| Seq | Timestamp | Type | Name | Duration |
|---|---|---|---|---|
| 0/0 | 2026/09/06 16:38 | flow | patch-triage |
1mArgs:null Results: {
"EnableConfigs": [
"DAMON",
"DAMON_VADDR",
"DAMON_PADDR",
"DAMON_SYSFS",
"MEMCG",
"TRANSPARENT_HUGEPAGE",
"HUGETLBFS"
],
"FocusSymbols": [
"damon_ops_filter_match",
"damon_va_prep_probes",
"damon_va_apply_probes",
"damon_va_probe_pmd_entry",
"damon_va_probe_hugetlb_entry",
"damon_va_filter_match",
"damon_pa_filter_match"
],
"KMSANReasoning": "The patch refactors DAMON filter matching logic across physical and virtual address spaces by introducing damon_ops_filter_match() and implements virtual address space probe handling (damon_va_prep_probes, damon_va_apply_probes, damon_va_probe_pmd_entry, damon_va_probe_hugetlb_entry).\n\nAnalysis of memory safety and sanitizer applicability:\n1. No uninitialized memory usage: All stack-allocated structs (such as struct damon_va_probe_walk_private and struct mm_walk_ops) and scalar variables (e.g. booleans, loop counters, accumulator sums) are explicitly initialized with designated initializers or zero-initialization before use.\n2. No data copied to userspace: The patch does not introduce or modify any copy_to_user, put_user, netlink messages, or ioctl outputs that could leak uninitialized kernel memory.\n3. Memory safety considerations: Any potential issues relating to page-table walking, folio locking/reference counting, concurrency, or array indexing (e.g., probe_hits) fall under standard detectors (KASAN, LOCKDEP, and page table asserts).\n\nBecause there are no uninitialized memory access risks or info-leaks, a dedicated KMSAN fuzzing session is not warranted.",
"NeedsKMSAN": false,
"Reasoning": "The patch adds probe preparation and probe application operations for DAMON virtual address space monitoring, including page table walking (for PMD, huge PMD, and hugetlb entries) and access/age filtering. It also consolidates filter matching logic into damon_ops_filter_match(). These core memory management paths are reachable from user space via the DAMON sysfs interface in standard virtualized environments.",
"WorthFuzzing": true
} |
| 1/1 | 2026/09/06 16:38 | action | read-patch-diff |
0mArgs:null Results: {
"PatchDiff": "commit 451ccddaea518675570d294a25c681cffee51683\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Sun Sep 6 16:38:12 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/mm/damon/ops-common.c b/mm/damon/ops-common.c\nindex 7219c608b1952..cfcd4edee346a 100644\n--- a/mm/damon/ops-common.c\n+++ b/mm/damon/ops-common.c\n@@ -444,3 +444,35 @@ bool damos_ops_has_filter(struct damos *s)\n \t\treturn true;\n \treturn false;\n }\n+\n+bool damon_ops_filter_match(struct damon_filter *filter, struct folio *folio)\n+{\n+\tbool matched = false;\n+\tstruct mem_cgroup *memcg;\n+\n+\tswitch (filter-\u003etype) {\n+\tcase DAMON_FILTER_TYPE_ANON:\n+\t\tif (!folio) {\n+\t\t\tmatched = false;\n+\t\t\tbreak;\n+\t\t}\n+\t\tmatched = folio_test_anon(folio);\n+\t\tbreak;\n+\tcase DAMON_FILTER_TYPE_MEMCG:\n+\t\tif (!folio) {\n+\t\t\tmatched = false;\n+\t\t\tbreak;\n+\t\t}\n+\t\trcu_read_lock();\n+\t\tmemcg = folio_memcg_check(folio);\n+\t\tif (!memcg)\n+\t\t\tmatched = false;\n+\t\telse\n+\t\t\tmatched = filter-\u003ememcg_id == mem_cgroup_id(memcg);\n+\t\trcu_read_unlock();\n+\t\tbreak;\n+\tdefault:\n+\t\tbreak;\n+\t}\n+\treturn matched == filter-\u003ematching;\n+}\ndiff --git a/mm/damon/ops-common.h b/mm/damon/ops-common.h\nindex 38d295488fa18..b832169b1cf8c 100644\n--- a/mm/damon/ops-common.h\n+++ b/mm/damon/ops-common.h\n@@ -21,3 +21,5 @@ bool damos_folio_filter_match(struct damos_filter *filter, struct folio *folio);\n unsigned long damon_migrate_pages(struct list_head *folio_list, int target_nid);\n \n bool damos_ops_has_filter(struct damos *s);\n+\n+bool damon_ops_filter_match(struct damon_filter *filter, struct folio *folio);\ndiff --git a/mm/damon/paddr.c b/mm/damon/paddr.c\nindex c1e7d7a4f40df..ffde88ea7a13c 100644\n--- a/mm/damon/paddr.c\n+++ b/mm/damon/paddr.c\n@@ -143,29 +143,8 @@ static bool damon_pa_filter_match(struct damon_filter *filter,\n \t\tstruct folio *folio)\n {\n \tbool matched = false;\n-\tstruct mem_cgroup *memcg;\n \n \tswitch (filter-\u003etype) {\n-\tcase DAMON_FILTER_TYPE_ANON:\n-\t\tif (!folio) {\n-\t\t\tmatched = false;\n-\t\t\tbreak;\n-\t\t}\n-\t\tmatched = folio_test_anon(folio);\n-\t\tbreak;\n-\tcase DAMON_FILTER_TYPE_MEMCG:\n-\t\tif (!folio) {\n-\t\t\tmatched = false;\n-\t\t\tbreak;\n-\t\t}\n-\t\trcu_read_lock();\n-\t\tmemcg = folio_memcg_check(folio);\n-\t\tif (!memcg)\n-\t\t\tmatched = false;\n-\t\telse\n-\t\t\tmatched = filter-\u003ememcg_id == mem_cgroup_id(memcg);\n-\t\trcu_read_unlock();\n-\t\tbreak;\n \tcase DAMON_FILTER_TYPE_PGIDLE_UNSET:\n \t\tif (!folio)\n \t\t\tmatched = false;\n@@ -173,7 +152,7 @@ static bool damon_pa_filter_match(struct damon_filter *filter,\n \t\t\tmatched = damon_folio_young(folio);\n \t\tbreak;\n \tdefault:\n-\t\tbreak;\n+\t\treturn damon_ops_filter_match(filter, folio);\n \t}\n \treturn matched == filter-\u003ematching;\n }\ndiff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c\nindex f884d3f78f30a..090317191973b 100644\n--- a/mm/damon/vaddr.c\n+++ b/mm/damon/vaddr.c\n@@ -510,6 +510,236 @@ static unsigned int damon_va_check_accesses(struct damon_ctx *ctx)\n \treturn max_nr_accesses;\n }\n \n+static void damon_va_prep_probe_region(struct damon_ctx *ctx,\n+\t\tstruct mm_struct *mm, struct damon_region *r,\n+\t\tstruct damon_probe *probe)\n+{\n+\tstruct damon_prep *p;\n+\n+\tdamon_for_each_prep(p, probe) {\n+\t\tswitch (p-\u003eaction) {\n+\t\tcase DAMON_PREP_SET_PGIDLE:\n+\t\t\tdamon_va_mkold(mm, r-\u003esampling_addr);\n+\t\t\tbreak;\n+\t\tdefault:\n+\t\t\tbreak;\n+\t\t}\n+\t}\n+}\n+\n+static void damon_va_prep_probes(struct damon_ctx *ctx, bool set_samples)\n+{\n+\tstruct damon_target *t;\n+\tstruct mm_struct *mm;\n+\tstruct damon_region *r;\n+\tstruct damon_probe *p;\n+\n+\tdamon_for_each_target(t, ctx) {\n+\t\tmm = damon_get_mm(t);\n+\t\tif (!mm)\n+\t\t\tcontinue;\n+\t\tdamon_for_each_region(r, t) {\n+\t\t\tif (set_samples)\n+\t\t\t\tr-\u003esampling_addr = damon_rand(ctx, r-\u003ear.start,\n+\t\t\t\t\t\tr-\u003ear.end);\n+\t\t\tdamon_for_each_probe(p, ctx)\n+\t\t\t\tdamon_va_prep_probe_region(ctx, mm, r, p);\n+\t\t}\n+\t\tmmput(mm);\n+\t}\n+}\n+\n+static bool damon_va_young_addr(struct folio *folio, pte_t *pte, pmd_t *pmd,\n+\t\tstruct mm_struct *mm, unsigned long addr)\n+{\n+\tbool young = false;\n+\n+\tif (pte)\n+\t\tyoung = pte_young(*pte);\n+\telse if (pmd)\n+\t\tyoung = pmd_young(*pmd);\n+\tyoung = young || !folio_test_idle(folio) ||\n+\t\tmmu_notifier_test_young(mm, addr);\n+\treturn young;\n+}\n+\n+static bool damon_va_filter_match(struct damon_filter *filter,\n+\t\tstruct folio *folio, pte_t *pte, pmd_t *pmd,\n+\t\tstruct mm_struct *mm, unsigned long addr)\n+{\n+\tbool matched = false;\n+\n+\tswitch (filter-\u003etype) {\n+\tcase DAMON_FILTER_TYPE_PGIDLE_UNSET:\n+\t\tif (!folio)\n+\t\t\tmatched = false;\n+\t\telse\n+\t\t\tmatched = damon_va_young_addr(folio, pte, pmd, mm,\n+\t\t\t\t\taddr);\n+\t\tbreak;\n+\tdefault:\n+\t\treturn damon_ops_filter_match(filter, folio);\n+\t}\n+\treturn matched == filter-\u003ematching;\n+}\n+\n+static bool damon_va_filter_pass(struct folio *folio, struct damon_probe *p,\n+\t\tpte_t *pte, pmd_t *pmd, struct mm_struct *mm,\n+\t\tunsigned long addr)\n+{\n+\tstruct damon_filter *f;\n+\tbool pass = true;\n+\n+\tdamon_for_each_filter(f, p) {\n+\t\tif (damon_va_filter_match(f, folio, pte, pmd, mm, addr)) {\n+\t\t\tpass = f-\u003eallow;\n+\t\t\tbreak;\n+\t\t}\n+\t\tpass = !f-\u003eallow;\n+\t}\n+\treturn pass;\n+}\n+\n+struct damon_va_probe_walk_private {\n+\tstruct damon_ctx *ctx;\n+\tstruct damon_region *r;\n+};\n+\n+static void damon_va_probe_folio(struct damon_ctx *ctx,\n+\t\tstruct damon_region *r, struct folio *folio,\n+\t\tpte_t *pte, pmd_t *pmd, struct mm_struct *mm)\n+{\n+\tstruct damon_probe *probe;\n+\tint i = 0;\n+\n+\tdamon_for_each_probe(probe, ctx) {\n+\t\tif (damon_va_filter_pass(folio, probe, pte, pmd, mm,\n+\t\t\t\t\tr-\u003esampling_addr))\n+\t\t\tr-\u003eprobe_hits[i]++;\n+\t\ti++;\n+\t}\n+}\n+\n+static int damon_va_probe_pmd_entry(pmd_t *pmd, unsigned long addr,\n+\t\tunsigned long next, struct mm_walk *walk)\n+{\n+\tpte_t *pte;\n+\tpte_t ptent;\n+\tspinlock_t *ptl;\n+\tstruct folio *folio;\n+\tstruct damon_va_probe_walk_private *priv = walk-\u003eprivate;\n+\n+#ifdef CONFIG_TRANSPARENT_HUGEPAGE\n+\tptl = pmd_trans_huge_lock(pmd, walk-\u003evma);\n+\tif (ptl) {\n+\t\tpmd_t pmde = pmdp_get(pmd);\n+\n+\t\tif (!pmd_present(pmde))\n+\t\t\tgoto huge_out;\n+\t\tfolio = vm_normal_folio_pmd(walk-\u003evma, addr, pmde);\n+\t\tif (!folio)\n+\t\t\tgoto huge_out;\n+\t\tdamon_va_probe_folio(priv-\u003ectx, priv-\u003er, folio, NULL, \u0026pmde,\n+\t\t\t\twalk-\u003evma-\u003evm_mm);\n+\n+huge_out:\n+\t\tspin_unlock(ptl);\n+\t\treturn 0;\n+\t}\n+#endif\t/* CONFIG_TRANSPARENT_HUGEPAGE */\n+\n+\tpte = pte_offset_map_lock(walk-\u003emm, pmd, addr, \u0026ptl);\n+\tif (!pte)\n+\t\treturn 0;\n+\tptent = ptep_get(pte);\n+\tif (!pte_present(ptent))\n+\t\tgoto out;\n+\tfolio = vm_normal_folio(walk-\u003evma, addr, ptent);\n+\tif (!folio)\n+\t\tgoto out;\n+\tdamon_va_probe_folio(priv-\u003ectx, priv-\u003er, folio, \u0026ptent, NULL,\n+\t\t\twalk-\u003evma-\u003evm_mm);\n+\n+out:\n+\tpte_unmap_unlock(pte, ptl);\n+\treturn 0;\n+}\n+\n+#ifdef CONFIG_HUGETLB_PAGE\n+static int damon_va_probe_hugetlb_entry(pte_t *pte, unsigned long hmask,\n+\t\tunsigned long addr, unsigned long end, struct mm_walk *walk)\n+{\n+\tstruct damon_va_probe_walk_private *priv = walk-\u003eprivate;\n+\tstruct hstate *h = hstate_vma(walk-\u003evma);\n+\tstruct folio *folio;\n+\tspinlock_t *ptl;\n+\tpte_t entry;\n+\n+\tptl = huge_pte_lock(h, walk-\u003emm, pte);\n+\tentry = huge_ptep_get(walk-\u003emm, addr, pte);\n+\tif (!pte_present(entry))\n+\t\tgoto out;\n+\n+\tfolio = pfn_folio(pte_pfn(entry));\n+\tfolio_get(folio);\n+\tdamon_va_probe_folio(priv-\u003ectx, priv-\u003er, folio, \u0026entry, NULL,\n+\t\t\twalk-\u003evma-\u003evm_mm);\n+\tfolio_put(folio);\n+\n+out:\n+\tspin_unlock(ptl);\n+\treturn 0;\n+}\n+#else\n+#define damon_va_probe_hugetlb_entry NULL\n+#endif /* CONFIG_HUGETLB_PAGE */\n+\n+static void __damon_va_apply_probes(struct damon_ctx *ctx,\n+\t\tstruct mm_struct *mm, struct damon_region *r)\n+{\n+\tstruct damon_va_probe_walk_private arg = {\n+\t\t.ctx = ctx,\n+\t\t.r = r,\n+\t};\n+\tstruct mm_walk_ops damon_probe_walk_ops = {\n+\t\t.pmd_entry = damon_va_probe_pmd_entry,\n+\t\t.hugetlb_entry = damon_va_probe_hugetlb_entry,\n+\t};\n+\tunsigned long addr = r-\u003esampling_addr;\n+\n+\tif (!mm)\n+\t\treturn;\n+\n+\tdamon_va_walk_page_range(mm, addr, addr + 1, \u0026damon_probe_walk_ops,\n+\t\t\t\u0026arg);\n+}\n+\n+static unsigned int damon_va_apply_probes(struct damon_ctx *ctx,\n+\t\tbool set_samples, bool return_max_wsum)\n+{\n+\tstruct damon_target *t;\n+\tstruct mm_struct *mm;\n+\tstruct damon_region *r;\n+\tunsigned int max_wsum = 0;\n+\n+\tdamon_for_each_target(t, ctx) {\n+\t\tmm = damon_get_mm(t);\n+\t\tdamon_for_each_region(r, t) {\n+\t\t\tif (set_samples)\n+\t\t\t\tr-\u003esampling_addr = damon_rand(ctx, r-\u003ear.start,\n+\t\t\t\t\t\tr-\u003ear.end);\n+\t\t\t__damon_va_apply_probes(ctx, mm, r);\n+\t\t\tif (return_max_wsum)\n+\t\t\t\tmax_wsum = max(damon_probe_hits_wsum(r, false,\n+\t\t\t\t\t\t\tctx), max_wsum);\n+\t\t}\n+\t\tif (mm)\n+\t\t\tmmput(mm);\n+\t}\n+\n+\treturn max_wsum;\n+}\n+\n static bool damos_va_filter_young_match(struct damos_filter *filter,\n \t\tstruct folio *folio, struct vm_area_struct *vma,\n \t\tunsigned long addr, pte_t *ptep, pmd_t *pmdp)\n@@ -938,6 +1168,8 @@ static int __init damon_va_initcall(void)\n \t\t.update = damon_va_update,\n \t\t.prepare_access_checks = damon_va_prepare_access_checks,\n \t\t.check_accesses = damon_va_check_accesses,\n+\t\t.prep_probes = damon_va_prep_probes,\n+\t\t.apply_probes = damon_va_apply_probes,\n \t\t.target_valid = damon_va_target_valid,\n \t\t.cleanup_target = damon_va_cleanup_target,\n \t\t.apply_scheme = damon_va_apply_scheme,\n"
} |
| 2/1 | 2026/09/06 16:38 | agent | patch-evaluator |
0mModel:core Args: null Results: {
"EnableConfigs": [
"DAMON",
"DAMON_VADDR",
"DAMON_PADDR",
"DAMON_SYSFS",
"MEMCG",
"TRANSPARENT_HUGEPAGE",
"HUGETLBFS"
],
"FocusSymbols": [
"damon_ops_filter_match",
"damon_va_prep_probes",
"damon_va_apply_probes",
"damon_va_probe_pmd_entry",
"damon_va_probe_hugetlb_entry",
"damon_va_filter_match",
"damon_pa_filter_match"
],
"Reasoning": "The patch adds probe preparation and probe application operations for DAMON virtual address space monitoring, including page table walking (for PMD, huge PMD, and hugetlb entries) and access/age filtering. It also consolidates filter matching logic into damon_ops_filter_match(). These core memory management paths are reachable from user space via the DAMON sysfs interface in standard virtualized environments.",
"WorthFuzzing": true
}Instruction: 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.
