AI Trajectory


Trajectory: (Expand/Collapse All)
Seq Timestamp Type Name Duration
0/0 2026/08/07 12:03 flow patch-triage
12m Args: 
null

Results: 
{
  "EnableConfigs": [
    "LRU_GEN",
    "LRU_GEN_ENABLED"
  ],
  "FocusSymbols": [
    "try_to_free_pages",
    "remove_migration_ptes"
  ],
  "KMSANReasoning": "The patch introduces new fields to `struct mm_struct` and `struct lru_gen_mm_walk` for MGLRU empty-walk suppression. All new fields are properly initialized (e.g., in `lru_gen_init_mm` and via `kzalloc` for `mm_walk`). The tracepoint `mm_vmscan_lru_gen_walk` only exposes fully initialized local variables and struct fields. The debugfs interface correctly checks the return value of `sscanf` before using the parsed value. There are no uninitialized memory reads, uninitialized structure padding sent to user space, or complex data structures where uninitialized fields could be read. Any potential issues like out-of-bounds accesses would be caught by KASAN. Therefore, a dedicated KMSAN fuzzing session is not necessary.",
  "NeedsKMSAN": false,
  "Reasoning": "The patch modifies the Multi-Gen LRU (MGLRU) subsystem to suppress empty page table walks across NUMA nodes. It introduces `empty_map` tracking to `struct mm_struct` and modifies page fault and migration paths to invalidate the empty skip when a page is accessed on a node. It also adds a tunable `skip_empty` in debugfs and tracepoints for MGLRU walks. These are functional changes to core memory management and reclaim logic, which are reachable and worth fuzzing.",
  "WorthFuzzing": true
}
1/1 2026/08/07 12:03 action read-patch-diff
0m Args: 
null

Results: 
{
  "PatchDiff": "commit 5bddd2e77cfeb9a61248429ddf81da817f69a5a2\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Fri Aug 7 12:03:21 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/include/linux/mm_types.h b/include/linux/mm_types.h\nindex b5d4cd3b067bf..89b7234836759 100644\n--- a/include/linux/mm_types.h\n+++ b/include/linux/mm_types.h\n@@ -1410,6 +1410,17 @@ struct mm_struct {\n \t\t\t * page table walkers cleared the corresponding bits.\n \t\t\t */\n \t\t\tunsigned long bitmap;\n+\t\t\t/*\n+\t\t\t * Cross-node empty-walk suppression: bit N set means\n+\t\t\t * node N's last aging walk of this mm found no folio\n+\t\t\t * for this lruvec (pure waste). Skip the mm on node N\n+\t\t\t * for up to K generations, then force a rescan.\n+\t\t\t * empty_map_seq is the oldest max_seq among the set\n+\t\t\t * bits (min(), conservative), so a bit is cleared when\n+\t\t\t * max_seq \u003e= empty_map_seq + K.\n+\t\t\t */\n+\t\t\tunsigned long empty_map;\n+\t\t\tunsigned long empty_map_seq;\n #ifdef CONFIG_MEMCG\n \t\t\t/* points to the memcg of \"owner\" above */\n \t\t\tstruct mem_cgroup *memcg;\n@@ -1503,6 +1514,8 @@ static inline void lru_gen_init_mm(struct mm_struct *mm)\n {\n \tINIT_LIST_HEAD(\u0026mm-\u003elru_gen.list);\n \tmm-\u003elru_gen.bitmap = 0;\n+\tmm-\u003elru_gen.empty_map = 0;\n+\tmm-\u003elru_gen.empty_map_seq = ~0UL;\n #ifdef CONFIG_MEMCG\n \tmm-\u003elru_gen.memcg = NULL;\n #endif\n@@ -1518,6 +1531,20 @@ static inline void lru_gen_use_mm(struct mm_struct *mm)\n \tWRITE_ONCE(mm-\u003elru_gen.bitmap, -1);\n }\n \n+/*\n+ * A page of this mm appeared on (or was accessed on) node @nid — e.g. a page\n+ * fault or a migration. Set that node's bitmap bit so the aging walker walks\n+ * the mm, and clear the empty-walk skip so a page that just appeared on a node\n+ * previously marked empty is not ignored for up to K generations.\n+ */\n+static inline void lru_gen_mm_accessed(struct mm_struct *mm, int nid)\n+{\n+\tunsigned long key = nid % BITS_PER_TYPE(mm-\u003elru_gen.bitmap);\n+\n+\tset_bit(key, \u0026mm-\u003elru_gen.bitmap);\n+\tclear_bit(key, \u0026mm-\u003elru_gen.empty_map);\n+}\n+\n #else /* !CONFIG_LRU_GEN_WALKS_MMU */\n \n static inline void lru_gen_add_mm(struct mm_struct *mm)\n@@ -1540,6 +1567,10 @@ static inline void lru_gen_use_mm(struct mm_struct *mm)\n {\n }\n \n+static inline void lru_gen_mm_accessed(struct mm_struct *mm, int nid)\n+{\n+}\n+\n #endif /* CONFIG_LRU_GEN_WALKS_MMU */\n \n struct vma_iterator {\ndiff --git a/include/linux/mmzone.h b/include/linux/mmzone.h\nindex 86891163e0ef4..e9341da1bfb89 100644\n--- a/include/linux/mmzone.h\n+++ b/include/linux/mmzone.h\n@@ -595,6 +595,10 @@ enum {\n \tMM_LEAF_YOUNG,\t\t/* young leaf entries */\n \tMM_NONLEAF_FOUND,\t/* non-leaf entries found in Bloom filters */\n \tMM_NONLEAF_ADDED,\t/* non-leaf entries added to Bloom filters */\n+\tMM_LEAF_ELIGIBLE,\t/* folios belonging to this lruvec (node+memcg) */\n+\tMM_WALK_TOTAL,\t\t/* page-table walks completed */\n+\tMM_WALK_EMPTY,\t\t/* walks that found no eligible folio */\n+\tMM_LEAF_TOTAL_EMPTY,\t/* leaf entries scanned by empty walks */\n \tNR_MM_STATS\n };\n \ndiff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h\nindex b4bf7b8def1f5..c7c2034715b65 100644\n--- a/include/trace/events/vmscan.h\n+++ b/include/trace/events/vmscan.h\n@@ -659,6 +659,34 @@ TRACE_EVENT(mm_vmscan_kswapd_clear_hopeless,\n \t\t__entry-\u003enid,\n \t\t__print_symbolic(__entry-\u003ereason, kswapd_clear_hopeless_reason_ops))\n );\n+TRACE_EVENT(mm_vmscan_lru_gen_walk,\n+\n+\tTP_PROTO(int nid, unsigned long seq, int leaf_total,\n+\t\t int leaf_eligible, bool empty),\n+\n+\tTP_ARGS(nid, seq, leaf_total, leaf_eligible, empty),\n+\n+\tTP_STRUCT__entry(\n+\t\t__field(int, nid)\n+\t\t__field(unsigned long, seq)\n+\t\t__field(int, leaf_total)\n+\t\t__field(int, leaf_eligible)\n+\t\t__field(bool, empty)\n+\t),\n+\n+\tTP_fast_assign(\n+\t\t__entry-\u003enid = nid;\n+\t\t__entry-\u003eseq = seq;\n+\t\t__entry-\u003eleaf_total = leaf_total;\n+\t\t__entry-\u003eleaf_eligible = leaf_eligible;\n+\t\t__entry-\u003eempty = empty;\n+\t),\n+\n+\tTP_printk(\"nid=%d seq=%lu leaf_total=%d leaf_eligible=%d empty=%d\",\n+\t\t__entry-\u003enid, __entry-\u003eseq, __entry-\u003eleaf_total,\n+\t\t__entry-\u003eleaf_eligible, __entry-\u003eempty)\n+);\n+\n #endif /* _TRACE_VMSCAN_H */\n \n /* This part must be outside protection */\ndiff --git a/mm/memory.c b/mm/memory.c\nindex 6ae52e3869b1c..077e7353b4cd7 100644\n--- a/mm/memory.c\n+++ b/mm/memory.c\n@@ -5513,6 +5513,9 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)\n \t\tfolio_put(folio);\n \t\treturn handle_userfault(vmf, VM_UFFD_MISSING);\n \t}\n+\t/* a new page of this mm lands on this node: invalidate any empty skip */\n+\tlru_gen_mm_accessed(vma-\u003evm_mm, folio_nid(folio));\n+\n \tmap_anon_folio_pte_pf(folio, vmf-\u003epte, vma, addr,\n \t\t\t      vmf_orig_pte_uffd_wp(vmf));\n unlock:\n@@ -5773,6 +5776,10 @@ vm_fault_t finish_fault(struct vm_fault *vmf)\n \t\tpage = vmf-\u003epage;\n \n \tfolio = page_folio(page);\n+\n+\t/* mapping a page of this mm on this node: invalidate any empty skip */\n+\tlru_gen_mm_accessed(vma-\u003evm_mm, folio_nid(folio));\n+\n \t/*\n \t * check even for read faults because we might have lost our CoWed\n \t * page\ndiff --git a/mm/migrate.c b/mm/migrate.c\nindex b937cbd764808..2e0674e89ba86 100644\n--- a/mm/migrate.c\n+++ b/mm/migrate.c\n@@ -354,6 +354,9 @@ static bool remove_migration_pte(struct folio *folio,\n \tstruct rmap_walk_arg *rmap_walk_arg = arg;\n \tDEFINE_FOLIO_VMA_WALK(pvmw, rmap_walk_arg-\u003efolio, vma, addr, PVMW_SYNC | PVMW_MIGRATION);\n \n+\t/* the folio ends up on folio_nid(): notify MGLRU for this mm */\n+\tlru_gen_mm_accessed(vma-\u003evm_mm, folio_nid(folio));\n+\n \twhile (page_vma_mapped_walk(\u0026pvmw)) {\n \t\trmap_t rmap_flags = RMAP_NONE;\n \t\tpte_t old_pte;\ndiff --git a/mm/vmscan.c b/mm/vmscan.c\nindex 17d2b793cbfc4..631bcd89b1967 100644\n--- a/mm/vmscan.c\n+++ b/mm/vmscan.c\n@@ -2919,6 +2919,9 @@ static struct lru_gen_mm_state *get_mm_state(struct lruvec *lruvec)\n \treturn \u0026lruvec-\u003emm_state;\n }\n \n+/* tunable empty-walk skip threshold; defined later, get_next_mm() needs it */\n+static unsigned long mglru_empty_skip_gens;\n+\n static struct mm_struct *get_next_mm(struct lru_gen_mm_walk *walk)\n {\n \tint key;\n@@ -2929,9 +2932,27 @@ static struct mm_struct *get_next_mm(struct lru_gen_mm_walk *walk)\n \tmm = list_entry(mm_state-\u003ehead, struct mm_struct, lru_gen.list);\n \tkey = pgdat-\u003enode_id % BITS_PER_TYPE(mm-\u003elru_gen.bitmap);\n \n+\t/* skip if this mm hasn't been used on this node since the last walk */\n \tif (!walk-\u003eforce_scan \u0026\u0026 !test_bit(key, \u0026mm-\u003elru_gen.bitmap))\n \t\treturn NULL;\n \n+\t/*\n+\t * Skip if this node's last walk of this mm was empty and fewer than K\n+\t * generations have passed; after K, clear the bit to force a rescan.\n+\t * empty_map_seq tracks the oldest marking via min(), so the rescan\n+\t * never fires later than K generations on any node.\n+\t */\n+\tif (!walk-\u003eforce_scan \u0026\u0026 test_bit(key, \u0026mm-\u003elru_gen.empty_map)) {\n+\t\tDEFINE_MAX_SEQ(walk-\u003elruvec);\n+\t\tunsigned long empty_seq = READ_ONCE(mm-\u003elru_gen.empty_map_seq);\n+\n+\t\tif (max_seq \u003c empty_seq + READ_ONCE(mglru_empty_skip_gens))\n+\t\t\treturn NULL;\t\t/* skip: \u003c K gens since empty */\n+\n+\t\t/* K generations passed → force rescan */\n+\t\tclear_bit(key, \u0026mm-\u003elru_gen.empty_map);\n+\t}\n+\n \tclear_bit(key, \u0026mm-\u003elru_gen.bitmap);\n \tmmgrab(mm);\n \n@@ -3587,6 +3608,8 @@ static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end,\n \t\tif (!folio)\n \t\t\tcontinue;\n \n+\t\twalk-\u003emm_stats[MM_LEAF_ELIGIBLE]++;\n+\n \t\tif (folio_test_large(folio)) {\n \t\t\tconst unsigned int max_nr = (end - addr) \u003e\u003e PAGE_SHIFT;\n \n@@ -3687,6 +3710,8 @@ static void walk_pmd_range_locked(pud_t *pud, unsigned long addr, struct vm_area\n \t\tif (!folio)\n \t\t\tgoto next;\n \n+\t\twalk-\u003emm_stats[MM_LEAF_ELIGIBLE]++;\n+\n \t\tif (!pmdp_test_and_clear_young_notify(vma, addr, pmd + i))\n \t\t\tgoto next;\n \n@@ -4108,8 +4133,46 @@ static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long seq,\n \n \tdo {\n \t\tsuccess = iterate_mm_list(walk, \u0026mm);\n-\t\tif (mm)\n+\t\tif (mm) {\n+\t\t\tint nid = lruvec_pgdat(lruvec)-\u003enode_id;\n+\t\t\tint key = nid % BITS_PER_TYPE(mm-\u003elru_gen.bitmap);\n+\t\t\tbool empty = false;\n+\n \t\t\twalk_mm(mm, walk);\n+\n+\t\t\t/*\n+\t\t\t * Any walk that found no folio for this lruvec is empty -\n+\t\t\t * even if the PMD-level Bloom filter kept MM_LEAF_TOTAL at 0\n+\t\t\t * (the common case for a foreign mm). Mark it so get_next_mm()\n+\t\t\t * skips it next time; otherwise the empty-walk skip never\n+\t\t\t * engages for the walks that matter most.\n+\t\t\t */\n+\t\t\tif (walk-\u003emm_stats[MM_LEAF_ELIGIBLE] == 0) {\n+\t\t\t\tset_bit(key, \u0026mm-\u003elru_gen.empty_map);\n+\t\t\t\t/* track the oldest marking (conservative) */\n+\t\t\t\tWRITE_ONCE(mm-\u003elru_gen.empty_map_seq,\n+\t\t\t\t\tmin(READ_ONCE(mm-\u003elru_gen.empty_map_seq),\n+\t\t\t\t\t    walk-\u003eseq));\n+\t\t\t\tempty = true;\n+\t\t\t} else {\n+\t\t\t\t/* found eligible folios: clear the marking */\n+\t\t\t\tclear_bit(key, \u0026mm-\u003elru_gen.empty_map);\n+\t\t\t}\n+\n+\t\t\t/* measurement stats keep the leaf_total gate */\n+\t\t\tif (walk-\u003emm_stats[MM_LEAF_TOTAL]) {\n+\t\t\t\twalk-\u003emm_stats[MM_WALK_TOTAL]++;\n+\t\t\t\tif (empty) {\n+\t\t\t\t\twalk-\u003emm_stats[MM_WALK_EMPTY]++;\n+\t\t\t\t\twalk-\u003emm_stats[MM_LEAF_TOTAL_EMPTY] +=\n+\t\t\t\t\t\twalk-\u003emm_stats[MM_LEAF_TOTAL];\n+\t\t\t\t}\n+\t\t\t}\n+\t\t\ttrace_mm_vmscan_lru_gen_walk(\n+\t\t\t\t\tlruvec_pgdat(lruvec)-\u003enode_id, walk-\u003eseq,\n+\t\t\t\t\twalk-\u003emm_stats[MM_LEAF_TOTAL],\n+\t\t\t\t\twalk-\u003emm_stats[MM_LEAF_ELIGIBLE], empty);\n+\t\t}\n \t} while (mm);\n done:\n \tif (success) {\n@@ -4205,6 +4268,15 @@ static bool lruvec_is_reclaimable(struct lruvec *lruvec, struct scan_control *sc\n /* to protect the working set of the last N jiffies */\n static unsigned long lru_gen_min_ttl __read_mostly;\n \n+/*\n+ * Cross-node empty-walk skip threshold: skip an mm on node N for up to\n+ * @mglru_empty_skip_gens generations after an empty walk, then force-rescan\n+ * (closes migration/mlock/NUMA-balancing windows). Default 4 matches\n+ * MAX_NR_GENS; 0 disables the suppression. Tunable via:\n+ * echo \"skip_empty \u003cN\u003e\" \u003e /sys/kernel/debug/lru_gen\n+ */\n+static unsigned long mglru_empty_skip_gens __read_mostly = 4;\n+\n static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)\n {\n \tstruct mem_cgroup *memcg;\n@@ -5588,14 +5660,14 @@ static void lru_gen_seq_show_full(struct seq_file *m, struct lruvec *lruvec,\n \n \tseq_puts(m, \"                      \");\n \tfor (i = 0; i \u003c NR_MM_STATS; i++) {\n-\t\tconst char *s = \"xxxx\";\n+\t\tconst char *s = \"xxxxxxxx\";\n \t\tunsigned long n = 0;\n \n \t\tif (seq == max_seq \u0026\u0026 NR_HIST_GENS == 1) {\n-\t\t\ts = \"TYFA\";\n+\t\t\ts = \"TYFALWEE\";\n \t\t\tn = READ_ONCE(mm_state-\u003estats[hist][i]);\n \t\t} else if (seq != max_seq \u0026\u0026 NR_HIST_GENS \u003e 1) {\n-\t\t\ts = \"tyfa\";\n+\t\t\ts = \"tyfalwee\";\n \t\t\tn = READ_ONCE(mm_state-\u003estats[hist][i]);\n \t\t}\n \n@@ -5802,6 +5874,25 @@ static ssize_t lru_gen_seq_write(struct file *file, const char __user *src,\n \t\tif (!*cur)\n \t\t\tcontinue;\n \n+\t\t/*\n+\t\t * set/show the empty-walk skip threshold: \"skip_empty \u003cN\u003e\"\n+\t\t */\n+\t\tif (!strncmp(cur, \"skip_empty\", 10)) {\n+\t\t\tcur += 10;\n+\t\t\tcur = skip_spaces(cur);\n+\t\t\tif (*cur) {\n+\t\t\t\tunsigned long val;\n+\n+\t\t\t\tif (sscanf(cur, \"%lu\", \u0026val) == 1)\n+\t\t\t\t\tWRITE_ONCE(mglru_empty_skip_gens, val);\n+\t\t\t} else {\n+\t\t\t\tpr_info(\"MGLRU empty skip threshold: %lu generations (0=disabled)\\n\",\n+\t\t\t\t\tREAD_ONCE(mglru_empty_skip_gens));\n+\t\t\t}\n+\t\t\terr = 0;\n+\t\t\tcontinue;\n+\t\t}\n+\n \t\tn = sscanf(cur, \"%c %llu %u %lu %n %4s %n %lu %n\", \u0026cmd, \u0026memcg_id, \u0026nid,\n \t\t\t   \u0026seq, \u0026end, swap_string, \u0026end, \u0026opt, \u0026end);\n \t\tif (n \u003c 4 || cur[end]) {\n"
}
2/1 2026/08/07 12:03 agent patch-evaluator
4m Model: 
best-expensive

Args: 
null

Results: 
{
  "EnableConfigs": [
    "LRU_GEN",
    "LRU_GEN_ENABLED"
  ],
  "FocusSymbols": [
    "try_to_free_pages",
    "remove_migration_ptes"
  ],
  "Reasoning": "The patch modifies the Multi-Gen LRU (MGLRU) subsystem to suppress empty page table walks across NUMA nodes. It introduces `empty_map` tracking to `struct mm_struct` and modifies page fault and migration paths to invalidate the empty skip when a page is accessed on a node. It also adds a tunable `skip_empty` in debugfs and tracepoints for MGLRU walks. These are functional changes to core memory management and reclaim logic, which are reachable and worth fuzzing.",
  "WorthFuzzing": true
}

Instruction: 
You are an expert Linux kernel maintainer.
Your job is to review a provided patch series and determine
if it makes functional changes to the kernel that should be fuzzed.

IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on your internal knowledge of the kernel. You must actively
use your code access tools to examine the actual source code and confirm any assumptions.

Return WorthFuzzing=false if the patch only contains:
- Modifications to Documentation/, Kconfig files, or code comments.
- Purely decorative changes, such as logging (e.g., pr_err, printk) or tracepoints.
- Changes to numeric constants or macros that do not functionally alter execution flow.
- Code paths that are impossible to reach in virtualized environments like GCE or QEMU,
  even when utilizing software-emulated hardware (e.g., usb gadget, mac80211_hwsim).
- Code in vendor-specific PCIe switch, SmartNIC, or GPU drivers (e.g., mlxsw, pds_core, qed,
  ionic, amdgpu) that require physical PCIe hardware cards not emulated in standard QEMU.
- Driver .remove, .shutdown, or pci_unregister_driver teardown callbacks (e.g., igb_remove)
  that are executed only during PCI hot-unplug or sysfs driver unbind operations.

If it modifies reachable core kernel logic, drivers, or architectures, use your code search
tools to verify the code can be executed, then return WorthFuzzing=true.

