t\tstart_rgn = idx;\n 708:\t\t\t\t\tend_rgn = idx + 1;\n 709:\t\t\t\t\tmemblock_insert_region(type, idx++, base,\n"
}

gemini-3.7-flash

null

null

							input: 38620
							output: 34
							thoughts: 12
						

Okay, here's my attempt at summarizing that thought process, keeping in mind I'm speaking to a fellow expert:

**Investigating `memblock_isolate_range`**

Right, let's dive right in. My first thought is to zero in on `memblock_isolate_range`. That function has the potential to be a crucial component in this specific context, and it's where I should be directing my immediate attention. I need to understand its behavior thoroughly, its inputs, and what its specific role is in the bigger picture of memory management, based on whatever problem I am trying to resolve. I'm going to start there and see what insights I can glean.

{
  "File": "mm/memblock.c",
  "FirstLine": 840,
  "LineCount": 60
}

{
  "Contents": " 840:\t * first region after the range is returned in *@end_rgn.\n 841:\t *\n 842:\t * Return:\n 843:\t * 0 on success, -errno on failure.\n 844:\t */\n 845:\tstatic int __init_memblock memblock_isolate_range(struct memblock_type *type,\n 846:\t\t\t\t\t\tphys_addr_t base, phys_addr_t size,\n 847:\t\t\t\t\t\tint *start_rgn, int *end_rgn)\n 848:\t{\n 849:\t\tphys_addr_t end = base + memblock_cap_size(base, \u0026size);\n 850:\t\tint idx;\n 851:\t\tstruct memblock_region *rgn;\n 852:\t\n 853:\t\t*start_rgn = *end_rgn = 0;\n 854:\t\n 855:\t\tif (!size)\n 856:\t\t\treturn 0;\n 857:\t\n 858:\t\t/* we'll create at most two more regions */\n 859:\t\twhile (type-\u003ecnt + 2 \u003e type-\u003emax)\n 860:\t\t\tif (memblock_double_array(type, base, size) \u003c 0)\n 861:\t\t\t\treturn -ENOMEM;\n 862:\t\n 863:\t\tfor_each_memblock_type_from(idx, type, rgn,\n 864:\t\t\t\t\t    memblock_bsearch_start(type, base)) {\n 865:\t\t\tphys_addr_t rbase = rgn-\u003ebase;\n 866:\t\t\tphys_addr_t rend = rbase + rgn-\u003esize;\n 867:\t\n 868:\t\t\tif (rbase \u003e= end)\n 869:\t\t\t\tbreak;\n 870:\t\t\tif (rend \u003c= base)\n 871:\t\t\t\tcontinue;\n 872:\t\n 873:\t\t\tif (rbase \u003c base) {\n 874:\t\t\t\t/*\n 875:\t\t\t\t * @rgn intersects from below.  Split and continue\n 876:\t\t\t\t * to process the next region - the new top half.\n 877:\t\t\t\t */\n 878:\t\t\t\trgn-\u003ebase = base;\n 879:\t\t\t\trgn-\u003esize -= base - rbase;\n 880:\t\t\t\ttype-\u003etotal_size -= base - rbase;\n 881:\t\t\t\tmemblock_insert_region(type, idx, rbase, base - rbase,\n 882:\t\t\t\t\t\t       memblock_get_region_node(rgn),\n 883:\t\t\t\t\t\t       rgn-\u003eflags);\n 884:\t\t\t} else if (rend \u003e end) {\n 885:\t\t\t\t/*\n 886:\t\t\t\t * @rgn intersects from above.  Split and redo the\n 887:\t\t\t\t * current region - the new bottom half.\n 888:\t\t\t\t */\n 889:\t\t\t\trgn-\u003ebase = end;\n 890:\t\t\t\trgn-\u003esize -= end - rbase;\n 891:\t\t\t\ttype-\u003etotal_size -= end - rbase;\n 892:\t\t\t\tmemblock_insert_region(type, idx--, rbase, end - rbase,\n 893:\t\t\t\t\t\t       memblock_get_region_node(rgn),\n 894:\t\t\t\t\t\t       rgn-\u003eflags);\n 895:\t\t\t} else {\n 896:\t\t\t\t/* @rgn is fully contained, record it */\n 897:\t\t\t\tif (!*end_rgn)\n 898:\t\t\t\t\t*start_rgn = idx;\n 899:\t\t\t\t*end_rgn = idx + 1;\n"
}

gemini-3.7-flash

null

null

							input: 39747
							output: 37
							thoughts: 2844
						

**Fuzzing Triage: Analyzing Modifications to `memblock_add_range` and `memblock_isolate_range`**

Okay, let's break this down. My initial assessment is that `memblock_add_range` and `memblock_isolate_range` have been modified, and that immediately triggers some core triage questions. Given my expertise, I'm going to follow the core triage philosophy laid out in Section 1, 2, and 3. My primary concern is reachability. I need to determine if these functions are dynamically reachable at runtime within a standard virtualized environment like GCE or QEMU. Simply put, can syzkaller, or any fuzzing strategy, actually *hit* this code?