Prompt: Target architecture: amd64
For your convenience, here is the diff of the changes:
commit 451ccddaea518675570d294a25c681cffee51683
Author: syz-cluster <triage@syzkaller.com>
Date: Sun Sep 6 16:38:12 2026 +0000
syz-cluster: applied patch under review
diff --git a/mm/damon/ops-common.c b/mm/damon/ops-common.c
index 7219c608b1952..cfcd4edee346a 100644
--- a/mm/damon/ops-common.c
+++ b/mm/damon/ops-common.c
@@ -444,3 +444,35 @@ bool damos_ops_has_filter(struct damos *s)
return true;
return false;
}
+
+bool damon_ops_filter_match(struct damon_filter *filter, struct folio *folio)
+{
+ bool matched = false;
+ struct mem_cgroup *memcg;
+
+ switch (filter->type) {
+ case DAMON_FILTER_TYPE_ANON:
+ if (!folio) {
+ matched = false;
+ break;
+ }
+ matched = folio_test_anon(folio);
+ break;
+ case DAMON_FILTER_TYPE_MEMCG:
+ if (!folio) {
+ matched = false;
+ break;
+ }
+ rcu_read_lock();
+ memcg = folio_memcg_check(folio);
+ if (!memcg)
+ matched = false;
+ else
+ matched = filter->memcg_id == mem_cgroup_id(memcg);
+ rcu_read_unlock();
+ break;
+ default:
+ break;
+ }
+ return matched == filter->matching;
+}
diff --git a/mm/damon/ops-common.h b/mm/damon/ops-common.h
index 38d295488fa18..b832169b1cf8c 100644
--- a/mm/damon/ops-common.h
+++ b/mm/damon/ops-common.h
@@ -21,3 +21,5 @@ bool damos_folio_filter_match(struct damos_filter *filter, struct folio *folio);
unsigned long damon_migrate_pages(struct list_head *folio_list, int target_nid);
bool damos_ops_has_filter(struct damos *s);
+
+bool damon_ops_filter_match(struct damon_filter *filter, struct folio *folio);
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index c1e7d7a4f40df..ffde88ea7a13c 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -143,29 +143,8 @@ static bool damon_pa_filter_match(struct damon_filter *filter,
struct folio *folio)
{
bool matched = false;
- struct mem_cgroup *memcg;
switch (filter->type) {
- case DAMON_FILTER_TYPE_ANON:
- if (!folio) {
- matched = false;
- break;
- }
- matched = folio_test_anon(folio);
- break;
- case DAMON_FILTER_TYPE_MEMCG:
- if (!folio) {
- matched = false;
- break;
- }
- rcu_read_lock();
- memcg = folio_memcg_check(folio);
- if (!memcg)
- matched = false;
- else
- matched = filter->memcg_id == mem_cgroup_id(memcg);
- rcu_read_unlock();
- break;
case DAMON_FILTER_TYPE_PGIDLE_UNSET:
if (!folio)
matched = false;
@@ -173,7 +152,7 @@ static bool damon_pa_filter_match(struct damon_filter *filter,
matched = damon_folio_young(folio);
break;
default:
- break;
+ return damon_ops_filter_match(filter, folio);
}
return matched == filter->matching;
}
diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index f884d3f78f30a..090317191973b 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -510,6 +510,236 @@ static unsigned int damon_va_check_accesses(struct damon_ctx *ctx)
return max_nr_accesses;
}
+static void damon_va_prep_probe_region(struct damon_ctx *ctx,
+ struct mm_struct *mm, struct damon_region *r,
+ struct damon_probe *probe)
+{
+ struct damon_prep *p;
+
+ damon_for_each_prep(p, probe) {
+ switch (p->action) {
+ case DAMON_PREP_SET_PGIDLE:
+ damon_va_mkold(mm, r->sampling_addr);
+ break;
+ default:
+ break;
+ }
+ }
+}
+
+static void damon_va_prep_probes(struct damon_ctx *ctx, bool set_samples)
+{
+ struct damon_target *t;
+ struct mm_struct *mm;
+ struct damon_region *r;
+ struct damon_probe *p;
+
+ damon_for_each_target(t, ctx) {
+ mm = damon_get_mm(t);
+ if (!mm)
+ continue;
+ damon_for_each_region(r, t) {
+ if (set_samples)
+ r->sampling_addr = damon_rand(ctx, r->ar.start,
+ r->ar.end);
+ damon_for_each_probe(p, ctx)
+ damon_va_prep_probe_region(ctx, mm, r, p);
+ }
+ mmput(mm);
+ }
+}
+
+static bool damon_va_young_addr(struct folio *folio, pte_t *pte, pmd_t *pmd,
+ struct mm_struct *mm, unsigned long addr)
+{
+ bool young = false;
+
+ if (pte)
+ young = pte_young(*pte);
+ else if (pmd)
+ young = pmd_young(*pmd);
+ young = young || !folio_test_idle(folio) ||
+ mmu_notifier_test_young(mm, addr);
+ return young;
+}
+
+static bool damon_va_filter_match(struct damon_filter *filter,
+ struct folio *folio, pte_t *pte, pmd_t *pmd,
+ struct mm_struct *mm, unsigned long addr)
+{
+ bool matched = false;
+
+ switch (filter->type) {
+ case DAMON_FILTER_TYPE_PGIDLE_UNSET:
+ if (!folio)
+ matched = false;
+ else
+ matched = damon_va_young_addr(folio, pte, pmd, mm,
+ addr);
+ break;
+ default:
+ return damon_ops_filter_match(filter, folio);
+ }
+ return matched == filter->matching;
+}
+
+static bool damon_va_filter_pass(struct folio *folio, struct damon_probe *p,
+ pte_t *pte, pmd_t *pmd, struct mm_struct *mm,
+ unsigned long addr)
+{
+ struct damon_filter *f;
+ bool pass = true;
+
+ damon_for_each_filter(f, p) {
+ if (damon_va_filter_match(f, folio, pte, pmd, mm, addr)) {
+ pass = f->allow;
+ break;
+ }
+ pass = !f->allow;
+ }
+ return pass;
+}
+
+struct damon_va_probe_walk_private {
+ struct damon_ctx *ctx;
+ struct damon_region *r;
+};
+
+static void damon_va_probe_folio(struct damon_ctx *ctx,
+ struct damon_region *r, struct folio *folio,
+ pte_t *pte, pmd_t *pmd, struct mm_struct *mm)
+{
+ struct damon_probe *probe;
+ int i = 0;
+
+ damon_for_each_probe(probe, ctx) {
+ if (damon_va_filter_pass(folio, probe, pte, pmd, mm,
+ r->sampling_addr))
+ r->probe_hits[i]++;
+ i++;
+ }
+}
+
+static int damon_va_probe_pmd_entry(pmd_t *pmd, unsigned long addr,
+ unsigned long next, struct mm_walk *walk)
+{
+ pte_t *pte;
+ pte_t ptent;
+ spinlock_t *ptl;
+ struct folio *folio;
+ struct damon_va_probe_walk_private *priv = walk->private;
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ ptl = pmd_trans_huge_lock(pmd, walk->vma);
+ if (ptl) {
+ pmd_t pmde = pmdp_get(pmd);
+
+ if (!pmd_present(pmde))
+ goto huge_out;
+ folio = vm_normal_folio_pmd(walk->vma, addr, pmde);
+ if (!folio)
+ goto huge_out;
+ damon_va_probe_folio(priv->ctx, priv->r, folio, NULL, &pmde,
+ walk->vma->vm_mm);
+
+huge_out:
+ spin_unlock(ptl);
+ return 0;
+ }
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
+ pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+ if (!pte)
+ return 0;
+ ptent = ptep_get(pte);
+ if (!pte_present(ptent))
+ goto out;
+ folio = vm_normal_folio(walk->vma, addr, ptent);
+ if (!folio)
+ goto out;
+ damon_va_probe_folio(priv->ctx, priv->r, folio, &ptent, NULL,
+ walk->vma->vm_mm);
+
+out:
+ pte_unmap_unlock(pte, ptl);
+ return 0;
+}
+
+#ifdef CONFIG_HUGETLB_PAGE
+static int damon_va_probe_hugetlb_entry(pte_t *pte, unsigned long hmask,
+ unsigned long addr, unsigned long end, struct mm_walk *walk)
+{
+ struct damon_va_probe_walk_private *priv = walk->private;
+ struct hstate *h = hstate_vma(walk->vma);
+ struct folio *folio;
+ spinlock_t *ptl;
+ pte_t entry;
+
+ ptl = huge_pte_lock(h, walk->mm, pte);
+ entry = huge_ptep_get(walk->mm, addr, pte);
+ if (!pte_present(entry))
+ goto out;
+
+ folio = pfn_folio(pte_pfn(entry));
+ folio_get(folio);
+ damon_va_probe_folio(priv->ctx, priv->r, folio, &entry, NULL,
+ walk->vma->vm_mm);
+ folio_put(folio);
+
+out:
+ spin_unlock(ptl);
+ return 0;
+}
+#else
+#define damon_va_probe_hugetlb_entry NULL
+#endif /* CONFIG_HUGETLB_PAGE */
+
+static void __damon_va_apply_probes(struct damon_ctx *ctx,
+ struct mm_struct *mm, struct damon_region *r)
+{
+ struct damon_va_probe_walk_private arg = {
+ .ctx = ctx,
+ .r = r,
+ };
+ struct mm_walk_ops damon_probe_walk_ops = {
+ .pmd_entry = damon_va_probe_pmd_entry,
+ .hugetlb_entry = damon_va_probe_hugetlb_entry,
+ };
+ unsigned long addr = r->sampling_addr;
+
+ if (!mm)
+ return;
+
+ damon_va_walk_page_range(mm, addr, addr + 1, &damon_probe_walk_ops,
+ &arg);
+}
+
+static unsigned int damon_va_apply_probes(struct damon_ctx *ctx,
+ bool set_samples, bool return_max_wsum)
+{
+ struct damon_target *t;
+ struct mm_struct *mm;
+ struct damon_region *r;
+ unsigned int max_wsum = 0;
+
+ damon_for_each_target(t, ctx) {
+ mm = damon_get_mm(t);
+ damon_for_each_region(r, t) {
+ if (set_samples)
+ r->sampling_addr = damon_rand(ctx, r->ar.start,
+ r->ar.end);
+ __damon_va_apply_probes(ctx, mm, r);
+ if (return_max_wsum)
+ max_wsum = max(damon_probe_hits_wsum(r, false,
+ ctx), max_wsum);
+ }
+ if (mm)
+ mmput(mm);
+ }
+
+ return max_wsum;
+}
+
static bool damos_va_filter_young_match(struct damos_filter *filter,
struct folio *folio, struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep, pmd_t *pmdp)
@@ -938,6 +1168,8 @@ static int __init damon_va_initcall(void)
.update = damon_va_update,
.prepare_access_checks = damon_va_prepare_access_checks,
.check_accesses = damon_va_check_accesses,
+ .prep_probes = damon_va_prep_probes,
+ .apply_probes = damon_va_apply_probes,
.target_valid = damon_va_target_valid,
.cleanup_target = damon_va_cleanup_target,
.apply_scheme = damon_va_apply_scheme,
|
| 3/2 | 2026/09/06 16:38 | llm | patch-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 6489 output: 29 thoughts: 132 Thoughts: **Analyzing a Linux Kernel Patch for Syzkaller Fuzzing** Okay, so I need to evaluate this Linux kernel patch series. The goal is fuzzing with syzkaller, which is always a good thing to see – more robust kernels are better for everyone. Let's dive in. First things first, I'll need to understand the specifics of the patch. I need to know *exactly* what it's touching. Okay, so it looks like the changes are focused on `mm/damon/`: specifically `ops-common.c`, `ops-common.h`, `paddr.c`, and `vaddr.c`. DAMON... Data Access MONitor. Interesting. This likely means it has something to do with memory access profiling or monitoring. I wonder how it's being used and how this patch impacts that. Now, instead of just reading code, it's time to get a *real* picture. I'll need to use my tools - grep, code search, whatever gets the job done – to understand the full context. I'll search the kernel tree for Kconfig options related to DAMON, any callers of these functions, and anything else relevant to get a clear picture of what the code is doing. I need to figure out exactly *how* this is used, what it's connected to, and potential implications for system behavior. I'll start with some quick greps to get a broad overview. Then, I can drill down further based on what those initial searches reveal. Gotta know the "who, what, where, when, and why" before I can even start to think about fuzzing implications. |
| 4/2 | 2026/09/06 16:38 | tool | grepper |
0mArgs:{
"Expression": "DAMON_VADDR",
"PathPrefix": "mm/damon"
}Results: {
"Output": "mm/damon/Kconfig=26=config DAMON_KUNIT_TEST\n--\nmm/damon/Kconfig-37-\nmm/damon/Kconfig:38:config DAMON_VADDR\nmm/damon/Kconfig-39-\tbool \"Data access monitoring operations for virtual address spaces\"\n--\nmm/damon/Kconfig=47=config DAMON_PADDR\n--\nmm/damon/Kconfig-55-\nmm/damon/Kconfig:56:config DAMON_VADDR_KUNIT_TEST\nmm/damon/Kconfig-57-\tbool \"Test for DAMON operations\" if !KUNIT_ALL_TESTS\nmm/damon/Kconfig:58:\tdepends on DAMON_VADDR \u0026\u0026 KUNIT=y\nmm/damon/Kconfig-59-\tdefault KUNIT_ALL_TESTS\n--\nmm/damon/Makefile=3=obj-y\t\t\t\t:= core.o\nmm/damon/Makefile:4:obj-$(CONFIG_DAMON_VADDR)\t+= ops-common.o vaddr.o\nmm/damon/Makefile-5-obj-$(CONFIG_DAMON_PADDR)\t+= ops-common.o paddr.o\n--\nmm/damon/tests/.kunitconfig=8=CONFIG_PAGE_IDLE_FLAG=y\nmm/damon/tests/.kunitconfig:9:CONFIG_DAMON_VADDR=y\nmm/damon/tests/.kunitconfig:10:CONFIG_DAMON_VADDR_KUNIT_TEST=y\nmm/damon/tests/.kunitconfig-11-\n--\nmm/damon/tests/core-kunit.h=418=static void damon_test_ops_registration(struct kunit *test)\n--\nmm/damon/tests/core-kunit.h-426-\nmm/damon/tests/core-kunit.h:427:\t/* DAMON_OPS_VADDR is registered only if CONFIG_DAMON_VADDR is set */\nmm/damon/tests/core-kunit.h-428-\tif (!damon_is_registered_ops(DAMON_OPS_VADDR)) {\n--\nmm/damon/tests/vaddr-kunit.h-5-\nmm/damon/tests/vaddr-kunit.h:6:#ifdef CONFIG_DAMON_VADDR_KUNIT_TEST\nmm/damon/tests/vaddr-kunit.h-7-\nmm/damon/tests/vaddr-kunit.h:8:#ifndef _DAMON_VADDR_TEST_H\nmm/damon/tests/vaddr-kunit.h:9:#define _DAMON_VADDR_TEST_H\nmm/damon/tests/vaddr-kunit.h-10-\n--\nmm/damon/tests/vaddr-kunit.h=282=kunit_test_suite(damon_test_suite);\nmm/damon/tests/vaddr-kunit.h-283-\nmm/damon/tests/vaddr-kunit.h:284:#endif /* _DAMON_VADDR_TEST_H */\nmm/damon/tests/vaddr-kunit.h-285-\nmm/damon/tests/vaddr-kunit.h:286:#endif\t/* CONFIG_DAMON_VADDR_KUNIT_TEST */\n--\nmm/damon/vaddr.c-19-\nmm/damon/vaddr.c:20:#ifdef CONFIG_DAMON_VADDR_KUNIT_TEST\nmm/damon/vaddr.c-21-#undef DAMON_MIN_REGION_SZ\n"
} |
| 5/2 | 2026/09/06 16:38 | llm | patch-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 7894 output: 33 thoughts: 26 Thoughts: Here's my take on the process, presented as a first-person expert summary: **Diving into the DAMON Kconfig Structure** Okay, so I need to get a clear picture of the DAMON configuration options and how they relate to the rest of the kernel build system. The best place to start, as always, is the `Kconfig` file. I'll head straight for `mm/damon/Kconfig`. This should give me the top-level view of the DAMON configuration options and, critically, expose all of the dependencies. I know this file will define all the `CONFIG_DAMON_*` symbols, and tracing those back up the dependency tree will illuminate exactly what other kernel features need to be enabled or are being impacted by a DAMON configuration. Understanding that Kconfig structure fully allows one to see the full scope of how DAMON can be built and configured. With this in hand, I can effectively navigate the entire DAMON subsystem. |
| 6/2 | 2026/09/06 16:38 | tool | read-file |
0mArgs:{
"File": "mm/damon/Kconfig",
"FirstLine": 1,
"LineCount": 80
}Results: {
"Contents": " 1:\t# SPDX-License-Identifier: GPL-2.0-only\n 2:\t\n 3:\tmenu \"Data Access Monitoring\"\n 4:\t\n 5:\tconfig DAMON\n 6:\t\tbool \"DAMON: Data Access Monitoring Framework\"\n 7:\t\thelp\n 8:\t\t This builds a framework that allows kernel subsystems to monitor\n 9:\t\t access frequency of each memory region. The information can be useful\n 10:\t\t for performance-centric DRAM level memory management.\n 11:\t\n 12:\t\t See https://www.kernel.org/doc/html/latest/mm/damon/index.html for\n 13:\t\t more information.\n 14:\t\n 15:\tconfig DAMON_DEBUG_SANITY\n 16:\t\tbool \"Check sanity of DAMON code\"\n 17:\t\tdepends on DAMON\n 18:\t\thelp\n 19:\t\t This enables additional DAMON debugging-purpose sanity checks in\n 20:\t\t DAMON code. This can be useful for finding bugs, but impose\n 21:\t\t additional overhead. This is therefore recommended to be enabled on\n 22:\t\t only development and test setups.\n 23:\t\n 24:\t\t If unsure, say N.\n 25:\t\n 26:\tconfig DAMON_KUNIT_TEST\n 27:\t\tbool \"Test for damon\" if !KUNIT_ALL_TESTS\n 28:\t\tdepends on DAMON \u0026\u0026 KUNIT=y\n 29:\t\tdefault KUNIT_ALL_TESTS\n 30:\t\thelp\n 31:\t\t This builds the DAMON Kunit test suite.\n 32:\t\n 33:\t\t For more information on KUnit and unit tests in general, please refer\n 34:\t\t to the KUnit documentation.\n 35:\t\n 36:\t\t If unsure, say N.\n 37:\t\n 38:\tconfig DAMON_VADDR\n 39:\t\tbool \"Data access monitoring operations for virtual address spaces\"\n 40:\t\tdepends on DAMON \u0026\u0026 MMU\n 41:\t\tselect PAGE_IDLE_FLAG\n 42:\t\tdefault DAMON\n 43:\t\thelp\n 44:\t\t This builds the default data access monitoring operations for DAMON\n 45:\t\t that work for virtual address spaces.\n 46:\t\n 47:\tconfig DAMON_PADDR\n 48:\t\tbool \"Data access monitoring operations for the physical address space\"\n 49:\t\tdepends on DAMON \u0026\u0026 MMU\n 50:\t\tselect PAGE_IDLE_FLAG\n 51:\t\tdefault DAMON\n 52:\t\thelp\n 53:\t\t This builds the default data access monitoring operations for DAMON\n 54:\t\t that works for the physical address space.\n 55:\t\n 56:\tconfig DAMON_VADDR_KUNIT_TEST\n 57:\t\tbool \"Test for DAMON operations\" if !KUNIT_ALL_TESTS\n 58:\t\tdepends on DAMON_VADDR \u0026\u0026 KUNIT=y\n 59:\t\tdefault KUNIT_ALL_TESTS\n 60:\t\thelp\n 61:\t\t This builds the DAMON virtual addresses operations Kunit test suite.\n 62:\t\n 63:\t\t For more information on KUnit and unit tests in general, please refer\n 64:\t\t to the KUnit documentation.\n 65:\t\n 66:\t\t If unsure, say N.\n 67:\t\n 68:\tconfig DAMON_SYSFS\n 69:\t\tbool \"DAMON sysfs interface\"\n 70:\t\tdepends on DAMON \u0026\u0026 SYSFS\n 71:\t\tdefault DAMON\n 72:\t\thelp\n 73:\t\t This builds the sysfs interface for DAMON. The user space can use\n 74:\t\t the interface for arbitrary data access monitoring.\n 75:\t\n 76:\tconfig DAMON_SYSFS_KUNIT_TEST\n 77:\t\tbool \"Test for damon sysfs interface\" if !KUNIT_ALL_TESTS\n 78:\t\tdepends on DAMON_SYSFS \u0026\u0026 KUNIT=y\n 79:\t\tdefault KUNIT_ALL_TESTS\n 80:\t\thelp\n"