When returning WorthFuzzing=true, you MUST ALSO:
1. Extract any specific kernel functions that should be heavily fuzzed into FocusSymbols.
   Avoid listing generic hot-path functions to prevent skewed test distributions.
   Prefer non-static, non-inlined API entrypoint functions over internal static helper functions
   (which are inlined by the compiler and do not have distinct symbol addresses).
2. Identify any specific CONFIG_ options required to properly test this new/modified feature.
   Go and look into the Kconfig files and check for ifdefs around the code, do not make assumptions.
   Also check "depends on" lines in Kconfig to include any non-standard parent subsystem configs
   needed for Kbuild to compile the code statically into vmlinux. List them in the EnableConfigs
   output array, and DO NOT add a '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: 
For your convenience, here is the diff of the changes:
commit 5bddd2e77cfeb9a61248429ddf81da817f69a5a2
Author: syz-cluster <triage@syzkaller.com>
Date:   Fri Aug 7 12:03:21 2026 +0000

    syz-cluster: applied patch under review

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index b5d4cd3b067bf..89b7234836759 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -1410,6 +1410,17 @@ struct mm_struct {
 			 * page table walkers cleared the corresponding bits.
 			 */
 			unsigned long bitmap;
+			/*
+			 * Cross-node empty-walk suppression: bit N set means
+			 * node N's last aging walk of this mm found no folio
+			 * for this lruvec (pure waste). Skip the mm on node N
+			 * for up to K generations, then force a rescan.
+			 * empty_map_seq is the oldest max_seq among the set
+			 * bits (min(), conservative), so a bit is cleared when
+			 * max_seq >= empty_map_seq + K.
+			 */
+			unsigned long empty_map;
+			unsigned long empty_map_seq;
 #ifdef CONFIG_MEMCG
 			/* points to the memcg of "owner" above */
 			struct mem_cgroup *memcg;
@@ -1503,6 +1514,8 @@ static inline void lru_gen_init_mm(struct mm_struct *mm)
 {
 	INIT_LIST_HEAD(&mm->lru_gen.list);
 	mm->lru_gen.bitmap = 0;
+	mm->lru_gen.empty_map = 0;
+	mm->lru_gen.empty_map_seq = ~0UL;
 #ifdef CONFIG_MEMCG
 	mm->lru_gen.memcg = NULL;
 #endif
@@ -1518,6 +1531,20 @@ static inline void lru_gen_use_mm(struct mm_struct *mm)
 	WRITE_ONCE(mm->lru_gen.bitmap, -1);
 }
 
+/*
+ * A page of this mm appeared on (or was accessed on) node @nid — e.g. a page
+ * fault or a migration. Set that node's bitmap bit so the aging walker walks
+ * the mm, and clear the empty-walk skip so a page that just appeared on a node
+ * previously marked empty is not ignored for up to K generations.
+ */
+static inline void lru_gen_mm_accessed(struct mm_struct *mm, int nid)
+{
+	unsigned long key = nid % BITS_PER_TYPE(mm->lru_gen.bitmap);
+
+	set_bit(key, &mm->lru_gen.bitmap);
+	clear_bit(key, &mm->lru_gen.empty_map);
+}
+
 #else /* !CONFIG_LRU_GEN_WALKS_MMU */
 
 static inline void lru_gen_add_mm(struct mm_struct *mm)
@@ -1540,6 +1567,10 @@ static inline void lru_gen_use_mm(struct mm_struct *mm)
 {
 }
 
+static inline void lru_gen_mm_accessed(struct mm_struct *mm, int nid)
+{
+}
+
 #endif /* CONFIG_LRU_GEN_WALKS_MMU */
 
 struct vma_iterator {
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 86891163e0ef4..e9341da1bfb89 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -595,6 +595,10 @@ enum {
 	MM_LEAF_YOUNG,		/* young leaf entries */
 	MM_NONLEAF_FOUND,	/* non-leaf entries found in Bloom filters */
 	MM_NONLEAF_ADDED,	/* non-leaf entries added to Bloom filters */
+	MM_LEAF_ELIGIBLE,	/* folios belonging to this lruvec (node+memcg) */
+	MM_WALK_TOTAL,		/* page-table walks completed */
+	MM_WALK_EMPTY,		/* walks that found no eligible folio */
+	MM_LEAF_TOTAL_EMPTY,	/* leaf entries scanned by empty walks */
 	NR_MM_STATS
 };
 
diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
index b4bf7b8def1f5..c7c2034715b65 100644
--- a/include/trace/events/vmscan.h
+++ b/include/trace/events/vmscan.h
@@ -659,6 +659,34 @@ TRACE_EVENT(mm_vmscan_kswapd_clear_hopeless,
 		__entry->nid,
 		__print_symbolic(__entry->reason, kswapd_clear_hopeless_reason_ops))
 );
+TRACE_EVENT(mm_vmscan_lru_gen_walk,
+
+	TP_PROTO(int nid, unsigned long seq, int leaf_total,
+		 int leaf_eligible, bool empty),
+
+	TP_ARGS(nid, seq, leaf_total, leaf_eligible, empty),
+
+	TP_STRUCT__entry(
+		__field(int, nid)
+		__field(unsigned long, seq)
+		__field(int, leaf_total)
+		__field(int, leaf_eligible)
+		__field(bool, empty)
+	),
+
+	TP_fast_assign(
+		__entry->nid = nid;
+		__entry->seq = seq;
+		__entry->leaf_total = leaf_total;
+		__entry->leaf_eligible = leaf_eligible;
+		__entry->empty = empty;
+	),
+
+	TP_printk("nid=%d seq=%lu leaf_total=%d leaf_eligible=%d empty=%d",
+		__entry->nid, __entry->seq, __entry->leaf_total,
+		__entry->leaf_eligible, __entry->empty)
+);
+
 #endif /* _TRACE_VMSCAN_H */
 
 /* This part must be outside protection */
diff --git a/mm/memory.c b/mm/memory.c
index 6ae52e3869b1c..077e7353b4cd7 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5513,6 +5513,9 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
 		folio_put(folio);
 		return handle_userfault(vmf, VM_UFFD_MISSING);
 	}
+	/* a new page of this mm lands on this node: invalidate any empty skip */
+	lru_gen_mm_accessed(vma->vm_mm, folio_nid(folio));
+
 	map_anon_folio_pte_pf(folio, vmf->pte, vma, addr,
 			      vmf_orig_pte_uffd_wp(vmf));
 unlock:
@@ -5773,6 +5776,10 @@ vm_fault_t finish_fault(struct vm_fault *vmf)
 		page = vmf->page;
 
 	folio = page_folio(page);
+
+	/* mapping a page of this mm on this node: invalidate any empty skip */
+	lru_gen_mm_accessed(vma->vm_mm, folio_nid(folio));
+
 	/*
 	 * check even for read faults because we might have lost our CoWed
 	 * page
diff --git a/mm/migrate.c b/mm/migrate.c
index b937cbd764808..2e0674e89ba86 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -354,6 +354,9 @@ static bool remove_migration_pte(struct folio *folio,
 	struct rmap_walk_arg *rmap_walk_arg = arg;
 	DEFINE_FOLIO_VMA_WALK(pvmw, rmap_walk_arg->folio, vma, addr, PVMW_SYNC | PVMW_MIGRATION);
 
+	/* the folio ends up on folio_nid(): notify MGLRU for this mm */
+	lru_gen_mm_accessed(vma->vm_mm, folio_nid(folio));
+
 	while (page_vma_mapped_walk(&pvmw)) {
 		rmap_t rmap_flags = RMAP_NONE;
 		pte_t old_pte;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 17d2b793cbfc4..631bcd89b1967 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2919,6 +2919,9 @@ static struct lru_gen_mm_state *get_mm_state(struct lruvec *lruvec)
 	return &lruvec->mm_state;
 }
 
+/* tunable empty-walk skip threshold; defined later, get_next_mm() needs it */
+static unsigned long mglru_empty_skip_gens;
+
 static struct mm_struct *get_next_mm(struct lru_gen_mm_walk *walk)
 {
 	int key;
@@ -2929,9 +2932,27 @@ static struct mm_struct *get_next_mm(struct lru_gen_mm_walk *walk)
 	mm = list_entry(mm_state->head, struct mm_struct, lru_gen.list);
 	key = pgdat->node_id % BITS_PER_TYPE(mm->lru_gen.bitmap);
 
+	/* skip if this mm hasn't been used on this node since the last walk */
 	if (!walk->force_scan && !test_bit(key, &mm->lru_gen.bitmap))
 		return NULL;
 
+	/*
+	 * Skip if this node's last walk of this mm was empty and fewer than K
+	 * generations have passed; after K, clear the bit to force a rescan.
+	 * empty_map_seq tracks the oldest marking via min(), so the rescan
+	 * never fires later than K generations on any node.
+	 */
+	if (!walk->force_scan && test_bit(key, &mm->lru_gen.empty_map)) {
+		DEFINE_MAX_SEQ(walk->lruvec);
+		unsigned long empty_seq = READ_ONCE(mm->lru_gen.empty_map_seq);
+
+		if (max_seq < empty_seq + READ_ONCE(mglru_empty_skip_gens))
+			return NULL;		/* skip: < K gens since empty */
+
+		/* K generations passed → force rescan */
+		clear_bit(key, &mm->lru_gen.empty_map);
+	}
+
 	clear_bit(key, &mm->lru_gen.bitmap);
 	mmgrab(mm);
 
@@ -3587,6 +3608,8 @@ static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end,
 		if (!folio)
 			continue;
 
+		walk->mm_stats[MM_LEAF_ELIGIBLE]++;
+
 		if (folio_test_large(folio)) {
 			const unsigned int max_nr = (end - addr) >> PAGE_SHIFT;
 
@@ -3687,6 +3710,8 @@ static void walk_pmd_range_locked(pud_t *pud, unsigned long addr, struct vm_area
 		if (!folio)
 			goto next;
 
+		walk->mm_stats[MM_LEAF_ELIGIBLE]++;
+
 		if (!pmdp_test_and_clear_young_notify(vma, addr, pmd + i))
 			goto next;
 
@@ -4108,8 +4133,46 @@ static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long seq,
 
 	do {
 		success = iterate_mm_list(walk, &mm);
-		if (mm)
+		if (mm) {
+			int nid = lruvec_pgdat(lruvec)->node_id;
+			int key = nid % BITS_PER_TYPE(mm->lru_gen.bitmap);
+			bool empty = false;
+
 			walk_mm(mm, walk);
+
+			/*
+			 * Any walk that found no folio for this lruvec is empty -
+			 * even if the PMD-level Bloom filter kept MM_LEAF_TOTAL at 0
+			 * (the common case for a foreign mm). Mark it so get_next_mm()
+			 * skips it next time; otherwise the empty-walk skip never
+			 * engages for the walks that matter most.
+			 */
+			if (walk->mm_stats[MM_LEAF_ELIGIBLE] == 0) {
+				set_bit(key, &mm->lru_gen.empty_map);
+				/* track the oldest marking (conservative) */
+				WRITE_ONCE(mm->lru_gen.empty_map_seq,
+					min(READ_ONCE(mm->lru_gen.empty_map_seq),
+					    walk->seq));
+				empty = true;
+			} else {
+				/* found eligible folios: clear the marking */
+				clear_bit(key, &mm->lru_gen.empty_map);
+			}
+
+			/* measurement stats keep the leaf_total gate */
+			if (walk->mm_stats[MM_LEAF_TOTAL]) {
+				walk->mm_stats[MM_WALK_TOTAL]++;
+				if (empty) {
+					walk->mm_stats[MM_WALK_EMPTY]++;
+					walk->mm_stats[MM_LEAF_TOTAL_EMPTY] +=
+						walk->mm_stats[MM_LEAF_TOTAL];
+				}
+			}
+			trace_mm_vmscan_lru_gen_walk(
+					lruvec_pgdat(lruvec)->node_id, walk->seq,
+					walk->mm_stats[MM_LEAF_TOTAL],
+					walk->mm_stats[MM_LEAF_ELIGIBLE], empty);
+		}
 	} while (mm);
 done:
 	if (success) {
@@ -4205,6 +4268,15 @@ static bool lruvec_is_reclaimable(struct lruvec *lruvec, struct scan_control *sc
 /* to protect the working set of the last N jiffies */
 static unsigned long lru_gen_min_ttl __read_mostly;
 
+/*
+ * Cross-node empty-walk skip threshold: skip an mm on node N for up to
+ * @mglru_empty_skip_gens generations after an empty walk, then force-rescan
+ * (closes migration/mlock/NUMA-balancing windows). Default 4 matches
+ * MAX_NR_GENS; 0 disables the suppression. Tunable via:
+ * echo "skip_empty <N>" > /sys/kernel/debug/lru_gen
+ */
+static unsigned long mglru_empty_skip_gens __read_mostly = 4;
+
 static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)
 {
 	struct mem_cgroup *memcg;
@@ -5588,14 +5660,14 @@ static void lru_gen_seq_show_full(struct seq_file *m, struct lruvec *lruvec,
 
 	seq_puts(m, "                      ");
 	for (i = 0; i < NR_MM_STATS; i++) {
-		const char *s = "xxxx";
+		const char *s = "xxxxxxxx";
 		unsigned long n = 0;
 
 		if (seq == max_seq && NR_HIST_GENS == 1) {
-			s = "TYFA";
+			s = "TYFALWEE";
 			n = READ_ONCE(mm_state->stats[hist][i]);
 		} else if (seq != max_seq && NR_HIST_GENS > 1) {
-			s = "tyfa";
+			s = "tyfalwee";
 			n = READ_ONCE(mm_state->stats[hist][i]);
 		}
 
@@ -5802,6 +5874,25 @@ static ssize_t lru_gen_seq_write(struct file *file, const char __user *src,
 		if (!*cur)
 			continue;
 
+		/*
+		 * set/show the empty-walk skip threshold: "skip_empty <N>"
+		 */
+		if (!strncmp(cur, "skip_empty", 10)) {
+			cur += 10;
+			cur = skip_spaces(cur);
+			if (*cur) {
+				unsigned long val;
+
+				if (sscanf(cur, "%lu", &val) == 1)
+					WRITE_ONCE(mglru_empty_skip_gens, val);
+			} else {
+				pr_info("MGLRU empty skip threshold: %lu generations (0=disabled)\n",
+					READ_ONCE(mglru_empty_skip_gens));
+			}
+			err = 0;
+			continue;
+		}
+
 		n = sscanf(cur, "%c %llu %u %lu %n %4s %n %lu %n", &cmd, &memcg_id, &nid,
 			   &seq, &end, swap_string, &end, &opt, &end);
 		if (n < 4 || cur[end]) {

3/2 2026/08/07 12:03 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 6283
							output: 19
							thoughts: 240

Thoughts: 
**Analyzing the MGLRU Patch for Fuzzing Potential**

Okay, so I'm looking at this patch for MGLRU, which is interesting. It seems like they're introducing a clever optimization to the Multi-Gen LRU algorithm – suppressing these empty walks across nodes, which sounds like it could save some significant overhead. They've added `empty_map` and `empty_map_seq` to the `lru_gen` structure within the `mm_struct`, which is where all the memory management metadata lives. That makes sense, keeps things organized. They're also adjusting `lru_gen_mm_accessed` and adding tracepoints, which is good for debugging and performance analysis. Modifying `get_next_mm` and `try_to_inc_max_seq` indicates they are tweaking the core walking logic. Plus, a tunable `skip_empty` in `/sys/kernel/debug/lru_gen` suggests this optimization can be controlled at runtime.

My immediate thought is: is this reachable code? Worth fuzzing? MGLRU, being a core memory management feature, screams "attack surface." But I need to be sure the config is enabled, is it `CONFIG_LRU_GEN` only? I need to check what other config options are required for this to be active. Is it `CONFIG_LRU_GEN_WALKS_MMU` or something like that? I'll probably grep for `LRU_GEN` in the kernel source to get a complete picture of the dependencies. Understanding the context is crucial before I start poking at it with fuzzers. I need to know the exact configuration options, what code paths this patch introduces, and how often this optimization will be triggered in real-world scenarios.

4/2 2026/08/07 12:03 tool grepper
0m Args: 
{
  "Expression": "config LRU_GEN"
}

Results: 
{
  "Output": "mm/Kconfig=1392=config PTE_MARKER_UFFD_WP\n--\nmm/Kconfig-1402-# multi-gen LRU {\nmm/Kconfig:1403:config LRU_GEN\nmm/Kconfig-1404-\tbool \"Multi-Gen LRU\"\n--\nmm/Kconfig-1411-\nmm/Kconfig:1412:config LRU_GEN_ENABLED\nmm/Kconfig-1413-\tbool \"Enable by default\"\n--\nmm/Kconfig-1417-\nmm/Kconfig:1418:config LRU_GEN_STATS\nmm/Kconfig-1419-\tbool \"Full stats for debugging\"\n--\nmm/Kconfig-1426-\nmm/Kconfig:1427:config LRU_GEN_WALKS_MMU\nmm/Kconfig-1428-\tdef_bool y\n"
}
5/2 2026/08/07 12:03 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 7152
							output: 23
							thoughts: 364

Thoughts: 
**Analyzing the LRU Generation Patch**

Okay, so I'm looking at this patch related to LRU generation, specifically the `LRU_GEN` and `LRU_GEN_ENABLED` configs. My initial thought is to zero in on any particularly significant functions that have been touched. The patch has made changes to: `do_anonymous_page`, `finish_fault`, `remove_migration_pte`, `get_next_mm`, `try_to_inc_max_seq`, and `lru_gen_seq_write`.

Right away, `lru_gen_seq_write` is jumping out at me because that's directly related to the `/sys/kernel/debug/lru_gen` interface. Then there's `try_to_inc_max_seq` and `get_next_mm`, which are clearly part of the aging process. The other two, `do_anonymous_page` and `finish_fault`, are hot-path page fault handlers, and `remove_migration_pte` relates to memory migration.

Given the context, I believe the core logic of interest here is going to be in the aging process and the debug interface, so I'll concentrate on `try_to_inc_max_seq` and `lru_gen_seq_write`. I need to understand how the aging mechanism is being adjusted. Let me quickly check if `try_to_inc_max_seq` is static... yes, it is. Wait... Hold on! The instructions specify to "Prefer non-static, non-inlined API entrypoint functions over internal static helper functions". This throws a bit of a wrench in my focus. It seems I should be searching for callers of `try_to_inc_max_seq`, as that may shed light on the higher-level function.

6/2 2026/08/07 12:03 tool grepper
0m Args: 
{
  "Expression": "try_to_inc_max_seq"
}

Results: 
{
  "Output": "mm/vmscan.c=4029=static bool inc_max_seq(struct lruvec *lruvec, unsigned long seq, int swappiness)\n--\nmm/vmscan.c-4093-\nmm/vmscan.c:4094:static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long seq,\nmm/vmscan.c-4095-\t\t\t       int swappiness, bool force_scan)\n--\nmm/vmscan.c=4572=bool recheck_lru_gen_max_memcg(struct mem_cgroup *memcg, int nid)\n--\nmm/vmscan.c-4584-\nmm/vmscan.c:4585:static void try_to_inc_max_seq_nowalk(struct mem_cgroup *memcg,\nmm/vmscan.c-4586-\t\t\t\t      struct lruvec *lruvec)\n--\nmm/vmscan.c=4619=void max_lru_gen_memcg(struct mem_cgroup *memcg, int nid)\n--\nmm/vmscan.c-4625-\t\twhile (get_nr_gens(lruvec, type) \u003c MAX_NR_GENS) {\nmm/vmscan.c:4626:\t\t\ttry_to_inc_max_seq_nowalk(memcg, lruvec);\nmm/vmscan.c-4627-\t\t\tcond_resched();\n--\nmm/vmscan.c=5092=static bool should_abort_scan(struct lruvec *lruvec, struct scan_control *sc)\n--\nmm/vmscan.c-5123- * For future optimizations:\nmm/vmscan.c:5124: * 1. Defer try_to_inc_max_seq() to workqueues to reduce latency for memcg\nmm/vmscan.c-5125- *    reclaim.\n--\nmm/vmscan.c=5127=static bool try_to_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\n--\nmm/vmscan.c-5144-\t\tif (should_run_aging(lruvec, max_seq, sc, swappiness)) {\nmm/vmscan.c:5145:\t\t\tif (try_to_inc_max_seq(lruvec, max_seq, swappiness, false))\nmm/vmscan.c-5146-\t\t\t\tneed_rotate = true;\n--\nmm/vmscan.c=5743=static int run_aging(struct lruvec *lruvec, unsigned long seq,\n--\nmm/vmscan.c-5750-\nmm/vmscan.c:5751:\treturn try_to_inc_max_seq(lruvec, max_seq, swappiness, force_scan) ? 0 : -EEXIST;\nmm/vmscan.c-5752-}\n"
}
7/2 2026/08/07 12:03 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 8674
							output: 24
							thoughts: 117

Thoughts: 
**Tracing the Dependencies of `try_to_inc_max_seq`**

Okay, so I need to understand the call graph for `try_to_inc_max_seq`. Right, I remember that `try_to_shrink_lruvec` and `run_aging` both call it. I know `run_aging` is triggered by `lru_gen_seq_write`, so that's a downstream effect I need to keep in mind. Now, `try_to_shrink_lruvec` itself is called from `lru_gen_shrink_lruvec` and `lru_gen_shrink_node`.

Alright, it looks like `lru_gen_shrink_lruvec` and `lru_gen_shrink_node` are the two real sources of the `try_to_inc_max_seq` call path I need to examine more closely. Time to dig into those and see what's driving *them*. I need to understand the conditions under which the shrinkage logic is invoked, because that's what ultimately impacts the increment.

8/2 2026/08/07 12:03 tool grepper
0m Args: 
{
  "Expression": "lru_gen_shrink_lruvec"
}

Results: 
{
  "Output": "mm/vmscan.c=5213=static void shrink_many(struct pglist_data *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-5282-\nmm/vmscan.c:5283:static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\nmm/vmscan.c-5284-{\n--\nmm/vmscan.c=6046=static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-6050-\nmm/vmscan.c:6051:static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\nmm/vmscan.c-6052-{\n--\nmm/vmscan.c=6063=static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\n--\nmm/vmscan.c-6074-\tif ((lru_gen_enabled() || lru_gen_switching()) \u0026\u0026 !root_reclaim(sc)) {\nmm/vmscan.c:6075:\t\tlru_gen_shrink_lruvec(lruvec, sc);\nmm/vmscan.c-6076-\n"
}
9/2 2026/08/07 12:03 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 9405
							output: 22
							thoughts: 50

Thoughts: 
Okay, here's my take on those thoughts, framed as my own mental process, given my expertise:

**Examining Potential Focus Symbols in the Codebase**

Alright, I'm thinking about where to start digging into this particular area. *`shrink_lruvec`* feels like a solid starting point; it's likely a core component related to memory management within the LRU vector, which is a key structure. I'm imagining it's the function that orchestrates the actual shrinking operation.

But then, *`lru_gen_seq_write`* also jumps out at me as potentially crucial. The name implies that it's handling the generation of some sequence associated with write operations in the LRU context. That could be equally central to the overall behavior. So, let's keep an open mind about which is the most relevant starting point.

Before I go too deep, I want to confirm something about `lru_gen_seq_write`. I need to ascertain if this function is declared static. If it is, that'll limit its scope, which could significantly impact how easily I can understand and potentially refactor the code that calls it. Knowing its visibility is critical for understanding the overall design and control flow.

10/2 2026/08/07 12:03 tool grepper
0m Args: 
{
  "Expression": "lru_gen_seq_write"
}

Results: 
{
  "Output": "mm/vmscan.c=5784=static int run_cmd(char cmd, u64 memcg_id, int nid, unsigned long seq,\n--\nmm/vmscan.c-5825-/* see Documentation/admin-guide/mm/multigen_lru.rst for details */\nmm/vmscan.c:5826:static ssize_t lru_gen_seq_write(struct file *file, const char __user *src,\nmm/vmscan.c-5827-\t\t\t\t size_t len, loff_t *pos)\n--\nmm/vmscan.c=5934=static const struct file_operations lru_gen_rw_fops = {\n--\nmm/vmscan.c-5936-\t.read = seq_read,\nmm/vmscan.c:5937:\t.write = lru_gen_seq_write,\nmm/vmscan.c-5938-\t.llseek = seq_lseek,\n"
}
11/2 2026/08/07 12:04 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 9991
							output: 19
							thoughts: 101

Thoughts: 
**Analyzing the File Operation Write Handler**

Okay, so I'm looking at this `lru_gen_seq_write` function. It's marked as `static`, which is interesting, because it's being used within `lru_gen_rw_fops`. Ah, right, `lru_gen_seq_write` is a write handler for file operations, a likely entry point for examining how this particular system is writing data. However, the `static` declaration is throwing up a flag. If it's `static`, it might not be exported as a symbol, which makes debugging potentially harder. I need to be sure. Let me see if there are other functions declared `static` here. *Looks at `shrink_lruvec`*. Yup, `shrink_lruvec` is also `static`. I'll have to keep that in mind as I try to understand the flow here.

12/2 2026/08/07 12:04 tool grepper
0m Args: 
{
  "Expression": "shrink_lruvec"
}

Results: 
{
  "Output": "mm/vmscan.c=5092=static bool should_abort_scan(struct lruvec *lruvec, struct scan_control *sc)\n--\nmm/vmscan.c-5126- */\nmm/vmscan.c:5127:static bool try_to_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\nmm/vmscan.c-5128-{\n--\nmm/vmscan.c=5172=static int shrink_one(struct lruvec *lruvec, struct scan_control *sc)\n--\nmm/vmscan.c-5191-\nmm/vmscan.c:5192:\tneed_rotate = try_to_shrink_lruvec(lruvec, sc);\nmm/vmscan.c-5193-\n--\nmm/vmscan.c=5213=static void shrink_many(struct pglist_data *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-5282-\nmm/vmscan.c:5283:static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\nmm/vmscan.c-5284-{\n--\nmm/vmscan.c-5295-\nmm/vmscan.c:5296:\tif (try_to_shrink_lruvec(lruvec, sc))\nmm/vmscan.c-5297-\t\tlru_gen_rotate_memcg(lruvec, MEMCG_LRU_YOUNG);\n--\nmm/vmscan.c=6046=static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-6050-\nmm/vmscan.c:6051:static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\nmm/vmscan.c-6052-{\n--\nmm/vmscan.c=6056=static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-6062-\nmm/vmscan.c:6063:static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\nmm/vmscan.c-6064-{\n--\nmm/vmscan.c-6074-\tif ((lru_gen_enabled() || lru_gen_switching()) \u0026\u0026 !root_reclaim(sc)) {\nmm/vmscan.c:6075:\t\tlru_gen_shrink_lruvec(lruvec, sc);\nmm/vmscan.c-6076-\n--\nmm/vmscan.c=6254=static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-6313-\nmm/vmscan.c:6314:\t\tshrink_lruvec(lruvec, sc);\nmm/vmscan.c-6315-\n--\nmm/vmscan.c=6909=unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,\n--\nmm/vmscan.c-6939-\t */\nmm/vmscan.c:6940:\tshrink_lruvec(lruvec, \u0026sc);\nmm/vmscan.c-6941-\n"
}
13/2 2026/08/07 12:04 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 11208
							output: 22
							thoughts: 47

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

**Examining Memory Shrinkage Logic**

Alright, I'm diving into this memory management stuff. Let's see... I'm thinking about how the system handles shrinking memory within a cgroup context. Now, I see `shrink_node_memcgs` - that's a static function, right? Which means it's pretty well-defined in its behavior and scope. But that's not the primary function used to shrink the node, it would seem.

I also see `mem_cgroup_shrink_node`. This one isn't static, and that immediately piques my interest. It likely has more flexibility or a dynamic element to its implementation. Let's dig deeper into `mem_cgroup_shrink_node`. I need to understand its behavior and see how it interacts with the overall memory shrinking process. Time to check its implementation and determine if it's the right function to examine in depth.

