AI Trajectory

null

{
  "EnableConfigs": [
    "LRU_GEN",
    "LRU_GEN_ENABLED"
  ],
  "FocusSymbols": [
    "folio_referenced",
    "folio_check_references",
    "shrink_active_list",
    "folio_update_gen",
    "walk_update_folio",
    "lru_gen_look_around",
    "lru_gen_set_refs"
  ],
  "Reasoning": "The patch modifies memory reclaim logic (both standard LRU and MGLRU) to activate file-backed executable folios after their first usage, preventing IO thrashing. It also changes how VMA flags are passed and evaluated during reclaim. This is a functional change to core memory management and is highly reachable.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit bfd39249881df724f7bb86e5cde295c7c55fbca4\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Mon Jul 20 15:34:53 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/include/linux/rmap.h b/include/linux/rmap.h\nindex 8dc0871e5f0011..e090aa09825d52 100644\n--- a/include/linux/rmap.h\n+++ b/include/linux/rmap.h\n@@ -843,7 +843,7 @@ static inline int folio_try_share_anon_rmap_pmd(struct folio *folio,\n  * Called from mm/vmscan.c to handle paging out\n  */\n int folio_referenced(struct folio *, int is_locked,\n-\t\t\tstruct mem_cgroup *memcg, vm_flags_t *vm_flags);\n+\t\tstruct mem_cgroup *memcg, vma_flags_t *vma_flags);\n \n void try_to_migrate(struct folio *folio, enum ttu_flags flags);\n void try_to_unmap(struct folio *, enum ttu_flags flags);\n@@ -975,10 +975,9 @@ struct anon_vma *folio_lock_anon_vma_read(const struct folio *folio,\n #define anon_vma_prepare(vma)\t(0)\n \n static inline int folio_referenced(struct folio *folio, int is_locked,\n-\t\t\t\t  struct mem_cgroup *memcg,\n-\t\t\t\t  vm_flags_t *vm_flags)\n+\t\tstruct mem_cgroup *memcg, vma_flags_t *vma_flags)\n {\n-\t*vm_flags = 0;\n+\tvma_flags_clear_all(vma_flags);\n \treturn 0;\n }\n \ndiff --git a/mm/rmap.c b/mm/rmap.c\nindex ad820fe86f7d8c..73c2fe2d194625 100644\n--- a/mm/rmap.c\n+++ b/mm/rmap.c\n@@ -907,7 +907,7 @@ pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)\n struct folio_referenced_arg {\n \tint mapcount;\n \tint referenced;\n-\tvm_flags_t vm_flags;\n+\tvma_flags_t vma_flags;\n \tstruct mem_cgroup *memcg;\n };\n \n@@ -926,7 +926,7 @@ static bool folio_referenced_one(struct folio *folio,\n \t\taddress = pvmw.address;\n \t\tnr = 1;\n \n-\t\tif (vma-\u003evm_flags \u0026 VM_LOCKED) {\n+\t\tif (vma_test(vma, VMA_LOCKED_BIT)) {\n \t\t\tptes++;\n \t\t\tpra-\u003emapcount--;\n \n@@ -947,7 +947,7 @@ static bool folio_referenced_one(struct folio *folio,\n \t\t\t/* Restore the mlock which got missed */\n \t\t\tmlock_vma_folio(folio, vma);\n \t\t\tpage_vma_mapped_walk_done(\u0026pvmw);\n-\t\t\tpra-\u003evm_flags |= VM_LOCKED;\n+\t\t\tvma_flags_set(\u0026pra-\u003evma_flags, VMA_LOCKED_BIT);\n \t\t\treturn false; /* To break the loop */\n \t\t}\n \n@@ -1015,8 +1015,11 @@ static bool folio_referenced_one(struct folio *folio,\n \t\treferenced++;\n \n \tif (referenced) {\n+\t\tvma_flags_t vma_flags = vma-\u003eflags;\n+\n \t\tpra-\u003ereferenced++;\n-\t\tpra-\u003evm_flags |= vma-\u003evm_flags \u0026 ~VM_LOCKED;\n+\t\tvma_flags_clear(\u0026vma_flags, VMA_LOCKED_BIT);\n+\t\tvma_flags_set_mask(\u0026pra-\u003evma_flags, vma_flags);\n \t}\n \n \tif (!pra-\u003emapcount)\n@@ -1054,7 +1057,7 @@ static bool invalid_folio_referenced_vma(struct vm_area_struct *vma, void *arg)\n  * @folio: The folio to test.\n  * @is_locked: Caller holds lock on the folio.\n  * @memcg: target memory cgroup\n- * @vm_flags: A combination of all the vma-\u003evm_flags which referenced the folio.\n+ * @vma_flags: A combination of all the vma-\u003eflags which referenced the folio.\n  *\n  * Quick test_and_clear_referenced for all mappings of a folio,\n  *\n@@ -1062,7 +1065,7 @@ static bool invalid_folio_referenced_vma(struct vm_area_struct *vma, void *arg)\n  * the function bailed out due to rmap lock contention.\n  */\n int folio_referenced(struct folio *folio, int is_locked,\n-\t\t     struct mem_cgroup *memcg, vm_flags_t *vm_flags)\n+\t\tstruct mem_cgroup *memcg, vma_flags_t *vma_flags)\n {\n \tbool we_locked = false;\n \tstruct folio_referenced_arg pra = {\n@@ -1078,7 +1081,7 @@ int folio_referenced(struct folio *folio, int is_locked,\n \t};\n \n \tVM_WARN_ON_ONCE_FOLIO(folio_is_zone_device(folio), folio);\n-\t*vm_flags = 0;\n+\tvma_flags_clear_all(vma_flags);\n \tif (!pra.mapcount)\n \t\treturn 0;\n \n@@ -1092,7 +1095,7 @@ int folio_referenced(struct folio *folio, int is_locked,\n \t}\n \n \trmap_walk(folio, \u0026rwc);\n-\t*vm_flags = pra.vm_flags;\n+\tvma_flags_set_mask(vma_flags, pra.vma_flags);\n \n \tif (we_locked)\n \t\tfolio_unlock(folio);\ndiff --git a/mm/vmscan.c b/mm/vmscan.c\nindex b7ef032e78a0bd..b1ec65fb8947cd 100644\n--- a/mm/vmscan.c\n+++ b/mm/vmscan.c\n@@ -268,6 +268,12 @@ static int sc_swappiness(struct scan_control *sc, struct mem_cgroup *memcg)\n }\n #endif\n \n+static inline bool is_exec_file_folio(const struct folio *folio,\n+\t\tconst vma_flags_t *vma_flags)\n+{\n+\treturn vma_flags_test(vma_flags, VMA_EXEC_BIT) \u0026\u0026 folio_is_file_lru(folio);\n+}\n+\n static void set_task_reclaim_state(struct task_struct *task,\n \t\t\t\t   struct reclaim_state *rs)\n {\n@@ -835,10 +841,16 @@ enum folio_references {\n  * with PG_active set. In contrast, the aging (page table walk) path uses\n  * folio_update_gen().\n  */\n-static bool lru_gen_set_refs(struct folio *folio)\n+static bool lru_gen_set_refs(struct folio *folio, const vma_flags_t *vma_flags)\n {\n \t/* see the comment on LRU_REFS_FLAGS */\n \tif (!folio_test_referenced(folio) \u0026\u0026 !folio_test_workingset(folio)) {\n+\t\t/* Activate file-backed executable folios after first usage. */\n+\t\tif (is_exec_file_folio(folio, vma_flags)) {\n+\t\t\tset_mask_bits(\u0026folio-\u003eflags.f, LRU_REFS_FLAGS, BIT(PG_workingset));\n+\t\t\treturn true;\n+\t\t}\n+\n \t\tset_mask_bits(\u0026folio-\u003eflags.f, LRU_REFS_MASK, BIT(PG_referenced));\n \t\treturn false;\n \t}\n@@ -851,7 +863,7 @@ static bool lru_gen_set_refs(struct folio *folio)\n \treturn true;\n }\n #else\n-static bool lru_gen_set_refs(struct folio *folio)\n+static bool lru_gen_set_refs(struct folio *folio, const vma_flags_t *vma_flags)\n {\n \treturn false;\n }\n@@ -861,16 +873,16 @@ static enum folio_references folio_check_references(struct folio *folio,\n \t\t\t\t\t\t  struct scan_control *sc)\n {\n \tint referenced_ptes, referenced_folio;\n-\tvm_flags_t vm_flags;\n+\tvma_flags_t vma_flags;\n \n \treferenced_ptes = folio_referenced(folio, 1, sc-\u003etarget_mem_cgroup,\n-\t\t\t\t\t   \u0026vm_flags);\n+\t\t\t\t\t   \u0026vma_flags);\n \n \t/*\n \t * The supposedly reclaimable folio was found to be in a VM_LOCKED vma.\n \t * Let the folio, now marked Mlocked, be moved to the unevictable list.