} |
| 7/2 | 2026/09/06 16:38 | llm | patch-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 9201 output: 34 thoughts: 16 Thoughts: Okay, here's my interpretation of that thought process, tailored for an expert audience, and written in the first person: **Navigating the Kconfig Landscape** Alright, so I'm looking at something – most likely, the build configuration for the MM/DAMON subsystem. I see the starting point is to dive into the rest of the `mm/damon/Kconfig` file. I'm assuming there's some interesting detail there that warrants a deeper look. I need to understand the dependencies, features, or maybe even the default configurations within DAMON's Kconfig file. I'm hoping to get a lay of the land; identify potential customization points for this subsystem. Given this is a Kconfig file, it contains the build options. I'll need to figure out what options are available, and what logic governs them to understand the specific configurations and behavior of DAMON. I'm expecting to find a complex dependency tree, with potential cross-architectural considerations. I am interested to see what options might be relevant for my current area of focus. |
| 8/2 | 2026/09/06 16:38 | tool | read-file |
0mArgs:{
"File": "mm/damon/Kconfig",
"FirstLine": 81,
"LineCount": 50
}Results: {
"Contents": " 81:\t\t This builds the DAMON sysfs interface Kunit test suite.\n 82:\t\n 83:\t\t For more information on KUnit and unit tests in general, please refer\n 84:\t\t to the KUnit documentation.\n 85:\t\n 86:\t\t If unsure, say N.\n 87:\t\n 88:\tconfig DAMON_RECLAIM\n 89:\t\tbool \"Build DAMON-based reclaim (DAMON_RECLAIM)\"\n 90:\t\tdepends on DAMON_PADDR\n 91:\t\thelp\n 92:\t\t This builds the DAMON-based reclamation subsystem. It finds pages\n 93:\t\t that not accessed for a long time (cold) using DAMON and reclaim\n 94:\t\t those.\n 95:\t\n 96:\t\t This is suggested to be used as a proactive and lightweight\n 97:\t\t reclamation under light memory pressure, while the traditional page\n 98:\t\t scanning-based reclamation is used for heavy pressure.\n 99:\t\n 100:\tconfig DAMON_LRU_SORT\n 101:\t\tbool \"Build DAMON-based LRU-lists sorting (DAMON_LRU_SORT)\"\n 102:\t\tdepends on DAMON_PADDR\n 103:\t\thelp\n 104:\t\t This builds the DAMON-based LRU-lists sorting subsystem. It tries to\n 105:\t\t protect frequently accessed (hot) pages while rarely accessed (cold)\n 106:\t\t pages reclaimed first under memory pressure.\n 107:\t\n 108:\tconfig DAMON_STAT\n 109:\t\tbool \"Build data access monitoring stat (DAMON_STAT)\"\n 110:\t\tdepends on DAMON_PADDR\n 111:\t\thelp\n 112:\t\t This builds the DAMON-based access monitoring statistics subsystem.\n 113:\t\t It runs DAMON and expose access monitoring results in simple stat\n 114:\t\t metrics.\n 115:\t\n 116:\tconfig DAMON_STAT_ENABLED_DEFAULT\n 117:\t\tbool \"Enable DAMON_STAT by default\"\n 118:\t\tdepends on DAMON_STAT\n 119:\t\tdefault DAMON_STAT\n 120:\t\thelp\n 121:\t\t Whether to enable DAMON_STAT by default. Users can disable it in\n 122:\t\t boot or runtime using its 'enabled' parameter.\n 123:\t\n 124:\tendmenu\n"
} |
| 9/2 | 2026/09/06 16:38 | llm | patch-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 10111 output: 33 thoughts: 72 Thoughts: **Investigating the Damon Probes** Okay, let's dive in. My immediate goal is to understand the control flow around the DAMON functionality, specifically focusing on how the filtering and probe application processes are initiated and managed. I need to trace the calls to the core functions: `damon_filter`, `damon_ops_filter_match`, `prep_probes`, and `apply_probes`. I'm curious to see how the kernel's sysfs interface, or perhaps some other configuration mechanism, hooks into these functions and triggers their execution. I expect to find this information by looking at the call stacks. Therefore, I will begin by searching the kernel source code for calls to `prep_probes` and `apply_probes`. This search will be the starting point to understand the broader context of these operations. |
| 10/2 | 2026/09/06 16:38 | tool | grepper |
0mArgs:{
"Expression": "prep_probes|apply_probes",
"PathPrefix": "mm/damon"
}Results: {
"Output": "mm/damon/core.c=3893=static int kdamond_fn(void *data)\n--\nmm/damon/core.c-3933-\nmm/damon/core.c:3934:\t\tdo_prep = ctx-\u003eops.prep_probes \u0026\u0026 damon_has_prep(ctx);\nmm/damon/core.c-3935-\n--\nmm/damon/core.c-3938-\t\tif (do_prep)\nmm/damon/core.c:3939:\t\t\tctx-\u003eops.prep_probes(ctx, access_check_disabled);\nmm/damon/core.c-3940-\n--\nmm/damon/core.c-3945-\t\t\tmax_merge_score = ctx-\u003eops.check_accesses(ctx);\nmm/damon/core.c:3946:\t\tif (ctx-\u003eops.apply_probes) {\nmm/damon/core.c-3947-\t\t\tif (time_after_eq(ctx-\u003epassed_sample_intervals,\n--\nmm/damon/core.c-3952-\t\t\t\tget_max_wsum = false;\nmm/damon/core.c:3953:\t\t\tmax_wsum = ctx-\u003eops.apply_probes(ctx,\nmm/damon/core.c-3954-\t\t\t\t\taccess_check_disabled \u0026\u0026 !do_prep,\n--\nmm/damon/paddr.c=92=static unsigned int damon_pa_check_accesses(struct damon_ctx *ctx)\n--\nmm/damon/paddr.c-107-\nmm/damon/paddr.c:108:static void damon_pa_prep_probes_region(struct damon_region *r,\nmm/damon/paddr.c-109-\t\tstruct damon_probe *probe, struct damon_ctx *ctx)\n--\nmm/damon/paddr.c-124-\nmm/damon/paddr.c:125:static void damon_pa_prep_probes(struct damon_ctx *ctx, bool set_samples)\nmm/damon/paddr.c-126-{\n--\nmm/damon/paddr.c-136-\t\t\tdamon_for_each_probe(p, ctx)\nmm/damon/paddr.c:137:\t\t\t\tdamon_pa_prep_probes_region(r, p, ctx);\nmm/damon/paddr.c-138-\t\t}\n--\nmm/damon/paddr.c=160=static bool damon_pa_filter_pass(phys_addr_t pa, struct folio *folio,\n--\nmm/damon/paddr.c-175-\nmm/damon/paddr.c:176:static unsigned int damon_pa_apply_probes(struct damon_ctx *ctx,\nmm/damon/paddr.c-177-\t\tbool set_samples, bool return_max_wsum)\n--\nmm/damon/paddr.c=456=static int __init damon_pa_initcall(void)\n--\nmm/damon/paddr.c-463-\t\t.check_accesses = damon_pa_check_accesses,\nmm/damon/paddr.c:464:\t\t.prep_probes = damon_pa_prep_probes,\nmm/damon/paddr.c:465:\t\t.apply_probes = damon_pa_apply_probes,\nmm/damon/paddr.c-466-\t\t.target_valid = NULL,\n--\nmm/damon/vaddr.c=513=static void damon_va_prep_probe_region(struct damon_ctx *ctx,\n--\nmm/damon/vaddr.c-529-\nmm/damon/vaddr.c:530:static void damon_va_prep_probes(struct damon_ctx *ctx, bool set_samples)\nmm/damon/vaddr.c-531-{\n--\nmm/damon/vaddr.c=669=static int damon_va_probe_hugetlb_entry(pte_t *pte, unsigned long hmask,\n--\nmm/damon/vaddr.c-696-\nmm/damon/vaddr.c:697:static void __damon_va_apply_probes(struct damon_ctx *ctx,\nmm/damon/vaddr.c-698-\t\tstruct mm_struct *mm, struct damon_region *r)\n--\nmm/damon/vaddr.c-716-\nmm/damon/vaddr.c:717:static unsigned int damon_va_apply_probes(struct damon_ctx *ctx,\nmm/damon/vaddr.c-718-\t\tbool set_samples, bool return_max_wsum)\n--\nmm/damon/vaddr.c-730-\t\t\t\t\t\tr-\u003ear.end);\nmm/damon/vaddr.c:731:\t\t\t__damon_va_apply_probes(ctx, mm, r);\nmm/damon/vaddr.c-732-\t\t\tif (return_max_wsum)\n--\nmm/damon/vaddr.c=1163=static int __init damon_va_initcall(void)\n--\nmm/damon/vaddr.c-1170-\t\t.check_accesses = damon_va_check_accesses,\nmm/damon/vaddr.c:1171:\t\t.prep_probes = damon_va_prep_probes,\nmm/damon/vaddr.c:1172:\t\t.apply_probes = damon_va_apply_probes,\nmm/damon/vaddr.c-1173-\t\t.target_valid = damon_va_target_valid,\n"
} |
| 11/2 | 2026/09/06 16:38 | llm | patch-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 11870 output: 25 thoughts: 594 Thoughts: **Fuzzing Target Identification: DAMON Virtual Address Space Probes**
Okay, so I've got this section in the Linux kernel, specifically the Data Access Monitoring subsystem, DAMON, located in `mm/damon/`. It's pretty interesting, and definitely seems like a potential target for fuzzing. It's user-controllable through sysfs, which is a great starting point for interaction, assuming `CONFIG_DAMON_SYSFS` is enabled.
The patch seems to add probing support to the virtual address space operations within DAMON. This includes functions like `damon_va_prep_probes`, `damon_va_apply_probes`, `damon_va_probe_pmd_entry`, `damon_va_probe_hugetlb_entry`, and `damon_va_filter_match`. They've also refactored `damon_ops_filter_match` into `ops-common.c`. Essentially, we're talking about modifying core memory management monitoring logic, particularly around page table walking and THP/hugetlb locking, and folio checks. That's a lot of touchpoints in critical memory management code.
Given its reach into the kernel's memory management and accessibility through sysfs, it's immediately worth fuzzing. It's executable code and interacts with crucial data structures.
Let's verify the fuzzing criteria:
* **WorthFuzzing: TRUE** - Check!
* **EnableConfigs:** Alright, what configurations are required to get this running and accessible? I need to check Kconfig dependencies:
* `DAMON` (obviously, it's the core of the functionality)
* `DAMON_VADDR`
* `DAMON_PADDR` (because `ops-common` is compiled if either `DAMON_VADDR` or `DAMON_PADDR` is enabled)
* `DAMON_SYSFS` (vital to control DAMON and configure probes/filters via sysfs from userspace).
* `MEMCG` (important for `DAMON_FILTER_TYPE_MEMCG` functionality, especially regarding `folio_memcg_check`)
* `TRANSPARENT_HUGEPAGE` (essential for the `damon_va_probe_pmd_entry` function)
* `HUGETLB_PAGE` (needed for `damon_va_probe_hugetlb_entry`).
The last few configurations seem to relate to huge page support, so that's something to keep in mind for test setup.
Next, I should probably check how `damon_ops_filter_match` utilizes memcg and verify whether the `MEMCG` configuration is essential for it.
Looking in `mm/damon/ops-common.c`, the following lines of code are of relevance.
```c
memcg = folio_memcg_check(folio);
filter->memcg_id == mem_cgroup_id(memcg);
```
Okay, so the `folio_memcg_check` function requires `CONFIG_MEMCG`. Good to know.
Lastly, I should search for `damon_probe` or `probes` in `mm/damon/sysfs*` to confirm that sysfs supports the probes. Then, I can start building some initial fuzzing harnesses and test setups, focusing on variations in the probed address space, the filter configurations, and the interaction with page tables and huge pages.
|
| 12/2 | 2026/09/06 16:38 | tool | grepper |
0mArgs:{
"Expression": "probe",
"PathPrefix": "mm/damon"
}Results: {
"Output": "\nFull output is too long, showing 500 out of 1143 lines.\nUse more precise expression if possible.\n\nmm/damon/core.c=114=struct damon_prep *damon_new_prep(enum damon_prep_action action)\n--\nmm/damon/core.c-125-\nmm/damon/core.c:126:void damon_add_prep(struct damon_probe *p, struct damon_prep *prep)\nmm/damon/core.c-127-{\n--\nmm/damon/core.c=141=static void damon_destroy_prep(struct damon_prep *p)\n--\nmm/damon/core.c-146-\nmm/damon/core.c:147:static struct damon_prep *damon_nth_prep(int n, struct damon_probe *p)\nmm/damon/core.c-148-{\n--\nmm/damon/core.c=159=static bool damon_has_prep(struct damon_ctx *c)\n--\nmm/damon/core.c-161-\tstruct damon_prep *prep;\nmm/damon/core.c:162:\tstruct damon_probe *probe;\nmm/damon/core.c-163-\nmm/damon/core.c:164:\tdamon_for_each_probe(probe, c) {\nmm/damon/core.c:165:\t\tdamon_for_each_prep(prep, probe)\nmm/damon/core.c-166-\t\t\treturn true;\n--\nmm/damon/core.c=171=struct damon_filter *damon_new_filter(enum damon_filter_type type,\n--\nmm/damon/core.c-185-\nmm/damon/core.c:186:void damon_add_filter(struct damon_probe *p, struct damon_filter *f)\nmm/damon/core.c-187-{\n--\nmm/damon/core.c=201=void damon_destroy_filter(struct damon_filter *f)\n--\nmm/damon/core.c-206-\nmm/damon/core.c:207:static struct damon_filter *damon_nth_filter(int n, struct damon_probe *p)\nmm/damon/core.c-208-{\n--\nmm/damon/core.c-218-\nmm/damon/core.c:219:struct damon_probe *damon_new_probe(void)\nmm/damon/core.c-220-{\nmm/damon/core.c:221:\tstruct damon_probe *p;\nmm/damon/core.c-222-\n--\nmm/damon/core.c-232-\nmm/damon/core.c:233:void damon_add_probe(struct damon_ctx *ctx, struct damon_probe *probe)\nmm/damon/core.c-234-{\nmm/damon/core.c:235:\tlist_add_tail(\u0026probe-\u003elist, \u0026ctx-\u003eprobes);\nmm/damon/core.c-236-}\nmm/damon/core.c-237-\nmm/damon/core.c:238:static void damon_del_probe(struct damon_probe *p)\nmm/damon/core.c-239-{\n--\nmm/damon/core.c-242-\nmm/damon/core.c:243:static void damon_free_probe(struct damon_probe *p)\nmm/damon/core.c-244-{\n--\nmm/damon/core.c-254-\nmm/damon/core.c:255:static void damon_destroy_probe(struct damon_probe *p)\nmm/damon/core.c-256-{\nmm/damon/core.c:257:\tdamon_del_probe(p);\nmm/damon/core.c:258:\tdamon_free_probe(p);\nmm/damon/core.c-259-}\nmm/damon/core.c-260-\nmm/damon/core.c:261:static struct damon_probe *damon_nth_probe(int n, struct damon_ctx *ctx)\nmm/damon/core.c-262-{\nmm/damon/core.c:263:\tstruct damon_probe *p;\nmm/damon/core.c-264-\tint i = 0;\nmm/damon/core.c-265-\nmm/damon/core.c:266:\tdamon_for_each_probe(p, ctx) {\nmm/damon/core.c-267-\t\tif (i++ == n)\n--\nmm/damon/core.c-272-\nmm/damon/core.c:273:static bool damon_has_probe_weights(struct damon_ctx *c)\nmm/damon/core.c-274-{\nmm/damon/core.c:275:\tstruct damon_probe *p;\nmm/damon/core.c-276-\nmm/damon/core.c:277:\tdamon_for_each_probe(p, c) {\nmm/damon/core.c-278-\t\tif (p-\u003eweight)\n--\nmm/damon/core.c=325=unsigned int damon_nr_accesses_mvsum(struct damon_region *r,\n--\nmm/damon/core.c-348-\nmm/damon/core.c:349:unsigned char damon_probe_hits_mvsum(int probe_idx, struct damon_region *r,\nmm/damon/core.c-350-\t\tstruct damon_ctx *ctx)\n--\nmm/damon/core.c-366-\tif (left_window_bp == 10000)\nmm/damon/core.c:367:\t\treturn r-\u003elast_probe_hits[probe_idx];\nmm/damon/core.c-368-\nmm/damon/core.c:369:\treturn damon_mvsum(r-\u003eprobe_hits[probe_idx],\nmm/damon/core.c:370:\t\t\tr-\u003elast_probe_hits[probe_idx], left_window_bp);\nmm/damon/core.c-371-}\n--\nmm/damon/core.c=389=struct damon_region *damon_new_region(unsigned long start, unsigned long end)\n--\nmm/damon/core.c-402-\tfor (i = 0; i \u003c DAMON_MAX_PROBES; i++) {\nmm/damon/core.c:403:\t\tregion-\u003eprobe_hits[i] = 0;\nmm/damon/core.c:404:\t\tregion-\u003elast_probe_hits[i] = 0;\nmm/damon/core.c-405-\t}\n--\nmm/damon/core.c=462=static bool damon_is_last_region(struct damon_region *r,\n--\nmm/damon/core.c-468-/**\nmm/damon/core.c:469: * damon_probe_hits_wsum() - Returns probe hits weighted sum of a region.\nmm/damon/core.c-470- * @r:\t\tregion to get the weighted sum of.\nmm/damon/core.c:471: * @last:\tif the request is for last-window aggregated probe hits.\nmm/damon/core.c-472- * @ctx:\tcontext of \u0026r.\nmm/damon/core.c-473- *\nmm/damon/core.c:474: * Return: the weighted sum of probe hits of the region.