14/2 2026/08/07 12:04 tool grepper
0m Args: 
{
  "Expression": "mem_cgroup_shrink_node"
}

Results: 
{
  "Output": "mm/internal.h=83=unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,\n--\nmm/internal.h-87-\t\t\t\t\t   int *swappiness);\nmm/internal.h:88:unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,\nmm/internal.h-89-\t\t\t\t     gfp_t gfp_mask, bool noswap,\n--\nmm/memcontrol-v1.c=273=static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,\n--\nmm/memcontrol-v1.c-312-\t\t}\nmm/memcontrol-v1.c:313:\t\ttotal += mem_cgroup_shrink_node(victim, gfp_mask, false,\nmm/memcontrol-v1.c-314-\t\t\t\t\tpgdat, \u0026nr_scanned);\n--\nmm/vmscan.c=6863=unsigned long try_to_free_pages(struct zonelist *zonelist, int order,\n--\nmm/vmscan.c-6908-/* Only used by soft limit reclaim. Do not reuse for anything else. */\nmm/vmscan.c:6909:unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,\nmm/vmscan.c-6910-\t\t\t\t\t\tgfp_t gfp_mask, bool noswap,\n"
}
15/2 2026/08/07 12:05 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 11859
							output: 21
							thoughts: 41

Thoughts: 
Okay, here's my take on those thoughts, framed as an expert's internal monologue:

**Investigating Memory Pressure and Page Reclamation**

Right, so we're seeing some kind of memory pressure, and my first instinct is to zero in on the core reclamation mechanisms. I'm thinking about the most direct page-reclaiming functions, especially those that would be called under stress. Specifically, I'm wondering if `try_to_free_pages` or potentially its memcg-aware counterpart, `try_to_free_mem_cgroup_pages`, are likely culprits. The difference between those two calls will tell me who is being throttled. Let's start with a deep dive into `try_to_free_pages`. I need to understand what its doing.

16/2 2026/08/07 12:05 tool grepper
0m Args: 
{
  "Expression": "try_to_free_pages"
}

Results: 
{
  "Output": "fs/fuse/file.c=2351=static void fuse_vma_close(struct vm_area_struct *vma)\n--\nfs/fuse/file.c-2371- * - sync(2)\nfs/fuse/file.c:2372: * - try_to_free_pages() with order \u003e PAGE_ALLOC_COSTLY_ORDER\nfs/fuse/file.c-2373- */\n--\nmm/internal.h=69=unsigned long zone_reclaimable_pages(struct zone *zone);\nmm/internal.h:70:unsigned long try_to_free_pages(struct zonelist *zonelist, int order,\nmm/internal.h-71-\t\t\t\tgfp_t gfp_mask, const nodemask_t *mask);\n--\nmm/page_alloc.c=4496=__perform_reclaim(gfp_t gfp_mask, unsigned int order,\n--\nmm/page_alloc.c-4508-\nmm/page_alloc.c:4509:\tprogress = try_to_free_pages(ac-\u003ezonelist, order, gfp_mask,\nmm/page_alloc.c-4510-\t\t\t\t\t\t\t\tac-\u003enodemask);\n--\nmm/vmscan.c=6610=static void snapshot_refaults(struct mem_cgroup *target_memcg, pg_data_t *pgdat)\n--\nmm/vmscan.c-6640- */\nmm/vmscan.c:6641:static unsigned long do_try_to_free_pages(struct zonelist *zonelist,\nmm/vmscan.c-6642-\t\t\t\t\t  struct scan_control *sc)\n--\nmm/vmscan.c=6783=static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,\n--\nmm/vmscan.c-6862-\nmm/vmscan.c:6863:unsigned long try_to_free_pages(struct zonelist *zonelist, int order,\nmm/vmscan.c-6864-\t\t\t\tgfp_t gfp_mask, const nodemask_t *nodemask)\n--\nmm/vmscan.c-6897-\nmm/vmscan.c:6898:\tnr_reclaimed = do_try_to_free_pages(zonelist, \u0026sc);\nmm/vmscan.c-6899-\n--\nmm/vmscan.c=6949=unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,\n--\nmm/vmscan.c-6980-\nmm/vmscan.c:6981:\tnr_reclaimed = do_try_to_free_pages(zonelist, \u0026sc);\nmm/vmscan.c-6982-\n--\nmm/vmscan.c=7747=unsigned long shrink_all_memory(unsigned long nr_to_reclaim)\n--\nmm/vmscan.c-7766-\nmm/vmscan.c:7767:\tnr_reclaimed = do_try_to_free_pages(zonelist, \u0026sc);\nmm/vmscan.c-7768-\n"
}
17/2 2026/08/07 12:05 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 12895
							output: 19
							thoughts: 43

Thoughts: 
Okay, here's my take on those thoughts, framed from my perspective as someone deeply familiar with this code:

**Checking Static Scope for Key Page Management Functions**

Right, so `try_to_free_pages` seems like a pretty significant symbol to focus on right now. It's obviously tied to memory management, which is always a critical area. And I see that `do_anonymous_page` and `finish_fault` have been modified too, which immediately draws my attention as they are vital for memory operations. I'm going to quickly check the scope of those functions, specifically, I need to know if they're declared as `static`. Knowing if they're static will tell me a lot about their intended use and potential impact. It helps me understand the modularity and what other functions could be interacting with these critical memory operations. It's the first step in understanding the changes and what implications those changes might have.

18/2 2026/08/07 12:05 tool grepper
0m Args: 
{
  "Expression": "do_anonymous_page"
}

Results: 
{
  "Output": "Documentation/admin-guide/mm/userfaultfd.rst=380=the range remain unpopulated; when first accessed they fault through the\nDocumentation/admin-guide/mm/userfaultfd.rst:381:normal missing path (``do_anonymous_page()``, ``do_swap_page()``,\nDocumentation/admin-guide/mm/userfaultfd.rst-382-``finish_fault()``) and the resulting PTE is not RWP-protected. To observe\n--\narch/sparc/lib/clear_page.S=32=_clear_page:\t\t/* %o0=dest */\n--\narch/sparc/lib/clear_page.S-36-\t/* This thing is pretty important, it shows up\narch/sparc/lib/clear_page.S:37:\t * on the profiles via do_anonymous_page().\narch/sparc/lib/clear_page.S-38-\t */\n--\nmm/memory.c=97=static vm_fault_t do_fault(struct vm_fault *vmf);\nmm/memory.c:98:static vm_fault_t do_anonymous_page(struct vm_fault *vmf);\nmm/memory.c-99-static bool vmf_pte_changed(struct vm_fault *vmf);\n--\nmm/memory.c=3648=int apply_to_existing_page_range(struct mm_struct *mm, unsigned long addr,\n--\nmm/memory.c-3659- * proceeding (but do_wp_page is only called after already making such a check;\nmm/memory.c:3660: * and do_anonymous_page can safely check later on).\nmm/memory.c-3661- */\n--\nmm/memory.c=4691=static vm_fault_t do_pte_missing(struct vm_fault *vmf)\n--\nmm/memory.c-4693-\tif (vma_is_anonymous(vmf-\u003evma))\nmm/memory.c:4694:\t\treturn do_anonymous_page(vmf);\nmm/memory.c-4695-\telse\n--\nmm/memory.c=5408=static void map_anon_folio_pte_pf(struct folio *folio, pte_t *pte,\n--\nmm/memory.c-5423- */\nmm/memory.c:5424:static vm_fault_t do_anonymous_page(struct vm_fault *vmf)\nmm/memory.c-5425-{\n--\nmm/migrate_device.c=955=static unsigned long migrate_vma_nr_pages(unsigned long *src)\n--\nmm/migrate_device.c-971- *     handle_pte_fault()\nmm/migrate_device.c:972: *       do_anonymous_page()\nmm/migrate_device.c-973- * to map in an anonymous zero page but the struct page will be a ZONE_DEVICE\n"
}
19/2 2026/08/07 12:05 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 13885
							output: 17
							thoughts: 20

Thoughts: 
Here's my understanding, as if these were my own thoughts:

**Static vs. Dynamic in the System**

Okay, so I'm looking at this code, and it's pretty clear that `do_anonymous_page` is defined as *static*. That implies a certain immutability, a fixed scope likely internal to its compilation unit. Contrast that with `finish_fault`. That one is *not* static, so it's probably got a broader visibility, and its behavior could potentially be more dynamic, influenced by things outside its immediate scope. This is important to keep in mind for memory management.

20/2 2026/08/07 12:05 tool grepper
0m Args: 
{
  "Expression": "finish_fault"
}

Results: 
{
  "Output": "Documentation/admin-guide/mm/userfaultfd.rst=381=normal missing path (``do_anonymous_page()``, ``do_swap_page()``,\nDocumentation/admin-guide/mm/userfaultfd.rst:382:``finish_fault()``) and the resulting PTE is not RWP-protected. To observe\nDocumentation/admin-guide/mm/userfaultfd.rst-383-the population itself, co-register the range with\n--\nfs/dax.c=1803=static vm_fault_t dax_fault_cow_page(struct vm_fault *vmf,\n--\nfs/dax.c-1826-\t__SetPageUptodate(vmf-\u003ecow_page);\nfs/dax.c:1827:\tret = finish_fault(vmf);\nfs/dax.c-1828-\tif (!ret)\n--\ninclude/linux/mm.h=2039=void set_pte_range(struct vm_fault *vmf, struct folio *folio,\n--\ninclude/linux/mm.h-2041-\ninclude/linux/mm.h:2042:vm_fault_t finish_fault(struct vm_fault *vmf);\ninclude/linux/mm.h-2043-#endif\n--\nlib/vdso/datastore.c=32=void __init vdso_setup_data_pages(void)\n--\nlib/vdso/datastore.c-42-\t * Do not use folios. In time namespaces the pages are mapped in a different order\nlib/vdso/datastore.c:43:\t * to userspace, which is not handled by the folio optimizations in finish_fault().\nlib/vdso/datastore.c-44-\t */\n--\nmm/memory.c=5734=static bool vmf_pte_changed(struct vm_fault *vmf)\n--\nmm/memory.c-5742-/**\nmm/memory.c:5743: * finish_fault - finish page fault once we have prepared the page to fault\nmm/memory.c-5744- *\n--\nmm/memory.c-5756- */\nmm/memory.c:5757:vm_fault_t finish_fault(struct vm_fault *vmf)\nmm/memory.c-5758-{\n--\nmm/memory.c=5984=static vm_fault_t do_read_fault(struct vm_fault *vmf)\n--\nmm/memory.c-6007-\nmm/memory.c:6008:\tret |= finish_fault(vmf);\nmm/memory.c-6009-\tfolio = page_folio(vmf-\u003epage);\n--\nmm/memory.c=6016=static vm_fault_t do_cow_fault(struct vm_fault *vmf)\n--\nmm/memory.c-6045-\nmm/memory.c:6046:\tret |= finish_fault(vmf);\nmm/memory.c-6047-unlock:\n--\nmm/memory.c=6058=static vm_fault_t do_shared_fault(struct vm_fault *vmf)\n--\nmm/memory.c-6087-\nmm/memory.c:6088:\tret |= finish_fault(vmf);\nmm/memory.c-6089-\tif (unlikely(ret \u0026 (VM_FAULT_ERROR | VM_FAULT_NOPAGE |\n"
}
21/2 2026/08/07 12:05 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 14919
							output: 20
							thoughts: 40

Thoughts: 
Okay, here's my interpretation of those thoughts, tailored for an expert audience, presented in the first person:

**Symbol Focus and Potential Optimization**

Right, `finish_fault` seems like a solid, well-defined focus symbol. Makes sense. But my mind is already jumping to potential optimizations. What about `remove_migration_pte`? That one's got a static qualifier, which usually implies something specific about its use. I should check that one out. Let's dig deeper into `remove_migration_ptes` to be sure. It feels like a place where inefficiencies might be lurking.

22/2 2026/08/07 12:05 tool grepper
0m Args: 
{
  "Expression": "remove_migration_ptes"
}

Results: 
{
  "Output": "include/linux/rmap.h=936=int pfn_mkclean_range(unsigned long pfn, unsigned long nr_pages, pgoff_t pgoff,\n--\ninclude/linux/rmap.h-938-\ninclude/linux/rmap.h:939:void remove_migration_ptes(struct folio *src, struct folio *dst,\ninclude/linux/rmap.h-940-\t\tenum ttu_flags flags);\n--\nmm/huge_memory.c=3589=static void remap_page(struct folio *folio, unsigned long nr, int flags)\n--\nmm/huge_memory.c-3596-\tfor (;;) {\nmm/huge_memory.c:3597:\t\tremove_migration_ptes(folio, folio, TTU_RMAP_LOCKED | flags);\nmm/huge_memory.c-3598-\t\ti += folio_nr_pages(folio);\n--\nmm/migrate.c=351=static bool remove_migration_pte(struct folio *folio,\n--\nmm/migrate.c-472- */\nmm/migrate.c:473:void remove_migration_ptes(struct folio *src, struct folio *dst,\nmm/migrate.c-474-\t\tenum ttu_flags flags)\n--\nmm/migrate.c=1179=static void migrate_folio_undo_src(struct folio *src, int was_mapped,\n--\nmm/migrate.c-1182-\tif (was_mapped)\nmm/migrate.c:1183:\t\tremove_migration_ptes(src, src, 0);\nmm/migrate.c-1184-\t/* Drop an anon_vma reference if we took one */\n--\nmm/migrate.c=1369=static int migrate_folio_move(free_folio_t put_new_folio, unsigned long private,\n--\nmm/migrate.c-1412-\t * When successful, push dst to LRU immediately: so that if it\nmm/migrate.c:1413:\t * turns out to be an mlocked page, remove_migration_ptes() will\nmm/migrate.c-1414-\t * automatically build up the correct dst-\u003emlock_count for it.\n--\nmm/migrate.c-1424-\tif (old_folio_state \u0026 FOLIO_WAS_MAPPED)\nmm/migrate.c:1425:\t\tremove_migration_ptes(src, dst, 0);\nmm/migrate.c-1426-\n--\nmm/migrate.c=1486=static int unmap_and_move_hugetlb_folio(new_folio_t get_new_folio,\n--\nmm/migrate.c-1558-\tif (was_mapped)\nmm/migrate.c:1559:\t\tremove_migration_ptes(src, !rc ? dst : src, ttu);\nmm/migrate.c-1560-\n--\nmm/migrate_device.c=571=static unsigned long migrate_device_unmap(unsigned long *src_pfns,\n--\nmm/migrate_device.c-646-\t\tfolio = page_folio(page);\nmm/migrate_device.c:647:\t\tremove_migration_ptes(folio, folio, 0);\nmm/migrate_device.c-648-\n--\nmm/migrate_device.c=1292=static void __migrate_device_finalize(unsigned long *src_pfns,\n--\nmm/migrate_device.c-1330-\t\t\tfolio_add_lru(dst);\nmm/migrate_device.c:1331:\t\tremove_migration_ptes(src, dst, 0);\nmm/migrate_device.c-1332-\t\tif (fault_folio != src)\n--\nmm/rmap.c=2975=static struct anon_vma *rmap_walk_anon_lock(const struct folio *folio,\n--\nmm/rmap.c-2983-\t/*\nmm/rmap.c:2984:\t * Note: remove_migration_ptes() cannot use folio_lock_anon_vma_read()\nmm/rmap.c-2985-\t * because that depends on folio_mapped(); but not all its usages\n"
}
23/2 2026/08/07 12:05 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 16166
							output: 26
							thoughts: 376

Thoughts: 
**Focusing on Memory Management**

Okay, so I'm trying to nail down a good focus symbol for this memory management investigation. `remove_migration_ptes` seems like a good starting point, let's keep that in mind. Now, let's explore related functions. I was initially drawn to `lru_gen_seq_write`, but it's static and I can't directly use that as a focus point. Wait, I see, this is called through VFS write, so I could use `sys_write` or some other similar function, but that's going to be too broad.

Let's see, what about `lru_gen_shrink_lruvec` and then just `shrink_lruvec`? Both are also static. Let me see what other non-static functions are here. Hmm, `mem_cgroup_shrink_node`, `try_to_free_pages`, `try_to_free_mem_cgroup_pages`, `shrink_all_memory`, `finish_fault`, and also `remove_migration_ptes` are all non-static.

Now, let's make sure the configuration is correct. `LRU_GEN` is the key configuration option. I need to make sure there aren't any other related configurations. The patch modifies `mm/vmscan.c`, `mm/memory.c`, and `mm/migrate.c`, so that should be a good indicator. Looking at `mm/memory.c`, there's this `lru_gen_mm_accessed` function that seems interesting. It's defined within a `CONFIG_LRU_GEN_WALKS_MMU` conditional and I see it's actually defined in `include/linux/mm_types.h`.

24/2 2026/08/07 12:05 tool grepper
0m Args: 
{
  "Expression": "CONFIG_LRU_GEN_WALKS_MMU"
}

Results: 
{
  "Output": "include/linux/memcontrol.h=202=struct mem_cgroup {\n--\ninclude/linux/memcontrol.h-278-\ninclude/linux/memcontrol.h:279:#ifdef CONFIG_LRU_GEN_WALKS_MMU\ninclude/linux/memcontrol.h-280-\t/* per-memcg mm_struct list */\n--\ninclude/linux/mm_types.h=1175=struct mm_struct {\n--\ninclude/linux/mm_types.h-1402-#endif /* CONFIG_KSM */\ninclude/linux/mm_types.h:1403:#ifdef CONFIG_LRU_GEN_WALKS_MMU\ninclude/linux/mm_types.h-1404-\t\tstruct {\n--\ninclude/linux/mm_types.h-1428-\t\t} lru_gen;\ninclude/linux/mm_types.h:1429:#endif /* CONFIG_LRU_GEN_WALKS_MMU */\ninclude/linux/mm_types.h-1430-#ifdef CONFIG_MM_ID\n--\ninclude/linux/mm_types.h=1498=struct lru_gen_mm_list {\n--\ninclude/linux/mm_types.h-1506-\ninclude/linux/mm_types.h:1507:#ifdef CONFIG_LRU_GEN_WALKS_MMU\ninclude/linux/mm_types.h-1508-\n--\ninclude/linux/mm_types.h=1540=static inline void lru_gen_mm_accessed(struct mm_struct *mm, int nid)\n--\ninclude/linux/mm_types.h-1547-\ninclude/linux/mm_types.h:1548:#else /* !CONFIG_LRU_GEN_WALKS_MMU */\ninclude/linux/mm_types.h-1549-\n--\ninclude/linux/mm_types.h=1570=static inline void lru_gen_mm_accessed(struct mm_struct *mm, int nid)\n--\ninclude/linux/mm_types.h-1573-\ninclude/linux/mm_types.h:1574:#endif /* CONFIG_LRU_GEN_WALKS_MMU */\ninclude/linux/mm_types.h-1575-\n--\ninclude/linux/mmzone.h=770=struct lruvec {\n--\ninclude/linux/mmzone.h-792-\tstruct lru_gen_folio\t\tlrugen;\ninclude/linux/mmzone.h:793:#ifdef CONFIG_LRU_GEN_WALKS_MMU\ninclude/linux/mmzone.h-794-\t/* to concurrently iterate lru_gen_mm_list */\n--\nkernel/fork.c=2694=pid_t kernel_clone(struct kernel_clone_args *args)\n--\nkernel/fork.c-2771-\nkernel/fork.c:2772:\tif (IS_ENABLED(CONFIG_LRU_GEN_WALKS_MMU) \u0026\u0026 !(clone_flags \u0026 CLONE_VM)) {\nkernel/fork.c-2773-\t\t/* lock the task to synchronize with memcg migration */\n--\nmm/vmscan.c=2879=static void reset_bloom_filter(struct lru_gen_mm_state *mm_state, unsigned long seq)\n--\nmm/vmscan.c-2898-\nmm/vmscan.c:2899:#ifdef CONFIG_LRU_GEN_WALKS_MMU\nmm/vmscan.c-2900-\n--\nmm/vmscan.c=3029=void lru_gen_migrate_mm(struct mm_struct *mm)\n--\nmm/vmscan.c-3057-\nmm/vmscan.c:3058:#else /* !CONFIG_LRU_GEN_WALKS_MMU */\nmm/vmscan.c-3059-\n"
}
25/2 2026/08/07 12:05 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 17930
							output: 25
							thoughts: 64

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

**Diving into LRU Generation Configuration**

Right, so `CONFIG_LRU_GEN_WALKS_MMU` is the key. I know this config is the gateway to the `lru_gen_mm_accessed` function and those `empty_map` fields. It's the lynchpin, essentially, for enabling the LRU generation walks that need to access the MMU. Before I go further down that rabbit hole though, I should really check the source of this config. Let's head over to `mm/Kconfig` to confirm what this does, and what dependencies it has. That'll be the starting point, since I'll need to know the preconditions of this feature before I can start delving into the code and its impact.

26/2 2026/08/07 12:05 tool grepper
0m Args: 
{
  "Expression": "config LRU_GEN_WALKS_MMU"
}

Results: 
{
  "Output": "mm/Kconfig=1418=config LRU_GEN_STATS\n--\nmm/Kconfig-1426-\nmm/Kconfig:1427:config LRU_GEN_WALKS_MMU\nmm/Kconfig-1428-\tdef_bool y\n"
}
27/2 2026/08/07 12:05 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 18282
							output: 19
							thoughts: 18

Thoughts: 
Okay, here's my interpretation of that thought process, tailored for an expert audience, and presented as if it were my own internal monologue:

**My Deductions on `def_bool y`**

Alright, let's break this down. The core issue is `def_bool y`. This looks like a boolean definition, likely related to some kind of configuration or control flow within this system. The real kicker is the dependency on `LRU_GEN`. This immediately flags a key area: we're dealing with something probably related to Least Recently Used (LRU) cache generation or management. `y` is *conditionally* defined based on the state of `LRU_GEN`. My immediate questions are: What is the nature of `y`? Is it an enable/disable flag? A threshold value? What does its specific value actually *mean* in this context? Understanding `LRU_GEN` is paramount here. I need to know the possible states or values of `LRU_GEN`, and how those map to the definition (or lack thereof) of `y`. The impact here is that `y` is not unconditionally active or present, so it may need to be accounted for, to ensure that the logic that is implemented as a result functions correctly. From this thought, I will have to look at the surrounding code to determine how `LRU_GEN` affects the execution of the code. Is `y` being used for optimization, resource allocation, or something more fundamental to the LRU algorithm's behavior? The answer to that will determine how critical the handling of `y` really is.

28/2 2026/08/07 12:05 tool grepper
0m Args: 
{
  "Expression": "config LRU_GEN"
}

Results: 
{
  "Output": "mm/Kconfig=1392=config PTE_MARKER_UFFD_WP\n--\nmm/Kconfig-1402-# multi-gen LRU {\nmm/Kconfig:1403:config LRU_GEN\nmm/Kconfig-1404-\tbool \"Multi-Gen LRU\"\n--\nmm/Kconfig-1411-\nmm/Kconfig:1412:config LRU_GEN_ENABLED\nmm/Kconfig-1413-\tbool \"Enable by default\"\n--\nmm/Kconfig-1417-\nmm/Kconfig:1418:config LRU_GEN_STATS\nmm/Kconfig-1419-\tbool \"Full stats for debugging\"\n--\nmm/Kconfig-1426-\nmm/Kconfig:1427:config LRU_GEN_WALKS_MMU\nmm/Kconfig-1428-\tdef_bool y\n"
}
29/2 2026/08/07 12:05 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 18893
							output: 33
							thoughts: 13

Thoughts: 
Here's my take on the dependencies of `LRU_GEN`:

**Analyzing Dependencies for `LRU_GEN`**

Okay, so `LRU_GEN`. Time to dive in and understand its ecosystem. First, I need to get a clear picture of what this thing relies on. I'm thinking I'll need to trace its connections to other components, both internally and externally. Are there specific libraries it utilizes? Are there shared data structures, or perhaps external APIs it interfaces with? Understanding these dependencies is crucial for any kind of performance tuning, debugging, or even just general maintenance. I'll need to consider how changes in those dependencies might impact `LRU_GEN` itself. I need to know where I might encounter cascading effects. So, let's start mapping out this dependency graph, visualizing the relationships, and identifying any potential bottlenecks or areas of concern. This is the foundation upon which any effective analysis will be built.

30/2 2026/08/07 12:05 tool read-file
0m Args: 
{
  "File": "mm/Kconfig",
  "FirstLine": 1400,
  "LineCount": 30
}

Results: 
{
  "Contents": "1400:\t\t  file-backed memory types like shmem and hugetlbfs.\n1401:\t\n1402:\t# multi-gen LRU {\n1403:\tconfig LRU_GEN\n1404:\t\tbool \"Multi-Gen LRU\"\n1405:\t\tdepends on MMU\n1406:\t\t# make sure folio-\u003eflags has enough spare bits\n1407:\t\tdepends on 64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP\n1408:\t\thelp\n1409:\t\t  A high performance LRU implementation to overcommit memory. See\n1410:\t\t  Documentation/admin-guide/mm/multigen_lru.rst for details.\n1411:\t\n1412:\tconfig LRU_GEN_ENABLED\n1413:\t\tbool \"Enable by default\"\n1414:\t\tdepends on LRU_GEN\n1415:\t\thelp\n1416:\t\t  This option enables the multi-gen LRU by default.\n1417:\t\n1418:\tconfig LRU_GEN_STATS\n1419:\t\tbool \"Full stats for debugging\"\n1420:\t\tdepends on LRU_GEN\n1421:\t\thelp\n1422:\t\t  Do not enable this option unless you plan to look at historical stats\n1423:\t\t  from evicted generations for debugging purpose.\n1424:\t\n1425:\t\t  This option has a per-memcg and per-node memory overhead.\n1426:\t\n1427:\tconfig LRU_GEN_WALKS_MMU\n1428:\t\tdef_bool y\n1429:\t\tdepends on LRU_GEN \u0026\u0026 ARCH_HAS_HW_PTE_YOUNG\n"
}
31/2 2026/08/07 12:05 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 19585
							output: 21
							thoughts: 502

Thoughts: 
**MGLRU Focus Symbol Selection**

Okay, so I need to figure out the right focus symbols for this MGLRU analysis. First, I need to confirm the configuration requirements. Looks like `LRU_GEN` and `LRU_GEN_ENABLED` are the key configs, with `LRU_GEN_WALKS_MMU` depending on those plus `ARCH_HAS_HW_PTE_YOUNG`. Thankfully, `ARCH_HAS_HW_PTE_YOUNG` is typically enabled on x86_64, so I'm good there.