My first step is to dig into the call paths of `memblock_add_range` and `memblock_isolate_range`.  I see that they're both directly or indirectly called from `mm/memory_hotplug.c` via `memblock_add_node` and `memblock_remove`.  Specifically, `__add_memory_resource()` which then calls `memblock_add_node` and `memblock_remove` is called from memory hotplug routines like virtio-mem, sysfs memory probe, DAX/dev_dax kmem, and memory offline operations.

Crucially, I need to know under what conditions these paths are taken. `CONFIG_ARCH_KEEP_MEMBLOCK` seems relevant, as it affects the use of `memblock_add_node` in `__add_memory_resource()`. My hypothesis is that, when `CONFIG_ARCH_KEEP_MEMBLOCK` is enabled, on architectures like INTEL_TDX_HOST or arm64, memory hotplug operations will indeed lead to the execution of `memblock_add_range` and `memblock_isolate_range`.  I can see that when memory is hotplugged via virtio_mem, sysfs, or kmem, `__add_memory_resource()` is called, and, if `CONFIG_ARCH_KEEP_MEMBLOCK` is set, calls `memblock_add_node()` and `memblock_remove()` which in turn, call our modified functions.

Now, I'll need to confirm these assumptions based on config options. `CONFIG_MEMORY_HOTPLUG`, `CONFIG_ARCH_KEEP_MEMBLOCK`, `CONFIG_INTEL_TDX_HOST`, and potentially others are all prime suspects for creating a viable fuzzing target.

The modifications themselves involve replacing a linear search (`for_each_memblock_type`) with a binary search (`memblock_bsearch_start`) to find the starting index within the `memblock_type`. This is a non-trivial algorithmic change within a core memory management component. This is a significant change: a core subsystem in memory management (`mm/memblock.c`) has seen a change to its fundamental logic.

Let's now analyze the code that has changed. `memblock_bsearch_start` returns the index of the first region where the base of the memory that we're inserting or removing doesn't overlap. Looking closely at `memblock_isolate_range`, I can see that the binary search result is used to determine the starting point.

In `memblock_add_range`, the binary search is performed at the beginning of the `for_each_memblock_type_from` loop. The key is that base doesn't change during the loop (so the search only has to happen once), and the loop only processes those entries which could be affected by the memblock operation.

My initial assessment indicates that these functions are indeed reachable via runtime memory hotplug paths, and the algorithmic change is significant enough to warrant fuzzing.

{
  "Expression": "config MEMORY_HOTPLUG|config ARCH_KEEP_MEMBLOCK",
  "PathPrefix": "mm/"
}

{
  "Output": "mm/Kconfig=482=config MEMBLOCK_KHO_SCRATCH\n--\nmm/Kconfig-487-# Also, memblocks are updated with memory hot(un)plug.\nmm/Kconfig:488:config ARCH_KEEP_MEMBLOCK\nmm/Kconfig-489-\tbool\n--\nmm/Kconfig=505=config ARCH_ENABLE_MEMORY_HOTPLUG\n--\nmm/Kconfig-508-# eventually, we can have this option just 'select SPARSEMEM'\nmm/Kconfig:509:menuconfig MEMORY_HOTPLUG\nmm/Kconfig-510-\tbool \"Memory hotplug\"\n"
}

gemini-3.7-flash

null

null

							input: 43600
							output: 34
							thoughts: 24
						

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

**Diving into the Kernel Configuration**

Okay, so I need to track down where `INTEL_TDX_HOST` is defined within the kernel's build configuration. Specifically, I should start by checking `arch/x86/Kconfig`. That's the logical place to begin, given that TDX (Trusted Domain Extensions) is an x86-specific technology from Intel. I know this from working with similar hardware security features in the past. It's almost guaranteed to be nested somewhere in the x86-related Kconfig files. Time to dig in and see what I find. This will give me a good understanding of what other options might be related, and dependencies or configuration options that could be affected by it.