\nmm/damon/core.c-475- */\nmm/damon/core.c:476:unsigned int damon_probe_hits_wsum(struct damon_region *r, bool last,\nmm/damon/core.c-477-\t\tstruct damon_ctx *ctx)\nmm/damon/core.c-478-{\nmm/damon/core.c:479:\tstruct damon_probe *probe;\nmm/damon/core.c-480-\tunsigned int sum = 0;\n--\nmm/damon/core.c-482-\nmm/damon/core.c:483:\tdamon_for_each_probe(probe, ctx) {\nmm/damon/core.c-484-\t\tif (last)\nmm/damon/core.c:485:\t\t\tsum += r-\u003elast_probe_hits[i++] * probe-\u003eweight;\nmm/damon/core.c-486-\t\telse\nmm/damon/core.c:487:\t\t\tsum += r-\u003eprobe_hits[i++] * probe-\u003eweight;\nmm/damon/core.c-488-\t}\n--\nmm/damon/core.c=901=struct damon_ctx *damon_new_ctx(void)\n--\nmm/damon/core.c-927-\nmm/damon/core.c:928:\tINIT_LIST_HEAD(\u0026ctx-\u003eprobes);\nmm/damon/core.c-929-\n--\nmm/damon/core.c=950=void damon_destroy_ctx(struct damon_ctx *ctx)\n--\nmm/damon/core.c-952-\tstruct damos *s, *next_s;\nmm/damon/core.c:953:\tstruct damon_probe *p, *next_p;\nmm/damon/core.c-954-\n--\nmm/damon/core.c-959-\nmm/damon/core.c:960:\tdamon_for_each_probe_safe(p, next_p, ctx)\nmm/damon/core.c:961:\t\tdamon_destroy_probe(p);\nmm/damon/core.c-962-\n--\nmm/damon/core.c=1003=static unsigned int damon_nr_samples_for_new_attrs(unsigned int nr,\n--\nmm/damon/core.c-1009-\nmm/damon/core.c:1010:static void damon_update_probe_hits(struct damon_region *r,\nmm/damon/core.c-1011-\t\tstruct damon_attrs *old_attrs, struct damon_attrs *new_attrs,\n--\nmm/damon/core.c-1013-{\nmm/damon/core.c:1014:\tstruct damon_probe *p;\nmm/damon/core.c-1015-\tint i = 0;\nmm/damon/core.c-1016-\nmm/damon/core.c:1017:\tdamon_for_each_probe(p, ctx) {\nmm/damon/core.c:1018:\t\tr-\u003elast_probe_hits[i] = damon_nr_samples_for_new_attrs(\nmm/damon/core.c:1019:\t\t\t\tr-\u003elast_probe_hits[i], old_attrs, new_attrs);\nmm/damon/core.c-1020-\t\tif (!aggregating)\nmm/damon/core.c:1021:\t\t\tr-\u003eprobe_hits[i] = damon_nr_samples_for_new_attrs(\nmm/damon/core.c:1022:\t\t\t\t\tr-\u003eprobe_hits[i], old_attrs,\nmm/damon/core.c-1023-\t\t\t\t\tnew_attrs);\nmm/damon/core.c-1024-\t\telse\nmm/damon/core.c:1025:\t\t\tr-\u003eprobe_hits[i] = 0;\nmm/damon/core.c-1026-\t\ti++;\n--\nmm/damon/core.c=1030=static void damon_update_monitoring_result(struct damon_region *r,\n--\nmm/damon/core.c-1033-{\nmm/damon/core.c:1034:\tdamon_update_probe_hits(r, old_attrs, new_attrs, aggregating, ctx);\nmm/damon/core.c-1035-\n--\nmm/damon/core.c=1416=static void damos_set_filters_default_reject(struct damos *s)\n--\nmm/damon/core.c-1426-\nmm/damon/core.c:1427:static bool damon_valid_probe_params(struct damon_ctx *ctx)\nmm/damon/core.c-1428-{\nmm/damon/core.c-1429-\tunsigned long sample_interval;\nmm/damon/core.c:1430:\tunsigned char max_probe_hits;\nmm/damon/core.c:1431:\tstruct damon_probe *probe;\nmm/damon/core.c-1432-\tunsigned int wsum, wsum_to_add;\nmm/damon/core.c:1433:\tint nr_probes;\nmm/damon/core.c-1434-\nmm/damon/core.c:1435:\tnr_probes = 0;\nmm/damon/core.c:1436:\tdamon_for_each_probe(probe, ctx)\nmm/damon/core.c:1437:\t\tnr_probes++;\nmm/damon/core.c:1438:\tif (nr_probes \u003e DAMON_MAX_PROBES)\nmm/damon/core.c-1439-\t\treturn false;\nmm/damon/core.c-1440-\nmm/damon/core.c:1441:\tif (!damon_has_probe_weights(ctx))\nmm/damon/core.c-1442-\t\treturn true;\n--\nmm/damon/core.c-1447-\nmm/damon/core.c:1448:\t/* invalid if probe hits weighted sum can overflow */\nmm/damon/core.c:1449:\tmax_probe_hits = damon_nr_samples_per_aggr(\u0026ctx-\u003eattrs);\nmm/damon/core.c-1450-\twsum = 0;\nmm/damon/core.c:1451:\tdamon_for_each_probe(probe, ctx) {\nmm/damon/core.c:1452:\t\tif (probe-\u003eweight \u003e UINT_MAX / max_probe_hits)\nmm/damon/core.c-1453-\t\t\treturn false;\nmm/damon/core.c:1454:\t\twsum_to_add = probe-\u003eweight * max_probe_hits;\nmm/damon/core.c-1455-\t\tif (UINT_MAX - wsum \u003c wsum_to_add)\n--\nmm/damon/core.c=1761=static void damon_commit_prep(struct damon_prep *dst, struct damon_prep *src)\n--\nmm/damon/core.c-1765-\nmm/damon/core.c:1766:static int damon_commit_preps(struct damon_probe *dst, struct damon_probe *src)\nmm/damon/core.c-1767-{\n--\nmm/damon/core.c=1791=static void damon_commit_filter(struct damon_filter *dst,\n--\nmm/damon/core.c-1805-\nmm/damon/core.c:1806:static int damon_commit_filters(struct damon_probe *dst,\nmm/damon/core.c:1807:\t\tstruct damon_probe *src)\nmm/damon/core.c-1808-{\n--\nmm/damon/core.c-1839-\nmm/damon/core.c:1840:static int damon_commit_probes(struct damon_ctx *dst, struct damon_ctx *src)\nmm/damon/core.c-1841-{\nmm/damon/core.c:1842:\tstruct damon_probe *dst_probe, *next, *src_probe, *new_probe;\nmm/damon/core.c-1843-\tint i = 0, j = 0, err;\nmm/damon/core.c-1844-\nmm/damon/core.c:1845:\tdamon_for_each_probe_safe(dst_probe, next, dst) {\nmm/damon/core.c:1846:\t\tsrc_probe = damon_nth_probe(i++, src);\nmm/damon/core.c:1847:\t\tif (src_probe) {\nmm/damon/core.c:1848:\t\t\tdst_probe-\u003eweight = src_probe-\u003eweight;\nmm/damon/core.c:1849:\t\t\terr = damon_commit_preps(dst_probe, src_probe);\nmm/damon/core.c-1850-\t\t\tif (err)\nmm/damon/core.c-1851-\t\t\t\treturn err;\nmm/damon/core.c:1852:\t\t\terr = damon_commit_filters(dst_probe, src_probe);\nmm/damon/core.c-1853-\t\t\tif (err)\n--\nmm/damon/core.c-1855-\t\t} else {\nmm/damon/core.c:1856:\t\t\tdamon_destroy_probe(dst_probe);\nmm/damon/core.c-1857-\t\t}\n--\nmm/damon/core.c-1859-\nmm/damon/core.c:1860:\tdamon_for_each_probe_safe(src_probe, next, src) {\nmm/damon/core.c-1861-\t\tif (j++ \u003c i)\n--\nmm/damon/core.c-1863-\nmm/damon/core.c:1864:\t\tnew_probe = damon_new_probe();\nmm/damon/core.c:1865:\t\tif (!new_probe)\nmm/damon/core.c-1866-\t\t\treturn -ENOMEM;\nmm/damon/core.c:1867:\t\tdamon_add_probe(dst, new_probe);\nmm/damon/core.c:1868:\t\tnew_probe-\u003eweight = src_probe-\u003eweight;\nmm/damon/core.c:1869:\t\terr = damon_commit_preps(new_probe, src_probe);\nmm/damon/core.c-1870-\t\tif (err)\nmm/damon/core.c-1871-\t\t\treturn err;\nmm/damon/core.c:1872:\t\terr = damon_commit_filters(new_probe, src_probe);\nmm/damon/core.c-1873-\t\tif (err)\n--\nmm/damon/core.c=1879=static int __damon_commit_ctx(struct damon_ctx *dst, struct damon_ctx *src)\n--\nmm/damon/core.c-1901-\nmm/damon/core.c:1902:\tif (!damon_valid_probe_params(src))\nmm/damon/core.c-1903-\t\treturn -EINVAL;\n--\nmm/damon/core.c-1926-\tdst-\u003eops = src-\u003eops;\nmm/damon/core.c:1927:\terr = damon_commit_probes(dst, src);\nmm/damon/core.c-1928-\tif (err)\n--\nmm/damon/core.c=2293=static void kdamond_reset_aggregated(struct damon_ctx *c)\n--\nmm/damon/core.c-2296-\tunsigned int ti = 0;\t/* target's index */\nmm/damon/core.c:2297:\tunsigned int nr_probes = 0;\nmm/damon/core.c:2298:\tstruct damon_probe *probe;\nmm/damon/core.c-2299-\nmm/damon/core.c-2300-\tif (trace_damon_region_aggregated_enabled()) {\nmm/damon/core.c:2301:\t\tdamon_for_each_probe(probe, c)\nmm/damon/core.c:2302:\t\t\tnr_probes++;\nmm/damon/core.c-2303-\t}\n--\nmm/damon/core.c-2312-\t\t\ttrace_damon_region_aggregated(ti, r,\nmm/damon/core.c:2313:\t\t\t\t\tdamon_nr_regions(t), nr_probes);\nmm/damon/core.c-2314-\t\t\tr-\u003elast_nr_accesses = r-\u003enr_accesses;\n--\nmm/damon/core.c-2316-\t\t\tfor (i = 0; i \u003c DAMON_MAX_PROBES; i++) {\nmm/damon/core.c:2317:\t\t\t\tr-\u003elast_probe_hits[i] = r-\u003eprobe_hits[i];\nmm/damon/core.c:2318:\t\t\t\tr-\u003eprobe_hits[i] = 0;\nmm/damon/core.c-2319-\t\t\t}\n--\nmm/damon/core.c=3426=static void damon_merge_two_regions(struct damon_target *t,\n--\nmm/damon/core.c-3435-\tl-\u003ear.end = r-\u003ear.end;\nmm/damon/core.c:3436:\t/* todo: do this for only installed probes */\nmm/damon/core.c-3437-\tfor (i = 0; i \u003c DAMON_MAX_PROBES; i++)\nmm/damon/core.c:3438:\t\tl-\u003eprobe_hits[i] = (l-\u003eprobe_hits[i] * sz_l + r-\u003eprobe_hits[i]\nmm/damon/core.c-3439-\t\t\t\t* sz_r) / (sz_l + sz_r);\n--\nmm/damon/core.c=3444=static unsigned int damon_merge_score(struct damon_region *r, bool last,\nmm/damon/core.c:3445:\t\tstruct damon_ctx *ctx, bool use_probe_hits)\nmm/damon/core.c-3446-{\nmm/damon/core.c:3447:\tif (use_probe_hits)\nmm/damon/core.c:3448:\t\treturn damon_probe_hits_wsum(r, last, ctx);\nmm/damon/core.c-3449-\tif (last)\n--\nmm/damon/core.c=3461=static void damon_merge_regions_of(struct damon_target *t, unsigned int thres,\n--\nmm/damon/core.c-3464-\tstruct damon_region *r, *prev = NULL, *next;\nmm/damon/core.c:3465:\tbool use_probe_hits = damon_has_probe_weights(ctx);\nmm/damon/core.c-3466-\n--\nmm/damon/core.c-3469-\nmm/damon/core.c:3470:\t\tscore = damon_merge_score(r, false, ctx, use_probe_hits);\nmm/damon/core.c:3471:\t\tlast_score = damon_merge_score(r, true, ctx, use_probe_hits);\nmm/damon/core.c-3472-\n--\nmm/damon/core.c-3486-\t\tdiff = abs_diff(score, damon_merge_score(prev, false, ctx,\nmm/damon/core.c:3487:\t\t\t\t\tuse_probe_hits));\nmm/damon/core.c-3488-\t\tif (diff \u003e thres)\n--\nmm/damon/core.c=3566=static int damon_split_region_at(struct damon_target *t,\n--\nmm/damon/core.c-3580-\tnew-\u003enr_accesses = r-\u003enr_accesses;\nmm/damon/core.c:3581:\t/* todo: do this for only installed probes */\nmm/damon/core.c:3582:\tmemcpy(new-\u003eprobe_hits, r-\u003eprobe_hits, sizeof(r-\u003eprobe_hits));\nmm/damon/core.c:3583:\tmemcpy(new-\u003elast_probe_hits, r-\u003elast_probe_hits,\nmm/damon/core.c:3584:\t\t\tsizeof(r-\u003elast_probe_hits));\nmm/damon/core.c-3585-\n--\nmm/damon/core.c=3893=static int kdamond_fn(void *data)\n--\nmm/damon/core.c-3925-\t\tunsigned long sample_interval = ctx-\u003eattrs.sample_interval;\nmm/damon/core.c:3926:\t\tbool access_check_disabled = damon_has_probe_weights(ctx);\nmm/damon/core.c-3927-\t\tbool do_prep;\n--\nmm/damon/core.c-3933-\nmm/damon/core.c:3934:\t\tdo_prep = ctx-\u003eops.prep_probes \u0026\u0026 damon_has_prep(ctx);\nmm/damon/core.c-3935-\n--\nmm/damon/core.c-3938-\t\tif (do_prep)\nmm/damon/core.c:3939:\t\t\tctx-\u003eops.prep_probes(ctx, access_check_disabled);\nmm/damon/core.c-3940-\n--\nmm/damon/core.c-3945-\t\t\tmax_merge_score = ctx-\u003eops.check_accesses(ctx);\nmm/damon/core.c:3946:\t\tif (ctx-\u003eops.apply_probes) {\nmm/damon/core.c-3947-\t\t\tif (time_after_eq(ctx-\u003epassed_sample_intervals,\n--\nmm/damon/core.c-3952-\t\t\t\tget_max_wsum = false;\nmm/damon/core.c:3953:\t\t\tmax_wsum = ctx-\u003eops.apply_probes(ctx,\nmm/damon/core.c-3954-\t\t\t\t\taccess_check_disabled \u0026\u0026 !do_prep,\n--\nmm/damon/paddr.c=92=static unsigned int damon_pa_check_accesses(struct damon_ctx *ctx)\n--\nmm/damon/paddr.c-107-\nmm/damon/paddr.c:108:static void damon_pa_prep_probes_region(struct damon_region *r,\nmm/damon/paddr.c:109:\t\tstruct damon_probe *probe, struct damon_ctx *ctx)\nmm/damon/paddr.c-110-{\n--\nmm/damon/paddr.c-112-\nmm/damon/paddr.c:113:\tdamon_for_each_prep(p, probe) {\nmm/damon/paddr.c-114-\t\tswitch (p-\u003eaction) {\n--\nmm/damon/paddr.c-124-\nmm/damon/paddr.c:125:static void damon_pa_prep_probes(struct damon_ctx *ctx, bool set_samples)\nmm/damon/paddr.c-126-{\n--\nmm/damon/paddr.c-128-\tstruct damon_region *r;\nmm/damon/paddr.c:129:\tstruct damon_probe *p;\nmm/damon/paddr.c-130-\n--\nmm/damon/paddr.c-135-\t\t\t\t\t\tr-\u003ear.end);\nmm/damon/paddr.c:136:\t\t\tdamon_for_each_probe(p, ctx)\nmm/damon/paddr.c:137:\t\t\t\tdamon_pa_prep_probes_region(r, p, ctx);\nmm/damon/paddr.c-138-\t\t}\n--\nmm/damon/paddr.c=160=static bool damon_pa_filter_pass(phys_addr_t pa, struct folio *folio,\nmm/damon/paddr.c:161:\t\tstruct damon_probe *p)\nmm/damon/paddr.c-162-{\n--\nmm/damon/paddr.c-175-\nmm/damon/paddr.c:176:static unsigned int damon_pa_apply_probes(struct damon_ctx *ctx,\nmm/damon/paddr.c-177-\t\tbool set_samples, bool return_max_wsum)\n--\nmm/damon/paddr.c-180-\tstruct damon_region *r;\nmm/damon/paddr.c:181:\tstruct damon_probe *p;\nmm/damon/paddr.c-182-\tunsigned int max_wsum = 0;\n--\nmm/damon/paddr.c-195-\t\t\tfolio = damon_get_folio(PHYS_PFN(pa));\nmm/damon/paddr.c:196:\t\t\tdamon_for_each_probe(p, ctx) {\nmm/damon/paddr.c-197-\t\t\t\tif (damon_pa_filter_pass(pa, folio, p))\nmm/damon/paddr.c:198:\t\t\t\t\tr-\u003eprobe_hits[i]++;\nmm/damon/paddr.c-199-\t\t\t\ti++;\n--\nmm/damon/paddr.c-203-\t\t\tif (return_max_wsum)\nmm/damon/paddr.c:204:\t\t\t\tmax_wsum = max(damon_probe_hits_wsum(r, false,\nmm/damon/paddr.c-205-\t\t\t\t\t\t\tctx), max_wsum);\n--\nmm/damon/paddr.c=456=static int __init damon_pa_initcall(void)\n--\nmm/damon/paddr.c-463-\t\t.check_accesses = damon_pa_check_accesses,\nmm/damon/paddr.c:464:\t\t.prep_probes = damon_pa_prep_probes,\nmm/damon/paddr.c:465:\t\t.apply_probes = damon_pa_apply_probes,\nmm/damon/paddr.c-466-\t\t.target_valid = NULL,\n--\nmm/damon/sysfs-schemes.c-11-/*\nmm/damon/sysfs-schemes.c:12: * probe directory\nmm/damon/sysfs-schemes.c-13- */\nmm/damon/sysfs-schemes.c-14-\nmm/damon/sysfs-schemes.c:15:struct damos_sysfs_probe {\nmm/damon/sysfs-schemes.c-16-\tstruct kobject kobj;\n--\nmm/damon/sysfs-schemes.c-19-\nmm/damon/sysfs-schemes.c:20:static struct damos_sysfs_probe *damos_sysfs_probe_alloc(unsigned char hits)\nmm/damon/sysfs-schemes.c-21-{\nmm/damon/sysfs-schemes.c:22:\tstruct damos_sysfs_probe *probe;\nmm/damon/sysfs-schemes.c-23-\nmm/damon/sysfs-schemes.c:24:\tprobe = kzalloc_obj(*probe);\nmm/damon/sysfs-schemes.c:25:\tif (!probe)\nmm/damon/sysfs-schemes.c-26-\t\treturn NULL;\nmm/damon/sysfs-schemes.c:27:\tprobe-\u003ehits = hits;\nmm/damon/sysfs-schemes.c:28:\treturn probe;\nmm/damon/sysfs-schemes.c-29-}\n--\nmm/damon/sysfs-schemes.c=31=static ssize_t hits_show(struct kobject *kobj, struct kobj_attribute *attr,\n--\nmm/damon/sysfs-schemes.c-33-{\nmm/damon/sysfs-schemes.c:34:\tstruct damos_sysfs_probe *probe = container_of(kobj,\nmm/damon/sysfs-schemes.c:35:\t\t\tstruct damos_sysfs_probe, kobj);\nmm/damon/sysfs-schemes.c-36-\nmm/damon/sysfs-schemes.c:37:\treturn sysfs_emit(buf, \"%hhu\\n\", probe-\u003ehits);\nmm/damon/sysfs-schemes.c-38-}\nmm/damon/sysfs-schemes.c-39-\nmm/damon/sysfs-schemes.c:40:static void damos_sysfs_probe_release(struct kobject *kobj)\nmm/damon/sysfs-schemes.c-41-{\nmm/damon/sysfs-schemes.c:42:\tstruct damos_sysfs_probe *probe = container_of(kobj,\nmm/damon/sysfs-schemes.c:43:\t\t\tstruct damos_sysfs_probe, kobj);\nmm/damon/sysfs-schemes.c-44-\nmm/damon/sysfs-schemes.c:45:\tkfree(probe);\nmm/damon/sysfs-schemes.c-46-}\nmm/damon/sysfs-schemes.c-47-\nmm/damon/sysfs-schemes.c:48:static struct kobj_attribute damos_sysfs_probe_hits_attr =\nmm/damon/sysfs-schemes.c-49-\t\t__ATTR_RO_MODE(hits, 0400);\nmm/damon/sysfs-schemes.c-50-\nmm/damon/sysfs-schemes.c:51:static struct attribute *damos_sysfs_probe_attrs[] = {\nmm/damon/sysfs-schemes.c:52:\t\u0026damos_sysfs_probe_hits_attr.attr,\nmm/damon/sysfs-schemes.c-53-\tNULL,\nmm/damon/sysfs-schemes.c-54-};\nmm/damon/sysfs-schemes.c:55:ATTRIBUTE_GROUPS(damos_sysfs_probe);\nmm/damon/sysfs-schemes.c-56-\nmm/damon/sysfs-schemes.c:57:static const struct kobj_type damos_sysfs_probe_ktype = {\nmm/damon/sysfs-schemes.c:58:\t.release = damos_sysfs_probe_release,\nmm/damon/sysfs-schemes.c-59-\t.sysfs_ops = \u0026kobj_sysfs_ops,\nmm/damon/sysfs-schemes.c:60:\t.default_groups = damos_sysfs_probe_groups,\nmm/damon/sysfs-schemes.c-61-};\n--\nmm/damon/sysfs-schemes.c-63-/*\nmm/damon/sysfs-schemes.c:64: * probes directory\nmm/damon/sysfs-schemes.c-65- */\nmm/damon/sysfs-schemes.c-66-\nmm/damon/sysfs-schemes.c:67:struct damos_sysfs_probes {\nmm/damon/sysfs-schemes.c-68-\tstruct kobject kobj;\nmm/damon/sysfs-schemes.c:69:\tstruct damos_sysfs_probe **probes_arr;\nmm/damon/sysfs-schemes.c-70-\tint nr;\n--\nmm/damon/sysfs-schemes.c-72-\nmm/damon/sysfs-schemes.c:73:static struct damos_sysfs_probes *damos_sysfs_probes_alloc(void)\nmm/damon/sysfs-schemes.c-74-{\nmm/damon/sysfs-schemes.c:75:\treturn kzalloc_obj(struct damos_sysfs_probes);\nmm/damon/sysfs-schemes.c-76-}\nmm/damon/sysfs-schemes.c-77-\nmm/damon/sysfs-schemes.c:78:static void damos_sysfs_probes_rm_dirs(struct damos_sysfs_probes *probes)\nmm/damon/sysfs-schemes.c-79-{\nmm/damon/sysfs-schemes.c:80:\tstruct damos_sysfs_probe **probes_arr = probes-\u003eprobes_arr;\nmm/damon/sysfs-schemes.c-81-\tint i;\nmm/damon/sysfs-schemes.c-82-\nmm/damon/sysfs-schemes.c:83:\tfor (i = 0; i \u003c probes-\u003enr; i++)\nmm/damon/sysfs-schemes.c:84:\t\tkobject_put(\u0026probes_arr[i]-\u003ekobj);\nmm/damon/sysfs-schemes.c:85:\tprobes-\u003enr = 0;\nmm/damon/sysfs-schemes.c:86:\tkfree(probes_arr);\nmm/damon/sysfs-schemes.c:87:\tprobes-\u003eprobes_arr = NULL;\nmm/damon/sysfs-schemes.c-88-}\nmm/damon/sysfs-schemes.c-89-\nmm/damon/sysfs-schemes.c:90:static int damos_sysfs_probes_add_dirs(struct damos_sysfs_probes *probes,\nmm/damon/sysfs-schemes.c-91-\t\tstruct damon_ctx *ctx, struct damon_region *region)\nmm/damon/sysfs-schemes.c-92-{\nmm/damon/sysfs-schemes.c:93:\tstruct damon_probe *probe;\nmm/damon/sysfs-schemes.c:94:\tstruct damos_sysfs_probe **probes_arr;\nmm/damon/sysfs-schemes.c-95-\tint i = 0;\nmm/damon/sysfs-schemes.c-96-\nmm/damon/sysfs-schemes.c:97:\tdamon_for_each_probe(probe, ctx)\nmm/damon/sysfs-schemes.c-98-\t\ti++;\n--\nmm/damon/sysfs-schemes.c-102-\nmm/damon/sysfs-schemes.c:103:\tprobes_arr = kmalloc_objs(*probes_arr, i);\nmm/damon/sysfs-schemes.c:104:\tif (!probes_arr)\nmm/damon/sysfs-schemes.c-105-\t\treturn -ENOMEM;\nmm/damon/sysfs-schemes.c:106:\tprobes-\u003eprobes_arr = probes_arr;\nmm/damon/sysfs-schemes.c-107-\nmm/damon/sysfs-schemes.c-108-\ti = 0;\nmm/damon/sysfs-schemes.c:109:\tdamon_for_each_probe(probe, ctx) {\nmm/damon/sysfs-schemes.c:110:\t\tstruct damos_sysfs_probe *sys_probe;\nmm/damon/sysfs-schemes.c-111-\t\tint err;\nmm/damon/sysfs-schemes.c-112-\nmm/damon/sysfs-schemes.c:113:\t\tsys_probe = damos_sysfs_probe_alloc(\nmm/damon/sysfs-schemes.c:114:\t\t\t\tdamon_probe_hits_mvsum(i, region, ctx));\nmm/damon/sysfs-schemes.c:115:\t\tif (!sys_probe) {\nmm/damon/sysfs-schemes.c:116:\t\t\tdamos_sysfs_probes_rm_dirs(probes);\nmm/damon/sysfs-schemes.c-117-\t\t\treturn -ENOMEM;\nmm/damon/sysfs-schemes.c-118-\t\t}\nmm/damon/sysfs-schemes.c:119:\t\terr = kobject_init_and_add(\u0026sys_probe-\u003ekobj,\nmm/damon/sysfs-schemes.c:120:\t\t\t\t\u0026damos_sysfs_probe_ktype, \u0026probes-\u003ekobj, \"%d\",\nmm/damon/sysfs-schemes.c-121-\t\t\t\ti);\nmm/damon/sysfs-schemes.c-122-\t\tif (err) {\nmm/damon/sysfs-schemes.c:123:\t\t\tkobject_put(\u0026sys_probe-\u003ekobj);\nmm/damon/sysfs-schemes.c:124:\t\t\tdamos_sysfs_probes_rm_dirs(probes);\nmm/damon/sysfs-schemes.c-125-\t\t\treturn err;\nmm/damon/sysfs-schemes.c-126-\t\t}\nmm/damon/sysfs-schemes.c:127:\t\tprobes_arr[i++] = sys_probe;\n\n"