Now, let's think about good focus symbols. The instructions explicitly warn against using hot-path functions to avoid skewed test distributions. My first thought was `finish_fault`, since that's a common page fault function, but that's a definite no-go. The same goes for `do_anonymous_page`, also a hot path.

Alright, what else? `remove_migration_ptes` seems somewhat reasonable; it's related to page migration, which isn't a *generic* hot path, though it can still be relatively common. What about functions related to memory pressure or reclaim? `try_to_free_pages`, `mem_cgroup_shrink_node`, and `shrink_all_memory` are all options, but they might be too specific to certain scenarios.

Then I considered `lru_gen_seq_write`, the debugfs write handler. However, it's static, which is a problem. The instructions say to prefer non-static, non-inlined entry points. I checked and `lru_gen_seq_write` is a function pointer in `lru_gen_rw_fops`, so it's *not* inlined. Still, it's static, so it's out.

The issue then is to look for non-static functions specific to MGLRU. Time to go through `mm/vmscan.c` and hunt for exported or non-static functions related to MGLRU that might fit the bill.

32/2 2026/08/07 12:06 tool grepper
0m Args: 
{
  "Expression": "^void lru_gen_"
}

Results: 
{
  "Output": "include/linux/mm_types.h=1498=struct lru_gen_mm_list {\n--\ninclude/linux/mm_types.h-1508-\ninclude/linux/mm_types.h:1509:void lru_gen_add_mm(struct mm_struct *mm);\ninclude/linux/mm_types.h:1510:void lru_gen_del_mm(struct mm_struct *mm);\ninclude/linux/mm_types.h:1511:void lru_gen_migrate_mm(struct mm_struct *mm);\ninclude/linux/mm_types.h-1512-\n--\ninclude/linux/mmzone.h=683=struct lru_gen_memcg {\n--\ninclude/linux/mmzone.h-693-\ninclude/linux/mmzone.h:694:void lru_gen_init_pgdat(struct pglist_data *pgdat);\ninclude/linux/mmzone.h:695:void lru_gen_init_lruvec(struct lruvec *lruvec);\ninclude/linux/mmzone.h-696-bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw, unsigned int nr);\ninclude/linux/mmzone.h-697-\ninclude/linux/mmzone.h:698:void lru_gen_init_memcg(struct mem_cgroup *memcg);\ninclude/linux/mmzone.h:699:void lru_gen_exit_memcg(struct mem_cgroup *memcg);\ninclude/linux/mmzone.h:700:void lru_gen_online_memcg(struct mem_cgroup *memcg);\ninclude/linux/mmzone.h:701:void lru_gen_offline_memcg(struct mem_cgroup *memcg);\ninclude/linux/mmzone.h:702:void lru_gen_release_memcg(struct mem_cgroup *memcg);\ninclude/linux/mmzone.h:703:void lru_gen_soft_reclaim(struct mem_cgroup *memcg, int nid);\ninclude/linux/mmzone.h-704-void max_lru_gen_memcg(struct mem_cgroup *memcg, int nid);\ninclude/linux/mmzone.h=705=bool recheck_lru_gen_max_memcg(struct mem_cgroup *memcg, int nid);\ninclude/linux/mmzone.h:706:void lru_gen_reparent_memcg(struct mem_cgroup *memcg, struct mem_cgroup *parent, int nid);\ninclude/linux/mmzone.h-707-\n--\ninclude/linux/mmzone.h=757=static inline\ninclude/linux/mmzone.h:758:void lru_gen_reparent_memcg(struct mem_cgroup *memcg, struct mem_cgroup *parent, int nid)\ninclude/linux/mmzone.h-759-{\n--\nmm/vmscan.c=2925=static struct mm_struct *get_next_mm(struct lru_gen_mm_walk *walk)\n--\nmm/vmscan.c-2961-\nmm/vmscan.c:2962:void lru_gen_add_mm(struct mm_struct *mm)\nmm/vmscan.c-2963-{\n--\nmm/vmscan.c-2988-\nmm/vmscan.c:2989:void lru_gen_del_mm(struct mm_struct *mm)\nmm/vmscan.c-2990-{\n--\nmm/vmscan.c-3028-#ifdef CONFIG_MEMCG\nmm/vmscan.c:3029:void lru_gen_migrate_mm(struct mm_struct *mm)\nmm/vmscan.c-3030-{\n--\nmm/vmscan.c=4453=static void lru_gen_rotate_memcg(struct lruvec *lruvec, int op)\n--\nmm/vmscan.c-4500-\nmm/vmscan.c:4501:void lru_gen_online_memcg(struct mem_cgroup *memcg)\nmm/vmscan.c-4502-{\n--\nmm/vmscan.c-4525-\nmm/vmscan.c:4526:void lru_gen_offline_memcg(struct mem_cgroup *memcg)\nmm/vmscan.c-4527-{\n--\nmm/vmscan.c-4536-\nmm/vmscan.c:4537:void lru_gen_release_memcg(struct mem_cgroup *memcg)\nmm/vmscan.c-4538-{\n--\nmm/vmscan.c-4562-\nmm/vmscan.c:4563:void lru_gen_soft_reclaim(struct mem_cgroup *memcg, int nid)\nmm/vmscan.c-4564-{\n--\nmm/vmscan.c=4660=static void __lru_gen_reparent_memcg(struct lruvec *child_lruvec, struct lruvec *parent_lruvec,\n--\nmm/vmscan.c-4690-\nmm/vmscan.c:4691:void lru_gen_reparent_memcg(struct mem_cgroup *memcg, struct mem_cgroup *parent, int nid)\nmm/vmscan.c-4692-{\n--\nmm/vmscan.c=5942=static const struct file_operations lru_gen_ro_fops = {\n--\nmm/vmscan.c-5952-\nmm/vmscan.c:5953:void lru_gen_init_pgdat(struct pglist_data *pgdat)\nmm/vmscan.c-5954-{\n--\nmm/vmscan.c-5964-\nmm/vmscan.c:5965:void lru_gen_init_lruvec(struct lruvec *lruvec)\nmm/vmscan.c-5966-{\n--\nmm/vmscan.c-5986-\nmm/vmscan.c:5987:void lru_gen_init_memcg(struct mem_cgroup *memcg)\nmm/vmscan.c-5988-{\n--\nmm/vmscan.c-5997-\nmm/vmscan.c:5998:void lru_gen_exit_memcg(struct mem_cgroup *memcg)\nmm/vmscan.c-5999-{\n--\ntools/testing/selftests/kvm/include/lru_gen_util.h=37=struct memcg_stats {\n--\ntools/testing/selftests/kvm/include/lru_gen_util.h-42-\ntools/testing/selftests/kvm/include/lru_gen_util.h:43:void lru_gen_read_memcg_stats(struct memcg_stats *stats, const char *memcg);\ntools/testing/selftests/kvm/include/lru_gen_util.h-44-long lru_gen_sum_memcg_stats(const struct memcg_stats *stats);\ntools/testing/selftests/kvm/include/lru_gen_util.h=45=long lru_gen_sum_memcg_stats_for_gen(int gen, const struct memcg_stats *stats);\ntools/testing/selftests/kvm/include/lru_gen_util.h:46:void lru_gen_do_aging(struct memcg_stats *stats, const char *memcg);\ntools/testing/selftests/kvm/include/lru_gen_util.h-47-int lru_gen_find_generation(const struct memcg_stats *stats,\n--\ntools/testing/selftests/kvm/lib/lru_gen_util.c=181=static void print_memcg_stats(const struct memcg_stats *stats, const char *name)\n--\ntools/testing/selftests/kvm/lib/lru_gen_util.c-200-/* Re-read lru_gen debugfs information for @memcg into @stats. */\ntools/testing/selftests/kvm/lib/lru_gen_util.c:201:void lru_gen_read_memcg_stats(struct memcg_stats *stats, const char *memcg)\ntools/testing/selftests/kvm/lib/lru_gen_util.c-202-{\n--\ntools/testing/selftests/kvm/lib/lru_gen_util.c=282=static void run_aging_impl(unsigned long memcg_id, int node_id, int max_gen)\n--\ntools/testing/selftests/kvm/lib/lru_gen_util.c-301-\ntools/testing/selftests/kvm/lib/lru_gen_util.c:302:void lru_gen_do_aging(struct memcg_stats *stats, const char *memcg)\ntools/testing/selftests/kvm/lib/lru_gen_util.c-303-{\n"
}
33/2 2026/08/07 12:06 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 22871
							output: 26
							thoughts: 590

Thoughts: 
**My Analysis of LRU Generation and Related Code Paths**

Okay, let's break this down. My initial observation is that `lru_gen_look_around` is non-static, which is a key point. However, `shrink_lruvec` is static, which is a point of divergence. This makes me immediately think of other related functions, to see how they connect, and what the key focus symbols are.

I see that `try_to_free_pages` is non-static, and it calls a whole chain: `do_try_to_free_pages` -> `shrink_node` -> `shrink_node_memcgs` -> `shrink_lruvec` -> `lru_gen_shrink_lruvec` -> `try_to_shrink_lruvec` -> `try_to_inc_max_seq`. So, `try_to_free_pages` looks like a strong candidate for further inspection. It's a key entry point in the reclaim process.

Then, there's `mem_cgroup_shrink_node`, also non-static, which calls `shrink_lruvec`. This is another potential area of interest. Next, `remove_migration_ptes` is non-static and calls `remove_migration_pte`, which then calls `lru_gen_mm_accessed`. Finally, `finish_fault` is also non-static and calls `lru_gen_mm_accessed`.

Hold on a second, `finish_fault` is a *hot path*! That's a critical point. `remove_migration_ptes` on the other hand, is used during migration, so it's not a generic hot path.

Now, I need to evaluate if `try_to_free_pages` is also a hot path. The text explicitly says this is the *direct reclaim path*, which is only invoked under memory pressure. So, that's not a general hot path (like a page fault), so I can focus on it in the context of memory pressure.

Now, let's explore if any other configuration options are at play.

Looking at the code, the patch modifies `mm/vmscan.c` and `mm/memory.c`. In `mm/vmscan.c`, there's a setting:
```c
static unsigned long mglru_empty_skip_gens __read_mostly = 4;
```

This value, `mglru_empty_skip_gens`, can be adjusted via `/sys/kernel/debug/lru_gen` using `skip_empty <N>`. That's only accessible if `CONFIG_DEBUG_FS` is enabled, but the core logic is always active, with a default value of 4.

The core logic is clearly under `CONFIG_LRU_GEN` and `CONFIG_LRU_GEN_WALKS_MMU`. `CONFIG_LRU_GEN_WALKS_MMU` is a default setting (`def_bool y`) and depends on `LRU_GEN && ARCH_HAS_HW_PTE_YOUNG`. That means I just need to make sure that `LRU_GEN` and `LRU_GEN_ENABLED` are set.

34/2 2026/08/07 12:06 tool grepper
0m Args: 
{
  "Expression": "config ARCH_HAS_HW_PTE_YOUNG"
}

Results: 
{
  "Output": "arch/Kconfig=1774=config HAVE_ARCH_NODE_DEV_GROUP\n--\narch/Kconfig-1776-\narch/Kconfig:1777:config ARCH_HAS_HW_PTE_YOUNG\narch/Kconfig-1778-\tbool\n"
}
35/2 2026/08/07 12:06 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 24269
							output: 22
							thoughts: 1280

Thoughts: 
**MGLRU Patch Analysis: Focus Points and Fuzzing Strategy**

Okay, so I've been digging into this MGLRU patch, and here's the breakdown of my thoughts.  It seems the architecture leverages `ARCH_HAS_HW_PTE_YOUNG` and the `LRU_GEN` and `LRU_GEN_ENABLED` configs, specifically on x86, to achieve its goals.

My immediate goal here is to identify good entry points for fuzzing this new functionality. The code adds a new inline function `lru_gen_mm_accessed`, and I traced its call path. It seems like the core logic revolves around `lru_gen_mm_accessed` being invoked, which then links to `try_to_free_pages`, `remove_migration_ptes`, and `mem_cgroup_shrink_node`.

Initially, I considered `lru_gen_seq_write`, because a fuzzer like syzkaller could easily trigger it through a file operation. However, the documentation emphasized preferring non-static, non-inlined entry points. Though `lru_gen_seq_write` is *not* inlined and is present in the symbol table, it is a file operation, which means a certain type of interaction to trigger.

Therefore, I went to check `try_to_free_pages`, `remove_migration_ptes`, and `mem_cgroup_shrink_node`, since those are core memory management functions. They all appeared to be non-static, and thus, good candidates. The call graphs are: `remove_migration_ptes` called from `remove_migration_ptes`, and then from `finish_fault`. And `try_to_free_pages` gets called from multiple functions in memory management. Then `mem_cgroup_shrink_node` is another.

So, I will focus on `try_to_free_pages`, `remove_migration_ptes`, and `mem_cgroup_shrink_node`.

But wait. `mem_cgroup_shrink_node` is only available if `CONFIG_MEMCG` is enabled! Therefore, this target is not always present.

Beyond the call paths, I checked what other changes occur. I saw that the patch modifies some enums and adds a trace event, which reinforces that it has significant functional changes to core memory management. The suppression of empty walks across nodes is interesting, as that may influence performance. So fuzzing is definitely warranted here.

Therefore, the key configurations to focus on are:
*   `LRU_GEN`
*   `LRU_GEN_ENABLED`

And the primary fuzzing entry points are:
*   `try_to_free_pages`
*   `remove_migration_ptes`
*   `mem_cgroup_shrink_node` (conditionally enabled by `CONFIG_MEMCG`)

36/2 2026/08/07 12:06 tool grepper
0m Args: 
{
  "Expression": "mem_cgroup_shrink_node"
}

Results: 
{
  "Output": "mm/internal.h=83=unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,\n--\nmm/internal.h-87-\t\t\t\t\t   int *swappiness);\nmm/internal.h:88:unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,\nmm/internal.h-89-\t\t\t\t     gfp_t gfp_mask, bool noswap,\n--\nmm/memcontrol-v1.c=273=static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,\n--\nmm/memcontrol-v1.c-312-\t\t}\nmm/memcontrol-v1.c:313:\t\ttotal += mem_cgroup_shrink_node(victim, gfp_mask, false,\nmm/memcontrol-v1.c-314-\t\t\t\t\tpgdat, \u0026nr_scanned);\n--\nmm/vmscan.c=6863=unsigned long try_to_free_pages(struct zonelist *zonelist, int order,\n--\nmm/vmscan.c-6908-/* Only used by soft limit reclaim. Do not reuse for anything else. */\nmm/vmscan.c:6909:unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,\nmm/vmscan.c-6910-\t\t\t\t\t\tgfp_t gfp_mask, bool noswap,\n"
}
37/2 2026/08/07 12:06 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 26561
							output: 20
							thoughts: 46

Thoughts: 
Okay, here's my take on those thoughts, framed as an expert's internal monologue:

**Investigating Memory CGroups and Node Shrinkage**

Right, `mem_cgroup_shrink_node`. That's a key function in memory management, isn't it? I remember seeing it in `mm/vmscan.c`. It's definitely responsible for shrinking memory within a node, likely in response to memory pressure or some other control mechanism. Now, the context is important here; I see that `mm/memcontrol-v1.c` is the caller. That immediately flags memory cgroups for me, or at least a related feature.

The main question now, is it conditionally compiled? I need to be sure; is this function guarded by `#ifdef CONFIG_MEMCG`? Because if so, it will only be available when memory cgroups are configured in the kernel. This is essential for understanding its use and impact. If not, its function would be more generalized for general memory control or paging.

38/2 2026/08/07 12:06 tool grepper
0m Args: 
{
  "Expression": "#ifdef CONFIG_MEMCG"
}