{
  "Expression": "config INTEL_TDX_HOST",
  "PathPrefix": "arch/x86/"
}

{
  "Output": "arch/x86/Kconfig=1846=config X86_USER_SHADOW_STACK\n--\narch/x86/Kconfig-1864-\narch/x86/Kconfig:1865:config INTEL_TDX_HOST\narch/x86/Kconfig-1866-\tbool \"Intel Trust Domain Extensions (TDX) host support\"\n"
}

gemini-3.7-flash

null

null

							input: 43937
							output: 37
							thoughts: 27
						

Here's my summary, as though I'm reading and processing the `arch/x86/Kconfig` file:

**Analyzing the `INTEL_TDX_HOST` Dependencies**

Okay, let's dive into the `arch/x86/Kconfig` file and parse the dependencies for the `INTEL_TDX_HOST` option. I need to understand the constraints and prerequisites for enabling this. First, I'll need to identify which other Kconfig symbols this one relies on. I'm looking for things that *must* be defined or enabled *before* I can even consider configuring TDX host support. This is critical for getting the build configuration correct. I'm anticipating that there are hardware requirements, and potentially some CPU feature flags that must be present. And, given that this relates to Intel's TDX, I'm expecting some specific processor or platform series might be needed. Let's see what the Kconfig code reveals...I'll mentally map out the implications of each dependency on the hardware requirements I might need to consider when enabling this support.

{
  "File": "arch/x86/Kconfig",
  "FirstLine": 1865,
  "LineCount": 20
}

{
  "Contents": "1865:\tconfig INTEL_TDX_HOST\n1866:\t\tbool \"Intel Trust Domain Extensions (TDX) host support\"\n1867:\t\tdepends on CPU_SUP_INTEL\n1868:\t\tdepends on X86_64\n1869:\t\tdepends on KVM_INTEL\n1870:\t\tdepends on X86_X2APIC\n1871:\t\tselect ARCH_KEEP_MEMBLOCK\n1872:\t\tdepends on CONTIG_ALLOC\n1873:\t\tdepends on X86_MCE\n1874:\t\thelp\n1875:\t\t  Intel Trust Domain Extensions (TDX) protects guest VMs from malicious\n1876:\t\t  host and certain physical attacks.  This option enables necessary TDX\n1877:\t\t  support in the host kernel to run confidential VMs.\n1878:\t\n1879:\t\t  If unsure, say N.\n1880:\t\n1881:\tconfig EFI\n1882:\t\tbool \"EFI runtime service support\"\n1883:\t\tdepends on ACPI\n1884:\t\tselect UCS2_STRING\n"
}

gemini-3.7-flash

null

null

							input: 44525
							output: 31
							thoughts: 111
						

**Investigating ARCH_KEEP_MEMBLOCK Dependencies**

Okay, so we need to see how `ARCH_KEEP_MEMBLOCK` is being selected or enabled beyond what we've already looked at. My initial grep was helpful, but we have to be thorough. I see that `INTEL_TDX_HOST` in `arch/x86/Kconfig` selects it, which makes sense. We're also seeing it tied to things like `MEMORY_HOTPLUG`, `MEMORY_HOTREMOVE`, and `VIRTIO_MEM`. The hotplug and hotremove aspects are consistent with the likely use-case.

Now, `VIRTIO_MEM` warrants closer attention. Given the nature of virtio devices, there could be interesting implications for memory management. Let me delve into the `drivers/virtio/Kconfig` file and confirm that it's acting as a source of enablement or a dependency. I need to understand the relationship. This is important to ensure we are not missing any side-effects.

{
  "Expression": "config VIRTIO_MEM",
  "PathPrefix": "drivers/virtio/"
}

{
  "Output": "drivers/virtio/Kconfig=112=config VIRTIO_BALLOON\n--\ndrivers/virtio/Kconfig-122-\ndrivers/virtio/Kconfig:123:config VIRTIO_MEM\ndrivers/virtio/Kconfig-124-\ttristate \"Virtio mem driver\"\n"
}

gemini-3.7-flash

null

null

							input: 44973
							output: 35
							thoughts: 20
						

Here's my summary, as if I were thinking these thoughts:

**Virtio Kconfig Inspection**

Okay, time to dive into the `drivers/virtio/Kconfig` file. I need to refresh my memory on the configuration options, particularly around line 123. There's probably something specific I'm looking for there, either related to a feature flag, a dependency, or a conditional. Let's see if this is related to the specific virtio device I'm working with or something more global within the virtio framework. I suspect the line number is important. Time to get my eyes on it.