} |
| 13/2 | 2026/09/06 16:38 | llm | patch-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 23927 output: 33 thoughts: 400 Thoughts: **Analyzing the Patch: DAMON Functionality**
Okay, let's break down this DAMON patch. First, I need to understand the scope of the modifications. It looks like we've got a decent-sized set of functions being touched. Specifically, the following are either new or have been changed:
* In `mm/damon/ops-common.c`, we have `damon_ops_filter_match`.
* In `mm/damon/paddr.c`, `damon_pa_filter_match` is in the mix.
* The bulk of the work seems to be in `mm/damon/vaddr.c`, with additions and modifications to functions:
* `damon_va_prep_probe_region`
* `damon_va_prep_probes`
* `damon_va_young_addr`
* `damon_va_filter_match`
* `damon_va_filter_pass`
* `damon_va_probe_folio`
* `damon_va_probe_pmd_entry`
* `damon_va_probe_hugetlb_entry`
* `__damon_va_apply_probes`
* `damon_va_apply_probes`
Next, I need to get a handle on the exposure of these functions, especially for potential integration with tools or analyses. I should quickly sort the static vs. non-static symbols. It's important to remember that static functions, while not directly visible, can still impact the interface if their callers or entry points are non-static or can be inlined. Key functions I'm focusing on include:
* `damon_ops_filter_match` (appears to be non-static in ops-common.c).
* `damon_va_prep_probes`
* `damon_va_apply_probes`
* `damon_va_probe_pmd_entry`
* `damon_va_probe_hugetlb_entry`
* `damon_va_filter_match`
* `damon_va_filter_pass`
* `damon_pa_filter_match`
Finally, before I get too deep into the code, I should quickly do a sanity check to see if there are any other files or symbols that have been affected. Then, I need to dive into the git log and the context surrounding these changes to get the bigger picture. Understanding the 'why' will give me a better basis for a detailed code inspection.
|
| 14/2 | 2026/09/06 16:38 | tool | grepper |
0mArgs:{
"Expression": "damon_va_apply_probes",
"PathPrefix": "mm/damon"
}Results: {
"Output": "mm/damon/vaddr.c=669=static int damon_va_probe_hugetlb_entry(pte_t *pte, unsigned long hmask,\n--\nmm/damon/vaddr.c-696-\nmm/damon/vaddr.c:697:static void __damon_va_apply_probes(struct damon_ctx *ctx,\nmm/damon/vaddr.c-698-\t\tstruct mm_struct *mm, struct damon_region *r)\n--\nmm/damon/vaddr.c-716-\nmm/damon/vaddr.c:717:static unsigned int damon_va_apply_probes(struct damon_ctx *ctx,\nmm/damon/vaddr.c-718-\t\tbool set_samples, bool return_max_wsum)\n--\nmm/damon/vaddr.c-730-\t\t\t\t\t\tr-\u003ear.end);\nmm/damon/vaddr.c:731:\t\t\t__damon_va_apply_probes(ctx, mm, r);\nmm/damon/vaddr.c-732-\t\t\tif (return_max_wsum)\n--\nmm/damon/vaddr.c=1163=static int __init damon_va_initcall(void)\n--\nmm/damon/vaddr.c-1171-\t\t.prep_probes = damon_va_prep_probes,\nmm/damon/vaddr.c:1172:\t\t.apply_probes = damon_va_apply_probes,\nmm/damon/vaddr.c-1173-\t\t.target_valid = damon_va_target_valid,\n"
} |
| 15/2 | 2026/09/06 16:38 | llm | patch-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 25382 output: 42 thoughts: 453 Thoughts: **DAMON Implementation and Configuration Review** Okay, let's dive into the DAMON core implementation. I want to quickly review how DAMON runs, specifically focusing on `kdamond_fn` in `mm/damon/core.c`. My understanding is that when DAMON is enabled, likely through the sysfs interface at `/sys/kernel/mm/damon/admin/kdamonds/...`, this `kdamond_fn` function gets initiated. From there, it makes calls to `ctx->ops.prep_probes` and `ctx->ops.apply_probes`. Given the `DAMON_VADDR` registration, I need to confirm that `ctx->ops.prep_probes` is, as expected, pointing to `damon_va_prep_probes`, and `ctx->ops.apply_probes` is set to `damon_va_apply_probes`. It's also worth confirming that `damon_ops_filter_match` is correctly invoked from both `damon_va_filter_match` and `damon_pa_filter_match` Now, let's shift gears and verify the required kernel configurations. I'm going to quickly list them out to make sure they're all there: * `DAMON`: The DAMON framework itself. * `DAMON_VADDR`: The virtual address space operations – this depends on DAMON and, naturally, the MMU. * `DAMON_PADDR`: The physical address space operations, also dependent on DAMON and the MMU. * `DAMON_SYSFS`: The sysfs interface, essential for configuring probes and targets from userspace. * `MEMCG`: This one is used in `damon_ops_filter_match` when `DAMON_FILTER_TYPE_MEMCG` is active, so we need to make sure this is available. * `TRANSPARENT_HUGEPAGE`: This is important for `damon_va_probe_pmd_entry`. * `HUGETLB_PAGE`: And this is used in `damon_va_probe_hugetlb_entry`, important for large pages. Just to confirm, I'll quickly double-check the exact config names and then I'll grep through the `Kconfig` files to verify that these config options are indeed defined and available in the kernel. I'll need to look for `CONFIG_DAMON`, `CONFIG_DAMON_VADDR`, `CONFIG_DAMON_PADDR`, `CONFIG_DAMON_SYSFS`, `CONFIG_MEMCG`, `CONFIG_TRANSPARENT_HUGEPAGE`, and `CONFIG_HUGETLB_PAGE`. After this, it's just a matter of confirming that these all exist and that the dependencies are met. |
| 16/2 | 2026/09/06 16:38 | tool | grepper |
0mArgs:{
"Expression": "config (MEMCG|TRANSPARENT_HUGEPAGE|HUGETLB_PAGE)",
"PathPrefix": "mm/"
}Results: {
"Output": "mm/Kconfig=689=config ARCH_HAS_PMD_SOFTLEAVES\n--\nmm/Kconfig-691-\nmm/Kconfig:692:config HUGETLB_PAGE_SIZE_VARIABLE\nmm/Kconfig-693-\tdef_bool n\n--\nmm/Kconfig=827=config MM_ID\n--\nmm/Kconfig-829-\nmm/Kconfig:830:menuconfig TRANSPARENT_HUGEPAGE\nmm/Kconfig-831-\tbool \"Transparent Hugepage Support\"\n--\nmm/Kconfig=848=choice\n--\nmm/Kconfig-853-\nmm/Kconfig:854:\tconfig TRANSPARENT_HUGEPAGE_ALWAYS\nmm/Kconfig-855-\t\tbool \"always\"\n--\nmm/Kconfig-860-\nmm/Kconfig:861:\tconfig TRANSPARENT_HUGEPAGE_MADVISE\nmm/Kconfig-862-\t\tbool \"madvise\"\n--\nmm/Kconfig-869-\nmm/Kconfig:870:\tconfig TRANSPARENT_HUGEPAGE_NEVER\nmm/Kconfig-871-\t\tbool \"never\"\n--\nmm/Kconfig=877=choice\n--\nmm/Kconfig-886-\nmm/Kconfig:887:\tconfig TRANSPARENT_HUGEPAGE_SHMEM_HUGE_NEVER\nmm/Kconfig-888-\t\tbool \"never\"\n--\nmm/Kconfig-896-\nmm/Kconfig:897:\tconfig TRANSPARENT_HUGEPAGE_SHMEM_HUGE_ALWAYS\nmm/Kconfig-898-\t\tbool \"always\"\n--\nmm/Kconfig-904-\nmm/Kconfig:905:\tconfig TRANSPARENT_HUGEPAGE_SHMEM_HUGE_WITHIN_SIZE\nmm/Kconfig-906-\t\tbool \"within_size\"\n--\nmm/Kconfig-912-\nmm/Kconfig:913:\tconfig TRANSPARENT_HUGEPAGE_SHMEM_HUGE_ADVISE\nmm/Kconfig-914-\t\tbool \"advise\"\n--\nmm/Kconfig=922=choice\n--\nmm/Kconfig-931-\nmm/Kconfig:932:\tconfig TRANSPARENT_HUGEPAGE_TMPFS_HUGE_NEVER\nmm/Kconfig-933-\t\tbool \"never\"\n--\nmm/Kconfig-940-\nmm/Kconfig:941:\tconfig TRANSPARENT_HUGEPAGE_TMPFS_HUGE_ALWAYS\nmm/Kconfig-942-\t\tbool \"always\"\n--\nmm/Kconfig-948-\nmm/Kconfig:949:\tconfig TRANSPARENT_HUGEPAGE_TMPFS_HUGE_WITHIN_SIZE\nmm/Kconfig-950-\t\tbool \"within_size\"\n--\nmm/Kconfig-956-\nmm/Kconfig:957:\tconfig TRANSPARENT_HUGEPAGE_TMPFS_HUGE_ADVISE\nmm/Kconfig-958-\t\tbool \"advise\"\n"
} |
| 17/2 | 2026/09/06 16:38 | llm | patch-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 27271 output: 35 thoughts: 20 Thoughts: Here's a summary of my immediate thought process, keeping in mind my expertise: **Checking Key Kernel Configurations** Okay, so I'm diving into something that likely involves memory management and resource constraints. My initial thought is to zero in on two critical kernel configurations: `CONFIG_HUGETLB_PAGE` and `CONFIG_MEMCG`. The interplay between these two is often at the heart of performance tuning and resource isolation in containerized or high-performance environments. `CONFIG_HUGETLB_PAGE` is crucial for applications that benefit from large page sizes, reducing TLB misses and improving memory access speeds. I'll need to immediately ascertain if it is enabled. At the same time, `CONFIG_MEMCG` is equally important, it enables control groups for memory, allowing granular allocation and isolation of memory resources between processes. I immediately need to understand how the system is currently configured, and how these configurations interplay, to properly assess the situation. |
| 18/2 | 2026/09/06 16:38 | tool | grepper |
0mArgs:{
"Expression": "config (HUGETLB_PAGE|MEMCG)$",
"PathPrefix": "init/Kconfig"
}Results: {
"Output": "init/Kconfig=1068=config CGROUP_FAVOR_DYNMODS\n--\ninit/Kconfig-1077-\ninit/Kconfig:1078:config MEMCG\ninit/Kconfig-1079-\tbool \"Memory controller\"\n"
} |
| 19/2 | 2026/09/06 16:38 | llm | patch-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 27602 output: 31 thoughts: 21 Thoughts: Here's my take on those thoughts, tailored for an expert audience: **Kernel Configuration Hunting** Okay, so I'm troubleshooting something, and the hugetlb subsystem is immediately popping into my head. First things first, I need to verify that `CONFIG_HUGETLB_PAGE` is actually enabled in the current kernel configuration. No point in chasing ghosts if HugeTLB support isn't even compiled in. I'm thinking the logical places to check are within the memory management config files – likely `mm/Kconfig` is a good starting point, but I might need to broaden the search if it's been moved or if it’s a dependency of something else. This check will save me a ton of debugging time later on. Gotta make sure the foundation is there before I start looking for architectural issues. |
| 20/2 | 2026/09/06 16:38 | tool | grepper |
0mError:no matches Args: {
"Expression": "config HUGETLB_PAGE$",
"PathPrefix": "mm/Kconfig"
}Results: {
"error": "no matches"
} |
| 21/2 | 2026/09/06 16:38 | llm | patch-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 27840 output: 21 thoughts: 16 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: **Hunting Down HUGETLB_PAGE** Alright, let's get down to brass tacks. I need to pinpoint the `config HUGETLB_PAGE` symbol within the kernel's configuration space. This likely means I'm troubleshooting, auditing, or perhaps even implementing a change related to huge page management. Given my expertise, I probably already have a decent idea of where to *start* looking, but a systematic search is the best approach. My mental model is probably forming a query that I'll run within the configuration build system (likely `kconfig`). I need to make sure I understand its dependencies and relationships with other related configuration options, and this is where I would start. Essentially, I'm forming a plan to rapidly locate the relevant definition and its associated context. The goal is efficiency. Let's do this. |
| 22/2 | 2026/09/06 16:38 | tool | grepper |
0mArgs:{
"Expression": "config HUGETLB_PAGE$"
}Results: {
"Output": "fs/Kconfig=271=endif # HUGETLBFS\nfs/Kconfig-272-\nfs/Kconfig:273:config HUGETLB_PAGE\nfs/Kconfig-274-\tdef_bool HUGETLBFS\n"
} |
| 23/2 | 2026/09/06 16:39 | llm | patch-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 28142 output: 249 thoughts: 333 Thoughts: **DAMON Patch Review: Virtual Address Space Probing** Okay, let's break this down. First, the foundation: `HUGETLBFS` enables `HUGETLB_PAGE`. Got it. Now, let's dive into the details. I see a list of relevant FocusSymbols: `damon_ops_filter_match`, `damon_va_prep_probes`, `damon_va_apply_probes`, `damon_va_probe_pmd_entry`, `damon_va_probe_hugetlb_entry`, `damon_va_filter_match`, and `damon_pa_filter_match`. Right, these are all specific to the changes in `mm/damon/vaddr.c`, `mm/damon/ops-common.c`, and `mm/damon/paddr.c` – not core kernel functionality, but directly part of this DAMON patch. Essentially, this patch is about adding DAMON probe prep and application specifically for virtual address spaces. We're looking at functions for setting up probes (`damon_va_prep_probes`, `damon_va_apply_probes`), then walking page tables, and handling both regular and huge page entries (`damon_va_probe_pmd_entry`, `damon_va_probe_hugetlb_entry`, `damon_va_young_addr`). There's filter logic included as well (`damon_va_filter_match`, `damon_va_filter_pass`), and we're seeing some common filter matching logic refactored into `damon_ops_filter_match()`. It's clearly modifying memory management monitoring via DAMON, and it's relevant in standard virtualized environments. Looks good. Everything seems to be well-defined, and the implications are clear. I've verified everything I need to, so I'll now call `set-results`. |
| 24/2 | 2026/09/06 16:39 | tool | set-results |
0mArgs:{
"EnableConfigs": [
"DAMON",
"DAMON_VADDR",
"DAMON_PADDR",
"DAMON_SYSFS",
"MEMCG",
"TRANSPARENT_HUGEPAGE",
"HUGETLBFS"
],
"FocusSymbols": [
"damon_ops_filter_match",
"damon_va_prep_probes",
"damon_va_apply_probes",
"damon_va_probe_pmd_entry",
"damon_va_probe_hugetlb_entry",
"damon_va_filter_match",
"damon_pa_filter_match"
],
"Reasoning": "The patch adds probe preparation and probe application operations for DAMON virtual address space monitoring, including page table walking (for PMD, huge PMD, and hugetlb entries) and access/age filtering. It also consolidates filter matching logic into damon_ops_filter_match(). These core memory management paths are reachable from user space via the DAMON sysfs interface in standard virtualized environments.",
"WorthFuzzing": true
}Results: {
"EnableConfigs": [
"DAMON",
"DAMON_VADDR",
"DAMON_PADDR",
"DAMON_SYSFS",
"MEMCG",
"TRANSPARENT_HUGEPAGE",
"HUGETLBFS"
],
"FocusSymbols": [
"damon_ops_filter_match",
"damon_va_prep_probes",
"damon_va_apply_probes",
"damon_va_probe_pmd_entry",
"damon_va_probe_hugetlb_entry",
"damon_va_filter_match",
"damon_pa_filter_match"
],
"Reasoning": "The patch adds probe preparation and probe application operations for DAMON virtual address space monitoring, including page table walking (for PMD, huge PMD, and hugetlb entries) and access/age filtering. It also consolidates filter matching logic into damon_ops_filter_match(). These core memory management paths are reachable from user space via the DAMON sysfs interface in standard virtualized environments.",
"WorthFuzzing": true
} |
| 25/1 | 2026/09/06 16:39 | action | If |
0mArgs:{
"WorthFuzzing": true
}Results: null |
| 26/2 | 2026/09/06 16:39 | agent | kmsan-evaluator |
0mModel:core Args: null Results: {
"KMSANReasoning": "The patch refactors DAMON filter matching logic across physical and virtual address spaces by introducing damon_ops_filter_match() and implements virtual address space probe handling (damon_va_prep_probes, damon_va_apply_probes, damon_va_probe_pmd_entry, damon_va_probe_hugetlb_entry).\n\nAnalysis of memory safety and sanitizer applicability:\n1. No uninitialized memory usage: All stack-allocated structs (such as struct damon_va_probe_walk_private and struct mm_walk_ops) and scalar variables (e.g. booleans, loop counters, accumulator sums) are explicitly initialized with designated initializers or zero-initialization before use.\n2. No data copied to userspace: The patch does not introduce or modify any copy_to_user, put_user, netlink messages, or ioctl outputs that could leak uninitialized kernel memory.\n3. Memory safety considerations: Any potential issues relating to page-table walking, folio locking/reference counting, concurrency, or array indexing (e.g., probe_hits) fall under standard detectors (KASAN, LOCKDEP, and page table asserts).\n\nBecause there are no uninitialized memory access risks or info-leaks, a dedicated KMSAN fuzzing session is not warranted.",
"NeedsKMSAN": false
}Instruction: 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.