\n \t */\n-\tif (vm_flags \u0026 VM_LOCKED)\n+\tif (vma_flags_test(\u0026vma_flags, VMA_LOCKED_BIT))\n \t\treturn FOLIOREF_ACTIVATE;\n \n \t/*\n@@ -886,7 +898,7 @@ static enum folio_references folio_check_references(struct folio *folio,\n \t\tif (!referenced_ptes)\n \t\t\treturn FOLIOREF_RECLAIM;\n \n-\t\treturn lru_gen_set_refs(folio) ? FOLIOREF_ACTIVATE : FOLIOREF_KEEP;\n+\t\treturn lru_gen_set_refs(folio, \u0026vma_flags) ? FOLIOREF_ACTIVATE : FOLIOREF_KEEP;\n \t}\n \n \treferenced_folio = folio_test_clear_referenced(folio);\n@@ -914,7 +926,7 @@ static enum folio_references folio_check_references(struct folio *folio,\n \t\t/*\n \t\t * Activate file-backed executable folios after first usage.\n \t\t */\n-\t\tif ((vm_flags \u0026 VM_EXEC) \u0026\u0026 folio_is_file_lru(folio))\n+\t\tif (is_exec_file_folio(folio, \u0026vma_flags))\n \t\t\treturn FOLIOREF_ACTIVATE;\n \n \t\treturn FOLIOREF_KEEP;\n@@ -2063,7 +2075,7 @@ static void shrink_active_list(unsigned long nr_to_scan,\n {\n \tunsigned long nr_taken;\n \tunsigned long nr_scanned;\n-\tvm_flags_t vm_flags;\n+\tvma_flags_t vma_flags;\n \tLIST_HEAD(l_hold);\t/* The folios which were snipped off */\n \tLIST_HEAD(l_active);\n \tLIST_HEAD(l_inactive);\n@@ -2107,7 +2119,7 @@ static void shrink_active_list(unsigned long nr_to_scan,\n \n \t\t/* Referenced or rmap lock contention: rotate */\n \t\tif (folio_referenced(folio, 0, sc-\u003etarget_mem_cgroup,\n-\t\t\t\t     \u0026vm_flags) != 0) {\n+\t\t\t\t     \u0026vma_flags) != 0) {\n \t\t\t/*\n \t\t\t * Identify referenced, file-backed active folios and\n \t\t\t * give them one more trip around the active list. So\n@@ -2117,7 +2129,7 @@ static void shrink_active_list(unsigned long nr_to_scan,\n \t\t\t * IO, plus JVM can create lots of anon VM_EXEC folios,\n \t\t\t * so we ignore them here.\n \t\t\t */\n-\t\t\tif ((vm_flags \u0026 VM_EXEC) \u0026\u0026 folio_is_file_lru(folio)) {\n+\t\t\tif (is_exec_file_folio(folio, \u0026vma_flags)) {\n \t\t\t\tnr_rotated += folio_nr_pages(folio);\n \t\t\t\tlist_add(\u0026folio-\u003elru, \u0026l_active);\n \t\t\t\tcontinue;\n@@ -3186,14 +3198,19 @@ static bool positive_ctrl_err(struct ctrl_pos *sp, struct ctrl_pos *pv)\n  ******************************************************************************/\n \n /* promote pages accessed through page tables */\n-static int folio_update_gen(struct folio *folio, int gen)\n+static int folio_update_gen(struct folio *folio, int gen, const vma_flags_t *vma_flags)\n {\n \tunsigned long new_flags, old_flags = READ_ONCE(folio-\u003eflags.f);\n \n \tVM_WARN_ON_ONCE(gen \u003e= MAX_NR_GENS);\n \n-\t/* see the comment on LRU_REFS_FLAGS */\n-\tif (!folio_test_referenced(folio) \u0026\u0026 !folio_test_workingset(folio)) {\n+\t/*\n+\t * See the comment on LRU_REFS_FLAGS, and activate file-backed\n+\t * executable folios after first usage to avoid typical IO\n+\t * thrashing from reclaiming.\n+\t */\n+\tif (!folio_test_referenced(folio) \u0026\u0026 !folio_test_workingset(folio) \u0026\u0026\n+\t    !is_exec_file_folio(folio, vma_flags)) {\n \t\tset_mask_bits(\u0026folio-\u003eflags.f, LRU_REFS_MASK, BIT(PG_referenced));\n \t\treturn -1;\n \t}\n@@ -3426,8 +3443,8 @@ static bool suitable_to_scan(int total, int young)\n \treturn young * n \u003e= total;\n }\n \n-static void walk_update_folio(struct lru_gen_mm_walk *walk, struct folio *folio,\n-\t\t\t      int new_gen, bool dirty)\n+static void walk_update_folio(struct lru_gen_mm_walk *walk, struct vm_area_struct *vma,\n+\t\tstruct folio *folio, int new_gen, bool dirty)\n {\n \tint old_gen;\n \n@@ -3440,10 +3457,10 @@ static void walk_update_folio(struct lru_gen_mm_walk *walk, struct folio *folio,\n \t\tfolio_mark_dirty(folio);\n \n \tif (walk) {\n-\t\told_gen = folio_update_gen(folio, new_gen);\n+\t\told_gen = folio_update_gen(folio, new_gen, \u0026vma-\u003eflags);\n \t\tif (old_gen \u003e= 0 \u0026\u0026 old_gen != new_gen)\n \t\t\tupdate_batch_size(walk, folio, old_gen, new_gen);\n-\t} else if (lru_gen_set_refs(folio)) {\n+\t} else if (lru_gen_set_refs(folio, \u0026vma-\u003eflags)) {\n \t\told_gen = folio_lru_gen(folio);\n \t\tif (old_gen \u003e= 0 \u0026\u0026 old_gen != new_gen)\n \t\t\tfolio_activate(folio);\n@@ -3516,7 +3533,7 @@ static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end,\n \t\t\tcontinue;\n \n \t\tif (last != folio) {\n-\t\t\twalk_update_folio(walk, last, gen, dirty);\n+\t\t\twalk_update_folio(walk, args-\u003evma, last, gen, dirty);\n \n \t\t\tlast = folio;\n \t\t\tdirty = false;\n@@ -3529,7 +3546,7 @@ static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end,\n \t\twalk-\u003emm_stats[MM_LEAF_YOUNG] += nr;\n \t}\n \n-\twalk_update_folio(walk, last, gen, dirty);\n+\twalk_update_folio(walk, args-\u003evma, last, gen, dirty);\n \tlast = NULL;\n \n \tif (i \u003c PTRS_PER_PTE \u0026\u0026 get_next_vma(PMD_MASK, PAGE_SIZE, args, \u0026start, \u0026end))\n@@ -3607,7 +3624,7 @@ static void walk_pmd_range_locked(pud_t *pud, unsigned long addr, struct vm_area\n \t\t\tgoto next;\n \n \t\tif (last != folio) {\n-\t\t\twalk_update_folio(walk, last, gen, dirty);\n+\t\t\twalk_update_folio(walk, vma, last, gen, dirty);\n \n \t\t\tlast = folio;\n \t\t\tdirty = false;\n@@ -3621,7 +3638,7 @@ static void walk_pmd_range_locked(pud_t *pud, unsigned long addr, struct vm_area\n \t\ti = i \u003e MIN_LRU_BATCH ? 0 : find_next_bit(bitmap, MIN_LRU_BATCH, i) + 1;\n \t} while (i \u003c= MIN_LRU_BATCH);\n \n-\twalk_update_folio(walk, last, gen, dirty);\n+\twalk_update_folio(walk, vma, last, gen, dirty);\n \n \tlazy_mmu_mode_disable();\n \tspin_unlock(ptl);\n@@ -4256,7 +4273,7 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw, unsigned int nr)\n \t\t\tcontinue;\n \n \t\tif (last != folio) {\n-\t\t\twalk_update_folio(walk, last, gen, dirty);\n+\t\t\twalk_update_folio(walk, vma, last, gen, dirty);\n \n \t\t\tlast = folio;\n \t\t\tdirty = false;\n@@ -4268,7 +4285,7 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw, unsigned int nr)\n \t\tyoung += nr;\n \t}\n \n-\twalk_update_folio(walk, last, gen, dirty);\n+\twalk_update_folio(walk, vma, last, gen, dirty);\n \n \tlazy_mmu_mode_disable();\n \n"
}

best-expensive

null

{
  "EnableConfigs": [
    "LRU_GEN",
    "LRU_GEN_ENABLED"
  ],
  "FocusSymbols": [
    "folio_referenced",
    "folio_check_references",
    "shrink_active_list",
    "folio_update_gen",
    "walk_update_folio",
    "lru_gen_look_around",
    "lru_gen_set_refs"
  ],
  "Reasoning": "The patch modifies memory reclaim logic (both standard LRU and MGLRU) to activate file-backed executable folios after their first usage, preventing IO thrashing. It also changes how VMA flags are passed and evaluated during reclaim. This is a functional change to core memory management and is highly reachable.",
  "WorthFuzzing": true
}

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).