{
  "File": "drivers/virtio/Kconfig",
  "FirstLine": 120,
  "LineCount": 20
}

{
  "Contents": " 120:\t\n 121:\t\t If unsure, say M.\n 122:\t\n 123:\tconfig VIRTIO_MEM\n 124:\t\ttristate \"Virtio mem driver\"\n 125:\t\tdepends on X86_64 || ARM64 || RISCV || S390\n 126:\t\tdepends on VIRTIO\n 127:\t\tdepends on MEMORY_HOTPLUG\n 128:\t\tdepends on MEMORY_HOTREMOVE\n 129:\t\tdepends on CONTIG_ALLOC\n 130:\t\tdepends on EXCLUSIVE_SYSTEM_RAM\n 131:\t\thelp\n 132:\t\t This driver provides access to virtio-mem paravirtualized memory\n 133:\t\t devices, allowing to hotplug and hotunplug memory.\n 134:\t\n 135:\t\t This driver currently supports x86-64, arm64, riscv and s390.\n 136:\t\t Although it should compile on other architectures that implement\n 137:\t\t memory hot(un)plug, architecture-specific and/or common\n 138:\t\t code changes may be required for virtio-mem, kdump and kexec to\n 139:\t\t work as expected.\n"
}

gemini-3.7-flash

null

null

							input: 45483
							output: 34
							thoughts: 23
						

Here's a summary of my thought process, as if I were thinking it:

**Investigating `DEV_DAX_KMEM`**

Okay, first things first, I need to check the configuration options related to DAX and KMEM. Given the context, my initial thought is to zero in on the `drivers/dax/Kconfig` file. That's where I'd expect to find the definition and any relevant dependencies or dependencies for a feature like `DEV_DAX_KMEM`. Time to navigate there and see what's what.

{
  "File": "drivers/dax/Kconfig",
  "FirstLine": 70,
  "LineCount": 20
}

{
  "Contents": "  70:\t\tdepends on DEV_DAX \u0026\u0026 FS_DAX\n  71:\t\tdefault DEV_DAX\n  72:\t\n  73:\tconfig DEV_DAX_KMEM\n  74:\t\ttristate \"KMEM DAX: map dax-devices as System-RAM\"\n  75:\t\tdefault DEV_DAX\n  76:\t\tdepends on DEV_DAX\n  77:\t\tdepends on MEMORY_HOTPLUG # for add_memory() and friends\n  78:\t\thelp\n  79:\t\t  Support access to persistent, or other performance\n  80:\t\t  differentiated memory as if it were System RAM. This allows\n  81:\t\t  easier use of persistent memory by unmodified applications, or\n  82:\t\t  adds core kernel memory services to heterogeneous memory types\n  83:\t\t  (HMEM) marked \"reserved\" by platform firmware.\n  84:\t\n  85:\t\t  To use this feature, a DAX device must be unbound from the\n  86:\t\t  device_dax driver and bound to this kmem driver on each boot.\n  87:\t\n  88:\t\t  Say N if unsure.\n  89:\t\n"
}

gemini-3.7-flash

null

null

							input: 45959
							output: 222
							thoughts: 931
						

**Focus Symbol and Configuration Determination for Memblock Optimization**

Okay, let's nail down these FocusSymbols. I've been looking at the patch and identifying the functions that were added or changed in `mm/memblock.c`. It looks like we have `memblock_bsearch_start` (a new static helper), and modifications to `memblock_add_range` and `memblock_isolate_range`, also static helpers.

Now, a quick check of the guidelines reveals that while static inline functions in headers are tricky, static functions *within .c files* do get compiled into symbols in `vmlinux`, unless completely inlined. That's good. But non-static callers and entrypoints are also valid and potentially more useful as FocusSymbols, so I'll be sure to include those.

Let's trace the callers of the modified functions: `memblock_add_range` is called by `memblock_add`, `memblock_add_node`, `__memblock_reserve`, and `memblock_physmem_add`. And `memblock_isolate_range` is called by `memblock_remove_range` (which is itself called by `memblock_remove` and `memblock_phys_free`), `memblock_setclr_flag`, `memblock_set_node`, and `memblock_cap_memory_range`. Okay, based on that information, and keeping the guidance from Section 4 in mind, these symbols look promising:

*   `memblock_bsearch_start`
*   `memblock_add_range`
*   `memblock_isolate_range`
*   `memblock_add_node`
*   `memblock_remove_range`
*   `memblock_remove`
*   `memblock_phys_free`

Alright, let's quickly check if any of these functions are ubiquitous hot-paths that could dilute the fuzzing. No, memblock operations are very specific to boot and memory hotplug/hotremove. They are not called on every page fault, malloc/free, or read/write syscall. So, we're good there.

Now, for the required configs, I've identified the following: `INTEL_TDX_HOST` (which selects `ARCH_KEEP_MEMBLOCK` on x86_64), `MEMORY_HOTPLUG`, `MEMORY_HOTREMOVE`, and `VIRTIO_MEM`.