Prompt: Target architecture: amd64
For your convenience, here is the diff of the changes:
commit 451ccddaea518675570d294a25c681cffee51683
Author: syz-cluster <triage@syzkaller.com>
Date: Sun Sep 6 16:38:12 2026 +0000
syz-cluster: applied patch under review
diff --git a/mm/damon/ops-common.c b/mm/damon/ops-common.c
index 7219c608b1952..cfcd4edee346a 100644
--- a/mm/damon/ops-common.c
+++ b/mm/damon/ops-common.c
@@ -444,3 +444,35 @@ bool damos_ops_has_filter(struct damos *s)
return true;
return false;
}
+
+bool damon_ops_filter_match(struct damon_filter *filter, struct folio *folio)
+{
+ bool matched = false;
+ struct mem_cgroup *memcg;
+
+ switch (filter->type) {
+ case DAMON_FILTER_TYPE_ANON:
+ if (!folio) {
+ matched = false;
+ break;
+ }
+ matched = folio_test_anon(folio);
+ break;
+ case DAMON_FILTER_TYPE_MEMCG:
+ if (!folio) {
+ matched = false;
+ break;
+ }
+ rcu_read_lock();
+ memcg = folio_memcg_check(folio);
+ if (!memcg)
+ matched = false;
+ else
+ matched = filter->memcg_id == mem_cgroup_id(memcg);
+ rcu_read_unlock();
+ break;
+ default:
+ break;
+ }
+ return matched == filter->matching;
+}
diff --git a/mm/damon/ops-common.h b/mm/damon/ops-common.h
index 38d295488fa18..b832169b1cf8c 100644
--- a/mm/damon/ops-common.h
+++ b/mm/damon/ops-common.h
@@ -21,3 +21,5 @@ bool damos_folio_filter_match(struct damos_filter *filter, struct folio *folio);
unsigned long damon_migrate_pages(struct list_head *folio_list, int target_nid);
bool damos_ops_has_filter(struct damos *s);
+
+bool damon_ops_filter_match(struct damon_filter *filter, struct folio *folio);
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index c1e7d7a4f40df..ffde88ea7a13c 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -143,29 +143,8 @@ static bool damon_pa_filter_match(struct damon_filter *filter,
struct folio *folio)
{
bool matched = false;
- struct mem_cgroup *memcg;
switch (filter->type) {
- case DAMON_FILTER_TYPE_ANON:
- if (!folio) {
- matched = false;
- break;
- }
- matched = folio_test_anon(folio);
- break;
- case DAMON_FILTER_TYPE_MEMCG:
- if (!folio) {
- matched = false;
- break;
- }
- rcu_read_lock();
- memcg = folio_memcg_check(folio);
- if (!memcg)
- matched = false;
- else
- matched = filter->memcg_id == mem_cgroup_id(memcg);
- rcu_read_unlock();
- break;
case DAMON_FILTER_TYPE_PGIDLE_UNSET:
if (!folio)
matched = false;
@@ -173,7 +152,7 @@ static bool damon_pa_filter_match(struct damon_filter *filter,
matched = damon_folio_young(folio);
break;
default:
- break;
+ return damon_ops_filter_match(filter, folio);
}
return matched == filter->matching;
}
diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index f884d3f78f30a..090317191973b 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -510,6 +510,236 @@ static unsigned int damon_va_check_accesses(struct damon_ctx *ctx)
return max_nr_accesses;
}
+static void damon_va_prep_probe_region(struct damon_ctx *ctx,
+ struct mm_struct *mm, struct damon_region *r,
+ struct damon_probe *probe)
+{
+ struct damon_prep *p;
+
+ damon_for_each_prep(p, probe) {
+ switch (p->action) {
+ case DAMON_PREP_SET_PGIDLE:
+ damon_va_mkold(mm, r->sampling_addr);
+ break;
+ default:
+ break;
+ }
+ }
+}
+
+static void damon_va_prep_probes(struct damon_ctx *ctx, bool set_samples)
+{
+ struct damon_target *t;
+ struct mm_struct *mm;
+ struct damon_region *r;
+ struct damon_probe *p;
+
+ damon_for_each_target(t, ctx) {
+ mm = damon_get_mm(t);
+ if (!mm)
+ continue;
+ damon_for_each_region(r, t) {
+ if (set_samples)
+ r->sampling_addr = damon_rand(ctx, r->ar.start,
+ r->ar.end);
+ damon_for_each_probe(p, ctx)
+ damon_va_prep_probe_region(ctx, mm, r, p);
+ }
+ mmput(mm);
+ }
+}
+
+static bool damon_va_young_addr(struct folio *folio, pte_t *pte, pmd_t *pmd,
+ struct mm_struct *mm, unsigned long addr)
+{
+ bool young = false;
+
+ if (pte)
+ young = pte_young(*pte);
+ else if (pmd)
+ young = pmd_young(*pmd);
+ young = young || !folio_test_idle(folio) ||
+ mmu_notifier_test_young(mm, addr);
+ return young;
+}
+
+static bool damon_va_filter_match(struct damon_filter *filter,
+ struct folio *folio, pte_t *pte, pmd_t *pmd,
+ struct mm_struct *mm, unsigned long addr)
+{
+ bool matched = false;
+
+ switch (filter->type) {
+ case DAMON_FILTER_TYPE_PGIDLE_UNSET:
+ if (!folio)
+ matched = false;
+ else
+ matched = damon_va_young_addr(folio, pte, pmd, mm,
+ addr);
+ break;
+ default:
+ return damon_ops_filter_match(filter, folio);
+ }
+ return matched == filter->matching;
+}
+
+static bool damon_va_filter_pass(struct folio *folio, struct damon_probe *p,
+ pte_t *pte, pmd_t *pmd, struct mm_struct *mm,
+ unsigned long addr)
+{
+ struct damon_filter *f;
+ bool pass = true;
+
+ damon_for_each_filter(f, p) {
+ if (damon_va_filter_match(f, folio, pte, pmd, mm, addr)) {
+ pass = f->allow;
+ break;
+ }
+ pass = !f->allow;
+ }
+ return pass;
+}
+
+struct damon_va_probe_walk_private {
+ struct damon_ctx *ctx;
+ struct damon_region *r;
+};
+
+static void damon_va_probe_folio(struct damon_ctx *ctx,
+ struct damon_region *r, struct folio *folio,
+ pte_t *pte, pmd_t *pmd, struct mm_struct *mm)
+{
+ struct damon_probe *probe;
+ int i = 0;
+
+ damon_for_each_probe(probe, ctx) {
+ if (damon_va_filter_pass(folio, probe, pte, pmd, mm,
+ r->sampling_addr))
+ r->probe_hits[i]++;
+ i++;
+ }
+}
+
+static int damon_va_probe_pmd_entry(pmd_t *pmd, unsigned long addr,
+ unsigned long next, struct mm_walk *walk)
+{
+ pte_t *pte;
+ pte_t ptent;
+ spinlock_t *ptl;
+ struct folio *folio;
+ struct damon_va_probe_walk_private *priv = walk->private;
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ ptl = pmd_trans_huge_lock(pmd, walk->vma);
+ if (ptl) {
+ pmd_t pmde = pmdp_get(pmd);
+
+ if (!pmd_present(pmde))
+ goto huge_out;
+ folio = vm_normal_folio_pmd(walk->vma, addr, pmde);
+ if (!folio)
+ goto huge_out;
+ damon_va_probe_folio(priv->ctx, priv->r, folio, NULL, &pmde,
+ walk->vma->vm_mm);
+
+huge_out:
+ spin_unlock(ptl);
+ return 0;
+ }
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
+ pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+ if (!pte)
+ return 0;
+ ptent = ptep_get(pte);
+ if (!pte_present(ptent))
+ goto out;
+ folio = vm_normal_folio(walk->vma, addr, ptent);
+ if (!folio)
+ goto out;
+ damon_va_probe_folio(priv->ctx, priv->r, folio, &ptent, NULL,
+ walk->vma->vm_mm);
+
+out:
+ pte_unmap_unlock(pte, ptl);
+ return 0;
+}
+
+#ifdef CONFIG_HUGETLB_PAGE
+static int damon_va_probe_hugetlb_entry(pte_t *pte, unsigned long hmask,
+ unsigned long addr, unsigned long end, struct mm_walk *walk)
+{
+ struct damon_va_probe_walk_private *priv = walk->private;
+ struct hstate *h = hstate_vma(walk->vma);
+ struct folio *folio;
+ spinlock_t *ptl;
+ pte_t entry;
+
+ ptl = huge_pte_lock(h, walk->mm, pte);
+ entry = huge_ptep_get(walk->mm, addr, pte);
+ if (!pte_present(entry))
+ goto out;
+
+ folio = pfn_folio(pte_pfn(entry));
+ folio_get(folio);
+ damon_va_probe_folio(priv->ctx, priv->r, folio, &entry, NULL,
+ walk->vma->vm_mm);
+ folio_put(folio);
+
+out:
+ spin_unlock(ptl);
+ return 0;
+}
+#else
+#define damon_va_probe_hugetlb_entry NULL
+#endif /* CONFIG_HUGETLB_PAGE */
+
+static void __damon_va_apply_probes(struct damon_ctx *ctx,
+ struct mm_struct *mm, struct damon_region *r)
+{
+ struct damon_va_probe_walk_private arg = {
+ .ctx = ctx,
+ .r = r,
+ };
+ struct mm_walk_ops damon_probe_walk_ops = {
+ .pmd_entry = damon_va_probe_pmd_entry,
+ .hugetlb_entry = damon_va_probe_hugetlb_entry,
+ };
+ unsigned long addr = r->sampling_addr;
+
+ if (!mm)
+ return;
+
+ damon_va_walk_page_range(mm, addr, addr + 1, &damon_probe_walk_ops,
+ &arg);
+}
+
+static unsigned int damon_va_apply_probes(struct damon_ctx *ctx,
+ bool set_samples, bool return_max_wsum)
+{
+ struct damon_target *t;
+ struct mm_struct *mm;
+ struct damon_region *r;
+ unsigned int max_wsum = 0;
+
+ damon_for_each_target(t, ctx) {
+ mm = damon_get_mm(t);
+ damon_for_each_region(r, t) {
+ if (set_samples)
+ r->sampling_addr = damon_rand(ctx, r->ar.start,
+ r->ar.end);
+ __damon_va_apply_probes(ctx, mm, r);
+ if (return_max_wsum)
+ max_wsum = max(damon_probe_hits_wsum(r, false,
+ ctx), max_wsum);
+ }
+ if (mm)
+ mmput(mm);
+ }
+
+ return max_wsum;
+}
+
static bool damos_va_filter_young_match(struct damos_filter *filter,
struct folio *folio, struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep, pmd_t *pmdp)
@@ -938,6 +1168,8 @@ static int __init damon_va_initcall(void)
.update = damon_va_update,
.prepare_access_checks = damon_va_prepare_access_checks,
.check_accesses = damon_va_check_accesses,
+ .prep_probes = damon_va_prep_probes,
+ .apply_probes = damon_va_apply_probes,
.target_valid = damon_va_target_valid,
.cleanup_target = damon_va_cleanup_target,
.apply_scheme = damon_va_apply_scheme,
|
| 27/3 | 2026/09/06 16:39 | llm | kmsan-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 5701 output: 27 thoughts: 509 Thoughts: **Analyzing the DAMON Patch for Memory Safety** Okay, let's dive into this DAMON patch and see if it introduces any uninitialized memory vulnerabilities that would necessitate a KMSAN fuzzing session. My initial thought is to assess whether standard detectors like KASAN will suffice or if this warrants a more in-depth investigation. First, I need to understand the changes. It looks like: 1. We have `mm/damon/ops-common.c` which defines `damon_ops_filter_match` that checks the filter type – `DAMON_FILTER_TYPE_ANON` and `DAMON_FILTER_TYPE_MEMCG` – and consolidates some existing filter matching logic. 2. The header file `mm/damon/ops-common.h` declares the newly added `damon_ops_filter_match` function. 3. `mm/damon/paddr.c` is just a simple refactor, replacing the duplicate code with a call to the new function. 4. The most significant change is in `mm/damon/vaddr.c`, which implements virtual address space probing for DAMON. It introduces a slew of new functions: `damon_va_prep_probe_region`, `damon_va_prep_probes`, `damon_va_young_addr`, `damon_va_filter_match`, `damon_va_filter_pass`, `damon_va_probe_folio`, `damon_va_probe_pmd_entry`, `damon_va_probe_hugetlb_entry`, `__damon_va_apply_probes`, and `damon_va_apply_probes`. These new functions are registered in `damon_va_initcall` via the ops table. Now, my key concern is whether this introduces any uninitialized memory accesses, copies of uninitialized memory to userspace, or uninitialized fields in the new structs. I need to dig deeper. I'll probably grep the kernel tree or read through the relevant files to understand how `r->probe_hits` is allocated and initialized, how these filters are initialized and used, and generally how the new functions are working under the hood. I have to look for data dependencies and potential control flow that could lead to an uninitialized read. It is also important to consider if the new functions are accessing any memory not properly protected. |
| 28/3 | 2026/09/06 16:39 | tool | grepper |
0mArgs:{
"Expression": "probe_hits",
"PathPrefix": "mm/damon"
}Results: {
"Output": "mm/damon/core.c=325=unsigned int damon_nr_accesses_mvsum(struct damon_region *r,\n--\nmm/damon/core.c-348-\nmm/damon/core.c:349:unsigned char damon_probe_hits_mvsum(int probe_idx, struct damon_region *r,\nmm/damon/core.c-350-\t\tstruct damon_ctx *ctx)\n--\nmm/damon/core.c-366-\tif (left_window_bp == 10000)\nmm/damon/core.c:367:\t\treturn r-\u003elast_probe_hits[probe_idx];\nmm/damon/core.c-368-\nmm/damon/core.c:369:\treturn damon_mvsum(r-\u003eprobe_hits[probe_idx],\nmm/damon/core.c:370:\t\t\tr-\u003elast_probe_hits[probe_idx], left_window_bp);\nmm/damon/core.c-371-}\n--\nmm/damon/core.c=389=struct damon_region *damon_new_region(unsigned long start, unsigned long end)\n--\nmm/damon/core.c-402-\tfor (i = 0; i \u003c DAMON_MAX_PROBES; i++) {\nmm/damon/core.c:403:\t\tregion-\u003eprobe_hits[i] = 0;\nmm/damon/core.c:404:\t\tregion-\u003elast_probe_hits[i] = 0;\nmm/damon/core.c-405-\t}\n--\nmm/damon/core.c=462=static bool damon_is_last_region(struct damon_region *r,\n--\nmm/damon/core.c-468-/**\nmm/damon/core.c:469: * damon_probe_hits_wsum() - Returns probe hits weighted sum of a region.\nmm/damon/core.c-470- * @r:\t\tregion to get the weighted sum of.\n--\nmm/damon/core.c-475- */\nmm/damon/core.c:476:unsigned int damon_probe_hits_wsum(struct damon_region *r, bool last,\nmm/damon/core.c-477-\t\tstruct damon_ctx *ctx)\n--\nmm/damon/core.c-484-\t\tif (last)\nmm/damon/core.c:485:\t\t\tsum += r-\u003elast_probe_hits[i++] * probe-\u003eweight;\nmm/damon/core.c-486-\t\telse\nmm/damon/core.c:487:\t\t\tsum += r-\u003eprobe_hits[i++] * probe-\u003eweight;\nmm/damon/core.c-488-\t}\n--\nmm/damon/core.c=1003=static unsigned int damon_nr_samples_for_new_attrs(unsigned int nr,\n--\nmm/damon/core.c-1009-\nmm/damon/core.c:1010:static void damon_update_probe_hits(struct damon_region *r,\nmm/damon/core.c-1011-\t\tstruct damon_attrs *old_attrs, struct damon_attrs *new_attrs,\n--\nmm/damon/core.c-1017-\tdamon_for_each_probe(p, ctx) {\nmm/damon/core.c:1018:\t\tr-\u003elast_probe_hits[i] = damon_nr_samples_for_new_attrs(\nmm/damon/core.c:1019:\t\t\t\tr-\u003elast_probe_hits[i], old_attrs, new_attrs);\nmm/damon/core.c-1020-\t\tif (!aggregating)\nmm/damon/core.c:1021:\t\t\tr-\u003eprobe_hits[i] = damon_nr_samples_for_new_attrs(\nmm/damon/core.c:1022:\t\t\t\t\tr-\u003eprobe_hits[i], old_attrs,\nmm/damon/core.c-1023-\t\t\t\t\tnew_attrs);\nmm/damon/core.c-1024-\t\telse\nmm/damon/core.c:1025:\t\t\tr-\u003eprobe_hits[i] = 0;\nmm/damon/core.c-1026-\t\ti++;\n--\nmm/damon/core.c=1030=static void damon_update_monitoring_result(struct damon_region *r,\n--\nmm/damon/core.c-1033-{\nmm/damon/core.c:1034:\tdamon_update_probe_hits(r, old_attrs, new_attrs, aggregating, ctx);\nmm/damon/core.c-1035-\n--\nmm/damon/core.c=1427=static bool damon_valid_probe_params(struct damon_ctx *ctx)\n--\nmm/damon/core.c-1429-\tunsigned long sample_interval;\nmm/damon/core.c:1430:\tunsigned char max_probe_hits;\nmm/damon/core.c-1431-\tstruct damon_probe *probe;\n--\nmm/damon/core.c-1448-\t/* invalid if probe hits weighted sum can overflow */\nmm/damon/core.c:1449:\tmax_probe_hits = damon_nr_samples_per_aggr(\u0026ctx-\u003eattrs);\nmm/damon/core.c-1450-\twsum = 0;\nmm/damon/core.c-1451-\tdamon_for_each_probe(probe, ctx) {\nmm/damon/core.c:1452:\t\tif (probe-\u003eweight \u003e UINT_MAX / max_probe_hits)\nmm/damon/core.c-1453-\t\t\treturn false;\nmm/damon/core.c:1454:\t\twsum_to_add = probe-\u003eweight * max_probe_hits;\nmm/damon/core.c-1455-\t\tif (UINT_MAX - wsum \u003c wsum_to_add)\n--\nmm/damon/core.c=2293=static void kdamond_reset_aggregated(struct damon_ctx *c)\n--\nmm/damon/core.c-2316-\t\t\tfor (i = 0; i \u003c DAMON_MAX_PROBES; i++) {\nmm/damon/core.c:2317:\t\t\t\tr-\u003elast_probe_hits[i] = r-\u003eprobe_hits[i];\nmm/damon/core.c:2318:\t\t\t\tr-\u003eprobe_hits[i] = 0;\nmm/damon/core.c-2319-\t\t\t}\n--\nmm/damon/core.c=3426=static void damon_merge_two_regions(struct damon_target *t,\n--\nmm/damon/core.c-3437-\tfor (i = 0; i \u003c DAMON_MAX_PROBES; i++)\nmm/damon/core.c:3438:\t\tl-\u003eprobe_hits[i] = (l-\u003eprobe_hits[i] * sz_l + r-\u003eprobe_hits[i]\nmm/damon/core.c-3439-\t\t\t\t* sz_r) / (sz_l + sz_r);\n--\nmm/damon/core.c=3444=static unsigned int damon_merge_score(struct damon_region *r, bool last,\nmm/damon/core.c:3445:\t\tstruct damon_ctx *ctx, bool use_probe_hits)\nmm/damon/core.c-3446-{\nmm/damon/core.c:3447:\tif (use_probe_hits)\nmm/damon/core.c:3448:\t\treturn damon_probe_hits_wsum(r, last, ctx);\nmm/damon/core.c-3449-\tif (last)\n--\nmm/damon/core.c=3461=static void