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.
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.
   Do not list too generic configs (we already have them enabled). Only list those that
   specifically cover the modified code. 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.

For your convenience, here is the diff of the changes:
commit bfd39249881df724f7bb86e5cde295c7c55fbca4
Author: syz-cluster <triage@syzkaller.com>
Date:   Mon Jul 20 15:34:53 2026 +0000

    syz-cluster: applied patch under review

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 8dc0871e5f0011..e090aa09825d52 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -843,7 +843,7 @@ static inline int folio_try_share_anon_rmap_pmd(struct folio *folio,
  * Called from mm/vmscan.c to handle paging out
  */
 int folio_referenced(struct folio *, int is_locked,
-			struct mem_cgroup *memcg, vm_flags_t *vm_flags);
+		struct mem_cgroup *memcg, vma_flags_t *vma_flags);
 
 void try_to_migrate(struct folio *folio, enum ttu_flags flags);
 void try_to_unmap(struct folio *, enum ttu_flags flags);
@@ -975,10 +975,9 @@ struct anon_vma *folio_lock_anon_vma_read(const struct folio *folio,
 #define anon_vma_prepare(vma)	(0)
 
 static inline int folio_referenced(struct folio *folio, int is_locked,
-				  struct mem_cgroup *memcg,
-				  vm_flags_t *vm_flags)
+		struct mem_cgroup *memcg, vma_flags_t *vma_flags)
 {
-	*vm_flags = 0;
+	vma_flags_clear_all(vma_flags);
 	return 0;
 }
 
diff --git a/mm/rmap.c b/mm/rmap.c
index ad820fe86f7d8c..73c2fe2d194625 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -907,7 +907,7 @@ pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
 struct folio_referenced_arg {
 	int mapcount;
 	int referenced;
-	vm_flags_t vm_flags;
+	vma_flags_t vma_flags;
 	struct mem_cgroup *memcg;
 };
 
@@ -926,7 +926,7 @@ static bool folio_referenced_one(struct folio *folio,
 		address = pvmw.address;
 		nr = 1;
 
-		if (vma->vm_flags & VM_LOCKED) {
+		if (vma_test(vma, VMA_LOCKED_BIT)) {
 			ptes++;
 			pra->mapcount--;
 
@@ -947,7 +947,7 @@ static bool folio_referenced_one(struct folio *folio,
 			/* Restore the mlock which got missed */
 			mlock_vma_folio(folio, vma);
 			page_vma_mapped_walk_done(&pvmw);
-			pra->vm_flags |= VM_LOCKED;
+			vma_flags_set(&pra->vma_flags, VMA_LOCKED_BIT);
 			return false; /* To break the loop */
 		}
 
@@ -1015,8 +1015,11 @@ static bool folio_referenced_one(struct folio *folio,
 		referenced++;
 
 	if (referenced) {
+		vma_flags_t vma_flags = vma->flags;
+
 		pra->referenced++;
-		pra->vm_flags |= vma->vm_flags & ~VM_LOCKED;
+		vma_flags_clear(&vma_flags, VMA_LOCKED_BIT);
+		vma_flags_set_mask(&pra->vma_flags, vma_flags);
 	}
 
 	if (!pra->mapcount)
@@ -1054,7 +1057,7 @@ static bool invalid_folio_referenced_vma(struct vm_area_struct *vma, void *arg)
  * @folio: The folio to test.
  * @is_locked: Caller holds lock on the folio.
  * @memcg: target memory cgroup
- * @vm_flags: A combination of all the vma->vm_flags which referenced the folio.
+ * @vma_flags: A combination of all the vma->flags which referenced the folio.
  *
  * Quick test_and_clear_referenced for all mappings of a folio,
  *
@@ -1062,7 +1065,7 @@ static bool invalid_folio_referenced_vma(struct vm_area_struct *vma, void *arg)
  * the function bailed out due to rmap lock contention.
  */
 int folio_referenced(struct folio *folio, int is_locked,
-		     struct mem_cgroup *memcg, vm_flags_t *vm_flags)
+		struct mem_cgroup *memcg, vma_flags_t *vma_flags)
 {
 	bool we_locked = false;
 	struct folio_referenced_arg pra = {
@@ -1078,7 +1081,7 @@ int folio_referenced(struct folio *folio, int is_locked,
 	};
 
 	VM_WARN_ON_ONCE_FOLIO(folio_is_zone_device(folio), folio);
-	*vm_flags = 0;
+	vma_flags_clear_all(vma_flags);
 	if (!pra.mapcount)
 		return 0;
 
@@ -1092,7 +1095,7 @@ int folio_referenced(struct folio *folio, int is_locked,
 	}
 
 	rmap_walk(folio, &rwc);
-	*vm_flags = pra.vm_flags;
+	vma_flags_set_mask(vma_flags, pra.vma_flags);
 
 	if (we_locked)
 		folio_unlock(folio);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b7ef032e78a0bd..b1ec65fb8947cd 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -268,6 +268,12 @@ static int sc_swappiness(struct scan_control *sc, struct mem_cgroup *memcg)
 }
 #endif
 
+static inline bool is_exec_file_folio(const struct folio *folio,
+		const vma_flags_t *vma_flags)
+{
+	return vma_flags_test(vma_flags, VMA_EXEC_BIT) && folio_is_file_lru(folio);
+}
+
 static void set_task_reclaim_state(struct task_struct *task,
 				   struct reclaim_state *rs)
 {
@@ -835,10 +841,16 @@ enum folio_references {
  * with PG_active set. In contrast, the aging (page table walk) path uses
  * folio_update_gen().
  */
-static bool lru_gen_set_refs(struct folio *folio)
+static bool lru_gen_set_refs(struct folio *folio, const vma_flags_t *vma_flags)
 {
 	/* see the comment on LRU_REFS_FLAGS */
 	if (!folio_test_referenced(folio) && !folio_test_workingset(folio)) {
+		/* Activate file-backed executable folios after first usage. */
+		if (is_exec_file_folio(folio, vma_flags)) {
+			set_mask_bits(&folio->flags.f, LRU_REFS_FLAGS, BIT(PG_workingset));
+			return true;
+		}
+
 		set_mask_bits(&folio->flags.f, LRU_REFS_MASK, BIT(PG_referenced));
 		return false;
 	}
@@ -851,7 +863,7 @@ static bool lru_gen_set_refs(struct folio *folio)
 	return true;
 }
 #else
-static bool lru_gen_set_refs(struct folio *folio)
+static bool lru_gen_set_refs(struct folio *folio, const vma_flags_t *vma_flags)
 {
 	return false;
 }
@@ -861,16 +873,16 @@ static enum folio_references folio_check_references(struct folio *folio,
 						  struct scan_control *sc)
 {
 	int referenced_ptes, referenced_folio;
-	vm_flags_t vm_flags;
+	vma_flags_t vma_flags;
 
 	referenced_ptes = folio_referenced(folio, 1, sc->target_mem_cgroup,
-					   &vm_flags);
+					   &vma_flags);
 
 	/*
 	 * The supposedly reclaimable folio was found to be in a VM_LOCKED vma.
 	 * Let the folio, now marked Mlocked, be moved to the unevictable list.
 	 */
-	if (vm_flags & VM_LOCKED)
+	if (vma_flags_test(&vma_flags, VMA_LOCKED_BIT))
 		return FOLIOREF_ACTIVATE;
 
 	/*
@@ -886,7 +898,7 @@ static enum folio_references folio_check_references(struct folio *folio,
 		if (!referenced_ptes)
 			return FOLIOREF_RECLAIM;
 