Okay, let's quickly go through a mental checklist:

1.  **Core triage philosophy:** Memory management subsystem (`mm/memblock.c`), replaces linear search, executable at runtime via memory hotplug/remove when memblock is retained, so worth fuzzing. Check!
2.  **FocusSymbols:** Confirmed list above. Check!
3.  **EnableConfigs:** Confirmed list above. Check!

And finally, a sanity check: `set-results` should be called exactly once before the final reply. Got it. So, that's everything!

{
  "EnableConfigs": [
    "MEMORY_HOTPLUG",
    "MEMORY_HOTREMOVE",
    "INTEL_TDX_HOST",
    "VIRTIO_MEM"
  ],
  "FocusSymbols": [
    "memblock_bsearch_start",
    "memblock_add_range",
    "memblock_isolate_range",
    "memblock_add_node",
    "memblock_remove_range",
    "memblock_remove",
    "memblock_phys_free"
  ],
  "Reasoning": "The patch modifies the memory block management subsystem (mm/memblock.c), introducing binary search (memblock_bsearch_start) to find candidate regions in memblock_add_range and memblock_isolate_range. This affects core memory management and region splitting/merging algorithms reachable at runtime during memory hotplug and hotremove when memblock metadata is retained (CONFIG_ARCH_KEEP_MEMBLOCK). Fuzzing is warranted to test region manipulation logic and boundaries.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "MEMORY_HOTPLUG",
    "MEMORY_HOTREMOVE",
    "INTEL_TDX_HOST",
    "VIRTIO_MEM"
  ],
  "FocusSymbols": [
    "memblock_bsearch_start",
    "memblock_add_range",
    "memblock_isolate_range",
    "memblock_add_node",
    "memblock_remove_range",
    "memblock_remove",
    "memblock_phys_free"
  ],
  "Reasoning": "The patch modifies the memory block management subsystem (mm/memblock.c), introducing binary search (memblock_bsearch_start) to find candidate regions in memblock_add_range and memblock_isolate_range. This affects core memory management and region splitting/merging algorithms reachable at runtime during memory hotplug and hotremove when memblock metadata is retained (CONFIG_ARCH_KEEP_MEMBLOCK). Fuzzing is warranted to test region manipulation logic and boundaries.",
  "WorthFuzzing": true
}

{
  "WorthFuzzing": true
}

null

core

null

{
  "KMSANReasoning": "The patch optimizes region lookup in early boot memblock management (mm/memblock.c) by introducing memblock_bsearch_start() and for_each_memblock_type_from(). The changes operate exclusively on existing, initialized memblock regions and internal indices. Potential bugs in this logic (such as index calculation errors or array out-of-bounds access) would be caught by KASAN and standard assertion/bounds checking. The patch does not introduce or expose uninitialized memory, does not copy kernel data to user space, and does not alter padding/uninitialized field initialization, making dedicated KMSAN fuzzing unnecessary.",
  "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 f6f0e825bfc8372d55dd8b0bf8b1501c090fd441
Author: syz-cluster <triage@syzkaller.com>
Date:   Sat Sep 5 00:53:12 2026 +0000

    syz-cluster: applied patch under review

diff --git a/mm/memblock.c b/mm/memblock.c
index 9ce86349a29fa..88940474b0203 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -160,6 +160,11 @@ static __refdata struct memblock_type *memblock_memory = &memblock.memory;
 	     i < memblock_type->cnt;					\
 	     i++, rgn = &memblock_type->regions[i])
 
+#define for_each_memblock_type_from(i, memblock_type, rgn, start)	\
+	for (i = (start), rgn = &memblock_type->regions[i];		\
+	     i < memblock_type->cnt;					\
+	     i++, rgn = &memblock_type->regions[i])
+
 #define memblock_dbg(fmt, ...)						\
 	do {								\
 		if (memblock_debug)					\
@@ -591,6 +596,33 @@ static void __init_memblock memblock_insert_region(struct memblock_type *type,
 	type->total_size += size;
 }
 
+/**
+ * memblock_bsearch_start - Find the first region index where rend > base
+ * @type: memblock type to search
+ * @base: base physical address of the candidate range
+ *
+ * Returns the first region index that could potentially overlap @base.
+ */
+static int __init_memblock memblock_bsearch_start(struct memblock_type *type,
+						  phys_addr_t base)
+{
+	int mid, low = 0;
+	int high = type->cnt;
+
+	if (type->cnt && base >= type->regions[type->cnt - 1].base +
+				 type->regions[type->cnt - 1].size)
+		return type->cnt;
+
+	while (low < high) {
+		mid = (low + high) / 2;
+		if (type->regions[mid].base + type->regions[mid].size <= base)
+			low = mid + 1;
+		else
+			high = mid;
+	}
+	return low;
+}
+
 /**
  * memblock_add_range - add new memblock region
  * @type: memblock type to add new region into
@@ -651,7 +683,8 @@ static int __init_memblock memblock_add_range(struct memblock_type *type,
 	base = obase;
 	nr_new = 0;
 