damon_merge_regions_of(struct damon_target *t, unsigned int thres,\n--\nmm/damon/core.c-3464-\tstruct damon_region *r, *prev = NULL, *next;\nmm/damon/core.c:3465:\tbool use_probe_hits = damon_has_probe_weights(ctx);\nmm/damon/core.c-3466-\n--\nmm/damon/core.c-3469-\nmm/damon/core.c:3470:\t\tscore = damon_merge_score(r, false, ctx, use_probe_hits);\nmm/damon/core.c:3471:\t\tlast_score = damon_merge_score(r, true, ctx, use_probe_hits);\nmm/damon/core.c-3472-\n--\nmm/damon/core.c-3486-\t\tdiff = abs_diff(score, damon_merge_score(prev, false, ctx,\nmm/damon/core.c:3487:\t\t\t\t\tuse_probe_hits));\nmm/damon/core.c-3488-\t\tif (diff \u003e thres)\n--\nmm/damon/core.c=3566=static int damon_split_region_at(struct damon_target *t,\n--\nmm/damon/core.c-3581-\t/* todo: do this for only installed probes */\nmm/damon/core.c:3582:\tmemcpy(new-\u003eprobe_hits, r-\u003eprobe_hits, sizeof(r-\u003eprobe_hits));\nmm/damon/core.c:3583:\tmemcpy(new-\u003elast_probe_hits, r-\u003elast_probe_hits,\nmm/damon/core.c:3584:\t\t\tsizeof(r-\u003elast_probe_hits));\nmm/damon/core.c-3585-\n--\nmm/damon/paddr.c=176=static unsigned int damon_pa_apply_probes(struct damon_ctx *ctx,\n--\nmm/damon/paddr.c-197-\t\t\t\tif (damon_pa_filter_pass(pa, folio, p))\nmm/damon/paddr.c:198:\t\t\t\t\tr-\u003eprobe_hits[i]++;\nmm/damon/paddr.c-199-\t\t\t\ti++;\n--\nmm/damon/paddr.c-203-\t\t\tif (return_max_wsum)\nmm/damon/paddr.c:204:\t\t\t\tmax_wsum = max(damon_probe_hits_wsum(r, false,\nmm/damon/paddr.c-205-\t\t\t\t\t\t\tctx), max_wsum);\n--\nmm/damon/sysfs-schemes.c=40=static void damos_sysfs_probe_release(struct kobject *kobj)\n--\nmm/damon/sysfs-schemes.c-47-\nmm/damon/sysfs-schemes.c:48:static struct kobj_attribute damos_sysfs_probe_hits_attr =\nmm/damon/sysfs-schemes.c-49-\t\t__ATTR_RO_MODE(hits, 0400);\n--\nmm/damon/sysfs-schemes.c=51=static struct attribute *damos_sysfs_probe_attrs[] = {\nmm/damon/sysfs-schemes.c:52:\t\u0026damos_sysfs_probe_hits_attr.attr,\nmm/damon/sysfs-schemes.c-53-\tNULL,\n--\nmm/damon/sysfs-schemes.c=90=static int damos_sysfs_probes_add_dirs(struct damos_sysfs_probes *probes,\n--\nmm/damon/sysfs-schemes.c-113-\t\tsys_probe = damos_sysfs_probe_alloc(\nmm/damon/sysfs-schemes.c:114:\t\t\t\tdamon_probe_hits_mvsum(i, region, ctx));\nmm/damon/sysfs-schemes.c-115-\t\tif (!sys_probe) {\n--\nmm/damon/tests/core-kunit.h=140=static void damon_test_split_at(struct kunit *test)\n--\nmm/damon/tests/core-kunit.h-154-\tr-\u003elast_nr_accesses = 15;\nmm/damon/tests/core-kunit.h:155:\tr-\u003eprobe_hits[0] = 7;\nmm/damon/tests/core-kunit.h:156:\tr-\u003elast_probe_hits[0] = 3;\nmm/damon/tests/core-kunit.h-157-\tr-\u003eage = 10;\n--\nmm/damon/tests/core-kunit.h-172-\tKUNIT_EXPECT_EQ(test, r-\u003elast_nr_accesses, r_new-\u003elast_nr_accesses);\nmm/damon/tests/core-kunit.h:173:\tKUNIT_EXPECT_EQ(test, r-\u003eprobe_hits[0], r_new-\u003eprobe_hits[0]);\nmm/damon/tests/core-kunit.h:174:\tKUNIT_EXPECT_EQ(test, r-\u003elast_probe_hits[0], r_new-\u003elast_probe_hits[0]);\nmm/damon/tests/core-kunit.h-175-\tKUNIT_EXPECT_EQ(test, r-\u003eage, r_new-\u003eage);\n--\nmm/damon/tests/core-kunit.h=181=static void damon_test_merge_two(struct kunit *test)\n--\nmm/damon/tests/core-kunit.h-195-\tr-\u003enr_accesses = 10;\nmm/damon/tests/core-kunit.h:196:\tr-\u003eprobe_hits[0] = 6;\nmm/damon/tests/core-kunit.h-197-\tr-\u003eage = 9;\n--\nmm/damon/tests/core-kunit.h-204-\tr2-\u003enr_accesses = 20;\nmm/damon/tests/core-kunit.h:205:\tr2-\u003eprobe_hits[0] = 14;\nmm/damon/tests/core-kunit.h-206-\tr2-\u003eage = 21;\n--\nmm/damon/tests/core-kunit.h-212-\tKUNIT_EXPECT_EQ(test, r-\u003enr_accesses, 16u);\nmm/damon/tests/core-kunit.h:213:\tKUNIT_EXPECT_EQ(test, r-\u003eprobe_hits[0], 11);\nmm/damon/tests/core-kunit.h-214-\tKUNIT_EXPECT_EQ(test, r-\u003eage, 17u);\n--\nmm/damon/tests/core-kunit.h=1514=static void damon_test_valid_probe_params(struct kunit *test)\n--\nmm/damon/tests/core-kunit.h-1538-\nmm/damon/tests/core-kunit.h:1539:\t/* More samples could overflow the probe_hits counters. */\nmm/damon/tests/core-kunit.h-1540-\tctx-\u003eattrs.aggr_interval = 256;\n--\nmm/damon/vaddr.c=608=static void damon_va_probe_folio(struct damon_ctx *ctx,\n--\nmm/damon/vaddr.c-617-\t\t\t\t\tr-\u003esampling_addr))\nmm/damon/vaddr.c:618:\t\t\tr-\u003eprobe_hits[i]++;\nmm/damon/vaddr.c-619-\t\ti++;\n--\nmm/damon/vaddr.c=717=static unsigned int damon_va_apply_probes(struct damon_ctx *ctx,\n--\nmm/damon/vaddr.c-732-\t\t\tif (return_max_wsum)\nmm/damon/vaddr.c:733:\t\t\t\tmax_wsum = max(damon_probe_hits_wsum(r, false,\nmm/damon/vaddr.c-734-\t\t\t\t\t\t\tctx), max_wsum);\n"
} |
| 29/3 | 2026/09/06 16:39 | llm | kmsan-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 10910 output: 34 thoughts: 70 Thoughts: Here's my analysis of those code sections: **Diving Deep into DAMON's Virtual Address Space Probes** Okay, so I need to get a really solid handle on how DAMON is handling virtual address probing, specifically around the `damon_va_apply_probes` function and any connected modifications. I'm worried about potential initialization issues here, so that's the primary focus. I know this code pretty well, but I need to make *absolutely* sure there aren't any sneaky bugs lurking in the shadows. Therefore, I'm zeroing in on `damon_va_probe_pmd_entry` and `damon_va_probe_hugetlb_entry`. I need to understand exactly how those functions are interacting with the page table entries, how they're handling potentially uninitialized data, and if any of the new changes have introduced unintended side effects. It's time to dig in and make sure this whole virtual address space probing mechanism is robust and safe. I'll be meticulously examining the logic flow and data dependencies, and I'll keep an eye out for any subtle vulnerabilities. |
| 30/3 | 2026/09/06 16:39 | tool | grepper |
0mArgs:{
"Expression": "damon_va_walk_page_range",
"PathPrefix": "mm/damon"
}Results: {
"Output": "mm/damon/vaddr.c=217=static void damon_va_update(struct damon_ctx *ctx)\n--\nmm/damon/vaddr.c-228-\nmm/damon/vaddr.c:229:static void damon_va_walk_page_range(struct mm_struct *mm, unsigned long start,\nmm/damon/vaddr.c-230-\t\tunsigned long end, struct mm_walk_ops *ops, void *private)\n--\nmm/damon/vaddr.c=336=static void damon_va_mkold(struct mm_struct *mm, unsigned long addr)\n--\nmm/damon/vaddr.c-342-\nmm/damon/vaddr.c:343:\tdamon_va_walk_page_range(mm, addr, addr + 1, \u0026damon_mkold_ops, NULL);\nmm/damon/vaddr.c-344-}\n--\nmm/damon/vaddr.c=458=static bool damon_va_young(struct mm_struct *mm, unsigned long addr)\n--\nmm/damon/vaddr.c-468-\nmm/damon/vaddr.c:469:\tdamon_va_walk_page_range(mm, addr, addr + 1, \u0026damon_young_ops, \u0026arg);\nmm/damon/vaddr.c-470-\treturn arg.young;\n--\nmm/damon/vaddr.c=697=static void __damon_va_apply_probes(struct damon_ctx *ctx,\n--\nmm/damon/vaddr.c-712-\nmm/damon/vaddr.c:713:\tdamon_va_walk_page_range(mm, addr, addr + 1, \u0026damon_probe_walk_ops,\nmm/damon/vaddr.c-714-\t\t\t\u0026arg);\n--\nmm/damon/vaddr.c=961=static unsigned long damos_va_migrate(struct damon_target *target,\n--\nmm/damon/vaddr.c-992-\nmm/damon/vaddr.c:993:\tdamon_va_walk_page_range(mm, r-\u003ear.start, r-\u003ear.end, \u0026walk_ops, \u0026priv);\nmm/damon/vaddr.c-994-\tmmput(mm);\n--\nmm/damon/vaddr.c=1080=static unsigned long damos_va_stat(struct damon_target *target,\n--\nmm/damon/vaddr.c-1099-\nmm/damon/vaddr.c:1100:\tdamon_va_walk_page_range(mm, r-\u003ear.start, r-\u003ear.end, \u0026walk_ops, \u0026priv);\nmm/damon/vaddr.c-1101-\tmmput(mm);\n"
} |
| 31/3 | 2026/09/06 16:39 | llm | kmsan-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 11992 output: 37 thoughts: 24 Thoughts: Here's my take on the process, framed as a first-person expert perspective: **Diving into `damon_va_walk_page_range`** Okay, so I need to refresh my memory on the `damon_va_walk_page_range` function, specifically how it's implemented within `vaddr.c`. This is where the virtual address space walking logic resides, and I need to understand it in the context of DAMON's operation. I'm probably going to be looking for how it handles different page table levels, how it iterates through the relevant virtual address range, and how it interacts with the underlying memory management structures. I should pay close attention to the potential pitfalls like race conditions, how it handles TLB invalidations if needed, and also any performance considerations that might come up, specifically with different page sizes and NUMA configurations. I need to make sure that the iteration logic is correctly handling unmapped regions and, of course, that it is compatible with the target architecture's page table format. Let's see how it's actually done. I'm going to quickly scan the code for the key algorithms and critical data structures involved. I'll need to focus on what happens during each step of the page walk. I will be looking for how the range is broken down, and how individual pages are identified and processed. I should also check how this function interacts with the overall DAMON infrastructure for monitoring and profiling memory access patterns. Let's get to it. |
| 32/3 | 2026/09/06 16:39 | tool | read-file |
0mArgs:{
"File": "mm/damon/vaddr.c",
"FirstLine": 225,
"LineCount": 40
}Results: {
"Contents": " 225:\t\t\tdamon_set_regions(t, three_regions, 3, DAMON_MIN_REGION_SZ);\n 226:\t\t}\n 227:\t}\n 228:\t\n 229:\tstatic void damon_va_walk_page_range(struct mm_struct *mm, unsigned long start,\n 230:\t\t\tunsigned long end, struct mm_walk_ops *ops, void *private)\n 231:\t{\n 232:\t\tstruct vm_area_struct *vma;\n 233:\t\n 234:\t\tvma = lock_vma_under_rcu(mm, start);\n 235:\t\tif (!vma)\n 236:\t\t\tgoto lock_mmap;\n 237:\t\n 238:\t\tif (end \u003e vma-\u003evm_end) {\n 239:\t\t\tvma_end_read(vma);\n 240:\t\t\tgoto lock_mmap;\n 241:\t\t}\n 242:\t\n 243:\t\tif (!(vma-\u003evm_flags \u0026 VM_PFNMAP)) {\n 244:\t\t\tops-\u003ewalk_lock = PGWALK_VMA_RDLOCK_VERIFY;\n 245:\t\t\twalk_page_range_vma(vma, start, end, ops, private);\n 246:\t\t}\n 247:\t\n 248:\t\tvma_end_read(vma);\n 249:\t\treturn;\n 250:\t\n 251:\tlock_mmap:\n 252:\t\tmmap_read_lock(mm);\n 253:\t\tops-\u003ewalk_lock = PGWALK_RDLOCK;\n 254:\t\twalk_page_range(mm, start, end, ops, private);\n 255:\t\tmmap_read_unlock(mm);\n 256:\t}\n 257:\t\n 258:\tstatic int damon_mkold_pmd_entry(pmd_t *pmd, unsigned long addr,\n 259:\t\t\tunsigned long next, struct mm_walk *walk)\n 260:\t{\n 261:\t\tpte_t *pte;\n 262:\t\tspinlock_t *ptl;\n 263:\t\n 264:\t\tptl = pmd_trans_huge_lock(pmd, walk-\u003evma);\n"
} |
| 33/3 | 2026/09/06 16:39 | llm | kmsan-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 12990 output: 33 thoughts: 18 Thoughts: Here's my take on those thoughts: **Analyzing the `damon_filter` Structure** Okay, so I need to understand how the `damon_filter` struct is defined and initialized. I'm going to dive right into the source code to see its structure. I want to look for the key members of the structure. I am expecting some sort of configuration and probably some state information. I'll focus on how it is being populated, are there hardcoded values, or are they sourced from other parts of the system? I will look for other associated functions or macro uses. This will help me understand how `damon_filter` contributes to the overall behavior. |
| 34/3 | 2026/09/06 16:39 | tool | grepper |
0mArgs:{
"Expression": "struct damon_filter",
"PathPrefix": "include/linux/damon.h"
}Results: {
"Output": "include/linux/damon.h=764=struct damon_prep {\n--\ninclude/linux/damon.h-771-/**\ninclude/linux/damon.h:772: * enum damon_filter_type - Type of \u0026struct damon_filter\ninclude/linux/damon.h-773- *\n--\ninclude/linux/damon.h=778=enum damon_filter_type {\n--\ninclude/linux/damon.h-784-/**\ninclude/linux/damon.h:785: * struct damon_filter - DAMON region filter for \u0026struct damon_probe.\ninclude/linux/damon.h-786- *\n--\ninclude/linux/damon.h-791- */\ninclude/linux/damon.h:792:struct damon_filter {\ninclude/linux/damon.h-793-\tenum damon_filter_type type;\n--\ninclude/linux/damon.h=1053=void damon_add_prep(struct damon_probe *p, struct damon_prep *prep);\ninclude/linux/damon.h-1054-\ninclude/linux/damon.h:1055:struct damon_filter *damon_new_filter(enum damon_filter_type type,\ninclude/linux/damon.h-1056-\t\tbool matching, bool allow);\ninclude/linux/damon.h:1057:void damon_add_filter(struct damon_probe *probe, struct damon_filter *f);\ninclude/linux/damon.h:1058:void damon_destroy_filter(struct damon_filter *f);\ninclude/linux/damon.h-1059-\n"
} |
| 35/3 | 2026/09/06 16:39 | llm | kmsan-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 13628 output: 36 thoughts: 21 Thoughts: Here's my thinking process: **Diving into the DAMON Filter** Okay, time to get a look at the `damon_filter`. I need to understand how this filter works in the context of DAMON. Right, so I'll go straight to the source, the include file: `include/linux/damon.h`. That's where the definition and likely the core implementation details should reside. Hopefully, it's well-commented; I'm expecting some clear struct members and maybe some insightful function prototypes related to how the filtering logic is actually applied to memory access. I'll be looking for things like how it handles different address ranges, access types, and potentially even user-defined criteria. It’s important to see what hooks it has into the core DAMON data structures and the overall monitoring process. Let's see what we've got! |
| 36/3 | 2026/09/06 16:39 | tool | read-file |
0mArgs:{
"File": "include/linux/damon.h",
"FirstLine": 780,
"LineCount": 40
}Results: {
"Contents": " 780:\t\tDAMON_FILTER_TYPE_MEMCG,\n 781:\t\tDAMON_FILTER_TYPE_PGIDLE_UNSET,\n 782:\t};\n 783:\t\n 784:\t/**\n 785:\t * struct damon_filter - DAMON region filter for \u0026struct damon_probe.\n 786:\t *\n 787:\t * @type:\tType of the region.\n 788:\t * @matching:\tWhether this filter is for the type-matching ones.\n 789:\t * @allow:\tWhether the @type-@matching ones should pass this filter.\n 790:\t * @memcg_id:\tMemcg id of the question if @type is DAMON_FILTER_MEMCG.\n 791:\t */\n 792:\tstruct damon_filter {\n 793:\t\tenum damon_filter_type type;\n 794:\t\tbool matching;\n 795:\t\tbool allow;\n 796:\t\tunion {\n 797:\t\t\tu64 memcg_id;\n 798:\t\t};\n 799:\t/* private: */\n 800:\t\t/* Siblings list. */\n 801:\t\tstruct list_head list;\n 802:\t};\n 803:\t\n 804:\t/**\n 805:\t * struct damon_probe - Data region attribute probe.\n 806:\t *\n 807:\t * @weight:\tRelative priority of the attribute for this probe.\n 808:\t */\n 809:\tstruct damon_probe {\n 810:\t\tunsigned int weight;\n 811:\t/* private: */\n 812:\t\t/* Preparation actions to apply to each probing memory. */\n 813:\t\tstruct list_head preps;\n 814:\t\t/* Filters for assessing if a given region is for this probe. */\n 815:\t\tstruct list_head filters;\n 816:\t\t/* Siblings list. */\n 817:\t\tstruct list_head list;\n 818:\t};\n 819:\t\n"
} |