-		return lru_gen_set_refs(folio) ? FOLIOREF_ACTIVATE : FOLIOREF_KEEP;
+		return lru_gen_set_refs(folio, &vma_flags) ? FOLIOREF_ACTIVATE : FOLIOREF_KEEP;
 	}
 
 	referenced_folio = folio_test_clear_referenced(folio);
@@ -914,7 +926,7 @@ static enum folio_references folio_check_references(struct folio *folio,
 		/*
 		 * Activate file-backed executable folios after first usage.
 		 */
-		if ((vm_flags & VM_EXEC) && folio_is_file_lru(folio))
+		if (is_exec_file_folio(folio, &vma_flags))
 			return FOLIOREF_ACTIVATE;
 
 		return FOLIOREF_KEEP;
@@ -2063,7 +2075,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
 {
 	unsigned long nr_taken;
 	unsigned long nr_scanned;
-	vm_flags_t vm_flags;
+	vma_flags_t vma_flags;
 	LIST_HEAD(l_hold);	/* The folios which were snipped off */
 	LIST_HEAD(l_active);
 	LIST_HEAD(l_inactive);
@@ -2107,7 +2119,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
 
 		/* Referenced or rmap lock contention: rotate */
 		if (folio_referenced(folio, 0, sc->target_mem_cgroup,
-				     &vm_flags) != 0) {
+				     &vma_flags) != 0) {
 			/*
 			 * Identify referenced, file-backed active folios and
 			 * give them one more trip around the active list. So
@@ -2117,7 +2129,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
 			 * IO, plus JVM can create lots of anon VM_EXEC folios,
 			 * so we ignore them here.
 			 */
-			if ((vm_flags & VM_EXEC) && folio_is_file_lru(folio)) {
+			if (is_exec_file_folio(folio, &vma_flags)) {
 				nr_rotated += folio_nr_pages(folio);
 				list_add(&folio->lru, &l_active);
 				continue;
@@ -3186,14 +3198,19 @@ static bool positive_ctrl_err(struct ctrl_pos *sp, struct ctrl_pos *pv)
  ******************************************************************************/
 
 /* promote pages accessed through page tables */
-static int folio_update_gen(struct folio *folio, int gen)
+static int folio_update_gen(struct folio *folio, int gen, const vma_flags_t *vma_flags)
 {
 	unsigned long new_flags, old_flags = READ_ONCE(folio->flags.f);
 
 	VM_WARN_ON_ONCE(gen >= MAX_NR_GENS);
 
-	/* see the comment on LRU_REFS_FLAGS */
-	if (!folio_test_referenced(folio) && !folio_test_workingset(folio)) {
+	/*
+	 * See the comment on LRU_REFS_FLAGS, and activate file-backed
+	 * executable folios after first usage to avoid typical IO
+	 * thrashing from reclaiming.
+	 */
+	if (!folio_test_referenced(folio) && !folio_test_workingset(folio) &&
+	    !is_exec_file_folio(folio, vma_flags)) {
 		set_mask_bits(&folio->flags.f, LRU_REFS_MASK, BIT(PG_referenced));
 		return -1;
 	}
@@ -3426,8 +3443,8 @@ static bool suitable_to_scan(int total, int young)
 	return young * n >= total;
 }
 
-static void walk_update_folio(struct lru_gen_mm_walk *walk, struct folio *folio,
-			      int new_gen, bool dirty)
+static void walk_update_folio(struct lru_gen_mm_walk *walk, struct vm_area_struct *vma,
+		struct folio *folio, int new_gen, bool dirty)
 {
 	int old_gen;
 
@@ -3440,10 +3457,10 @@ static void walk_update_folio(struct lru_gen_mm_walk *walk, struct folio *folio,
 		folio_mark_dirty(folio);
 
 	if (walk) {
-		old_gen = folio_update_gen(folio, new_gen);
+		old_gen = folio_update_gen(folio, new_gen, &vma->flags);
 		if (old_gen >= 0 && old_gen != new_gen)
 			update_batch_size(walk, folio, old_gen, new_gen);
-	} else if (lru_gen_set_refs(folio)) {
+	} else if (lru_gen_set_refs(folio, &vma->flags)) {
 		old_gen = folio_lru_gen(folio);
 		if (old_gen >= 0 && old_gen != new_gen)
 			folio_activate(folio);
@@ -3516,7 +3533,7 @@ static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end,
 			continue;
 
 		if (last != folio) {
-			walk_update_folio(walk, last, gen, dirty);
+			walk_update_folio(walk, args->vma, last, gen, dirty);
 
 			last = folio;
 			dirty = false;
@@ -3529,7 +3546,7 @@ static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end,
 		walk->mm_stats[MM_LEAF_YOUNG] += nr;
 	}
 
-	walk_update_folio(walk, last, gen, dirty);
+	walk_update_folio(walk, args->vma, last, gen, dirty);
 	last = NULL;
 
 	if (i < PTRS_PER_PTE && get_next_vma(PMD_MASK, PAGE_SIZE, args, &start, &end))
@@ -3607,7 +3624,7 @@ static void walk_pmd_range_locked(pud_t *pud, unsigned long addr, struct vm_area
 			goto next;
 
 		if (last != folio) {
-			walk_update_folio(walk, last, gen, dirty);
+			walk_update_folio(walk, vma, last, gen, dirty);
 
 			last = folio;
 			dirty = false;
@@ -3621,7 +3638,7 @@ static void walk_pmd_range_locked(pud_t *pud, unsigned long addr, struct vm_area
 		i = i > MIN_LRU_BATCH ? 0 : find_next_bit(bitmap, MIN_LRU_BATCH, i) + 1;
 	} while (i <= MIN_LRU_BATCH);
 
-	walk_update_folio(walk, last, gen, dirty);
+	walk_update_folio(walk, vma, last, gen, dirty);
 
 	lazy_mmu_mode_disable();
 	spin_unlock(ptl);
@@ -4256,7 +4273,7 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw, unsigned int nr)
 			continue;
 
 		if (last != folio) {
-			walk_update_folio(walk, last, gen, dirty);
+			walk_update_folio(walk, vma, last, gen, dirty);
 
 			last = folio;
 			dirty = false;
@@ -4268,7 +4285,7 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw, unsigned int nr)
 		young += nr;
 	}
 
-	walk_update_folio(walk, last, gen, dirty);
+	walk_update_folio(walk, vma, last, gen, dirty);
 
 	lazy_mmu_mode_disable();
 

gemini-3.1-pro-preview

null

null

							input: 6175
							output: 20
							thoughts: 272
						

**Analyzing This VM Flag Patch**

Okay, so I'm looking at this patch that's tweaking how we handle virtual memory area (VMA) flags, specifically in relation to `folio_referenced` and LRU generation. The core of the change seems to involve how we represent and manipulate these flags. Initially, I thought it was just a simple type rename – `vm_flags_t` to `vma_flags_t` or perhaps even just an underlying type change like `unsigned long`. That's the first assumption.

But looking closer at the diff reveals that it's actually changing how we work with pointers: `vma_flags_t *vma_flags` instead of `vm_flags_t *vm_flags`. Okay, that's more significant. This is not just a type rename, we are changing how the flags are passed.

The patch also introduces new functions: `vma_flags_clear_all`, `vma_test(vma, VMA_LOCKED_BIT)`, `vma_flags_set`, `vma_flags_clear`, and `vma_flags_set_mask`. That's a good sign; maybe this is a cleaner API, and they are using helpers to make things more robust.

Hang on a second. If they're using those helper functions, I have a feeling `vma_flags_t` is probably more than just a simple integer type. My gut says it's likely a `struct` or some sort of custom type that provides more structure. If this is the case, it makes sense; with so many flags in the system, you need a way to encapsulate them.

Time to look for the definition. I'll check `include/linux/rmap.h` or maybe `mm/rmap.c` first. Those are the most likely places to find a definition for something related to VMAs and memory management.

Right, need to be sure; is this a new type? Let me do a quick search through the codebase for `vma_flags_t` just to confirm it's not a pre-existing type that they are merely using here.