-	for_each_memblock_type(idx, type, rgn) {
+	for_each_memblock_type_from(idx, type, rgn,
+				    memblock_bsearch_start(type, base)) {
 		phys_addr_t rbase = rgn->base;
 		phys_addr_t rend = rbase + rgn->size;
 
@@ -827,7 +860,8 @@ static int __init_memblock memblock_isolate_range(struct memblock_type *type,
 		if (memblock_double_array(type, base, size) < 0)
 			return -ENOMEM;
 
-	for_each_memblock_type(idx, type, rgn) {
+	for_each_memblock_type_from(idx, type, rgn,
+				    memblock_bsearch_start(type, base)) {
 		phys_addr_t rbase = rgn->base;
 		phys_addr_t rend = rbase + rgn->size;
 

gemini-3.7-flash

null

null

							input: 2800
							output: 34
							thoughts: 186
						

**KMSAN Analysis of the Memblock Patch**

Okay, let's dive into this patch and figure out if KMSAN needs to be brought to bear here. First things first, let's take a look at the code itself. Alright, it's touching `mm/memblock.c`. Interesting. The patch introduces a few new pieces: a `for_each_memblock_type_from` macro, a helper function called `memblock_bsearch_start`, and it seems to be optimizing `memblock_add_range` and `memblock_isolate_range`. Specifically, it's replacing some linear scans with binary searches, searching for the first overlapping region.

To understand the implications, I need a better grasp of what `memblock` actually *does*. I know it's fundamental for early boot memory management, but let's refresh. I'll read the code around line 591 in `mm/memblock.c`. Context is key here; I need to see how these functions and the data structures they operate on are used in the broader picture. Then I can determine if any of these changes are vulnerable to memory safety issues that KMSAN might catch. Let's see what's happening.

{
  "File": "mm/memblock.c",
  "FirstLine": 580,
  "LineCount": 80
}

{
  "Contents": " 580:\t */\n 581:\tstatic void __init_memblock memblock_insert_region(struct memblock_type *type,\n 582:\t\t\t\t\t\t\t   int idx, phys_addr_t base,\n 583:\t\t\t\t\t\t\t   phys_addr_t size,\n 584:\t\t\t\t\t\t\t   int nid,\n 585:\t\t\t\t\t\t\t   enum memblock_flags flags)\n 586:\t{\n 587:\t\tstruct memblock_region *rgn = \u0026type-\u003eregions[idx];\n 588:\t\n 589:\t\tBUG_ON(type-\u003ecnt \u003e= type-\u003emax);\n 590:\t\tmemmove(rgn + 1, rgn, (type-\u003ecnt - idx) * sizeof(*rgn));\n 591:\t\trgn-\u003ebase = base;\n 592:\t\trgn-\u003esize = size;\n 593:\t\trgn-\u003eflags = flags;\n 594:\t\tmemblock_set_region_node(rgn, nid);\n 595:\t\ttype-\u003ecnt++;\n 596:\t\ttype-\u003etotal_size += size;\n 597:\t}\n 598:\t\n 599:\t/**\n 600:\t * memblock_bsearch_start - Find the first region index where rend \u003e base\n 601:\t * @type: memblock type to search\n 602:\t * @base: base physical address of the candidate range\n 603:\t *\n 604:\t * Returns the first region index that could potentially overlap @base.\n 605:\t */\n 606:\tstatic int __init_memblock memblock_bsearch_start(struct memblock_type *type,\n 607:\t\t\t\t\t\t\t  phys_addr_t base)\n 608:\t{\n 609:\t\tint mid, low = 0;\n 610:\t\tint high = type-\u003ecnt;\n 611:\t\n 612:\t\tif (type-\u003ecnt \u0026\u0026 base \u003e= type-\u003eregions[type-\u003ecnt - 1].base +\n 613:\t\t\t\t\t type-\u003eregions[type-\u003ecnt - 1].size)\n 614:\t\t\treturn type-\u003ecnt;\n 615:\t\n 616:\t\twhile (low \u003c high) {\n 617:\t\t\tmid = (low + high) / 2;\n 618:\t\t\tif (type-\u003eregions[mid].base + type-\u003eregions[mid].size \u003c= base)\n 619:\t\t\t\tlow = mid + 1;\n 620:\t\t\telse\n 621:\t\t\t\thigh = mid;\n 622:\t\t}\n 623:\t\treturn low;\n 624:\t}\n 625:\t\n 626:\t/**\n 627:\t * memblock_add_range - add new memblock region\n 628:\t * @type: memblock type to add new region into\n 629:\t * @base: base address of the new region\n 630:\t * @size: size of the new region\n 631:\t * @nid: nid of the new region\n 632:\t * @flags: flags of the new region\n 633:\t *\n 634:\t * Add new memblock region [@base, @base + @size) into @type.  The new region\n 635:\t * is allowed to overlap with existing ones - overlaps don't affect already\n 636:\t * existing regions.  @type is guaranteed to be minimal (all neighbouring\n 637:\t * compatible regions are merged) after the addition.\n 638:\t *\n 639:\t * Return:\n 640:\t * 0 on success, -errno on failure.\n 641:\t */\n 642:\tstatic int __init_memblock memblock_add_range(struct memblock_type *type,\n 643:\t\t\t\t\tphys_addr_t base, phys_addr_t size,\n 644:\t\t\t\t\tint nid, enum memblock_flags flags)\n 645:\t{\n 646:\t\tbool insert = false;\n 647:\t\tphys_addr_t obase = base;\n 648:\t\tphys_addr_t end = base + memblock_cap_size(base, \u0026size);\n 649:\t\tint idx, nr_new, start_rgn = -1, end_rgn;\n 650:\t\tstruct memblock_region *rgn;\n 651:\t\n 652:\t\tif (!size)\n 653:\t\t\treturn 0;\n 654:\t\n 655:\t\t/* special case for empty array */\n 656:\t\tif (type-\u003eregions[0].size == 0) {\n 657:\t\t\tWARN_ON(type-\u003ecnt != 0 || type-\u003etotal_size);\n 658:\t\t\ttype-\u003eregions[0].base = base;\n 659:\t\t\ttype-\u003eregions[0].size = size;\n"
}