| 37/3 | 2026/09/06 16:39 | llm | kmsan-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 14424 output: 30 thoughts: 22 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience and written in the first person: **Analyzing `damon_new_filter`'s Allocation and Initialization** Alright, let's dive into how `damon_new_filter` handles the crucial tasks of allocating and initializing a `damon_filter`. I need to understand the memory management here. What's the allocation strategy? Is it using a custom allocator, or relying on something standard like `kmalloc`? Are there any specific flags or sizes passed to the allocator that might hint at its intended use case? For example, is there a performance optimization with regard to NUMA nodes or cache line alignment? Next, I'll scrutinize the initialization process. What data structures within the `damon_filter` are being populated? Are any mutexes or spinlocks initialized? Are there any subtle race conditions or memory ordering issues I should be watching out for? I'll pay close attention to the order of operations, paying particular attention to whether the initialization of some fields depends on the success of others. Also, does it have a destructor that frees resources, and what might be the effects of any such teardown? I'm particularly interested in how the filter's internal state is set up. Does it use any internal structures? How are its parameters configured? How does the code handle potential errors during the initialization phase? Are there any specific sanity checks being performed on the input parameters to ensure the filter operates correctly? Is there a need to make a distinction between `init` and `reset` in the future? Essentially, I need to build a mental model of how this `damon_filter` comes into existence, ensuring it can perform its intended function reliably. This allocation and initialization are the bedrock of the entire filtering mechanism. |
| 38/3 | 2026/09/06 16:39 | tool | grepper |
0mArgs:{
"Expression": "damon_new_filter",
"PathPrefix": "mm/damon"
}Results: {
"Output": "mm/damon/core.c=159=static bool damon_has_prep(struct damon_ctx *c)\n--\nmm/damon/core.c-170-\nmm/damon/core.c:171:struct damon_filter *damon_new_filter(enum damon_filter_type type,\nmm/damon/core.c-172-\t\tbool matching, bool allow)\n--\nmm/damon/core.c=1806=static int damon_commit_filters(struct damon_probe *dst,\n--\nmm/damon/core.c-1823-\nmm/damon/core.c:1824:\t\tnew_filter = damon_new_filter(src_filter-\u003etype,\nmm/damon/core.c-1825-\t\t\t\tsrc_filter-\u003ematching, src_filter-\u003eallow);\n--\nmm/damon/sysfs.c=2199=static int damon_sysfs_set_filters(struct damon_probe *probe,\n--\nmm/damon/sysfs.c-2208-\nmm/damon/sysfs.c:2209:\t\tfilter = damon_new_filter(sys_filter-\u003etype,\nmm/damon/sysfs.c-2210-\t\t\t\tsys_filter-\u003ematching,\n"
} |
| 39/3 | 2026/09/06 16:39 | llm | kmsan-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 15193 output: 36 thoughts: 23 Thoughts: Here's my take on those thoughts, tailored for an expert audience: **Diving into `damon_new_filter`** Okay, time to get my hands dirty. I need to take a look at the `damon_new_filter` function. Let's start with `mm/damon/core.c`. I need to refresh my understanding of how DAMON handles its new filter logic within the core. I’m thinking I'll start by tracing the function's call graph and scrutinizing the arguments passed to it. I want to see how it's integrated with the other DAMON components and how it interacts with the underlying memory management infrastructure. Specifically, I'll need to dissect its error handling and what metrics it's using (or should be). I'm looking for potential bottlenecks or optimization opportunities in the filter creation. From there, I'll assess its performance impact in different scenarios. |
| 40/3 | 2026/09/06 16:39 | tool | read-file |
0mArgs:{
"File": "mm/damon/core.c",
"FirstLine": 170,
"LineCount": 20
}Results: {
"Contents": " 170:\t\n 171:\tstruct damon_filter *damon_new_filter(enum damon_filter_type type,\n 172:\t\t\tbool matching, bool allow)\n 173:\t{\n 174:\t\tstruct damon_filter *filter;\n 175:\t\n 176:\t\tfilter = kmalloc_obj(*filter);\n 177:\t\tif (!filter)\n 178:\t\t\treturn NULL;\n 179:\t\tfilter-\u003etype = type;\n 180:\t\tfilter-\u003ematching = matching;\n 181:\t\tfilter-\u003eallow = allow;\n 182:\t\tINIT_LIST_HEAD(\u0026filter-\u003elist);\n 183:\t\treturn filter;\n 184:\t}\n 185:\t\n 186:\tvoid damon_add_filter(struct damon_probe *p, struct damon_filter *f)\n 187:\t{\n 188:\t\tlist_add_tail(\u0026f-\u003elist, \u0026p-\u003efilters);\n 189:\t}\n"
} |
| 41/3 | 2026/09/06 16:39 | llm | kmsan-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 15726 output: 28 thoughts: 27 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: **Investigating `memcg_id` in DAMON Filter Context** Okay, so I'm diving into how `memcg_id` gets initialized, specifically within the DAMON context when we're dealing with `DAMON_FILTER_TYPE_MEMCG`. I need to trace the initialization path and understand where this value originates and how it's used. My primary goal here is to identify any potential gotchas or edge cases, maybe look for areas where a race could exist or where the ID might not be what the user expects. I'm assuming familiarity with the DAMON code base, so I'm not going to be super explicit about every function. I need to ensure that the code is behaving exactly how I expect it to. Ultimately, I am trying to determine what is the reliable place to access this value. |
| 42/3 | 2026/09/06 16:39 | tool | grepper |
0mArgs:{
"Expression": "memcg_id",
"PathPrefix": "mm/damon"
}Results: {
"Output": "mm/damon/core.c=1191=static void damos_commit_quota_goal_union(\n--\nmm/damon/core.c-1204-\t\tdst-\u003enid = src-\u003enid;\nmm/damon/core.c:1205:\t\tdst-\u003ememcg_id = src-\u003ememcg_id;\nmm/damon/core.c-1206-\t\tbreak;\n--\nmm/damon/core.c=1315=static void damos_commit_filter_arg(\n--\nmm/damon/core.c-1319-\tcase DAMOS_FILTER_TYPE_MEMCG:\nmm/damon/core.c:1320:\t\tdst-\u003ememcg_id = src-\u003ememcg_id;\nmm/damon/core.c-1321-\t\tbreak;\n--\nmm/damon/core.c=1791=static void damon_commit_filter(struct damon_filter *dst,\n--\nmm/damon/core.c-1798-\tcase DAMON_FILTER_TYPE_MEMCG:\nmm/damon/core.c:1799:\t\tdst-\u003ememcg_id = src-\u003ememcg_id;\nmm/damon/core.c-1800-\t\tbreak;\n--\nmm/damon/core.c=1806=static int damon_commit_filters(struct damon_probe *dst,\n--\nmm/damon/core.c-1829-\t\tcase DAMON_FILTER_TYPE_MEMCG:\nmm/damon/core.c:1830:\t\t\tnew_filter-\u003ememcg_id = src_filter-\u003ememcg_id;\nmm/damon/core.c-1831-\t\t\tbreak;\n--\nmm/damon/core.c=2943=static unsigned long damos_get_node_memcg_used_bp(\n--\nmm/damon/core.c-2957-\nmm/damon/core.c:2958:\tmemcg = mem_cgroup_get_from_id(goal-\u003ememcg_id);\nmm/damon/core.c-2959-\tif (!memcg) {\n--\nmm/damon/ops-common.c=266=bool damos_folio_filter_match(struct damos_filter *filter, struct folio *folio)\n--\nmm/damon/ops-common.c-284-\t\telse\nmm/damon/ops-common.c:285:\t\t\tmatched = filter-\u003ememcg_id == mem_cgroup_id(memcg);\nmm/damon/ops-common.c-286-\t\trcu_read_unlock();\n--\nmm/damon/ops-common.c=448=bool damon_ops_filter_match(struct damon_filter *filter, struct folio *folio)\n--\nmm/damon/ops-common.c-470-\t\telse\nmm/damon/ops-common.c:471:\t\t\tmatched = filter-\u003ememcg_id == mem_cgroup_id(memcg);\nmm/damon/ops-common.c-472-\t\trcu_read_unlock();\n--\nmm/damon/sysfs-schemes.c=2804=static int damon_sysfs_add_scheme_filters(struct damos *scheme,\n--\nmm/damon/sysfs-schemes.c-2822-\t\t\t\t\tsysfs_filter-\u003ememcg_path,\nmm/damon/sysfs-schemes.c:2823:\t\t\t\t\t\u0026filter-\u003ememcg_id);\nmm/damon/sysfs-schemes.c-2824-\t\t\tif (err) {\n--\nmm/damon/sysfs-schemes.c=2851=static int damos_sysfs_add_quota_score(\n--\nmm/damon/sysfs-schemes.c-2879-\t\t\terr = damon_sysfs_memcg_path_to_id(\nmm/damon/sysfs-schemes.c:2880:\t\t\t\t\tsysfs_goal-\u003epath, \u0026goal-\u003ememcg_id);\nmm/damon/sysfs-schemes.c-2881-\t\t\tif (err) {\n--\nmm/damon/sysfs.c=2199=static int damon_sysfs_set_filters(struct damon_probe *probe,\n--\nmm/damon/sysfs.c-2218-\t\t\t\t\tsys_filter-\u003epath,\nmm/damon/sysfs.c:2219:\t\t\t\t\t\u0026filter-\u003ememcg_id);\nmm/damon/sysfs.c-2220-\t\t\tif (err) {\n--\nmm/damon/tests/core-kunit.h=804=static void damos_test_commit_quota_goal_for(struct kunit *test,\n--\nmm/damon/tests/core-kunit.h-824-\t\tKUNIT_EXPECT_EQ(test, dst-\u003enid, src-\u003enid);\nmm/damon/tests/core-kunit.h:825:\t\tKUNIT_EXPECT_EQ(test, dst-\u003ememcg_id, src-\u003ememcg_id);\nmm/damon/tests/core-kunit.h-826-\t\tbreak;\n--\nmm/damon/tests/core-kunit.h=832=static void damos_test_commit_quota_goal(struct kunit *test)\n--\nmm/damon/tests/core-kunit.h-872-\t\t\t.nid = 6,\nmm/damon/tests/core-kunit.h:873:\t\t\t.memcg_id = 7,\nmm/damon/tests/core-kunit.h-874-\t\t\t});\n--\nmm/damon/tests/core-kunit.h-880-\t\t\t.nid = 10,\nmm/damon/tests/core-kunit.h:881:\t\t\t.memcg_id = 1,\nmm/damon/tests/core-kunit.h-882-\t\t\t});\n--\nmm/damon/tests/core-kunit.h=1118=static void damos_test_commit_filter_for(struct kunit *test,\n--\nmm/damon/tests/core-kunit.h-1126-\tcase DAMOS_FILTER_TYPE_MEMCG:\nmm/damon/tests/core-kunit.h:1127:\t\tKUNIT_EXPECT_EQ(test, dst-\u003ememcg_id, src-\u003ememcg_id);\nmm/damon/tests/core-kunit.h-1128-\t\tbreak;\n--\nmm/damon/tests/core-kunit.h=1147=static void damos_test_commit_filter(struct kunit *test)\n--\nmm/damon/tests/core-kunit.h-1165-\t\t\t.allow = false,\nmm/damon/tests/core-kunit.h:1166:\t\t\t.memcg_id = 123,\nmm/damon/tests/core-kunit.h-1167-\t\t\t});\n--\nmm/damon/tests/core-kunit.h=1367=static void damon_test_commit_filter_for(struct kunit *test,\n--\nmm/damon/tests/core-kunit.h-1375-\tcase DAMON_FILTER_TYPE_MEMCG:\nmm/damon/tests/core-kunit.h:1376:\t\tKUNIT_EXPECT_EQ(test, dst-\u003ememcg_id, src-\u003ememcg_id);\nmm/damon/tests/core-kunit.h-1377-\t\tbreak;\n--\nmm/damon/tests/core-kunit.h=1383=static void damon_test_commit_filter(struct kunit *test)\n--\nmm/damon/tests/core-kunit.h-1401-\t\t\t.allow = false,\nmm/damon/tests/core-kunit.h:1402:\t\t\t.memcg_id = 123,\nmm/damon/tests/core-kunit.h-1403-\t\t\t});\n"
} |
| 43/3 | 2026/09/06 16:39 | llm | kmsan-evaluator |
0mModel:gemini-3.7-flash Args: null Results: null Tokens: input: 17997 output: 307 thoughts: 1337 Thoughts: **KMSAN Analysis: DAMON Code Changes** Okay, let's break down these DAMON code changes from a KMSAN (Kernel Memory Sanitizer) perspective. My primary goal here is to identify any potential for uninitialized memory reads or leaks. I'll focus on the specific functions mentioned and how they handle memory. First, I examine the `damon_ops_filter_match` function. I see that `matched` is initialized to `false` and is assigned a value in all code paths, depending on the filter type (anon or memcg). No concerns here regarding uninitialized memory. Next, I look at `damon_pa_filter_match`. This appears to be a straightforward refactoring, and like the previous one, `matched` is initialized to `false` and gets assigned a value. Moving on to `mm/damon/vaddr.c`, I need to scrutinize these changes more closely. `damon_va_prep_probe_region` and `damon_va_prep_probes` seem like initialization steps, and I'm not seeing immediate red flags. `damon_va_young_addr` has `young` initialized to `false`, which is safe. I then go through `damon_va_filter_match`, which uses `damon_ops_filter_match` and also has `matched` initialized and assigned, and `damon_va_filter_pass` where `pass` is initialized to `true`. No issues there. The `damon_va_probe_folio` function increments `r->probe_hits[i]++` if the filter passed. It is crucial to check this. `i` is initialized to `0` and thus there is no uninitialized variable that could create an issue. The functions `damon_va_probe_pmd_entry` and `damon_va_probe_hugetlb_entry` employ local structs. `arg` is constructed using designated initializers, specifically `.ctx = ctx, .r = r`, and `damon_probe_walk_ops` is also initialized with designated initializers: `.pmd_entry = ..., .hugetlb_entry = ...`. This approach ensures that all members are initialized, thus preventing uninitialized memory use. Inside these functions, `folio` is derived from either `pte_pfn` or `vm_normal_folio` and is guaranteed to be initialized. Finally, I checked `__damon_va_apply_probes` and `damon_va_apply_probes`. `max_wsum` is initialized to `0`. I've carefully examined all the code paths and initializations within these functions. I'm not detecting any instances where uninitialized memory is used in conditions, branches, or passed around. No copy_to_user or potential info leak pathways are present. There are also no complex buffers or memory passed across boundaries that might expose uninitialized data. While there *could* be race conditions, page table walk bugs, or out-of-bounds access to `probe_hits`, these are issues that would be picked up by existing tools such as LOCKDEP, KASAN, and DAMON's own validation, and they are not related to KMSAN-specific vulnerabilities (uninitialized memory). **Conclusion:** Based on this thorough review, this patch does *not* introduce any risks related to uninitialized memory. Therefore, I'm confident that `NeedsKMSAN` should be set to `false`, and the analysis is comprehensive. |
| 44/3 | 2026/09/06 16:39 | tool | set-results |
0mArgs:{
"KMSANReasoning": "The patch refactors DAMON filter matching logic across physical and virtual address spaces by introducing damon_ops_filter_match() and implements virtual address space probe handling (damon_va_prep_probes, damon_va_apply_probes, damon_va_probe_pmd_entry, damon_va_probe_hugetlb_entry).\n\nAnalysis of memory safety and sanitizer applicability:\n1. No uninitialized memory usage: All stack-allocated structs (such as struct damon_va_probe_walk_private and struct mm_walk_ops) and scalar variables (e.g. booleans, loop counters, accumulator sums) are explicitly initialized with designated initializers or zero-initialization before use.\n2. No data copied to userspace: The patch does not introduce or modify any copy_to_user, put_user, netlink messages, or ioctl outputs that could leak uninitialized kernel memory.\n3. Memory safety considerations: Any potential issues relating to page-table walking, folio locking/reference counting, concurrency, or array indexing (e.g., probe_hits) fall under standard detectors (KASAN, LOCKDEP, and page table asserts).\n\nBecause there are no uninitialized memory access risks or info-leaks, a dedicated KMSAN fuzzing session is not warranted.",
"NeedsKMSAN": false
}Results: {
"KMSANReasoning": "The patch refactors DAMON filter matching logic across physical and virtual address spaces by introducing damon_ops_filter_match() and implements virtual address space probe handling (damon_va_prep_probes, damon_va_apply_probes, damon_va_probe_pmd_entry, damon_va_probe_hugetlb_entry).\n\nAnalysis of memory safety and sanitizer applicability:\n1. No uninitialized memory usage: All stack-allocated structs (such as struct damon_va_probe_walk_private and struct mm_walk_ops) and scalar variables (e.g. booleans, loop counters, accumulator sums) are explicitly initialized with designated initializers or zero-initialization before use.\n2. No data copied to userspace: The patch does not introduce or modify any copy_to_user, put_user, netlink messages, or ioctl outputs that could leak uninitialized kernel memory.\n3. Memory safety considerations: Any potential issues relating to page-table walking, folio locking/reference counting, concurrency, or array indexing (e.g., probe_hits) fall under standard detectors (KASAN, LOCKDEP, and page table asserts).\n\nBecause there are no uninitialized memory access risks or info-leaks, a dedicated KMSAN fuzzing session is not warranted.",
"NeedsKMSAN": false
} |
| Total Calls | Total Tokens | Avg Tokens | Total Duration (Seconds) | Avg Duration (Seconds) |
|---|
| Total Calls | Total Duration (Seconds) | Avg Duration (Seconds) |
|---|