Results: 
{
  "Output": "\nFull output is too long, showing 500 out of 744 lines.\nUse more precise expression if possible.\n\nblock/blk-cgroup.c=1508=struct cgroup_subsys io_cgrp_subsys = {\n--\nblock/blk-cgroup.c-1517-\t.exit = blkcg_exit,\nblock/blk-cgroup.c:1518:#ifdef CONFIG_MEMCG\nblock/blk-cgroup.c-1519-\t/*\n--\ndrivers/block/loop.c=1843=static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,\n--\ndrivers/block/loop.c-1871-\t\tcmd-\u003eblkcg_css = bio_blkcg_css(rq-\u003ebio);\ndrivers/block/loop.c:1872:#ifdef CONFIG_MEMCG\ndrivers/block/loop.c-1873-\t\tif (cmd-\u003eblkcg_css) {\n--\ndrivers/iommu/iommu-pages.c=19=IOPTDESC_MATCH(_refcount, __page_refcount);\ndrivers/iommu/iommu-pages.c:20:#ifdef CONFIG_MEMCG\ndrivers/iommu/iommu-pages.c-21-IOPTDESC_MATCH(memcg_data, memcg_data);\n--\ndrivers/iommu/iommu-pages.h=19=struct ioptdesc {\n--\ndrivers/iommu/iommu-pages.h-31-\tatomic_t __page_refcount;\ndrivers/iommu/iommu-pages.h:32:#ifdef CONFIG_MEMCG\ndrivers/iommu/iommu-pages.h-33-\tunsigned long memcg_data;\n--\nfs/proc/page.c=261=static const struct proc_ops kpageflags_proc_ops = {\n--\nfs/proc/page.c-266-\nfs/proc/page.c:267:#ifdef CONFIG_MEMCG\nfs/proc/page.c-268-static ssize_t kpagecgroup_read(struct file *file, char __user *buf,\n--\nfs/proc/page.c=280=static int __init proc_page_init(void)\n--\nfs/proc/page.c-283-\tproc_create(\"kpageflags\", S_IRUSR, NULL, \u0026kpageflags_proc_ops);\nfs/proc/page.c:284:#ifdef CONFIG_MEMCG\nfs/proc/page.c-285-\tproc_create(\"kpagecgroup\", S_IRUSR, NULL, \u0026kpagecgroup_proc_ops);\n--\ninclude/linux/bpf.h=300=struct bpf_map {\n--\ninclude/linux/bpf.h-320-\tstruct btf *btf;\ninclude/linux/bpf.h:321:#ifdef CONFIG_MEMCG\ninclude/linux/bpf.h-322-\tstruct obj_cgroup *objcg;\n--\ninclude/linux/bpf.h=2780=int bpf_map_alloc_pages(const struct bpf_map *map, int nid,\ninclude/linux/bpf.h-2781-\t\t\tunsigned long nr_pages, struct page **page_array);\ninclude/linux/bpf.h:2782:#ifdef CONFIG_MEMCG\ninclude/linux/bpf.h-2783-void bpf_map_memcg_enter(const struct bpf_map *map, struct mem_cgroup **old_memcg,\n--\ninclude/linux/list_lru.h=51=struct list_lru {\ninclude/linux/list_lru.h-52-\tstruct list_lru_node\t*node;\ninclude/linux/list_lru.h:53:#ifdef CONFIG_MEMCG\ninclude/linux/list_lru.h-54-\tstruct list_head\tlist;\n--\ninclude/linux/list_lru.h=82=int memcg_list_lru_alloc(struct mem_cgroup *memcg, struct list_lru *lru,\n--\ninclude/linux/list_lru.h-84-\ninclude/linux/list_lru.h:85:#ifdef CONFIG_MEMCG\ninclude/linux/list_lru.h-86-/**\n--\ninclude/linux/memcontrol.h=60=struct mem_cgroup_reclaim_cookie {\n--\ninclude/linux/memcontrol.h-64-\ninclude/linux/memcontrol.h:65:#ifdef CONFIG_MEMCG\ninclude/linux/memcontrol.h-66-\n--\ninclude/linux/memcontrol.h=89=struct mem_cgroup_per_node {\n--\ninclude/linux/memcontrol.h-97-\ninclude/linux/memcontrol.h:98:#ifdef CONFIG_MEMCG_V1\ninclude/linux/memcontrol.h-99-\t/*\n--\ninclude/linux/memcontrol.h-128-\ninclude/linux/memcontrol.h:129:#ifdef CONFIG_MEMCG_NMI_SAFETY_REQUIRES_ATOMIC\ninclude/linux/memcontrol.h-130-\t/* slab stats for nmi context */\n--\ninclude/linux/memcontrol.h=202=struct mem_cgroup {\n--\ninclude/linux/memcontrol.h-255-\ninclude/linux/memcontrol.h:256:#ifdef CONFIG_MEMCG_NMI_SAFETY_REQUIRES_ATOMIC\ninclude/linux/memcontrol.h-257-\t/* MEMCG_KMEM for nmi context */\n--\ninclude/linux/memcontrol.h-283-\ninclude/linux/memcontrol.h:284:#ifdef CONFIG_MEMCG_V1\ninclude/linux/memcontrol.h-285-\t/* Legacy consumer-oriented counters */\n--\ninclude/linux/memcontrol.h=354=enum objext_flags {\n--\ninclude/linux/memcontrol.h-367-\ninclude/linux/memcontrol.h:368:#ifdef CONFIG_MEMCG\ninclude/linux/memcontrol.h-369-/*\n--\ninclude/linux/memcontrol.h=1476=struct slabobj_ext {\ninclude/linux/memcontrol.h:1477:#ifdef CONFIG_MEMCG\ninclude/linux/memcontrol.h-1478-\tstruct obj_cgroup *objcg;\n--\ninclude/linux/memcontrol.h=1504=static inline struct lruvec *lruvec_live_lock_irq(struct lruvec *lruvec)\ninclude/linux/memcontrol.h-1505-{\ninclude/linux/memcontrol.h:1506:#ifdef CONFIG_MEMCG\ninclude/linux/memcontrol.h-1507-\tstruct pglist_data *pgdat = lruvec_pgdat(lruvec);\n--\ninclude/linux/memcontrol.h=1639=struct sock;\ninclude/linux/memcontrol.h:1640:#ifdef CONFIG_MEMCG\ninclude/linux/memcontrol.h-1641-extern struct static_key_false memcg_sockets_enabled_key;\n--\ninclude/linux/memcontrol.h=1727=static inline int shrinker_id(struct shrinker *shrinker)\n--\ninclude/linux/memcontrol.h-1732-\ninclude/linux/memcontrol.h:1733:#ifdef CONFIG_MEMCG\ninclude/linux/memcontrol.h-1734-bool mem_cgroup_kmem_disabled(void);\n--\ninclude/linux/memcontrol.h=1919=static inline bool mem_cgroup_zswap_writeback_enabled(struct mem_cgroup *memcg)\n--\ninclude/linux/memcontrol.h-1928-\ninclude/linux/memcontrol.h:1929:#ifdef CONFIG_MEMCG_V1\ninclude/linux/memcontrol.h-1930-unsigned long memcg1_soft_limit_reclaim(pg_data_t *pgdat, int order,\n--\ninclude/linux/mm_inline.h=47=static __always_inline void update_lru_size(struct lruvec *lruvec,\n--\ninclude/linux/mm_inline.h-51-\t__update_lru_size(lruvec, lru, zid, nr_pages);\ninclude/linux/mm_inline.h:52:#ifdef CONFIG_MEMCG\ninclude/linux/mm_inline.h-53-\tmem_cgroup_update_lru_size(lruvec, lru, zid, nr_pages);\n--\ninclude/linux/mm_types.h=80=struct page {\n--\ninclude/linux/mm_types.h-186-\ninclude/linux/mm_types.h:187:#ifdef CONFIG_MEMCG\ninclude/linux/mm_types.h-188-\tunsigned long memcg_data;\n--\ninclude/linux/mm_types.h=404=struct folio {\n--\ninclude/linux/mm_types.h-435-\t\t\tatomic_t _refcount;\ninclude/linux/mm_types.h:436:#ifdef CONFIG_MEMCG\ninclude/linux/mm_types.h-437-\t\t\tunsigned long memcg_data;\n--\ninclude/linux/mm_types.h=521=FOLIO_MATCH(_refcount, _refcount);\ninclude/linux/mm_types.h:522:#ifdef CONFIG_MEMCG\ninclude/linux/mm_types.h-523-FOLIO_MATCH(memcg_data, memcg_data);\n--\ninclude/linux/mm_types.h=576=struct ptdesc {\n--\ninclude/linux/mm_types.h-607-\tatomic_t __page_refcount;\ninclude/linux/mm_types.h:608:#ifdef CONFIG_MEMCG\ninclude/linux/mm_types.h-609-\tunsigned long pt_memcg_data;\n--\ninclude/linux/mm_types.h=622=TABLE_MATCH(_refcount, __page_refcount);\ninclude/linux/mm_types.h:623:#ifdef CONFIG_MEMCG\ninclude/linux/mm_types.h-624-TABLE_MATCH(memcg_data, pt_memcg_data);\n--\ninclude/linux/mm_types.h=1175=struct mm_struct {\n--\ninclude/linux/mm_types.h-1327-#endif\ninclude/linux/mm_types.h:1328:#ifdef CONFIG_MEMCG\ninclude/linux/mm_types.h-1329-\t\t/*\n--\ninclude/linux/mm_types.h-1423-\t\t\tunsigned long empty_map_seq;\ninclude/linux/mm_types.h:1424:#ifdef CONFIG_MEMCG\ninclude/linux/mm_types.h-1425-\t\t\t/* points to the memcg of \"owner\" above */\n--\ninclude/linux/mm_types.h=1513=static inline void lru_gen_init_mm(struct mm_struct *mm)\n--\ninclude/linux/mm_types.h-1518-\tmm-\u003elru_gen.empty_map_seq = ~0UL;\ninclude/linux/mm_types.h:1519:#ifdef CONFIG_MEMCG\ninclude/linux/mm_types.h-1520-\tmm-\u003elru_gen.memcg = NULL;\n--\ninclude/linux/mmzone.h=770=struct lruvec {\n--\ninclude/linux/mmzone.h-797-#endif /* CONFIG_LRU_GEN */\ninclude/linux/mmzone.h:798:#ifdef CONFIG_MEMCG\ninclude/linux/mmzone.h-799-\tstruct pglist_data *pgdat;\n--\ninclude/linux/mmzone.h=1670=static inline struct pglist_data *lruvec_pgdat(struct lruvec *lruvec)\ninclude/linux/mmzone.h-1671-{\ninclude/linux/mmzone.h:1672:#ifdef CONFIG_MEMCG\ninclude/linux/mmzone.h-1673-\treturn lruvec-\u003epgdat;\n--\ninclude/linux/sched.h=826=struct task_struct {\n--\ninclude/linux/sched.h-1021-#endif\ninclude/linux/sched.h:1022:#ifdef CONFIG_MEMCG_V1\ninclude/linux/sched.h-1023-\tunsigned\t\t\tin_user_fault:1;\n--\ninclude/linux/sched.h-1548-\ninclude/linux/sched.h:1549:#ifdef CONFIG_MEMCG_V1\ninclude/linux/sched.h-1550-\tstruct mem_cgroup\t\t*memcg_in_oom;\n--\ninclude/linux/sched.h-1552-\ninclude/linux/sched.h:1553:#ifdef CONFIG_MEMCG\ninclude/linux/sched.h-1554-\t/* Number of pages to reclaim on returning to userland: */\n--\ninclude/linux/sched/mm.h=161=extern void exec_mm_release(struct task_struct *, struct mm_struct *);\ninclude/linux/sched/mm.h-162-\ninclude/linux/sched/mm.h:163:#ifdef CONFIG_MEMCG\ninclude/linux/sched/mm.h-164-extern void mm_update_next_owner(struct mm_struct *mm);\n--\ninclude/linux/sched/mm.h=466=static inline void memalloc_pin_restore(unsigned int flags)\n--\ninclude/linux/sched/mm.h-470-\ninclude/linux/sched/mm.h:471:#ifdef CONFIG_MEMCG\ninclude/linux/sched/mm.h-472-DECLARE_PER_CPU(struct mem_cgroup *, int_active_memcg);\n--\ninclude/linux/shrinker.h=82=struct shrinker {\n--\ninclude/linux/shrinker.h-106-\tstruct list_head list;\ninclude/linux/shrinker.h:107:#ifdef CONFIG_MEMCG\ninclude/linux/shrinker.h-108-\t/* ID in shrinker_idr */\n--\ninclude/linux/slab.h=26=enum _slab_flag_bits {\n--\ninclude/linux/slab.h-45-#endif\ninclude/linux/slab.h:46:#ifdef CONFIG_MEMCG\ninclude/linux/slab.h-47-\t_SLAB_ACCOUNT,\n--\ninclude/linux/slab.h-204- */\ninclude/linux/slab.h:205:#ifdef CONFIG_MEMCG\ninclude/linux/slab.h-206-# define SLAB_ACCOUNT\t\t__SLAB_FLAG_BIT(_SLAB_ACCOUNT)\n--\ninclude/linux/slab.h=708=enum kmalloc_cache_type {\n--\ninclude/linux/slab.h-728-#endif\ninclude/linux/slab.h:729:#ifdef CONFIG_MEMCG\ninclude/linux/slab.h-730-\tKMALLOC_CGROUP,\n--\ninclude/linux/swap.h=469=static inline int add_swap_extent(struct swap_info_struct *sis,\n--\ninclude/linux/swap.h-475-#endif /* CONFIG_SWAP */\ninclude/linux/swap.h:476:#ifdef CONFIG_MEMCG\ninclude/linux/swap.h-477-void lru_reparent_memcg(struct mem_cgroup *memcg, struct mem_cgroup *parent, int nid);\n--\ninclude/linux/vmpressure.h=13=struct vmpressure {\n--\ninclude/linux/vmpressure.h-18-\ninclude/linux/vmpressure.h:19:#ifdef CONFIG_MEMCG_V1\ninclude/linux/vmpressure.h-20-\t/*\n--\ninclude/linux/vmpressure.h=43=struct mem_cgroup;\ninclude/linux/vmpressure.h-44-\ninclude/linux/vmpressure.h:45:#ifdef CONFIG_MEMCG\ninclude/linux/vmpressure.h-46-void vmpressure(gfp_t gfp, int order, struct mem_cgroup *memcg, bool tree,\n--\ninclude/linux/vmpressure.h=55=extern enum vmpressure_levels vmpressure_calc_level(unsigned long scanned,\n--\ninclude/linux/vmpressure.h-57-\ninclude/linux/vmpressure.h:58:#ifdef CONFIG_MEMCG_V1\ninclude/linux/vmpressure.h-59-extern void vmpressure_prio(gfp_t gfp, struct mem_cgroup *memcg, int prio);\n--\ninclude/linux/vmstat.h=522=static inline const char *vm_event_name(enum vm_event_item item)\n--\ninclude/linux/vmstat.h-531-\ninclude/linux/vmstat.h:532:#ifdef CONFIG_MEMCG\ninclude/linux/vmstat.h-533-\n--\ninclude/net/sock.h=365=struct sock {\n--\ninclude/net/sock.h-460-\tstruct socket\t\t*sk_socket;\ninclude/net/sock.h:461:#ifdef CONFIG_MEMCG\ninclude/net/sock.h-462-\tstruct mem_cgroup\t*sk_memcg;\n--\ninclude/net/sock.h=2686=static inline gfp_t gfp_memcg_charge(void)\n--\ninclude/net/sock.h-2690-\ninclude/net/sock.h:2691:#ifdef CONFIG_MEMCG\ninclude/net/sock.h-2692-static inline struct mem_cgroup *mem_cgroup_from_sk(const struct sock *sk)\n--\ninclude/net/sock.h=2702=static inline bool mem_cgroup_sk_under_memory_pressure(const struct sock *sk)\n--\ninclude/net/sock.h-2705-\ninclude/net/sock.h:2706:#ifdef CONFIG_MEMCG_V1\ninclude/net/sock.h-2707-\tif (!cgroup_subsys_on_dfl(memory_cgrp_subsys))\n--\ninclude/trace/events/vmscan.h=203=DEFINE_EVENT(mm_vmscan_direct_reclaim_begin_template, mm_vmscan_direct_reclaim_begin,\n--\ninclude/trace/events/vmscan.h-209-\ninclude/trace/events/vmscan.h:210:#ifdef CONFIG_MEMCG\ninclude/trace/events/vmscan.h-211-DEFINE_EVENT(mm_vmscan_direct_reclaim_begin_template, mm_vmscan_memcg_reclaim_begin,\n--\ninclude/trace/events/vmscan.h=249=DEFINE_EVENT(mm_vmscan_direct_reclaim_end_template, mm_vmscan_direct_reclaim_end,\n--\ninclude/trace/events/vmscan.h-255-\ninclude/trace/events/vmscan.h:256:#ifdef CONFIG_MEMCG\ninclude/trace/events/vmscan.h-257-DEFINE_EVENT(mm_vmscan_direct_reclaim_end_template, mm_vmscan_memcg_reclaim_end,\n--\nkernel/bpf/memalloc.c=160=static struct mem_cgroup *get_memcg(const struct bpf_mem_cache *c)\nkernel/bpf/memalloc.c-161-{\nkernel/bpf/memalloc.c:162:#ifdef CONFIG_MEMCG\nkernel/bpf/memalloc.c-163-\tif (c-\u003eobjcg)\n--\nkernel/bpf/memalloc.c=502=int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu)\n--\nkernel/bpf/memalloc.c-525-\nkernel/bpf/memalloc.c:526:#ifdef CONFIG_MEMCG\nkernel/bpf/memalloc.c-527-\t\tif (memcg_bpf_enabled())\n--\nkernel/bpf/memalloc.c-547-\t\treturn -ENOMEM;\nkernel/bpf/memalloc.c:548:#ifdef CONFIG_MEMCG\nkernel/bpf/memalloc.c-549-\tobjcg = get_obj_cgroup_from_current();\n--\nkernel/bpf/syscall.c=466=void bpf_map_free_id(struct bpf_map *map)\n--\nkernel/bpf/syscall.c-485-\nkernel/bpf/syscall.c:486:#ifdef CONFIG_MEMCG\nkernel/bpf/syscall.c-487-static void bpf_map_save_memcg(struct bpf_map *map)\n--\nkernel/bpf/verifier.c=5637=BTF_TYPE_SAFE_RCU_OR_NULL(struct mm_struct) {\nkernel/bpf/verifier.c-5638-\tstruct file __rcu *exe_file;\nkernel/bpf/verifier.c:5639:#ifdef CONFIG_MEMCG\nkernel/bpf/verifier.c-5640-\tstruct task_struct __rcu *owner;\n--\nkernel/exit.c=429=static void coredump_task_exit(struct task_struct *tsk,\n--\nkernel/exit.c-454-\nkernel/exit.c:455:#ifdef CONFIG_MEMCG\nkernel/exit.c-456-/* drops tasklist_lock if succeeds */\n--\nkernel/fork.c=914=static struct task_struct *dup_task_struct(struct task_struct *orig, int node)\n--\nkernel/fork.c-998-\nkernel/fork.c:999:#ifdef CONFIG_MEMCG\nkernel/fork.c-1000-\ttsk-\u003eactive_memcg = NULL;\n--\nkernel/fork.c=1052=static __always_inline void mm_clear_owner(struct mm_struct *mm,\n--\nkernel/fork.c-1054-{\nkernel/fork.c:1055:#ifdef CONFIG_MEMCG\nkernel/fork.c-1056-\tif (mm-\u003eowner == p)\n--\nkernel/fork.c=1061=static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)\nkernel/fork.c-1062-{\nkernel/fork.c:1063:#ifdef CONFIG_MEMCG\nkernel/fork.c-1064-\tmm-\u003eowner = p;\n--\nmm/damon/sysfs-common.c=106=static bool damon_sysfs_memcg_path_eq(struct mem_cgroup *memcg,\n--\nmm/damon/sysfs-common.c-108-{\nmm/damon/sysfs-common.c:109:#ifdef CONFIG_MEMCG\nmm/damon/sysfs-common.c-110-\tcgroup_path(memcg-\u003ecss.cgroup, memcg_path_buf, PATH_MAX);\n--\nmm/debug.c=70=static void __dump_folio(const struct folio *folio, const struct page *page,\n--\nmm/debug.c-96-\nmm/debug.c:97:#ifdef CONFIG_MEMCG\nmm/debug.c-98-\tif (folio-\u003ememcg_data)\n--\nmm/debug.c=175=void dump_mm(const struct mm_struct *mm)\n--\nmm/debug.c-188-#endif\nmm/debug.c:189:#ifdef CONFIG_MEMCG\nmm/debug.c-190-\t\t\"owner %px \"\n--\nmm/debug.c-217-#endif\nmm/debug.c:218:#ifdef CONFIG_MEMCG\nmm/debug.c-219-\t\tmm-\u003eowner,\n--\nmm/folio.c=1061=void folio_batch_remove_exceptionals(struct folio_batch *fbatch)\n--\nmm/folio.c-1072-\nmm/folio.c:1073:#ifdef CONFIG_MEMCG\nmm/folio.c-1074-static void lruvec_reparent_lru(struct lruvec *child_lruvec,\n--\nmm/huge_memory.c=3642=static void __split_folio_to_order(struct folio *folio, int old_order,\n--\nmm/huge_memory.c-3744-\t\t\tfolio_set_idle(new_folio);\nmm/huge_memory.c:3745:#ifdef CONFIG_MEMCG\nmm/huge_memory.c-3746-\t\tnew_folio-\u003ememcg_data = folio-\u003ememcg_data;\n--\nmm/hwpoison-inject.c=45=static int hwpoison_filter_flags(struct page *p)\n--\nmm/hwpoison-inject.c-66- */\nmm/hwpoison-inject.c:67:#ifdef CONFIG_MEMCG\nmm/hwpoison-inject.c-68-static u64 hwpoison_filter_memcg;\n--\nmm/hwpoison-inject.c=162=static int __init pfn_inject_init(void)\n--\nmm/hwpoison-inject.c-191-\nmm/hwpoison-inject.c:192:#ifdef CONFIG_MEMCG\nmm/hwpoison-inject.c-193-\tdebugfs_create_u64(\"corrupt-filter-memcg\", 0600, hwpoison_dir,\n--\nmm/kfence/core.c=611=static unsigned long kfence_init_pool(void)\n--\nmm/kfence/core.c-638-\t\t__SetPageSlab(page);\nmm/kfence/core.c:639:#ifdef CONFIG_MEMCG\nmm/kfence/core.c-640-\t\tstruct slab *slab = page_slab(page);\n--\nmm/kfence/core.c-706-\t\tpage = pfn_to_page(start_pfn + i);\nmm/kfence/core.c:707:#ifdef CONFIG_MEMCG\nmm/kfence/core.c-708-\t\tstruct slab *slab = page_slab(page);\n--\nmm/kfence/core.c=1247=void __kfence_free(void *addr)\n--\nmm/kfence/core.c-1250-\nmm/kfence/core.c:1251:#ifdef CONFIG_MEMCG\nmm/kfence/core.c-1252-\tKFENCE_WARN_ON(meta-\u003eobj_exts.objcg);\n--\nmm/kfence/kfence.h=59=struct kfence_metadata {\n--\nmm/kfence/kfence.h-104-\tu32 alloc_stack_hash __guarded_by(\u0026lock);\nmm/kfence/kfence.h:105:#ifdef CONFIG_MEMCG\nmm/kfence/kfence.h-106-\tstruct slabobj_ext obj_exts;\n--\nmm/list_lru.c=29=static inline void unlock_list_lru(struct list_lru_one *l, bool irq_off,\n--\nmm/list_lru.c-39-\nmm/list_lru.c:40:#ifdef CONFIG_MEMCG\nmm/list_lru.c-41-static LIST_HEAD(memcg_list_lrus);\n--\nmm/list_lru.c=413=unsigned long list_lru_walk_node(struct list_lru *lru, int nid,\n--\nmm/list_lru.c-421-\nmm/list_lru.c:422:#ifdef CONFIG_MEMCG\nmm/list_lru.c-423-\tif (*nr_to_walk \u003e 0 \u0026\u0026 list_lru_memcg_aware(lru)) {\n--\nmm/list_lru.c=451=static void init_one_lru(struct list_lru *lru, struct list_lru_one *l)\n--\nmm/list_lru.c-461-\nmm/list_lru.c:462:#ifdef CONFIG_MEMCG\nmm/list_lru.c-463-static struct list_lru_memcg *memcg_init_list_lru_one(struct list_lru *lru, gfp_t gfp)\n--\nmm/list_lru.c=664=int __list_lru_init(struct list_lru *lru, bool memcg_aware, struct shrinker *shrinker)\n--\nmm/list_lru.c-667-\nmm/list_lru.c:668:#ifdef CONFIG_MEMCG\nmm/list_lru.c-669-\tif (shrinker)\n--\nmm/list_lru.c=692=void list_lru_destroy(struct list_lru *lru)\n--\nmm/list_lru.c-703-\nmm/list_lru.c:704:#ifdef CONFIG_MEMCG\nmm/list_lru.c-705-\tlru-\u003eshrinker_id = -1;\n--\nmm/memcontrol-v1.h=25=struct mem_cgroup *mem_cgroup_private_id_get_online(struct mem_cgroup *memcg,\n--\nmm/memcontrol-v1.h-28-/* Cgroup v1-specific declarations */\nmm/memcontrol-v1.h:29:#ifdef CONFIG_MEMCG_V1\nmm/memcontrol-v1.h-30-\n--\nmm/memcontrol.c=215=static inline struct obj_cgroup *__memcg_reparent_objcgs(struct mem_cgroup *memcg,\n--\nmm/memcontrol.c-234-\nmm/memcontrol.c:235:#ifdef CONFIG_MEMCG_V1\nmm/memcontrol.c-236-static void __mem_cgroup_flush_stats(struct mem_cgroup *memcg, bool force);\n--\nmm/memcontrol.c=550=unsigned long lruvec_page_state_local(struct lruvec *lruvec,\n--\nmm/memcontrol.c-572-\nmm/memcontrol.c:573:#ifdef CONFIG_MEMCG_V1\nmm/memcontrol.c-574-static void __mod_memcg_lruvec_state(struct mem_cgroup_per_node *pn,\n--\nmm/memcontrol.c=598=static const unsigned int memcg_vm_event_stat[] = {\nmm/memcontrol.c:599:#ifdef CONFIG_MEMCG_V1\nmm/memcontrol.c-600-\tPGPGIN,\n--\nmm/memcontrol.c=832=static long memcg_state_val_in_pages(int idx, long val)\n--\nmm/memcontrol.c-847-\nmm/memcontrol.c:848:#ifdef CONFIG_MEMCG_V1\nmm/memcontrol.c-849-/*\n--\nmm/memcontrol.c=916=void mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx,\n--\nmm/memcontrol.c-928-\nmm/memcontrol.c:929:#ifdef CONFIG_MEMCG_V1\nmm/memcontrol.c-930-/* idx can be of type enum memcg_stat_item or node_stat_item. */\n--\nmm/memcontrol.c=1104=bool memcg_vm_event_item_valid(enum vm_event_item idx)\n--\nmm/memcontrol.c-1111-\nmm/memcontrol.c:1112:#ifdef CONFIG_MEMCG_V1\nmm/memcontrol.c-1113-unsigned long memcg_events_local(struct mem_cgroup *memcg, int event)\n--\nmm/memcontrol.c=1712=unsigned long memcg_page_state_output(struct mem_cgroup *memcg, int item)\n--\nmm/memcontrol.c-1717-\nmm/memcontrol.c:1718:#ifdef CONFIG_MEMCG_V1\nmm/memcontrol.c-1719-unsigned long memcg_page_state_local_output(struct mem_cgroup *memcg, int item)\n--\nmm/memcontrol.c=1738=static void memcg_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)\n--\nmm/memcontrol.c-1784-\tfor (i = 0; i \u003c ARRAY_SIZE(memcg_vm_event_stat); i++) {\nmm/memcontrol.c:1785:#ifdef CONFIG_MEMCG_V1\nmm/memcontrol.c-1786-\t\tif (memcg_vm_event_stat[i] == PGPGIN ||\n--\nmm/memcontrol.c=1836=void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg)\n--\nmm/memcontrol.c-1857-\t\t\tatomic_long_read(\u0026memcg-\u003ememory_events[MEMCG_SWAP_MAX]));\nmm/memcontrol.c:1858:#ifdef CONFIG_MEMCG_V1\nmm/memcontrol.c-1859-\telse {\n--\nmm/memcontrol.c=2858=static void commit_charge(struct folio *folio, struct obj_cgroup *objcg)\n--\nmm/memcontrol.c-2870-\nmm/memcontrol.c:2871:#ifdef CONFIG_MEMCG_NMI_SAFETY_REQUIRES_ATOMIC\nmm/memcontrol.c-2872-static inline void account_slab_nmi_safe(struct mem_cgroup *memcg,\n--\nmm/memcontrol.c=3090=struct obj_cgroup *get_obj_cgroup_from_folio(struct folio *folio)\n--\nmm/memcontrol.c-3100-\nmm/memcontrol.c:3101:#ifdef CONFIG_MEMCG_NMI_SAFETY_REQUIRES_ATOMIC\nmm/memcontrol.c-3102-static inline void account_kmem_nmi_safe(struct mem_cgroup *memcg, int val)\n--\nmm/memcontrol.c=4212=mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)\n--\nmm/memcontrol.c-4233-\t\tpage_counter_init(\u0026memcg-\u003eswap, \u0026parent-\u003eswap, false);\nmm/memcontrol.c:4234:#ifdef CONFIG_MEMCG_V1\nmm/memcontrol.c-4235-\t\tWRITE_ONCE(memcg-\u003eswappiness, mem_cgroup_swappiness(parent));\n\n"
}
39/2 2026/08/07 12:06 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 35541
							output: 24
							thoughts: 91

Thoughts: 
**Investigating the Scope of `mem_cgroup_shrink_node`**

Okay, so I'm looking at `mem_cgroup_shrink_node`. I remember it's defined in `mm/vmscan.c`. The thing that's bugging me is that I thought it was *only* used within `mm/memcontrol-v1.c`, specifically for handling soft limit reclaim. But that's not sitting quite right. I need to make sure I'm not missing something in its usage.

Right, let me quickly go back and verify. Let's dig into `mm/vmscan.c` and search the code for `mem_cgroup_shrink_node` itself. I need to confirm if its definition is unconditional or if there are any subtle build flags or conditionals affecting its availability. This is critical – if it's broadly accessible, then my initial understanding of its exclusivity might be incorrect, and I need to account for its potentially wider application across the memory management subsystem. Time to double-check the source.

40/2 2026/08/07 12:06 tool grepper
0m Args: 
{
  "Expression": "unsigned long mem_cgroup_shrink_node"
}

Results: 
{
  "Output": "mm/internal.h=83=unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,\n--\nmm/internal.h-87-\t\t\t\t\t   int *swappiness);\nmm/internal.h:88:unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,\nmm/internal.h-89-\t\t\t\t     gfp_t gfp_mask, bool noswap,\n--\nmm/vmscan.c=6863=unsigned long try_to_free_pages(struct zonelist *zonelist, int order,\n--\nmm/vmscan.c-6908-/* Only used by soft limit reclaim. Do not reuse for anything else. */\nmm/vmscan.c:6909:unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,\nmm/vmscan.c-6910-\t\t\t\t\t\tgfp_t gfp_mask, bool noswap,\n"
}
41/2 2026/08/07 12:06 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 36126
							output: 23
							thoughts: 90

Thoughts: 
Okay, here's my take on those thoughts, framed from my perspective as an expert in this area:

**Focusing on Memory Reclamation Entry Points**

Right, so we're talking about memory reclaim, and my initial thought is that while the memory scanning mechanism itself is unconditionally defined in `mm/vmscan.c`, the *real* heart of direct reclaim lies within `try_to_free_pages`. That's where the rubber meets the road, isn't it? It's the primary entry point when the kernel's under pressure and desperately needs to free up memory. That makes it a much more significant symbol to concentrate on for understanding the critical path.

`remove_migration_ptes` is another interesting function that comes to mind in the discussion.

I think I'll dive into `try_to_free_pages` in `mm/vmscan.c` right now and see what we can find.

42/2 2026/08/07 12:06 tool grepper
0m Args: 
{
  "Expression": "unsigned long try_to_free_pages"
}

Results: 
{
  "Output": "mm/internal.h=69=unsigned long zone_reclaimable_pages(struct zone *zone);\nmm/internal.h:70:unsigned long try_to_free_pages(struct zonelist *zonelist, int order,\nmm/internal.h-71-\t\t\t\tgfp_t gfp_mask, const nodemask_t *mask);\n--\nmm/vmscan.c=6783=static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,\n--\nmm/vmscan.c-6862-\nmm/vmscan.c:6863:unsigned long try_to_free_pages(struct zonelist *zonelist, int order,\nmm/vmscan.c-6864-\t\t\t\tgfp_t gfp_mask, const nodemask_t *nodemask)\n"
}
43/2 2026/08/07 12:06 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 36655
							output: 21
							thoughts: 29

Thoughts: 
Here's my attempt at summarizing the thought process, tailored for an expert audience:

**Considering Memory Management Strategies**

Okay, so I'm honing in on memory management optimization. `try_to_free_pages` feels like a particularly fruitful area to explore, a good place to center my attention for now. The implications here are pretty clear – efficiently reclaiming memory is always a critical performance factor.