gemini-3.7-flash

null

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							input: 4527
							output: 34
							thoughts: 23
						

Here's my attempt at summarizing the thought process, tailored for an expert audience and written in the first person:

**Diving into `memblock_isolate_range` in `mm/memblock.c`**

Okay, so I'm digging into `memblock_isolate_range` within `mm/memblock.c`. I'm going to want to understand exactly how this function works, and where it's called. My initial thought is it is being used to manipulate the memblock structure, perhaps to handle memory hotplug, or maybe for something like isolating memory ranges for a specific NUMA node or IOMMU assignment. I'll need to trace the calling paths to understand the context. I'll probably start by looking at what the function does with the arguments passed to it. Let's see how it interacts with the memblock structure. I need to keep in mind, I should look out for any potential race conditions, or lock contention issues that may arise in a multi-threaded or interrupt-driven environment. I also need to verify it is handling any potential memory fragmentation issues, as well.

{
  "File": "mm/memblock.c",
  "FirstLine": 820,
  "LineCount": 60
}

{
  "Contents": " 820:\t\t\t       (nr_pages \u003c\u003c PAGE_SHIFT) / SZ_1M, mem_size_mb);\n 821:\t\t\treturn false;\n 822:\t\t}\n 823:\t\n 824:\t\treturn true;\n 825:\t}\n 826:\t\n 827:\t\n 828:\t/**\n 829:\t * memblock_isolate_range - isolate given range into disjoint memblocks\n 830:\t * @type: memblock type to isolate range for\n 831:\t * @base: base of range to isolate\n 832:\t * @size: size of range to isolate\n 833:\t * @start_rgn: out parameter for the start of isolated region\n 834:\t * @end_rgn: out parameter for the end of isolated region\n 835:\t *\n 836:\t * Walk @type and ensure that regions don't cross the boundaries defined by\n 837:\t * [@base, @base + @size).  Crossing regions are split at the boundaries,\n 838:\t * which may create at most two more regions.  The index of the first\n 839:\t * region inside the range is returned in *@start_rgn and the index of the\n 840:\t * first region after the range is returned in *@end_rgn.\n 841:\t *\n 842:\t * Return:\n 843:\t * 0 on success, -errno on failure.\n 844:\t */\n 845:\tstatic int __init_memblock memblock_isolate_range(struct memblock_type *type,\n 846:\t\t\t\t\t\tphys_addr_t base, phys_addr_t size,\n 847:\t\t\t\t\t\tint *start_rgn, int *end_rgn)\n 848:\t{\n 849:\t\tphys_addr_t end = base + memblock_cap_size(base, \u0026size);\n 850:\t\tint idx;\n 851:\t\tstruct memblock_region *rgn;\n 852:\t\n 853:\t\t*start_rgn = *end_rgn = 0;\n 854:\t\n 855:\t\tif (!size)\n 856:\t\t\treturn 0;\n 857:\t\n 858:\t\t/* we'll create at most two more regions */\n 859:\t\twhile (type-\u003ecnt + 2 \u003e type-\u003emax)\n 860:\t\t\tif (memblock_double_array(type, base, size) \u003c 0)\n 861:\t\t\t\treturn -ENOMEM;\n 862:\t\n 863:\t\tfor_each_memblock_type_from(idx, type, rgn,\n 864:\t\t\t\t\t    memblock_bsearch_start(type, base)) {\n 865:\t\t\tphys_addr_t rbase = rgn-\u003ebase;\n 866:\t\t\tphys_addr_t rend = rbase + rgn-\u003esize;\n 867:\t\n 868:\t\t\tif (rbase \u003e= end)\n 869:\t\t\t\tbreak;\n 870:\t\t\tif (rend \u003c= base)\n 871:\t\t\t\tcontinue;\n 872:\t\n 873:\t\t\tif (rbase \u003c base) {\n 874:\t\t\t\t/*\n 875:\t\t\t\t * @rgn intersects from below.  Split and continue\n 876:\t\t\t\t * to process the next region - the new top half.\n 877:\t\t\t\t */\n 878:\t\t\t\trgn-\u003ebase = base;\n 879:\t\t\t\trgn-\u003esize -= base - rbase;\n"
}