{
  "Expression": "vma_flags_t"
}

{
  "Output": "\nFull output is too long, showing 500 out of 1679 lines.\nUse more precise expression if possible.\n\nDocumentation/filesystems/mmap_prepare.rst=58=Examining the struct vm_area_desc type:\n--\nDocumentation/filesystems/mmap_prepare.rst-71-        struct file *vm_file;\nDocumentation/filesystems/mmap_prepare.rst:72:        vma_flags_t vma_flags;\nDocumentation/filesystems/mmap_prepare.rst-73-        pgprot_t page_prot;\n--\ndrivers/dax/device.c-15-\ndrivers/dax/device.c:16:static int __check_vma(struct dev_dax *dev_dax, vma_flags_t flags,\ndrivers/dax/device.c-17-\t\t       unsigned long start, unsigned long end, struct file *file,\n--\ndrivers/dax/device.c-26-\t/* prevent private mappings from being established */\ndrivers/dax/device.c:27:\tif (!vma_flags_test_any(\u0026flags, VMA_MAYSHARE_BIT)) {\ndrivers/dax/device.c-28-\t\tdev_info_ratelimited(dev,\n--\ndrivers/gpu/drm/drm_gem.c=184=int drm_gem_object_init(struct drm_device *dev, struct drm_gem_object *obj,\n--\ndrivers/gpu/drm/drm_gem.c-188-\tstruct file *filp;\ndrivers/gpu/drm/drm_gem.c:189:\tconst vma_flags_t flags = mk_vma_flags(VMA_NORESERVE_BIT);\ndrivers/gpu/drm/drm_gem.c-190-\n--\ndrivers/gpu/drm/i915/gem/i915_gem_shmem.c=503=static int __create_shmem(struct drm_i915_private *i915,\n--\ndrivers/gpu/drm/i915/gem/i915_gem_shmem.c-507-{\ndrivers/gpu/drm/i915/gem/i915_gem_shmem.c:508:\tconst vma_flags_t shmem_flags = mk_vma_flags(VMA_NORESERVE_BIT);\ndrivers/gpu/drm/i915/gem/i915_gem_shmem.c-509-\tstruct vfsmount *huge_mnt;\n--\nfs/hugetlbfs/inode.c=99=static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)\n--\nfs/hugetlbfs/inode.c-104-\tstruct hstate *h = hstate_file(file);\nfs/hugetlbfs/inode.c:105:\tvma_flags_t vma_flags;\nfs/hugetlbfs/inode.c-106-\n--\nfs/hugetlbfs/inode.c=1498=struct file *hugetlb_file_setup(const char *name, size_t size,\nfs/hugetlbfs/inode.c:1499:\t\t\t\tvma_flags_t acctflag, int creat_flags,\nfs/hugetlbfs/inode.c-1500-\t\t\t\tint page_size_log)\n--\ninclude/linux/huge_mm.h=394=unsigned long thp_get_unmapped_area_vmaflags(struct file *filp, unsigned long addr,\ninclude/linux/huge_mm.h-395-\t\tunsigned long len, unsigned long pgoff, unsigned long flags,\ninclude/linux/huge_mm.h:396:\t\tvma_flags_t vma_flags);\ninclude/linux/huge_mm.h-397-\n--\ninclude/linux/huge_mm.h=620=thp_get_unmapped_area_vmaflags(struct file *filp, unsigned long addr,\ninclude/linux/huge_mm.h-621-\t\t\t       unsigned long len, unsigned long pgoff,\ninclude/linux/huge_mm.h:622:\t\t\t       unsigned long flags, vma_flags_t vma_flags)\ninclude/linux/huge_mm.h-623-{\n--\ninclude/linux/hugetlb.h=151=long hugetlb_reserve_pages(struct inode *inode, long from, long to,\ninclude/linux/hugetlb.h:152:\t\t\t   struct vm_area_struct *vma, vma_flags_t vma_flags);\ninclude/linux/hugetlb.h-153-long hugetlb_unreserve_pages(struct inode *inode, long start, long end,\n--\ninclude/linux/hugetlb.h=519=extern const struct vm_operations_struct hugetlb_vm_ops;\ninclude/linux/hugetlb.h:520:struct file *hugetlb_file_setup(const char *name, size_t size, vma_flags_t acct,\ninclude/linux/hugetlb.h-521-\t\t\t\tint creat_flags, int page_size_log);\n--\ninclude/linux/hugetlb.h=535=static inline struct file *\ninclude/linux/hugetlb.h:536:hugetlb_file_setup(const char *name, size_t size, vma_flags_t acctflag,\ninclude/linux/hugetlb.h-537-\t\tint creat_flags, int page_size_log)\n--\ninclude/linux/hugetlb_inline.h-8-\ninclude/linux/hugetlb_inline.h:9:static inline bool is_vma_hugetlb_flags(const vma_flags_t *flags)\ninclude/linux/hugetlb_inline.h-10-{\ninclude/linux/hugetlb_inline.h:11:\treturn vma_flags_test(flags, VMA_HUGETLB_BIT);\ninclude/linux/hugetlb_inline.h-12-}\n--\ninclude/linux/hugetlb_inline.h-15-\ninclude/linux/hugetlb_inline.h:16:static inline bool is_vma_hugetlb_flags(const vma_flags_t *flags)\ninclude/linux/hugetlb_inline.h-17-{\n--\ninclude/linux/ksm.h=18=int ksm_madvise(struct vm_area_struct *vma, unsigned long start,\ninclude/linux/ksm.h-19-\t\tunsigned long end, int advice, vm_flags_t *vm_flags);\ninclude/linux/ksm.h:20:vma_flags_t ksm_vma_flags(struct mm_struct *mm, const struct file *file,\ninclude/linux/ksm.h:21:\t\t\t  vma_flags_t vma_flags);\ninclude/linux/ksm.h-22-int ksm_enable_merge_any(struct mm_struct *mm);\n--\ninclude/linux/ksm.h=102=bool ksm_process_mergeable(struct mm_struct *mm);\n--\ninclude/linux/ksm.h-105-\ninclude/linux/ksm.h:106:static inline vma_flags_t ksm_vma_flags(struct mm_struct *mm,\ninclude/linux/ksm.h:107:\t\tconst struct file *file, vma_flags_t vma_flags)\ninclude/linux/ksm.h-108-{\n--\ninclude/linux/memfd.h=11=struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx);\n--\ninclude/linux/memfd.h-18- */\ninclude/linux/memfd.h:19:int memfd_check_seals_mmap(struct file *file, vma_flags_t *vma_flags_ptr);\ninclude/linux/memfd.h-20-struct file *memfd_alloc_file(const char *name, unsigned int flags);\n--\ninclude/linux/memfd.h=32=static inline int memfd_check_seals_mmap(struct file *file,\ninclude/linux/memfd.h:33:\t\t\t\t\t vma_flags_t *vma_flags_ptr)\ninclude/linux/memfd.h-34-{\n--\ninclude/linux/mm.h=294=enum {\n--\ninclude/linux/mm.h-513-/*\ninclude/linux/mm.h:514: * vma_flags_t masks for the userfaultfd VMA flags. The two high-bit modes are\ninclude/linux/mm.h-515- * gated on the same configs as their VM_* flags above -- both of which imply\n--\ninclude/linux/mm.h-576-/* Temporary until VMA flags conversion complete. */\ninclude/linux/mm.h:577:#define VM_STACK_FLAGS vma_flags_to_legacy(VMA_STACK_FLAGS)\ninclude/linux/mm.h-578-\n--\ninclude/linux/mm.h-594-\t\t\t\t       VMA_PFNMAP_BIT, VMA_MIXEDMAP_BIT)\ninclude/linux/mm.h:595:#define VM_SPECIAL vma_flags_to_legacy(VMA_SPECIAL_FLAGS)\ninclude/linux/mm.h-596-\n--\ninclude/linux/mm.h=1022=static inline void vma_flags_reset_once(struct vm_area_struct *vma,\ninclude/linux/mm.h:1023:\t\t\t\t\tvma_flags_t *flags)\ninclude/linux/mm.h-1024-{\n--\ninclude/linux/mm.h=1107=static __always_inline bool vma_test_atomic_flag(struct vm_area_struct *vma,\n--\ninclude/linux/mm.h-1116-/* Set an individual VMA flag in flags, non-atomically. */\ninclude/linux/mm.h:1117:static __always_inline void vma_flags_set_flag(vma_flags_t *flags,\ninclude/linux/mm.h-1118-\t\tvma_flag_t bit)\n--\ninclude/linux/mm.h-1124-\ninclude/linux/mm.h:1125:static __always_inline vma_flags_t __mk_vma_flags(vma_flags_t