But as I'm thinking about it, I'm wondering if I should expand my focus. What about the functions related to page table entries during migration?  `remove_migration_ptes`... I should consider how its functionality relates to the memory reclamation task I am currently looking at. I will investigate how the two relate.

44/2 2026/08/07 12:07 tool grepper
0m Args: 
{
  "Expression": "void remove_migration_ptes"
}

Results: 
{
  "Output": "include/linux/rmap.h=936=int pfn_mkclean_range(unsigned long pfn, unsigned long nr_pages, pgoff_t pgoff,\n--\ninclude/linux/rmap.h-938-\ninclude/linux/rmap.h:939:void remove_migration_ptes(struct folio *src, struct folio *dst,\ninclude/linux/rmap.h-940-\t\tenum ttu_flags flags);\n--\nmm/migrate.c=351=static bool remove_migration_pte(struct folio *folio,\n--\nmm/migrate.c-472- */\nmm/migrate.c:473:void remove_migration_ptes(struct folio *src, struct folio *dst,\nmm/migrate.c-474-\t\tenum ttu_flags flags)\n"
}
45/2 2026/08/07 12:07 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 37067
							output: 28
							thoughts: 37

Thoughts: 
Okay, here's my take on those thoughts, framed as an expert's self-reflection:

**Considering Memory Management Strategies**

Ah, yes, `remove_migration_ptes` is a very elegant solution to consider. It's a key strategy to keep in mind, and fits well into the overall picture of memory management optimization.

Now, let's turn our attention to `try_to_free_mem_cgroup_pages`. I need to evaluate whether that is performing as expected. I need to understand its impact. It's time to dive into that specific function and see if it is aligned with my expectations.

46/2 2026/08/07 12:07 tool grepper
0m Args: 
{
  "Expression": "unsigned long try_to_free_mem_cgroup_pages"
}

Results: 
{
  "Output": "mm/internal.h=72=unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru,\n--\nmm/internal.h-82-\nmm/internal.h:83:unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,\nmm/internal.h-84-\t\t\t\t\t   unsigned long nr_pages,\n--\nmm/vmscan.c=6909=unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,\n--\nmm/vmscan.c-6948-\nmm/vmscan.c:6949:unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,\nmm/vmscan.c-6950-\t\t\t\t\t   unsigned long nr_pages,\n--\nmm/vmscan.c-6989-#else\nmm/vmscan.c:6990:unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,\nmm/vmscan.c-6991-\t\t\t\t\t   unsigned long nr_pages,\n"
}
47/2 2026/08/07 12:07 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 37563
							output: 23
							thoughts: 207

Thoughts: 
**Analyzing Memory Reclamation Strategies**

Okay, so I'm looking at these memory freeing functions and trying to figure out the best approach. My initial thoughts were, "Hey, `try_to_free_mem_cgroup_pages` looks promising," but I quickly remembered that it's only relevant if the `CONFIG_MEMCG` kernel configuration is enabled. If not, it's essentially a no-op, a dummy function. That complicates things, makes it less generally useful.

So, I'm leaning towards focusing on the more fundamental functions: `try_to_free_pages` and `remove_migration_ptes`. They seem to offer broader applicability, and they're core to the memory management.

Then I paused and thought, what about `shrink_all_memory`? That's used for hibernation, which is a very different use case, so it might not be relevant here. And I just thought about `lru_gen_look_around` and its use in the page fault path. I should probably dive deeper into the code for that one to get a fuller understanding, since it's used so often.

48/2 2026/08/07 12:07 tool grepper
0m Args: 
{
  "Expression": "bool lru_gen_look_around"
}

Results: 
{
  "Output": "include/linux/mmzone.h=695=void lru_gen_init_lruvec(struct lruvec *lruvec);\ninclude/linux/mmzone.h:696:bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw, unsigned int nr);\ninclude/linux/mmzone.h-697-\n--\ninclude/linux/mmzone.h=714=static inline void lru_gen_init_lruvec(struct lruvec *lruvec)\n--\ninclude/linux/mmzone.h-717-\ninclude/linux/mmzone.h:718:static inline bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw,\ninclude/linux/mmzone.h-719-\t\tunsigned int nr)\n--\nmm/vmscan.c=4280=static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-4326- */\nmm/vmscan.c:4327:bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw, unsigned int nr)\nmm/vmscan.c-4328-{\n"
}
49/2 2026/08/07 12:07 llm patch-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 38364
							output: 168
							thoughts: 233

Thoughts: 
**Analyzing Potential Fuzzing Targets in the Multi-Gen LRU Subsystem**

Okay, so I'm looking at this patch and immediately, `lru_gen_look_around` is sticking out – it's called from `filemap_map_pages` and `do_set_pmd`, both *very* hot paths. That's a strong indicator. My intuition, based on the changes described, is leaning towards `try_to_free_pages` and `remove_migration_ptes` as the most promising targets for fuzzing.

Let me break down why. This patch fundamentally alters how the Multi-Gen LRU (MGLRU) interacts with NUMA nodes. It's suppressing those empty page table walks using a new `empty_map` tracker in `mm_struct`, and adjusting both page fault and migration paths to invalidate these "empty skips" when a page *is* actually accessed. We're talking core memory management and reclaim logic here – stuff that's not only reachable, but is *absolutely* worth a deep dive through fuzzing. The patch is adding a `skip_empty` tunable via debugfs and tracepoints for MGLRU walks, which also indicates the importance of these paths.

The key configurations to keep in mind are `LRU_GEN` and `LRU_GEN_ENABLED`. They'll likely be crucial for ensuring the fuzzing coverage hits the new code.

So, I'm zeroing in on `try_to_free_pages` and `remove_migration_ptes`. Time to bring up the `set-results` tool and start refining the fuzzing strategy.

50/2 2026/08/07 12:07 tool set-results
0m Args: 
{
  "EnableConfigs": [
    "LRU_GEN",
    "LRU_GEN_ENABLED"
  ],
  "FocusSymbols": [
    "try_to_free_pages",
    "remove_migration_ptes"
  ],
  "Reasoning": "The patch modifies the Multi-Gen LRU (MGLRU) subsystem to suppress empty page table walks across NUMA nodes. It introduces `empty_map` tracking to `struct mm_struct` and modifies page fault and migration paths to invalidate the empty skip when a page is accessed on a node. It also adds a tunable `skip_empty` in debugfs and tracepoints for MGLRU walks. These are functional changes to core memory management and reclaim logic, which are reachable and worth fuzzing.",
  "WorthFuzzing": true
}

Results: 
{
  "EnableConfigs": [
    "LRU_GEN",
    "LRU_GEN_ENABLED"
  ],
  "FocusSymbols": [
    "try_to_free_pages",
    "remove_migration_ptes"
  ],
  "Reasoning": "The patch modifies the Multi-Gen LRU (MGLRU) subsystem to suppress empty page table walks across NUMA nodes. It introduces `empty_map` tracking to `struct mm_struct` and modifies page fault and migration paths to invalidate the empty skip when a page is accessed on a node. It also adds a tunable `skip_empty` in debugfs and tracepoints for MGLRU walks. These are functional changes to core memory management and reclaim logic, which are reachable and worth fuzzing.",
  "WorthFuzzing": true
}
51/1 2026/08/07 12:07 action If
8m Args: 
{
  "WorthFuzzing": true
}

Results: 
null
52/2 2026/08/07 12:07 agent kmsan-evaluator
8m Model: 
best-expensive

Args: 
null

Results: 
{
  "KMSANReasoning": "The patch introduces new fields to `struct mm_struct` and `struct lru_gen_mm_walk` for MGLRU empty-walk suppression. All new fields are properly initialized (e.g., in `lru_gen_init_mm` and via `kzalloc` for `mm_walk`). The tracepoint `mm_vmscan_lru_gen_walk` only exposes fully initialized local variables and struct fields. The debugfs interface correctly checks the return value of `sscanf` before using the parsed value. There are no uninitialized memory reads, uninitialized structure padding sent to user space, or complex data structures where uninitialized fields could be read. Any potential issues like out-of-bounds accesses would be caught by KASAN. Therefore, a dedicated KMSAN fuzzing session is not necessary.",
  "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: 
For your convenience, here is the diff of the changes:
commit 5bddd2e77cfeb9a61248429ddf81da817f69a5a2
Author: syz-cluster <triage@syzkaller.com>
Date:   Fri Aug 7 12:03:21 2026 +0000

    syz-cluster: applied patch under review

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index b5d4cd3b067bf..89b7234836759 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -1410,6 +1410,17 @@ struct mm_struct {
 			 * page table walkers cleared the corresponding bits.
 			 */
 			unsigned long bitmap;
+			/*
+			 * Cross-node empty-walk suppression: bit N set means
+			 * node N's last aging walk of this mm found no folio
+			 * for this lruvec (pure waste). Skip the mm on node N
+			 * for up to K generations, then force a rescan.
+			 * empty_map_seq is the oldest max_seq among the set
+			 * bits (min(), conservative), so a bit is cleared when
+			 * max_seq >= empty_map_seq + K.
+			 */
+			unsigned long empty_map;
+			unsigned long empty_map_seq;
 #ifdef CONFIG_MEMCG
 			/* points to the memcg of "owner" above */
 			struct mem_cgroup *memcg;
@@ -1503,6 +1514,8 @@ static inline void lru_gen_init_mm(struct mm_struct *mm)
 {
 	INIT_LIST_HEAD(&mm->lru_gen.list);
 	mm->lru_gen.bitmap = 0;
+	mm->lru_gen.empty_map = 0;
+	mm->lru_gen.empty_map_seq = ~0UL;
 #ifdef CONFIG_MEMCG
 	mm->lru_gen.memcg = NULL;
 #endif
@@ -1518,6 +1531,20 @@ static inline void lru_gen_use_mm(struct mm_struct *mm)
 	WRITE_ONCE(mm->lru_gen.bitmap, -1);
 }
 
+/*
+ * A page of this mm appeared on (or was accessed on) node @nid — e.g. a page
+ * fault or a migration. Set that node's bitmap bit so the aging walker walks
+ * the mm, and clear the empty-walk skip so a page that just appeared on a node
+ * previously marked empty is not ignored for up to K generations.
+ */
+static inline void lru_gen_mm_accessed(struct mm_struct *mm, int nid)
+{
+	unsigned long key = nid % BITS_PER_TYPE(mm->lru_gen.bitmap);
+
+	set_bit(key, &mm->lru_gen.bitmap);
+	clear_bit(key, &mm->lru_gen.empty_map);
+}
+
 #else /* !CONFIG_LRU_GEN_WALKS_MMU */
 
 static inline void lru_gen_add_mm(struct mm_struct *mm)
@@ -1540,6 +1567,10 @@ static inline void lru_gen_use_mm(struct mm_struct *mm)
 {
 }
 
+static inline void lru_gen_mm_accessed(struct mm_struct *mm, int nid)
+{
+}
+
 #endif /* CONFIG_LRU_GEN_WALKS_MMU */
 
 struct vma_iterator {
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 86891163e0ef4..e9341da1bfb89 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -595,6 +595,10 @@ enum {
 	MM_LEAF_YOUNG,		/* young leaf entries */
 	MM_NONLEAF_FOUND,	/* non-leaf entries found in Bloom filters */
 	MM_NONLEAF_ADDED,	/* non-leaf entries added to Bloom filters */
+	MM_LEAF_ELIGIBLE,	/* folios belonging to this lruvec (node+memcg) */
+	MM_WALK_TOTAL,		/* page-table walks completed */
+	MM_WALK_EMPTY,		/* walks that found no eligible folio */
+	MM_LEAF_TOTAL_EMPTY,	/* leaf entries scanned by empty walks */
 	NR_MM_STATS
 };
 
diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
index b4bf7b8def1f5..c7c2034715b65 100644
--- a/include/trace/events/vmscan.h
+++ b/include/trace/events/vmscan.h
@@ -659,6 +659,34 @@ TRACE_EVENT(mm_vmscan_kswapd_clear_hopeless,
 		__entry->nid,
 		__print_symbolic(__entry->reason, kswapd_clear_hopeless_reason_ops))
 );
+TRACE_EVENT(mm_vmscan_lru_gen_walk,
+
+	TP_PROTO(int nid, unsigned long seq, int leaf_total,
+		 int leaf_eligible, bool empty),
+
+	TP_ARGS(nid, seq, leaf_total, leaf_eligible, empty),
+
+	TP_STRUCT__entry(
+		__field(int, nid)
+		__field(unsigned long, seq)
+		__field(int, leaf_total)
+		__field(int, leaf_eligible)
+		__field(bool, empty)
+	),
+
+	TP_fast_assign(
+		__entry->nid = nid;
+		__entry->seq = seq;
+		__entry->leaf_total = leaf_total;
+		__entry->leaf_eligible = leaf_eligible;
+		__entry->empty = empty;
+	),
+
+	TP_printk("nid=%d seq=%lu leaf_total=%d leaf_eligible=%d empty=%d",
+		__entry->nid, __entry->seq, __entry->leaf_total,
+		__entry->leaf_eligible, __entry->empty)
+);
+
 #endif /* _TRACE_VMSCAN_H */
 
 /* This part must be outside protection */
diff --git a/mm/memory.c b/mm/memory.c
index 6ae52e3869b1c..077e7353b4cd7 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5513,6 +5513,9 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
 		folio_put(folio);
 		return handle_userfault(vmf, VM_UFFD_MISSING);
 	}
+	/* a new page of this mm lands on this node: invalidate any empty skip */
+	lru_gen_mm_accessed(vma->vm_mm, folio_nid(folio));
+
 	map_anon_folio_pte_pf(folio, vmf->pte, vma, addr,
 			      vmf_orig_pte_uffd_wp(vmf));
 unlock:
@@ -5773,6 +5776,10 @@ vm_fault_t finish_fault(struct vm_fault *vmf)
 		page = vmf->page;
 
 	folio = page_folio(page);
+
+	/* mapping a page of this mm on this node: invalidate any empty skip */
+	lru_gen_mm_accessed(vma->vm_mm, folio_nid(folio));
+
 	/*
 	 * check even for read faults because we might have lost our CoWed
 	 * page
diff --git a/mm/migrate.c b/mm/migrate.c
index b937cbd764808..2e0674e89ba86 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -354,6 +354,9 @@ static bool remove_migration_pte(struct folio *folio,
 	struct rmap_walk_arg *rmap_walk_arg = arg;
 	DEFINE_FOLIO_VMA_WALK(pvmw, rmap_walk_arg->folio, vma, addr, PVMW_SYNC | PVMW_MIGRATION);
 
+	/* the folio ends up on folio_nid(): notify MGLRU for this mm */
+	lru_gen_mm_accessed(vma->vm_mm, folio_nid(folio));
+
 	while (page_vma_mapped_walk(&pvmw)) {
 		rmap_t rmap_flags = RMAP_NONE;
 		pte_t old_pte;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 17d2b793cbfc4..631bcd89b1967 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2919,6 +2919,9 @@ static struct lru_gen_mm_state *get_mm_state(struct lruvec *lruvec)
 	return &lruvec->mm_state;
 }
 
+/* tunable empty-walk skip threshold; defined later, get_next_mm() needs it */
+static unsigned long mglru_empty_skip_gens;
+
 static struct mm_struct *get_next_mm(struct lru_gen_mm_walk *walk)
 {
 	int key;
@@ -2929,9 +2932,27 @@ static struct mm_struct *get_next_mm(struct lru_gen_mm_walk *walk)
 	mm = list_entry(mm_state->head, struct mm_struct, lru_gen.list);
 	key = pgdat->node_id % BITS_PER_TYPE(mm->lru_gen.bitmap);
 
+	/* skip if this mm hasn't been used on this node since the last walk */
 	if (!walk->force_scan && !test_bit(key, &mm->lru_gen.bitmap))
 		return NULL;
 
+	/*
+	 * Skip if this node's last walk of this mm was empty and fewer than K
+	 * generations have passed; after K, clear the bit to force a rescan.
+	 * empty_map_seq tracks the oldest marking via min(), so the rescan
+	 * never fires later than K generations on any node.
+	 */
+	if (!walk->force_scan && test_bit(key, &mm->lru_gen.empty_map)) {
+		DEFINE_MAX_SEQ(walk->lruvec);
+		unsigned long empty_seq = READ_ONCE(mm->lru_gen.empty_map_seq);
+
+		if (max_seq < empty_seq + READ_ONCE(mglru_empty_skip_gens))
+			return NULL;		/* skip: < K gens since empty */
+
+		/* K generations passed → force rescan */
+		clear_bit(key, &mm->lru_gen.empty_map);
+	}
+
 	clear_bit(key, &mm->lru_gen.bitmap);
 	mmgrab(mm);
 
@@ -3587,6 +3608,8 @@ static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end,
 		if (!folio)
 			continue;
 
+		walk->mm_stats[MM_LEAF_ELIGIBLE]++;
+
 		if (folio_test_large(folio)) {
 			const unsigned int max_nr = (end - addr) >> PAGE_SHIFT;
 
@@ -3687,6 +3710,8 @@ static void walk_pmd_range_locked(pud_t *pud, unsigned long addr, struct vm_area
 		if (!folio)
 			goto next;
 
+		walk->mm_stats[MM_LEAF_ELIGIBLE]++;
+
 		if (!pmdp_test_and_clear_young_notify(vma, addr, pmd + i))
 			goto next;
 
@@ -4108,8 +4133,46 @@ static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long seq,
 
 	do {
 		success = iterate_mm_list(walk, &mm);
-		if (mm)
+		if (mm) {
+			int nid = lruvec_pgdat(lruvec)->node_id;
+			int key = nid % BITS_PER_TYPE(mm->lru_gen.bitmap);
+			bool empty = false;
+
 			walk_mm(mm, walk);
+
+			/*
+			 * Any walk that found no folio for this lruvec is empty -
+			 * even if the PMD-level Bloom filter kept MM_LEAF_TOTAL at 0
+			 * (the common case for a foreign mm). Mark it so get_next_mm()
+			 * skips it next time; otherwise the empty-walk skip never
+			 * engages for the walks that matter most.
+			 */
+			if (walk->mm_stats[MM_LEAF_ELIGIBLE] == 0) {
+				set_bit(key, &mm->lru_gen.empty_map);
+				/* track the oldest marking (conservative) */
+				WRITE_ONCE(mm->lru_gen.empty_map_seq,
+					min(READ_ONCE(mm->lru_gen.empty_map_seq),
+					    walk->seq));
+				empty = true;
+			} else {
+				/* found eligible folios: clear the marking */
+				clear_bit(key, &mm->lru_gen.empty_map);
+			}
+
+			/* measurement stats keep the leaf_total gate */
+			if (walk->mm_stats[MM_LEAF_TOTAL]) {
+				walk->mm_stats[MM_WALK_TOTAL]++;
+				if (empty) {
+					walk->mm_stats[MM_WALK_EMPTY]++;
+					walk->mm_stats[MM_LEAF_TOTAL_EMPTY] +=
+						walk->mm_stats[MM_LEAF_TOTAL];
+				}
+			}
+			trace_mm_vmscan_lru_gen_walk(
+					lruvec_pgdat(lruvec)->node_id, walk->seq,
+					walk->mm_stats[MM_LEAF_TOTAL],
+					walk->mm_stats[MM_LEAF_ELIGIBLE], empty);
+		}
 	} while (mm);
 done:
 	if (success) {
@@ -4205,6 +4268,15 @@ static bool lruvec_is_reclaimable(struct lruvec *lruvec, struct scan_control *sc
 /* to protect the working set of the last N jiffies */
 static unsigned long lru_gen_min_ttl __read_mostly;
 
+/*
+ * Cross-node empty-walk skip threshold: skip an mm on node N for up to
+ * @mglru_empty_skip_gens generations after an empty walk, then force-rescan
+ * (closes migration/mlock/NUMA-balancing windows). Default 4 matches
+ * MAX_NR_GENS; 0 disables the suppression. Tunable via:
+ * echo "skip_empty <N>" > /sys/kernel/debug/lru_gen
+ */
+static unsigned long mglru_empty_skip_gens __read_mostly = 4;
+
 static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)
 {
 	struct mem_cgroup *memcg;
@@ -5588,14 +5660,14 @@ static void lru_gen_seq_show_full(struct seq_file *m, struct lruvec *lruvec,
 
 	seq_puts(m, "                      ");
 	for (i = 0; i < NR_MM_STATS; i++) {
-		const char *s = "xxxx";
+		const char *s = "xxxxxxxx";
 		unsigned long n = 0;
 
 		if (seq == max_seq && NR_HIST_GENS == 1) {
-			s = "TYFA";
+			s = "TYFALWEE";
 			n = READ_ONCE(mm_state->stats[hist][i]);
 		} else if (seq != max_seq && NR_HIST_GENS > 1) {
-			s = "tyfa";
+			s = "tyfalwee";
 			n = READ_ONCE(mm_state->stats[hist][i]);
 		}
 
@@ -5802,6 +5874,25 @@ static ssize_t lru_gen_seq_write(struct file *file, const char __user *src,
 		if (!*cur)
 			continue;
 
+		/*
+		 * set/show the empty-walk skip threshold: "skip_empty <N>"
+		 */
+		if (!strncmp(cur, "skip_empty", 10)) {
+			cur += 10;
+			cur = skip_spaces(cur);
+			if (*cur) {
+				unsigned long val;
+
+				if (sscanf(cur, "%lu", &val) == 1)
+					WRITE_ONCE(mglru_empty_skip_gens, val);
+			} else {
+				pr_info("MGLRU empty skip threshold: %lu generations (0=disabled)\n",
+					READ_ONCE(mglru_empty_skip_gens));
+			}
+			err = 0;
+			continue;
+		}
+
 		n = sscanf(cur, "%c %llu %u %lu %n %4s %n %lu %n", &cmd, &memcg_id, &nid,
 			   &seq, &end, swap_string, &end, &opt, &end);
 		if (n < 4 || cur[end]) {

53/3 2026/08/07 12:07 llm kmsan-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 6280
							output: 23
							thoughts: 625

Thoughts: 
**Analyzing the mglru Patch: Empty MM Optimization**

Okay, so this patch introduces some optimizations within the `mglru` framework, specifically around handling "empty" memory maps (`mm_struct`). My initial concern is always around uninitialized memory, so let's dig into that first.

The first thing I notice is the addition of two new fields, `empty_map` and `empty_map_seq`, to `struct mm_struct`, specifically within the `lru_gen` substructure. These seem key to tracking whether an `mm_struct` is considered "empty" in some sense. The initialization of these fields is handled in `lru_gen_init_mm`, and that looks pretty straightforward, setting `empty_map` to 0 and `empty_map_seq` to ~0UL. This function is called during the creation of a new `mm_struct`, so we're covered there; no obvious uninitialized memory risk in sight.

There's a new tracepoint, `mm_vmscan_lru_gen_walk`, that seems to be for debugging/profiling the walk process. It logs information like node ID, sequence number, and importantly, some counts: `leaf_total`, `leaf_eligible`, and `empty`. These counts are intriguing.

The debugfs write support for "skip_empty <N>" to set `mglru_empty_skip_gens` is another signal. This hints at the core optimization: the system aims to skip `mm_struct` entries that are deemed "empty" to improve performance. The modifications to `get_next_mm` reflect this.

The crucial parts are in `try_to_inc_max_seq`, `walk_pte_range`, and `walk_pmd_range_locked`. These functions are all involved in page table walks. The patch appears to be using the `MM_LEAF_ELIGIBLE` counter within the `walk->mm_stats` structure. This counter is then used to decide whether the `empty_map` should be set or cleared. `walk->mm_stats` is an array within the `lru_gen_mm_walk` structure, so it's a critical point for determining what constitutes "empty".

Now I need to understand how `walk->mm_stats` is initialized. Let's look at `struct lru_gen_mm_walk` carefully. Aha! It appears the patch introduces several new elements to the `enum mm_stats_index`, including `MM_LEAF_ELIGIBLE`, `MM_WALK_TOTAL`, `MM_WALK_EMPTY`, and `MM_LEAF_TOTAL_EMPTY`. The key is to confirm that `walk->mm_stats` is zero-initialized or at least correctly initialized during the setup of a walk. This is where I need to focus to ensure there aren't any subtle initialization bugs. The logic around what constitutes a leaf and emptiness of the walk is critical for correctness. The addition of those enums is definitely an area to scrutinize.