gemini-3.7-flash

null

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							input: 5741
							output: 155
							thoughts: 631
						

**Analyzing the Memblock Optimization for Uninitialized Memory**

Okay, let's break this down. This patch introduces `memblock_bsearch_start`, an optimization for finding the starting index in the `memblock` data structure during memory range addition and isolation. My initial concern is always uninitialized memory; are we creating any risks here?

First, I need to look at if this patch allocates uninitialized memory, copies it to user space, or evaluates it in a conditional statement. It looks like `memblock_bsearch_start` works solely with `type->cnt` and the `base` and `size` fields of `type->regions`. Crucially, those regions from 0 up to `type->cnt - 1` are already initialized memblock regions, valid and ready to go. Even if `type->cnt` is zero, the while loop will quickly terminate. And, for the loop using the start index, if `start` is equal to `type->cnt` it does not run, and all variables are initialized integers/pointers.

Does this have any interaction with user-space data leaks, or uninitialized memory vulnerabilities? No. This code is early-boot, physical memory management within the `memblock` subsystem. Nothing is being copied to user space, nothing is exposed to uninitialized buffers. If we *did* have an indexing bug, or `start` was somehow out of bounds, that would trigger out-of-bounds reads or writes, which KASAN would immediately catch. There's no uninitialized memory usage, no padding leaks, no branching based on uninitialized data.

So, I think we're safe. KMSAN doesn't seem to be needed here. Let's double-check, though, based on my mental checklist:

1.  Kernel structures sent to user space? Nope.
2.  Conditional logic depending on potentially uninitialized variables? Nope.
3.  Complex data structures with uninitialized fields? Negative.
4.  Bounds checks that could lead to uninitialized memory exposure? Not in this patch.

Right. Time to contrast KASAN and KMSAN to solidify my reasoning. KASAN is the right tool here because these changes modify array indexing and loop initialization over `type->regions`. Any indexing errors or bounds mismatches will be caught as out-of-bounds array accesses. As for KMSAN, the patch doesn't allocate uninitialized memory, send it to user-space, and does not use uninitialized variables in conditional branches. The `memblock` subsystem manages initialized physical memory ranges from early boot, with region structures fully initialized.

Okay, I'm confident. Time to call `set-results`.

{
  "KMSANReasoning": "The patch optimizes region lookup in early boot memblock management (mm/memblock.c) by introducing memblock_bsearch_start() and for_each_memblock_type_from(). The changes operate exclusively on existing, initialized memblock regions and internal indices. Potential bugs in this logic (such as index calculation errors or array out-of-bounds access) would be caught by KASAN and standard assertion/bounds checking. The patch does not introduce or expose uninitialized memory, does not copy kernel data to user space, and does not alter padding/uninitialized field initialization, making dedicated KMSAN fuzzing unnecessary.",
  "NeedsKMSAN": false
}

{
  "KMSANReasoning": "The patch optimizes region lookup in early boot memblock management (mm/memblock.c) by introducing memblock_bsearch_start() and for_each_memblock_type_from(). The changes operate exclusively on existing, initialized memblock regions and internal indices. Potential bugs in this logic (such as index calculation errors or array out-of-bounds access) would be caught by KASAN and standard assertion/bounds checking. The patch does not introduce or expose uninitialized memory, does not copy kernel data to user space, and does not alter padding/uninitialized field initialization, making dedicated KMSAN fuzzing unnecessary.",
  "NeedsKMSAN": false
}