flags,\ninclude/linux/mm.h-1126-\t\tsize_t count, const vma_flag_t *bits)\n--\ninclude/linux/mm.h-1136- * Helper macro which bitwise-or combines the specified input flags into a\ninclude/linux/mm.h:1137: * vma_flags_t bitmap value. E.g.:\ninclude/linux/mm.h-1138- *\ninclude/linux/mm.h:1139: * vma_flags_t flags = mk_vma_flags(VMA_IO_BIT, VMA_PFNMAP_BIT,\ninclude/linux/mm.h-1140- *              VMA_DONTEXPAND_BIT, VMA_DONTDUMP_BIT);\n--\ninclude/linux/mm.h-1151- *\ninclude/linux/mm.h:1152: * vma_flags_t flags = append_vma_flags(VMA_STACK_DEFAULT_FLAGS, VMA_STACK_BIT,\ninclude/linux/mm.h-1153- *              VMA_ACCOUNT_BIT);\n--\ninclude/linux/mm.h-1158-/* Calculates the number of set bits in the specified VMA flags. */\ninclude/linux/mm.h:1159:static __always_inline int vma_flags_count(const vma_flags_t *flags)\ninclude/linux/mm.h-1160-{\n--\ninclude/linux/mm.h-1168- *\ninclude/linux/mm.h:1169: * if (vma_flags_test(flags, VMA_READ_BIT)) { ... }\ninclude/linux/mm.h-1170- */\ninclude/linux/mm.h:1171:static __always_inline bool vma_flags_test(const vma_flags_t *flags,\ninclude/linux/mm.h-1172-\t\tvma_flag_t bit)\n--\ninclude/linux/mm.h-1182- */\ninclude/linux/mm.h:1183:static __always_inline vma_flags_t vma_flags_and_mask(const vma_flags_t *flags,\ninclude/linux/mm.h:1184:\t\t\t\t\t\t      vma_flags_t to_and)\ninclude/linux/mm.h-1185-{\ninclude/linux/mm.h:1186:\tvma_flags_t dst;\ninclude/linux/mm.h-1187-\tunsigned long *bitmap_dst = dst.__vma_flags;\n--\ninclude/linux/mm.h-1198- *\ninclude/linux/mm.h:1199: * vma_flags_t read_flags = vma_flags_and(\u0026flags, VMA_READ_BIT,\ninclude/linux/mm.h-1200- *                                        VMA_MAY_READ_BIT);\n--\ninclude/linux/mm.h-1205-/*  Test each of to_test flags in flags, non-atomically. */\ninclude/linux/mm.h:1206:static __always_inline bool vma_flags_test_any_mask(const vma_flags_t *flags,\ninclude/linux/mm.h:1207:\t\tvma_flags_t to_test)\ninclude/linux/mm.h-1208-{\n--\ninclude/linux/mm.h-1217- *\ninclude/linux/mm.h:1218: * if (vma_flags_test_any(flags, VMA_READ_BIT, VMA_MAYREAD_BIT)) { ... }\ninclude/linux/mm.h-1219- */\ninclude/linux/mm.h:1220:#define vma_flags_test_any(flags, ...) \\\ninclude/linux/mm.h:1221:\tvma_flags_test_any_mask(flags, mk_vma_flags(__VA_ARGS__))\ninclude/linux/mm.h-1222-\ninclude/linux/mm.h-1223-/* Test that ALL of the to_test flags are set, non-atomically. */\ninclude/linux/mm.h:1224:static __always_inline bool vma_flags_test_all_mask(const vma_flags_t *flags,\ninclude/linux/mm.h:1225:\t\tvma_flags_t to_test)\ninclude/linux/mm.h-1226-{\n--\ninclude/linux/mm.h-1235- *\ninclude/linux/mm.h:1236: * if (vma_flags_test_all(flags, VMA_READ_BIT, VMA_MAYREAD_BIT)) { ... }\ninclude/linux/mm.h-1237- */\ninclude/linux/mm.h:1238:#define vma_flags_test_all(flags, ...) \\\ninclude/linux/mm.h:1239:\tvma_flags_test_all_mask(flags, mk_vma_flags(__VA_ARGS__))\ninclude/linux/mm.h-1240-\ninclude/linux/mm.h-1241-/*\ninclude/linux/mm.h:1242: * Helper to test that a flag mask of type vma_flags_t has a SINGLE flag set\ninclude/linux/mm.h-1243- * (returning false if flagmask has no flags set).\n--\ninclude/linux/mm.h-1247- *\ninclude/linux/mm.h:1248: * if (vma_flags_test_single_mask(\u0026flags, VMA_DROPPABLE)) { ... }\ninclude/linux/mm.h-1249- *\n--\ninclude/linux/mm.h-1252- */\ninclude/linux/mm.h:1253:static __always_inline bool vma_flags_test_single_mask(const vma_flags_t *flags,\ninclude/linux/mm.h:1254:\t\tvma_flags_t flagmask)\ninclude/linux/mm.h-1255-{\n--\ninclude/linux/mm.h-1257-\ninclude/linux/mm.h:1258:\treturn vma_flags_test_any_mask(flags, flagmask);\ninclude/linux/mm.h-1259-}\n--\ninclude/linux/mm.h-1261-/* Set each of the to_set flags in flags, non-atomically. */\ninclude/linux/mm.h:1262:static __always_inline void vma_flags_set_mask(vma_flags_t *flags,\ninclude/linux/mm.h:1263:\t\tvma_flags_t to_set)\ninclude/linux/mm.h-1264-{\n--\ninclude/linux/mm.h-1278-\ninclude/linux/mm.h:1279:static __always_inline vma_flags_t __mk_vma_flags_from_masks(size_t count,\ninclude/linux/mm.h:1280:\t\tconst vma_flags_t *masks)\ninclude/linux/mm.h-1281-{\ninclude/linux/mm.h:1282:\tvma_flags_t flags = EMPTY_VMA_FLAGS;\ninclude/linux/mm.h-1283-\tsize_t i;\n--\ninclude/linux/mm.h-1290-/*\ninclude/linux/mm.h:1291: * Combine pre-computed vma_flags_t masks into one value, e.g.:\ninclude/linux/mm.h-1292- *\ninclude/linux/mm.h:1293: * vma_flags_t flags = mk_vma_flags_from_masks(VMA_UFFD_WP, VMA_UFFD_MINOR);\ninclude/linux/mm.h-1294- *\n--\ninclude/linux/mm.h-1300-\t__mk_vma_flags_from_masks(COUNT_ARGS(__VA_ARGS__),\t\t\\\ninclude/linux/mm.h:1301:\t\t(const vma_flags_t []){__VA_ARGS__})\ninclude/linux/mm.h-1302-\ninclude/linux/mm.h-1303-/* Clear all of the to-clear flags in flags, non-atomically. */\ninclude/linux/mm.h:1304:static __always_inline void vma_flags_clear_mask(vma_flags_t *flags,\ninclude/linux/mm.h:1305:\t\tvma_flags_t to_clear)\ninclude/linux/mm.h-1306-{\n--\ninclude/linux/mm.h-1324- */\ninclude/linux/mm.h:1325:static __always_inline vma_flags_t vma_flags_diff_pair(const vma_flags_t *flags,\ninclude/linux/mm.h:1326:\t\tconst vma_flags_t *flags_other)\ninclude/linux/mm.h-1327-{\ninclude/linux/mm.h:1328:\tvma_flags_t dst;\ninclude/linux/mm.h-1329-\tconst unsigned long *bitmap_other = flags_other-\u003e__vma_flags;\n--\ninclude/linux/mm.h-1337-/* Determine if flags and flags_other have precisely the same flags set. */\ninclude/linux/mm.h:1338:static __always_inline bool vma_flags_same_pair(const vma_flags_t *flags,\ninclude/linux/mm.h:1339:\t\t\t\t\t\tconst vma_flags_t *flags_other)\ninclude/linux/mm.h-1340-{\n--\ninclude/linux/mm.h-1347-/* Determine if flags and flags_other have precisely the same flags set.  */\ninclude/linux/mm.h:1348:static __always_inline bool vma_flags_same_mask(const vma_flags_t *flags,\ninclude/linux/mm.h:1349:\t\t\t\t\t\tvma_flags_t flags_other)\ninclude/linux/mm.h-1350-{\n--\ninclude/linux/mm.h=1370=static __always_inline bool vma_test(const struct vm_area_struct *vma,\n--\ninclude/linux/mm.h-1372-{\ninclude/linux/mm.h:1373:\treturn vma_flags_test(\u0026vma-\u003eflags, bit);\ninclude/linux/mm.h-1374-}\n--\ninclude/linux/mm.h=1377=static __always_inline bool vma_test_any_mask(const struct vm_area_struct *vma,\ninclude/linux/mm.h:1378:\t\tvma_flags_t flags)\ninclude/linux/mm.h-1379-{\ninclude/linux/mm.h:1380:\treturn vma_flags_test_any_mask(\u0026vma-\u003eflags, flags);\ninclude/linux/mm.h-1381-}\n--\ninclude/linux/mm.h=1399=static __always_inline bool vma_test_all_mask(const struct vm_area_struct *vma,\ninclude/linux/mm.h:1400:\t\tvma_flags_t flags)\ninclude/linux/mm.h-1401-{\ninclude/linux/mm.h:1402:\treturn vma_flags_test_all_mask(\u0026vma-\u003eflags, flags);\ninclude/linux/mm.h-1403-}\n--\ninclude/linux/mm.h-1413-/*\ninclude/linux/mm.h:1414: * Helper to test that a flag mask of type vma_flags_t has a SINGLE flag set\ninclude/linux/mm.h-1415- * (returning false if flagmask has no flags set).