54/3 2026/08/07 12:07 tool grepper
0m Args: 
{
  "Expression": "struct lru_gen_mm_walk"
}

Results: 
{
  "Output": "include/linux/mmzone.h=608=struct lru_gen_mm_state {\n--\ninclude/linux/mmzone.h-620-\ninclude/linux/mmzone.h:621:struct lru_gen_mm_walk {\ninclude/linux/mmzone.h-622-\t/* the lruvec under reclaim */\n--\ninclude/linux/mmzone.h=1483=typedef struct pglist_data {\n--\ninclude/linux/mmzone.h-1602-\t/* kswap mm walk data */\ninclude/linux/mmzone.h:1603:\tstruct lru_gen_mm_walk mm_walk;\ninclude/linux/mmzone.h-1604-\t/* lru_gen_folio list */\n--\ninclude/linux/swap.h=146=struct reclaim_state {\n--\ninclude/linux/swap.h-150-\t/* per-thread mm walk data */\ninclude/linux/swap.h:151:\tstruct lru_gen_mm_walk *mm_walk;\ninclude/linux/swap.h-152-#endif\n--\nmm/vmscan.c=2923=static unsigned long mglru_empty_skip_gens;\nmm/vmscan.c-2924-\nmm/vmscan.c:2925:static struct mm_struct *get_next_mm(struct lru_gen_mm_walk *walk)\nmm/vmscan.c-2926-{\n--\nmm/vmscan.c=3065=static struct lru_gen_mm_state *get_mm_state(struct lruvec *lruvec)\n--\nmm/vmscan.c-3069-\nmm/vmscan.c:3070:static struct mm_struct *get_next_mm(struct lru_gen_mm_walk *walk)\nmm/vmscan.c-3071-{\n--\nmm/vmscan.c-3076-\nmm/vmscan.c:3077:static void reset_mm_stats(struct lru_gen_mm_walk *walk, bool last)\nmm/vmscan.c-3078-{\n--\nmm/vmscan.c-3101-\nmm/vmscan.c:3102:static bool iterate_mm_list(struct lru_gen_mm_walk *walk, struct mm_struct **iter)\nmm/vmscan.c-3103-{\n--\nmm/vmscan.c=3319=static int folio_inc_gen(struct lruvec *lruvec, struct folio *folio)\n--\nmm/vmscan.c-3344-\nmm/vmscan.c:3345:static void update_batch_size(struct lru_gen_mm_walk *walk, struct folio *folio,\nmm/vmscan.c-3346-\t\t\t      int old_gen, int new_gen)\n--\nmm/vmscan.c-3360-\nmm/vmscan.c:3361:static void reset_batch_size(struct lru_gen_mm_walk *walk)\nmm/vmscan.c-3362-{\n--\nmm/vmscan.c=3388=static int should_skip_vma(unsigned long start, unsigned long end, struct mm_walk *args)\n--\nmm/vmscan.c-3391-\tstruct vm_area_struct *vma = args-\u003evma;\nmm/vmscan.c:3392:\tstruct lru_gen_mm_walk *walk = args-\u003eprivate;\nmm/vmscan.c-3393-\n--\nmm/vmscan.c=3526=static bool suitable_to_scan(int total, int young)\n--\nmm/vmscan.c-3533-\nmm/vmscan.c:3534:static void walk_update_folio(struct lru_gen_mm_walk *walk, struct vm_area_struct *vma,\nmm/vmscan.c-3535-\t\tstruct folio *folio, int new_gen, bool dirty)\n--\nmm/vmscan.c=3558=static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end,\n--\nmm/vmscan.c-3568-\tstruct folio *last = NULL;\nmm/vmscan.c:3569:\tstruct lru_gen_mm_walk *walk = args-\u003eprivate;\nmm/vmscan.c-3570-\tstruct mem_cgroup *memcg = lruvec_memcg(walk-\u003elruvec);\n--\nmm/vmscan.c=3651=static void walk_pmd_range_locked(pud_t *pud, unsigned long addr, struct vm_area_struct *vma,\n--\nmm/vmscan.c-3658-\tstruct folio *last = NULL;\nmm/vmscan.c:3659:\tstruct lru_gen_mm_walk *walk = args-\u003eprivate;\nmm/vmscan.c-3660-\tstruct mem_cgroup *memcg = lruvec_memcg(walk-\u003elruvec);\n--\nmm/vmscan.c=3741=static void walk_pmd_range(pud_t *pud, unsigned long start, unsigned long end,\n--\nmm/vmscan.c-3750-\tunsigned long first = -1;\nmm/vmscan.c:3751:\tstruct lru_gen_mm_walk *walk = args-\u003eprivate;\nmm/vmscan.c-3752-\tstruct lru_gen_mm_state *mm_state = get_mm_state(walk-\u003elruvec);\n--\nmm/vmscan.c=3814=static int walk_pud_range(p4d_t *p4d, unsigned long start, unsigned long end,\n--\nmm/vmscan.c-3820-\tunsigned long next;\nmm/vmscan.c:3821:\tstruct lru_gen_mm_walk *walk = args-\u003eprivate;\nmm/vmscan.c-3822-\n--\nmm/vmscan.c-3855-\nmm/vmscan.c:3856:static void walk_mm(struct mm_struct *mm, struct lru_gen_mm_walk *walk)\nmm/vmscan.c-3857-{\n--\nmm/vmscan.c-3890-\nmm/vmscan.c:3891:static struct lru_gen_mm_walk *set_mm_walk(struct pglist_data *pgdat, bool force_alloc)\nmm/vmscan.c-3892-{\nmm/vmscan.c:3893:\tstruct lru_gen_mm_walk *walk = current-\u003ereclaim_state-\u003emm_walk;\nmm/vmscan.c-3894-\n--\nmm/vmscan.c=3911=static void clear_mm_walk(void)\nmm/vmscan.c-3912-{\nmm/vmscan.c:3913:\tstruct lru_gen_mm_walk *walk = current-\u003ereclaim_state-\u003emm_walk;\nmm/vmscan.c-3914-\n--\nmm/vmscan.c=4094=static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long seq,\n--\nmm/vmscan.c-4097-\tbool success;\nmm/vmscan.c:4098:\tstruct lru_gen_mm_walk *walk;\nmm/vmscan.c-4099-\tstruct mm_struct *mm = NULL;\n--\nmm/vmscan.c=4327=bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw, unsigned int nr)\n--\nmm/vmscan.c-4332-\tunsigned long end;\nmm/vmscan.c:4333:\tstruct lru_gen_mm_walk *walk;\nmm/vmscan.c-4334-\tstruct folio *last = NULL;\n--\nmm/vmscan.c=4948=static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,\n--\nmm/vmscan.c-4956-\tstruct reclaim_stat stat;\nmm/vmscan.c:4957:\tstruct lru_gen_mm_walk *walk;\nmm/vmscan.c-4958-\tint scanned, reclaimed;\n"
}
55/3 2026/08/07 12:07 llm kmsan-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 9701
							output: 19
							thoughts: 43

Thoughts: 
Okay, here's my interpretation of that thought process, assuming I'm an expert in memory management and looking at a kernel data structure:

**Investigating `lru_gen_mm_walk` and its Statistics**

Alright, so I'm looking at this `struct lru_gen_mm_walk` and, as expected, it appears to have an `mm_stats` array. My immediate thought is, "Where and how is this thing getting initialized?" Knowing this is crucial for understanding its lifecycle and use within the larger LRU (Least Recently Used) management context.

The next logical step is to track down the initialization. Hmm, it looks like `set_mm_walk` is the likely culprit, either allocating or retrieving this `mm_stats` array. That function call is definitely where I need to focus my attention to get a clear picture of how these performance metrics are managed. I'll need to dig into the implementation of `set_mm_walk` now to see the specifics.

56/3 2026/08/07 12:07 tool grepper
0m Args: 
{
  "Expression": "set_mm_walk"
}

Results: 
{
  "Output": "mm/vmscan.c=3856=static void walk_mm(struct mm_struct *mm, struct lru_gen_mm_walk *walk)\n--\nmm/vmscan.c-3890-\nmm/vmscan.c:3891:static struct lru_gen_mm_walk *set_mm_walk(struct pglist_data *pgdat, bool force_alloc)\nmm/vmscan.c-3892-{\n--\nmm/vmscan.c=4094=static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long seq,\n--\nmm/vmscan.c-4122-\nmm/vmscan.c:4123:\twalk = set_mm_walk(NULL, true);\nmm/vmscan.c-4124-\tif (!walk) {\n--\nmm/vmscan.c=5283=static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\n--\nmm/vmscan.c-5293-\nmm/vmscan.c:5294:\tset_mm_walk(NULL, sc-\u003eproactive);\nmm/vmscan.c-5295-\n--\nmm/vmscan.c=5304=static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-5322-\nmm/vmscan.c:5323:\tset_mm_walk(pgdat, sc-\u003eproactive);\nmm/vmscan.c-5324-\n--\nmm/vmscan.c=5826=static ssize_t lru_gen_seq_write(struct file *file, const char __user *src,\n--\nmm/vmscan.c-5854-\tblk_start_plug(\u0026plug);\nmm/vmscan.c:5855:\tif (!set_mm_walk(NULL, true)) {\nmm/vmscan.c-5856-\t\terr = -ENOMEM;\n"
}
57/3 2026/08/07 12:07 llm kmsan-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 10507
							output: 35
							thoughts: 13

Thoughts: 
Okay, let's dive into this. Here's my take on those thoughts, as an expert in this area:

**Deconstructing the `set_mm_walk` Implementation**

Right, so the first thing I'm doing is getting my bearings. I need to understand what's actually happening under the hood with this `set_mm_walk` function. The name itself suggests we're walking through a memory map, probably setting something along the way. I'm immediately thinking about virtual memory, page tables, and how the kernel handles address spaces.

I'm mentally preparing for a deep dive into the code. I'll need to look for key data structures – `mm_struct`, `vm_area_struct`, and the page table entries themselves – to understand the scope of the walk and what's being modified. I'm expecting to see logic for traversing the page table hierarchy, perhaps checking permissions, and most likely, some mechanism for actually setting or modifying page table entries. The "set" part of the name is critical. Is it setting permissions? Is it mapping physical pages? Allocating new pages? I need the context to know.

I'll be paying close attention to any locking mechanisms used to protect the memory map during this walk. Concurrency is always a concern in kernel code, and any race conditions could lead to significant problems.

Basically, I'm mentally formulating a plan to deconstruct this function piece by piece, starting with the big picture and then zooming in on the details of the page table manipulations. I'm eager to understand the efficiency and the potential bottlenecks of this implementation.

58/3 2026/08/07 12:07 tool read-file
0m Args: 
{
  "File": "mm/vmscan.c",
  "FirstLine": 3891,
  "LineCount": 20
}

Results: 
{
  "Contents": "3891:\tstatic struct lru_gen_mm_walk *set_mm_walk(struct pglist_data *pgdat, bool force_alloc)\n3892:\t{\n3893:\t\tstruct lru_gen_mm_walk *walk = current-\u003ereclaim_state-\u003emm_walk;\n3894:\t\n3895:\t\tif (pgdat \u0026\u0026 current_is_kswapd()) {\n3896:\t\t\tVM_WARN_ON_ONCE(walk);\n3897:\t\n3898:\t\t\twalk = \u0026pgdat-\u003emm_walk;\n3899:\t\t} else if (!walk \u0026\u0026 force_alloc) {\n3900:\t\t\tVM_WARN_ON_ONCE(current_is_kswapd());\n3901:\t\n3902:\t\t\twalk = kzalloc_obj(*walk,\n3903:\t\t\t\t\t   __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN);\n3904:\t\t}\n3905:\t\n3906:\t\tcurrent-\u003ereclaim_state-\u003emm_walk = walk;\n3907:\t\n3908:\t\treturn walk;\n3909:\t}\n3910:\t\n"
}
59/3 2026/08/07 12:07 llm kmsan-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 11211
							output: 35
							thoughts: 312

Thoughts: 
**Analyzing Memory Allocation and Usage in `try_to_inc_max_seq`**

Okay, so I'm looking at this `kzalloc_obj(*walk, ...)` call, which, as a zero-initializing allocation, immediately catches my attention. Since `walk` points to `pgdat->mm_walk`, which itself is part of a `pgdat` structure that's zero-initialized on allocation, that seems straightforward. But wait a minute... I see `walk->mm_stats` being used within `try_to_inc_max_seq`. That throws a wrench in the works.

Specifically, I'm concerned about this snippet:

```c
	do {
		success = iterate_mm_list(walk, &mm);
		if (mm) {
			int nid = lruvec_pgdat(lruvec)->node_id;
			int key = nid % BITS_PER_TYPE(mm->lru_gen.bitmap);
			bool empty = false;

			walk_mm(mm, walk);

			/*
			 * Any walk that found no folio for this lruvec is empty -
			 * even if the PMD-level Bloom filter kept MM_LEAF_TOTAL at 0
			 * (the common case for a foreign mm). Mark it so get_next_mm()
			 * skips it next time; otherwise the empty-walk skip never
			 * engages for the walks that matter most.
			 */
			if (walk->mm_stats[MM_LEAF_ELIGIBLE] == 0) {
```

I'm wondering if `walk->mm_stats` is properly reset or re-initialized for each iteration, for each `mm` being processed. If it isn't, the accumulated values from previous `mm` iterations would affect the logic. That would be a subtle bug!

The key here is understanding how `walk_mm` works. I need to dive into its implementation to confirm if it resets or appropriately manages `walk->mm_stats` before operating on each `mm`. That's where the answer lies. Let's dig in and see how it's handled.

60/3 2026/08/07 12:08 tool read-file
0m Args: 
{
  "File": "mm/vmscan.c",
  "FirstLine": 3856,
  "LineCount": 35
}

Results: 
{
  "Contents": "3856:\tstatic void walk_mm(struct mm_struct *mm, struct lru_gen_mm_walk *walk)\n3857:\t{\n3858:\t\tstatic const struct mm_walk_ops mm_walk_ops = {\n3859:\t\t\t.test_walk = should_skip_vma,\n3860:\t\t\t.p4d_entry = walk_pud_range,\n3861:\t\t\t.walk_lock = PGWALK_RDLOCK,\n3862:\t\t};\n3863:\t\tint err;\n3864:\t\tstruct lruvec *lruvec = walk-\u003elruvec;\n3865:\t\n3866:\t\twalk-\u003enext_addr = FIRST_USER_ADDRESS;\n3867:\t\n3868:\t\tdo {\n3869:\t\t\tDEFINE_MAX_SEQ(lruvec);\n3870:\t\n3871:\t\t\terr = -EBUSY;\n3872:\t\n3873:\t\t\t/* another thread might have called inc_max_seq() */\n3874:\t\t\tif (walk-\u003eseq != max_seq)\n3875:\t\t\t\tbreak;\n3876:\t\n3877:\t\t\t/* the caller might be holding the lock for write */\n3878:\t\t\tif (mmap_read_trylock(mm)) {\n3879:\t\t\t\terr = walk_page_range(mm, walk-\u003enext_addr, ULONG_MAX, \u0026mm_walk_ops, walk);\n3880:\t\n3881:\t\t\t\tmmap_read_unlock(mm);\n3882:\t\t\t}\n3883:\t\n3884:\t\t\tif (walk-\u003ebatched)\n3885:\t\t\t\treset_batch_size(walk);\n3886:\t\n3887:\t\t\tcond_resched();\n3888:\t\t} while (err == -EAGAIN);\n3889:\t}\n3890:\t\n"
}
61/3 2026/08/07 12:08 llm kmsan-evaluator
5m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 12536
							output: 19
							thoughts: 30

Thoughts: 
Here's a summary of my thought process:

**A Kernel Memory Management Question**

Okay, hold on a second. I'm looking at the memory management code, specifically the `walk->mm_stats` structure. I'm pretty sure I saw this used in `walk_mm`, but now I'm thinking, wait... is it *actually* being reset properly within that function? The more I look, the more I'm not convinced. The logic seems like it *should* be, but I need to be absolutely certain. My gut says there might be a subtle bug brewing here.

So, I need to verify. Let me immediately check the definition of `reset_mm_stats`. I want to see what that function *should* be doing and how it relates to what's happening, or not happening, in `walk_mm`. I'm going to follow the logic chain carefully to pinpoint exactly where things are getting initialized and reset. I'm betting that the source of an issue, if there is one, will lie in a missing or mis-applied call to that function, or in incorrect assumptions in the call site of `reset_mm_stats`. No, this is likely a problem. Let's see how much memory that is actually wasting and if it is an issue.

62/3 2026/08/07 12:13 tool grepper
0m Args: 
{
  "Expression": "reset_mm_stats"
}

Results: 
{
  "Output": "mm/vmscan.c=3070=static struct mm_struct *get_next_mm(struct lru_gen_mm_walk *walk)\n--\nmm/vmscan.c-3076-\nmm/vmscan.c:3077:static void reset_mm_stats(struct lru_gen_mm_walk *walk, bool last)\nmm/vmscan.c-3078-{\n--\nmm/vmscan.c=3102=static bool iterate_mm_list(struct lru_gen_mm_walk *walk, struct mm_struct **iter)\n--\nmm/vmscan.c-3150-\tif (*iter || last)\nmm/vmscan.c:3151:\t\treset_mm_stats(walk, last);\nmm/vmscan.c-3152-\n"
}
63/3 2026/08/07 12:14 llm kmsan-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 13073
							output: 35
							thoughts: 11

Thoughts: 
Okay, let's dive into this. Here's my take on understanding this `reset_mm_stats` function, as a seasoned professional:

**Deconstructing `reset_mm_stats`**

Alright, I'm going to take a look at the `reset_mm_stats` function. My initial thought is, based on the naming convention, it's pretty clear what its core purpose is: it's designed to clear or reset memory management statistics. Now, the key question is *which* statistics and *how* it's doing it.

I'll be looking for things like:

*   **Data Structures Targeted:** What specific data structures or counters are being zeroed out? Is it per-process (mm_struct), system-wide, or perhaps a combination? I'll pay close attention to the specific structures being accessed.
*   **Granularity:** What level of detail is being cleared? Does it reset everything at once, or are there options to reset specific subsets of statistics (e.g., just page fault counters, or just kernel allocations)? This will give me an insight into the intended usage model.
*   **Concurrency Considerations:** Since memory management is often highly concurrent, I'll be looking for any locks or synchronization primitives involved. A simple `memset` wouldn't be very interesting, but a subtle race condition in there would be. Are these stats protected by a mutex, a spinlock, or something more sophisticated? This matters for real-world performance implications and correctness.
*   **Error Handling (or lack thereof):** Is there any checking? Any error cases that might be handled? What happens if it encounters a bad address or if it can't update a particular counter? It's unlikely for a reset to fail, but it's worth checking.
*   **Caller Context:** Who is calling this function, and under what circumstances? Understanding the calling context will help me to deduce its purpose within the broader memory management architecture and how it's used. Is it called during boot, or in some sort of monitoring routine? Is there some particular point in execution where it makes sense to clear the stats?

I expect this is a fairly low-level function, so it's probably going to use fairly straightforward and efficient techniques. I'll focus on getting a good handle on those "what" and "how" questions and connecting them to the larger picture of the memory management system. Okay, let's see what's in there.

64/3 2026/08/07 12:14 tool read-file
0m Args: 
{
  "File": "mm/vmscan.c",
  "FirstLine": 3077,
  "LineCount": 25
}

Results: 
{
  "Contents": "3077:\tstatic void reset_mm_stats(struct lru_gen_mm_walk *walk, bool last)\n3078:\t{\n3079:\t\tint i;\n3080:\t\tint hist;\n3081:\t\tstruct lruvec *lruvec = walk-\u003elruvec;\n3082:\t\tstruct lru_gen_mm_state *mm_state = get_mm_state(lruvec);\n3083:\t\n3084:\t\tlockdep_assert_held(\u0026get_mm_list(lruvec_memcg(lruvec))-\u003elock);\n3085:\t\n3086:\t\thist = lru_hist_from_seq(walk-\u003eseq);\n3087:\t\n3088:\t\tfor (i = 0; i \u003c NR_MM_STATS; i++) {\n3089:\t\t\tWRITE_ONCE(mm_state-\u003estats[hist][i],\n3090:\t\t\t\t   mm_state-\u003estats[hist][i] + walk-\u003emm_stats[i]);\n3091:\t\t\twalk-\u003emm_stats[i] = 0;\n3092:\t\t}\n3093:\t\n3094:\t\tif (NR_HIST_GENS \u003e 1 \u0026\u0026 last) {\n3095:\t\t\thist = lru_hist_from_seq(walk-\u003eseq + 1);\n3096:\t\n3097:\t\t\tfor (i = 0; i \u003c NR_MM_STATS; i++)\n3098:\t\t\t\tWRITE_ONCE(mm_state-\u003estats[hist][i], 0);\n3099:\t\t}\n3100:\t}\n3101:\t\n"
}
65/3 2026/08/07 12:14 llm kmsan-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 14075
							output: 35
							thoughts: 31

Thoughts: 
Okay, here's my interpretation of that thought process, assuming I'm deep in the weeds of memory management code:

**Diving into the Iteration**

Okay, so `reset_mm_stats` gets called from within `iterate_mm_list`. That's an interesting hook. I need to understand how that interaction works. My next logical step is to delve into `iterate_mm_list` itself. I need to see the context in which `reset_mm_stats` is being invoked. What's the iteration doing? What data is being iterated over? What's the overall purpose of this loop, and how does `reset_mm_stats` fit into that process? Understanding `iterate_mm_list` is key to grasping the impact of `reset_mm_stats`. I need to read the code directly.

66/3 2026/08/07 12:14 tool read-file
0m Args: 
{
  "File": "mm/vmscan.c",
  "FirstLine": 3102,
  "LineCount": 50
}

Results: 
{
  "Contents": "3102:\tstatic bool iterate_mm_list(struct lru_gen_mm_walk *walk, struct mm_struct **iter)\n3103:\t{\n3104:\t\tbool first = false;\n3105:\t\tbool last = false;\n3106:\t\tstruct mm_struct *mm = NULL;\n3107:\t\tstruct lruvec *lruvec = walk-\u003elruvec;\n3108:\t\tstruct mem_cgroup *memcg = lruvec_memcg(lruvec);\n3109:\t\tstruct lru_gen_mm_list *mm_list = get_mm_list(memcg);\n3110:\t\tstruct lru_gen_mm_state *mm_state = get_mm_state(lruvec);\n3111:\t\n3112:\t\t/*\n3113:\t\t * mm_state-\u003eseq is incremented after each iteration of mm_list. There\n3114:\t\t * are three interesting cases for this page table walker:\n3115:\t\t * 1. It tries to start a new iteration with a stale max_seq: there is\n3116:\t\t *    nothing left to do.\n3117:\t\t * 2. It started the next iteration: it needs to reset the Bloom filter\n3118:\t\t *    so that a fresh set of PTE tables can be recorded.\n3119:\t\t * 3. It ended the current iteration: it needs to reset the mm stats\n3120:\t\t *    counters and tell its caller to increment max_seq.\n3121:\t\t */\n3122:\t\tspin_lock(\u0026mm_list-\u003elock);\n3123:\t\n3124:\t\tVM_WARN_ON_ONCE(mm_state-\u003eseq + 1 \u003c walk-\u003eseq);\n3125:\t\n3126:\t\tif (walk-\u003eseq \u003c= mm_state-\u003eseq)\n3127:\t\t\tgoto done;\n3128:\t\n3129:\t\tif (!mm_state-\u003ehead)\n3130:\t\t\tmm_state-\u003ehead = \u0026mm_list-\u003efifo;\n3131:\t\n3132:\t\tif (mm_state-\u003ehead == \u0026mm_list-\u003efifo)\n3133:\t\t\tfirst = true;\n3134:\t\n3135:\t\tdo {\n3136:\t\t\tmm_state-\u003ehead = mm_state-\u003ehead-\u003enext;\n3137:\t\t\tif (mm_state-\u003ehead == \u0026mm_list-\u003efifo) {\n3138:\t\t\t\tWRITE_ONCE(mm_state-\u003eseq, mm_state-\u003eseq + 1);\n3139:\t\t\t\tlast = true;\n3140:\t\t\t\tbreak;\n3141:\t\t\t}\n3142:\t\n3143:\t\t\t/* force scan for those added after the last iteration */\n3144:\t\t\tif (!mm_state-\u003etail || mm_state-\u003etail == mm_state-\u003ehead) {\n3145:\t\t\t\tmm_state-\u003etail = mm_state-\u003ehead-\u003enext;\n3146:\t\t\t\twalk-\u003eforce_scan = true;\n3147:\t\t\t}\n3148:\t\t} while (!(mm = get_next_mm(walk)));\n3149:\tdone:\n3150:\t\tif (*iter || last)\n3151:\t\t\treset_mm_stats(walk, last);\n"
}
67/3 2026/08/07 12:14 llm kmsan-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 15162
							output: 35
							thoughts: 1024

Thoughts: 
**Analyzing Potential Uninitialized Memory Reads in `try_to_inc_max_seq`**

Okay, so I'm looking at this patch and I need to make sure there aren't any uninitialized memory reads. My initial thought is that `walk->mm_stats` is zeroed in `reset_mm_stats`. But, hang on, `walk->mm_stats` is actually an array of size `NR_MM_STATS`. The patch increases the size of `NR_MM_STATS`, so I need to be careful. `reset_mm_stats` *should* iterate through all of them and zero them.