\n--\ninclude/linux/mm.h=1425=static __always_inline bool\ninclude/linux/mm.h:1426:vma_test_single_mask(const struct vm_area_struct *vma, vma_flags_t flagmask)\ninclude/linux/mm.h-1427-{\ninclude/linux/mm.h:1428:\treturn vma_flags_test_single_mask(\u0026vma-\u003eflags, flagmask);\ninclude/linux/mm.h-1429-}\n--\ninclude/linux/mm.h=1437=static __always_inline void vma_set_flags_mask(struct vm_area_struct *vma,\ninclude/linux/mm.h:1438:\t\tvma_flags_t flags)\ninclude/linux/mm.h-1439-{\n--\ninclude/linux/mm.h=1456=static __always_inline void vma_clear_flags_mask(struct vm_area_struct *vma,\ninclude/linux/mm.h:1457:\t\tvma_flags_t flags)\ninclude/linux/mm.h-1458-{\n--\ninclude/linux/mm.h=1476=static __always_inline bool vma_desc_test(const struct vm_area_desc *desc,\n--\ninclude/linux/mm.h-1478-{\ninclude/linux/mm.h:1479:\treturn vma_flags_test(\u0026desc-\u003evma_flags, bit);\ninclude/linux/mm.h-1480-}\n--\ninclude/linux/mm.h=1483=static __always_inline bool vma_desc_test_any_mask(const struct vm_area_desc *desc,\ninclude/linux/mm.h:1484:\t\tvma_flags_t flags)\ninclude/linux/mm.h-1485-{\ninclude/linux/mm.h:1486:\treturn vma_flags_test_any_mask(\u0026desc-\u003evma_flags, flags);\ninclude/linux/mm.h-1487-}\n--\ninclude/linux/mm.h=1500=static __always_inline bool vma_desc_test_all_mask(const struct vm_area_desc *desc,\ninclude/linux/mm.h:1501:\t\tvma_flags_t flags)\ninclude/linux/mm.h-1502-{\ninclude/linux/mm.h:1503:\treturn vma_flags_test_all_mask(\u0026desc-\u003evma_flags, flags);\ninclude/linux/mm.h-1504-}\n--\ninclude/linux/mm.h=1516=static __always_inline void vma_desc_set_flags_mask(struct vm_area_desc *desc,\ninclude/linux/mm.h:1517:\t\tvma_flags_t flags)\ninclude/linux/mm.h-1518-{\n--\ninclude/linux/mm.h=1533=static __always_inline void vma_desc_clear_flags_mask(struct vm_area_desc *desc,\ninclude/linux/mm.h:1534:\t\tvma_flags_t flags)\ninclude/linux/mm.h-1535-{\n--\ninclude/linux/mm.h=1578=static inline bool vma_is_initial_stack(const struct vm_area_struct *vma)\n--\ninclude/linux/mm.h-1588-\ninclude/linux/mm.h:1589:static inline bool vma_flags_can_grow(const vma_flags_t *flags)\ninclude/linux/mm.h-1590-{\ninclude/linux/mm.h:1591:\tif (vma_flags_test_single_mask(flags, VMA_GROWSUP))\ninclude/linux/mm.h-1592-\t\treturn true;\ninclude/linux/mm.h:1593:\tif (vma_flags_test(flags, VMA_GROWSDOWN_BIT))\ninclude/linux/mm.h-1594-\t\treturn true;\n--\ninclude/linux/mm.h=1627=static inline bool vma_is_accessible(const struct vm_area_struct *vma)\n--\ninclude/linux/mm.h-1631-\ninclude/linux/mm.h:1632:static inline bool is_shared_maywrite(const vma_flags_t *flags)\ninclude/linux/mm.h-1633-{\ninclude/linux/mm.h:1634:\treturn vma_flags_test_all(flags, VMA_SHARED_BIT, VMA_MAYWRITE_BIT);\ninclude/linux/mm.h-1635-}\n--\ninclude/linux/mm.h=2279=static inline bool vma_desc_is_cow_mapping(struct vm_area_desc *desc)\ninclude/linux/mm.h-2280-{\ninclude/linux/mm.h:2281:\tconst vma_flags_t *flags = \u0026desc-\u003evma_flags;\ninclude/linux/mm.h-2282-\ninclude/linux/mm.h:2283:\treturn vma_flags_test(flags, VMA_MAYWRITE_BIT) \u0026\u0026\ninclude/linux/mm.h:2284:\t\t!vma_flags_test(flags, VMA_SHARED_BIT);\ninclude/linux/mm.h-2285-}\n--\ninclude/linux/mm.h=2288=static inline bool is_nommu_shared_mapping(vm_flags_t flags)\n--\ninclude/linux/mm.h-2300-\ninclude/linux/mm.h:2301:static inline bool is_nommu_shared_vma_flags(const vma_flags_t *flags)\ninclude/linux/mm.h-2302-{\ninclude/linux/mm.h:2303:\treturn vma_flags_test_any(flags, VMA_MAYSHARE_BIT, VMA_MAYOVERLAY_BIT);\ninclude/linux/mm.h-2304-}\n--\ninclude/linux/mm.h=4197=__get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,\ninclude/linux/mm.h-4198-\t\t    unsigned long pgoff, unsigned long flags,\ninclude/linux/mm.h:4199:\t\t    vma_flags_t vma_flags);\ninclude/linux/mm.h-4200-\n--\ninclude/linux/mm.h=4209=unsigned long do_mmap(struct file *file, unsigned long addr,\ninclude/linux/mm.h-4210-\tunsigned long len, unsigned long prot, unsigned long flags,\ninclude/linux/mm.h:4211:\tvma_flags_t vma_flags, unsigned long pgoff, unsigned long *populate,\ninclude/linux/mm.h-4212-\tstruct list_head *uf);\n--\ninclude/linux/mm.h=4608=pgprot_t vm_get_page_prot(vm_flags_t vm_flags);\ninclude/linux/mm.h-4609-\ninclude/linux/mm.h:4610:static inline pgprot_t vma_flags_to_page_prot(vma_flags_t vma_flags)\ninclude/linux/mm.h-4611-{\ninclude/linux/mm.h:4612:\tconst vm_flags_t vm_flags = vma_flags_to_legacy(vma_flags);\ninclude/linux/mm.h-4613-\n--\ninclude/linux/mm.h=4617=static inline pgprot_t vma_get_page_prot(const struct vm_area_struct *vma)\ninclude/linux/mm.h-4618-{\ninclude/linux/mm.h:4619:\treturn vma_flags_to_page_prot(vma-\u003eflags);\ninclude/linux/mm.h-4620-}\n--\ninclude/linux/mm.h=4624=static inline pgprot_t vm_get_page_prot(vm_flags_t vm_flags)\n--\ninclude/linux/mm.h-4627-}\ninclude/linux/mm.h:4628:static inline pgprot_t vma_flags_to_page_prot(vma_flags_t vma_flags)\ninclude/linux/mm.h-4629-{\n--\ninclude/linux/mm_types.h=869=typedef struct {\ninclude/linux/mm_types.h-870-\tDECLARE_BITMAP(__vma_flags, NUM_VMA_FLAG_BITS);\ninclude/linux/mm_types.h:871:} vma_flags_t;\ninclude/linux/mm_types.h-872-\ninclude/linux/mm_types.h:873:#define EMPTY_VMA_FLAGS ((vma_flags_t){ })\ninclude/linux/mm_types.h-874-\ninclude/linux/mm_types.h-875-/* Are no flags set in the specified VMA flags? */\ninclude/linux/mm_types.h:876:static __always_inline bool vma_flags_empty(const vma_flags_t *flags)\ninclude/linux/mm_types.h-877-{\n--\ninclude/linux/mm_types.h=890=struct vm_area_desc {\n--\ninclude/linux/mm_types.h-899-\tstruct file *vm_file;\ninclude/linux/mm_types.h:900:\tvma_flags_t vma_flags;\ninclude/linux/mm_types.h-901-\tpgprot_t page_prot;\n--\ninclude/linux/mm_types.h=923=struct vm_area_struct {\n--\ninclude/linux/mm_types.h-949-\t\tconst vm_flags_t