Now, let's trace this through `try_to_inc_max_seq`. Looking at the code:

```c
	do {
		success = iterate_mm_list(walk, &mm);
		if (mm) {
			int nid = lruvec_pgdat(lruvec)->node_id;
			int key = nid % BITS_PER_TYPE(mm->lru_gen.bitmap);
			bool empty = false;

			walk_mm(mm, walk);

			/*
			 * Any walk that found no folio for this lruvec is empty -
			 * even if the PMD-level Bloom filter kept MM_LEAF_TOTAL at 0
			 * (the common case for a foreign mm). Mark it so get_next_mm()
			 * skips it next time; otherwise the empty-walk skip never
			 * engages for the walks that matter most.
			 */
			if (walk->mm_stats[MM_LEAF_ELIGIBLE] == 0) {
				set_bit(key, &mm->lru_gen.empty_map);
				/* track the oldest marking (conservative) */
				WRITE_ONCE(mm->lru_gen.empty_map_seq,
					min(READ_ONCE(mm->lru_gen.empty_map_seq),
					    walk->seq));
				empty = true;
			} else {
				/* found eligible folios: clear the marking */
				clear_bit(key, &mm->lru_gen.empty_map);
			}

			/* measurement stats keep the leaf_total gate */
			if (walk->mm_stats[MM_LEAF_TOTAL]) {
				walk->mm_stats[MM_WALK_TOTAL]++;
				if (empty) {
					walk->mm_stats[MM_WALK_EMPTY]++;
					walk->mm_stats[MM_LEAF_TOTAL_EMPTY] +=
						walk->mm_stats[MM_LEAF_TOTAL];
				}
			}
			trace_mm_vmscan_lru_gen_walk(
					lruvec_pgdat(lruvec)->node_id, walk->seq,
					walk->mm_stats[MM_LEAF_TOTAL],
					walk->mm_stats[MM_LEAF_ELIGIBLE], empty);
		}
	} while (mm);
```

I remember that `walk->mm_stats` is initialized to 0 in `set_mm_walk`, because it uses something like `kzalloc_obj`, or because `pgdat->mm_walk` gets zeroed. Okay, checking, `pgdat->mm_walk` is part of `pglist_data`. And `pglist_data` is initialized with `kzalloc` or similar, which means it should be zeroed as well. And `reset_mm_stats` should zero all the values in `walk->mm_stats`.

Alright, back to the code again. First `iterate_mm_list` is called. If `*iter` (which is `mm` from the previous iteration) is not NULL, then `reset_mm_stats` is called. Important. And `mm` is initialized to `NULL` before the loop starts:

```c
	struct mm_struct *mm = NULL;
	do {
		success = iterate_mm_list(walk, &mm);
		if (mm) {
```

So on the *first* iteration, `mm` is `NULL`, which means `*iter` is also `NULL`. This means `reset_mm_stats` is NOT called *unless* `last` is true. But `walk->mm_stats` should already be zeroed from when `walk` was allocated or retrieved.

The question is, what if `walk` was used previously and `reset_mm_stats` wasn't called at the end of the previous iteration? Let's see... `iterate_mm_list` does call `

68/3 2026/08/07 12:14 tool read-file
0m Args: 
{
  "File": "mm/vmscan.c",
  "FirstLine": 4094,
  "LineCount": 60
}

Results: 
{
  "Contents": "4094:\tstatic bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long seq,\n4095:\t\t\t\t       int swappiness, bool force_scan)\n4096:\t{\n4097:\t\tbool success;\n4098:\t\tstruct lru_gen_mm_walk *walk;\n4099:\t\tstruct mm_struct *mm = NULL;\n4100:\t\tstruct lru_gen_folio *lrugen = \u0026lruvec-\u003elrugen;\n4101:\t\tstruct lru_gen_mm_state *mm_state = get_mm_state(lruvec);\n4102:\t\n4103:\t\tVM_WARN_ON_ONCE(seq \u003e READ_ONCE(lrugen-\u003emax_seq));\n4104:\t\n4105:\t\tif (!mm_state)\n4106:\t\t\treturn inc_max_seq(lruvec, seq, swappiness);\n4107:\t\n4108:\t\t/* see the comment in iterate_mm_list() */\n4109:\t\tif (seq \u003c= READ_ONCE(mm_state-\u003eseq))\n4110:\t\t\treturn false;\n4111:\t\n4112:\t\t/*\n4113:\t\t * If the hardware doesn't automatically set the accessed bit, fallback\n4114:\t\t * to lru_gen_look_around(), which only clears the accessed bit in a\n4115:\t\t * handful of PTEs. Spreading the work out over a period of time usually\n4116:\t\t * is less efficient, but it avoids bursty page faults.\n4117:\t\t */\n4118:\t\tif (!should_walk_mmu()) {\n4119:\t\t\tsuccess = iterate_mm_list_nowalk(lruvec, seq);\n4120:\t\t\tgoto done;\n4121:\t\t}\n4122:\t\n4123:\t\twalk = set_mm_walk(NULL, true);\n4124:\t\tif (!walk) {\n4125:\t\t\tsuccess = iterate_mm_list_nowalk(lruvec, seq);\n4126:\t\t\tgoto done;\n4127:\t\t}\n4128:\t\n4129:\t\twalk-\u003elruvec = lruvec;\n4130:\t\twalk-\u003eseq = seq;\n4131:\t\twalk-\u003eswappiness = swappiness;\n4132:\t\twalk-\u003eforce_scan = force_scan;\n4133:\t\n4134:\t\tdo {\n4135:\t\t\tsuccess = iterate_mm_list(walk, \u0026mm);\n4136:\t\t\tif (mm) {\n4137:\t\t\t\tint nid = lruvec_pgdat(lruvec)-\u003enode_id;\n4138:\t\t\t\tint key = nid % BITS_PER_TYPE(mm-\u003elru_gen.bitmap);\n4139:\t\t\t\tbool empty = false;\n4140:\t\n4141:\t\t\t\twalk_mm(mm, walk);\n4142:\t\n4143:\t\t\t\t/*\n4144:\t\t\t\t * Any walk that found no folio for this lruvec is empty -\n4145:\t\t\t\t * even if the PMD-level Bloom filter kept MM_LEAF_TOTAL at 0\n4146:\t\t\t\t * (the common case for a foreign mm). Mark it so get_next_mm()\n4147:\t\t\t\t * skips it next time; otherwise the empty-walk skip never\n4148:\t\t\t\t * engages for the walks that matter most.\n4149:\t\t\t\t */\n4150:\t\t\t\tif (walk-\u003emm_stats[MM_LEAF_ELIGIBLE] == 0) {\n4151:\t\t\t\t\tset_bit(key, \u0026mm-\u003elru_gen.empty_map);\n4152:\t\t\t\t\t/* track the oldest marking (conservative) */\n4153:\t\t\t\t\tWRITE_ONCE(mm-\u003elru_gen.empty_map_seq,\n"
}
69/3 2026/08/07 12:14 llm kmsan-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 18248
							output: 22
							thoughts: 1262

Thoughts: 
**Analyzing the Initialization and State of the LRU Generation Walk**

Okay, so I'm looking at how the LRU generation walk is set up and ensuring everything is properly initialized to avoid any unexpected behavior. The first thing I see is the call to `set_mm_walk(NULL, true)`.  This function seems to be responsible for either retrieving an existing `lru_gen_mm_walk` structure associated with the current task (`current->reclaim_state->mm_walk`) or allocating a new one. The key is to understand if the returned `walk` structure's `mm_stats` member is consistently zeroed, or if we are relying on prior zeroing.

Diving into `set_mm_walk`, I confirm my suspicion: it either reuses an existing `walk` or allocates a new one with `kzalloc_obj`, which *does* guarantee zero initialization of the allocated memory, particularly `mm_stats`. I need to understand when and how `current->reclaim_state->mm_walk` is cleared because that would be a point where a previously initialized `walk` is released.  `clear_mm_walk` is the answer.

Looking at `clear_mm_walk`, there's a crucial `VM_WARN_ON_ONCE` that confirms `walk->mm_stats` *must* be zeroed before the walk is cleared, and specifically the check `memchr_inv(walk->mm_stats, 0, sizeof(walk->mm_stats))`. This means we are being very explicit about the expected state.  Also, it's clear the memory is only freed if the current task is *not* `kswapd`.

So, the design dictates that if a new walk is started, or reset during the walk, that `walk->mm_stats` is guaranteed to be zero. The `reset_mm_stats` function does this explicitly.

Next, I need to understand the control flow. What happens if `iterate_mm_list` returns a "failure" case, where `mm = NULL`?  It seems possible, in that case, `iterate_mm_list` may have called `reset_mm_stats` if `last = true`. However, if `last = false`, then the walk is short-circuited and `reset_mm_stats` is *not* called, but the condition `walk->seq <= mm_state->seq` should ensure that the zeroed `mm_stats` of `walk` is already up to date. This all means `walk->mm_stats` is always properly initialized.

Now, I want to verify that no uninitialized variables are used within the `trace_mm_vmscan_lru_gen_walk` tracepoint. The tracepoint seems to be the critical reporting location. I see `empty` being explicitly initialized to `false`, `walk->mm_stats` is initialized from the logic discussed above, `walk->seq` is initialized elsewhere, and `lruvec_pgdat(lruvec)->node_id` is derived from an initialized `lruvec`. All checks out!

Finally, I'll review `mglru_empty_skip_gens` which is initialized to 4 and can be modified at runtime.  The potential modification in `lru_gen_seq_write` uses `sscanf`, so it's only set if `sscanf` returns 1, so this is safe.

I also need to ensure `mm->lru_gen.empty_map` and `mm->lru_gen.empty_map_seq` are initialized. These variables appear to be correctly initialized in `lru_gen_init_mm`, which is called as part of `mm_init` so that checks out. I did a quick mental scan to make sure I'm not missing any other places where `mm_struct` could be created, but `lru_gen_init_mm` should have it covered.

In summary, based on my analysis of the code, all critical variables related to the LRU generation walk are initialized and handled correctly, making sure there are no uninitialized variables. The `mm_stats` data is always properly zeroed before use, either through initialization or reset. The logic involving the tracepoint, the empty skip gens, and the initialization of the `mm_struct` data, all seem robust.

70/3 2026/08/07 12:15 tool grepper
0m Args: 
{
  "Expression": "lru_gen_init_mm"
}

Results: 
{
  "Output": "include/linux/mm_types.h=1511=void lru_gen_migrate_mm(struct mm_struct *mm);\ninclude/linux/mm_types.h-1512-\ninclude/linux/mm_types.h:1513:static inline void lru_gen_init_mm(struct mm_struct *mm)\ninclude/linux/mm_types.h-1514-{\n--\ninclude/linux/mm_types.h=1558=static inline void lru_gen_migrate_mm(struct mm_struct *mm)\n--\ninclude/linux/mm_types.h-1561-\ninclude/linux/mm_types.h:1562:static inline void lru_gen_init_mm(struct mm_struct *mm)\ninclude/linux/mm_types.h-1563-{\n--\nkernel/fork.c=1085=static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)\n--\nkernel/fork.c-1144-\nkernel/fork.c:1145:\tlru_gen_init_mm(mm);\nkernel/fork.c-1146-\treturn mm;\n"
}
71/3 2026/08/07 12:15 llm kmsan-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 20781
							output: 35
							thoughts: 767

Thoughts: 
**Analyzing the LRU Generation Implementation**

Okay, so I'm diving into this LRU generation code. First, the `lru_gen_init_mm` function is initialized in `mm_init`, as expected. That makes sense, because it needs to set up the `mm_struct` structures.

Now, let's look at `get_next_mm`. The code checks if it can skip a scan based on the `empty_map`. It reads `empty_seq` from `mm->lru_gen.empty_map_seq` and also references `mglru_empty_skip_gens`.  `max_seq` is initialized using `DEFINE_MAX_SEQ` which reads `(lruvec)->lrugen.max_seq`. So far, this all appears safe, especially given my knowledge of concurrent access patterns in the kernel. No obvious race conditions or issues here.

Next, I'll examine `lru_gen_mm_accessed`. This function is called in `do_anonymous_page`, `finish_fault`, and `remove_migration_pte` – all critical paths. The `nid` is derived from `folio_nid(folio)`, which provides the node ID. A key is calculated by modulo operation.  This seems okay; the bit manipulation with `set_bit` and `clear_bit` looks correct for tracking access. No red flags here.

Finally, I'm checking `lru_gen_seq_show_full`. I see that `NR_MM_STATS` has been increased from 4 to 8. This is a significant change, so I'm keen to understand the consequences of this. The string `s` is updated to be eight characters long. And that string `s` is used to print stats. I'll need to examine exactly how `s` is used in that printing function. I need to be sure that the string format is consistent and that no buffer overflows or similar vulnerabilities are introduced with this change. It would be a problem to write outside allocated memory, and I'll need to check the format string itself.

72/3 2026/08/07 12:15 tool read-file
0m Args: 
{
  "File": "mm/vmscan.c",
  "FirstLine": 5660,
  "LineCount": 25
}

Results: 
{
  "Contents": "5660:\t\n5661:\t\tseq_puts(m, \"                      \");\n5662:\t\tfor (i = 0; i \u003c NR_MM_STATS; i++) {\n5663:\t\t\tconst char *s = \"xxxxxxxx\";\n5664:\t\t\tunsigned long n = 0;\n5665:\t\n5666:\t\t\tif (seq == max_seq \u0026\u0026 NR_HIST_GENS == 1) {\n5667:\t\t\t\ts = \"TYFALWEE\";\n5668:\t\t\t\tn = READ_ONCE(mm_state-\u003estats[hist][i]);\n5669:\t\t\t} else if (seq != max_seq \u0026\u0026 NR_HIST_GENS \u003e 1) {\n5670:\t\t\t\ts = \"tyfalwee\";\n5671:\t\t\t\tn = READ_ONCE(mm_state-\u003estats[hist][i]);\n5672:\t\t\t}\n5673:\t\n5674:\t\t\tseq_printf(m, \" %10lu%c\", n, s[i]);\n5675:\t\t}\n5676:\t\tseq_putc(m, '\\n');\n5677:\t}\n5678:\t\n5679:\t/* see Documentation/admin-guide/mm/multigen_lru.rst for details */\n5680:\tstatic int lru_gen_seq_show(struct seq_file *m, void *v)\n5681:\t{\n5682:\t\tunsigned long seq;\n5683:\t\tbool full = debugfs_get_aux_num(m-\u003efile);\n5684:\t\tstruct lruvec *lruvec = v;\n"
}
73/3 2026/08/07 12:15 llm kmsan-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 22459
							output: 24
							thoughts: 584

Thoughts: 
**Analyzing Memory Safety and Data Leakage**

Okay, let's break this down. First, the code uses `s[i]`. Given that `NR_MM_STATS` is 8, the loop index `i` ranges from 0 to 7.  The string `s` can be "xxxxxxxx", "TYFALWEE", or "tyfalwee", all of which are 8 characters long.  Therefore, accessing `s[i]` is perfectly safe; no out-of-bounds access there.  That's a relief.

Now, the more interesting question: is anything being leaked to user space? The code references `mm_vmscan_lru_gen_walk`, which suggests data is sent to userspace via the tracing subsystem, namely ftrace/perf. Looking at the tracepoint definition, it seems pretty clear that the information being sent consists of the fields: `nid`, `seq`, `leaf_total`, `leaf_eligible`, and `empty`.

It seems these fields are properly initialized:
*   `nid` is assigned from `lruvec_pgdat(lruvec)->node_id`.
*   `seq` is assigned from `walk->seq`.
*   `leaf_total` is assigned from `walk->mm_stats[MM_LEAF_TOTAL]`.
*   `leaf_eligible` is assigned from `walk->mm_stats[MM_LEAF_ELIGIBLE]`.
*   `empty` is assigned the boolean `empty`.

The tracing subsystem, as I recall, creates a copy of the fields before sending them to userspace.  So, no direct passing of internal pointers or memory to user space.  Also, since everything is initialized before being copied, there's no obvious uninitialized memory leak here. That's a good sign.

Finally, I'm thinking about `mm_state->stats`.  It's an array of size `[NR_HIST_GENS][NR_MM_STATS]`, which is part of a `struct lru_gen_mm_state`.  I should probably double-check the definition of `struct lru_gen_mm_state` just to be completely certain, but based on what I see here, I'm not immediately concerned about uninitialized memory in `mm_state->stats` being leaked.  I can come back to this to be sure, but for now, it's not a red flag.

74/3 2026/08/07 12:15 tool grepper
0m Error: 
bad expression: fatal: -e option, 'struct lru_gen_mm_state {': Unmatched \{

Args: 
{
  "Expression": "struct lru_gen_mm_state {"
}

Results: 
{
  "error": "bad expression: fatal: -e option, 'struct lru_gen_mm_state {': Unmatched \\{"
}
75/3 2026/08/07 12:15 llm kmsan-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 23629
							output: 24
							thoughts: 8

Thoughts: 
Okay, here's the summary, rendered as a first-person thought process, aimed at an expert, and starting with a bolded header:

**Encoding Considerations for Escaping Delimiters**

Right, so I'm encountering a `{`. I immediately need to think about how I'm going to handle this. It's a delimiter, almost certainly signifying something special, and therefore I need to make sure that whatever process I'm working with respects that and doesn't misinterpret its meaning. My primary concern right now is the encoding strategy I need to employ. What’s the context? Am I dealing with a configuration file, a templating system, or something else entirely? The method of escaping will vary widely depending on the purpose. I need to figure out the right escape character or method to prevent the literal interpretation of this character. I must avoid conflicts with other aspects of the system. I really need to remember my priorities: accuracy and security. I want to prevent unexpected behavior and any potential for injections. Right, I need to make sure I am on top of this.

76/3 2026/08/07 12:15 tool grepper
0m Args: 
{
  "Expression": "struct lru_gen_mm_state \\{"
}

Results: 
{
  "Output": "include/linux/mmzone.h=593=enum {\n--\ninclude/linux/mmzone.h-607-\ninclude/linux/mmzone.h:608:struct lru_gen_mm_state {\ninclude/linux/mmzone.h-609-\t/* synced with max_seq after each iteration */\n"
}
77/3 2026/08/07 12:15 llm kmsan-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 23979
							output: 36
							thoughts: 15

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

**Diving into `lru_gen_mm_state`**

Alright, let's get down to brass tacks. I need to understand what's going on with this `struct lru_gen_mm_state`. Given the name, I'm expecting this to be related to the Memory Management (MM) layer and likely some form of Least Recently Used (LRU) cache or management, possibly with generational aspects, too. "Gen" usually implies a multi-generational approach, which would be interesting to dissect. I'm immediately thinking about how this ties into page reclamation strategies, possibly with a focus on aging pages across different generations of memory usage to improve efficiency. I need to see how it interacts with other MM components and the overall system's memory management policy. Let's see what we're dealing with... time to dig in.

78/3 2026/08/07 12:15 tool read-file
0m Args: 
{
  "File": "include/linux/mmzone.h",
  "FirstLine": 608,
  "LineCount": 15
}

Results: 
{
  "Contents": " 608:\tstruct lru_gen_mm_state {\n 609:\t\t/* synced with max_seq after each iteration */\n 610:\t\tunsigned long seq;\n 611:\t\t/* where the current iteration continues after */\n 612:\t\tstruct list_head *head;\n 613:\t\t/* where the last iteration ended before */\n 614:\t\tstruct list_head *tail;\n 615:\t\t/* Bloom filters flip after each iteration */\n 616:\t\tunsigned long *filters[NR_BLOOM_FILTERS];\n 617:\t\t/* the mm stats for debugging */\n 618:\t\tunsigned long stats[NR_HIST_GENS][NR_MM_STATS];\n 619:\t};\n 620:\t\n 621:\tstruct lru_gen_mm_walk {\n 622:\t\t/* the lruvec under reclaim */\n"
}
79/3 2026/08/07 12:15 llm kmsan-evaluator
0m Model: 
gemini-3.1-pro-preview

Args: 
null

Results: 
null

Tokens: 
							input: 24473
							output: 200
							thoughts: 1437

Thoughts: 
**KMSAN Assessment: MGLRU Empty-Walk Suppression Patch**

Okay, let's break this down. My initial assessment is that this patch, focused on MGLRU and the empty-walk suppression feature, doesn't present any immediate KMSAN concerns. My thinking is based on a methodical review of the code changes, ensuring no uninitialized memory issues are introduced.

First, the core data structure, `struct lruvec`, is key. The relevant part, `struct lru_gen_mm_state`, which includes the statistics, is zero-initialized because `lruvec` itself is either part of `pglist_data` or `mem_cgroup_per_node`, both allocated using `kzalloc` or equivalent functions that guarantee zero initialization. Thus, any new fields added within are also zeroed at initialization. The same applies for `struct lru_gen_mm_walk`.

The patch introduces modifications to several functions. I made sure to check them to make sure there are no issues.

1.  **New Fields and Initialization:** The new fields in `struct mm_struct` and `struct lru_gen_mm_walk`, which are associated with this empty-walk suppression, are all initialized either directly (e.g., in `lru_gen_init_mm`) or inherited via `kzalloc`. This eliminates the risk of reading uninitialized memory.

2.  **Tracepoints:** The addition of the tracepoint, `mm_vmscan_lru_gen_walk`, is also safe. This tracepoint is only exposing fields of structures which are already properly initialized, ensuring no data leaks or unintended reads.

3.  **Debugfs Interface:** The debugfs write support, which allows for configuring the "skip\_empty" threshold, uses `sscanf`. The logic there is robust. If `sscanf` returns 1, meaning it successfully parsed a value, then that value is used. If `sscanf` returns 0, the uninitialized variable is not used.

4.  **Array Accesses:** The access to the `walk->mm_stats` array is safe. The array is zero-initialized and any increments occur within the bounds of the array. The code in `walk_pte_range` and `walk_pmd_range_locked` properly increment `walk->mm_stats[MM_LEAF_ELIGIBLE]`. The use of `BITS_PER_TYPE` in `lru_gen_mm_accessed` is also not a KMSAN issue, as the potential integer underflow would result in an out-of-bounds access if `nid` was negative, which would be caught by KASAN.

The increment of `walk->mm_stats[MM_LEAF_ELIGIBLE]` is correct. The array is zero-initialized.

Therefore, since all the added structures and variables are properly initialized, the arrays are within bounds, and the `sscanf` return value is checked, there is no risk of reading uninitialized memory. Standard bug detectors like KASAN and KASAN should be sufficient to identify any issues. I can confidently say that KMSAN is not necessary for this patch. My analysis confirms the absence of uninitialized memory reads.

80/3 2026/08/07 12:16 tool set-results
0m Args: 
{
  "KMSANReasoning": "The patch introduces new fields to `struct mm_struct` and `struct lru_gen_mm_walk` for MGLRU empty-walk suppression. All new fields are properly initialized (e.g., in `lru_gen_init_mm` and via `kzalloc` for `mm_walk`). The tracepoint `mm_vmscan_lru_gen_walk` only exposes fully initialized local variables and struct fields. The debugfs interface correctly checks the return value of `sscanf` before using the parsed value. There are no uninitialized memory reads, uninitialized structure padding sent to user space, or complex data structures where uninitialized fields could be read. Any potential issues like out-of-bounds accesses would be caught by KASAN. Therefore, a dedicated KMSAN fuzzing session is not necessary.",
  "NeedsKMSAN": false
}

Results: 
{
  "KMSANReasoning": "The patch introduces new fields to `struct mm_struct` and `struct lru_gen_mm_walk` for MGLRU empty-walk suppression. All new fields are properly initialized (e.g., in `lru_gen_init_mm` and via `kzalloc` for `mm_walk`). The tracepoint `mm_vmscan_lru_gen_walk` only exposes fully initialized local variables and struct fields. The debugfs interface correctly checks the return value of `sscanf` before using the parsed value. There are no uninitialized memory reads, uninitialized structure padding sent to user space, or complex data structures where uninitialized fields could be read. Any potential issues like out-of-bounds accesses would be caught by KASAN. Therefore, a dedicated KMSAN fuzzing session is not necessary.",
  "NeedsKMSAN": false
}
LLM Calls Summary:
Total Calls Total Tokens Avg Tokens Total Duration (Seconds) Avg Duration (Seconds)
Tool Calls Summary:
Total Calls Total Duration (Seconds) Avg Duration (Seconds)