vm_flags;\ninclude/linux/mm_types.h:950:\t\tvma_flags_t flags;\ninclude/linux/mm_types.h-951-\t};\n--\ninclude/linux/mm_types.h-1068-/* Clears all bits in the VMA flags bitmap, non-atomically. */\ninclude/linux/mm_types.h:1069:static __always_inline void vma_flags_clear_all(vma_flags_t *flags)\ninclude/linux/mm_types.h-1070-{\n--\ninclude/linux/mm_types.h-1074-/*\ninclude/linux/mm_types.h:1075: * Helper function which converts a vma_flags_t value to a legacy vm_flags_t\ninclude/linux/mm_types.h-1076- * value. This is only valid if the input flags value can be expressed in a\n--\ninclude/linux/mm_types.h-1080- */\ninclude/linux/mm_types.h:1081:static __always_inline vm_flags_t vma_flags_to_legacy(vma_flags_t flags)\ninclude/linux/mm_types.h-1082-{\n--\ninclude/linux/mm_types.h-1091- */\ninclude/linux/mm_types.h:1092:static __always_inline void vma_flags_overwrite_word(vma_flags_t *flags,\ninclude/linux/mm_types.h-1093-\t\tunsigned long value)\n--\ninclude/linux/mm_types.h-1100-/*\ninclude/linux/mm_types.h:1101: * Helper function which converts a legacy vm_flags_t value to a vma_flags_t\ninclude/linux/mm_types.h-1102- * value.\n--\ninclude/linux/mm_types.h-1105- */\ninclude/linux/mm_types.h:1106:static __always_inline vma_flags_t legacy_to_vma_flags(vm_flags_t flags)\ninclude/linux/mm_types.h-1107-{\ninclude/linux/mm_types.h:1108:\tvma_flags_t ret = EMPTY_VMA_FLAGS;\ninclude/linux/mm_types.h-1109-\n--\ninclude/linux/mm_types.h-1119- */\ninclude/linux/mm_types.h:1120:static __always_inline void vma_flags_overwrite_word_once(vma_flags_t *flags,\ninclude/linux/mm_types.h-1121-\t\tunsigned long value)\n--\ninclude/linux/mm_types.h-1128-/* Update the first system word of VMA flags setting bits, non-atomically. */\ninclude/linux/mm_types.h:1129:static __always_inline void vma_flags_set_word(vma_flags_t *flags,\ninclude/linux/mm_types.h-1130-\t\tunsigned long value)\n--\ninclude/linux/mm_types.h-1137-/* Update the first system word of VMA flags clearing bits, non-atomically. */\ninclude/linux/mm_types.h:1138:static __always_inline void vma_flags_clear_word(vma_flags_t *flags,\ninclude/linux/mm_types.h-1139-\t\tunsigned long value)\n--\ninclude/linux/mm_types.h=1163=struct mm_struct {\n--\ninclude/linux/mm_types.h-1279-\t\t\tvm_flags_t def_flags;\ninclude/linux/mm_types.h:1280:\t\t\tvma_flags_t def_vma_flags;\ninclude/linux/mm_types.h-1281-\t\t};\n--\ninclude/linux/rmap.h=845=int folio_referenced(struct folio *, int is_locked,\ninclude/linux/rmap.h:846:\t\tstruct mem_cgroup *memcg, vma_flags_t *vma_flags);\ninclude/linux/rmap.h-847-\n--\ninclude/linux/rmap.h=977=static inline int folio_referenced(struct folio *folio, int is_locked,\ninclude/linux/rmap.h:978:\t\tstruct mem_cgroup *memcg, vma_flags_t *vma_flags)\ninclude/linux/rmap.h-979-{\n--\ninclude/linux/sched/mm.h=196=unsigned long mm_get_unmapped_area_vmaflags(struct file *filp,\ninclude/linux/sched/mm.h-197-\t\tunsigned long addr, unsigned long len, unsigned long pgoff,\ninclude/linux/sched/mm.h:198:\t\tunsigned long flags, vma_flags_t vma_flags);\ninclude/linux/sched/mm.h-199-\n--\ninclude/linux/sched/mm.h=201=generic_get_unmapped_area(struct file *filp, unsigned long addr,\ninclude/linux/sched/mm.h-202-\t\t\t  unsigned long len, unsigned long pgoff,\ninclude/linux/sched/mm.h:203:\t\t\t  unsigned long flags, vma_flags_t vma_flags);\ninclude/linux/sched/mm.h-204-unsigned long\ninclude/linux/sched/mm.h=205=generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr,\ninclude/linux/sched/mm.h-206-\t\t\t\t  unsigned long len, unsigned long pgoff,\ninclude/linux/sched/mm.h:207:\t\t\t\t  unsigned long flags, vma_flags_t vma_flags);\ninclude/linux/sched/mm.h-208-#else\n--\ninclude/linux/shmem_fs.h=103=extern int shmem_init_fs_context(struct fs_context *fc);\ninclude/linux/shmem_fs.h:104:struct file *shmem_file_setup(const char *name, loff_t size, vma_flags_t flags);\ninclude/linux/shmem_fs.h:105:struct file *shmem_kernel_file_setup(const char *name, loff_t size, vma_flags_t vma_flags);\ninclude/linux/shmem_fs.h-106-extern struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt,\ninclude/linux/shmem_fs.h:107:\t\tconst char *name, loff_t size, vma_flags_t flags);\ninclude/linux/shmem_fs.h-108-int shmem_zero_setup(struct vm_area_struct *vma);\n--\nipc/shm.c=704=static int newseg(struct ipc_namespace *ns, struct ipc_params *params)\n--\nipc/shm.c-712-\tconst bool has_no_reserve = shmflg \u0026 SHM_NORESERVE;\nipc/shm.c:713:\tvma_flags_t acctflag = EMPTY_VMA_FLAGS;\nipc/shm.c-714-\tstruct file *file;\n--\nmm/huge_memory.c=1194=static unsigned long __thp_get_unmapped_area(struct file *filp,\n--\nmm/huge_memory.c-1196-\t\tloff_t off, unsigned long flags, unsigned long size,\nmm/huge_memory.c:1197:\t\tvma_flags_t vma_flags)\nmm/huge_memory.c-1198-{\n--\nmm/huge_memory.c=1240=unsigned long thp_get_unmapped_area_vmaflags(struct file *filp, unsigned long addr,\nmm/huge_memory.c-1241-\t\tunsigned long len, unsigned long pgoff, unsigned long flags,\nmm/huge_memory.c:1242:\t\tvma_flags_t vma_flags)\nmm/huge_memory.c-1243-{\n--\nmm/hugetlb.c=6672=long hugetlb_reserve_pages(struct inode *inode,\n--\nmm/hugetlb.c-6674-\t\tstruct vm_area_struct *vma,\nmm/hugetlb.c:6675:\t\tvma_flags_t vma_flags)\nmm/hugetlb.c-6676-{\n--\nmm/hugetlb.c-6701-\t */\nmm/hugetlb.c:6702:\tif (vma_flags_test(\u0026vma_flags, VMA_NORESERVE_BIT))\nmm/hugetlb.c-6703-\t\treturn 0;\n--\nmm/internal.h=1573=static inline int get_sysctl_max_map_count(void)\n--\nmm/internal.h-1577-\nmm/internal.h:1578:bool may_expand_vm(struct mm_struct *mm, const vma_flags_t *vma_flags,\nmm/internal.h-1579-\t\t   unsigned long npages);\n--\nmm/ksm.c=698=static int break_ksm(struct vm_area_struct *vma, unsigned long addr,\n--\nmm/ksm.c-743-\nmm/ksm.c:744:static bool ksm_compatible(const struct file *file, vma_flags_t vma_flags)\nmm/ksm.c-745-{\nmm/ksm.c-746-\t/* Just ignore the advice. */\nmm/ksm.c:747:\tif (vma_flags_test_any(\u0026vma_flags, VMA_SHARED_BIT, VMA_MAYSHARE_BIT,\nmm/ksm.c-748-\t\t\t       VMA_HUGETLB_BIT))\nmm/ksm.c-749-\t\treturn false;\nmm/ksm.c:750:\tif (vma_flags_test_single_mask(\u0026vma_flags, VMA_DROPPABLE))\nmm/ksm.c-751-\t\treturn false;\nmm/ksm.c:752:\tif (vma_flags_test_any_mask(\u0026vma_flags, VMA_SPECIAL_FLAGS))\nmm/ksm.c-753-\t\treturn false;\n--\nmm/ksm.c-756-#ifdef VM_SAO\nmm/ksm.c:757:\tif (vma_flags_test(\u0026vma_flags, VMA_SAO_BIT))\n\n"
}

gemini-3.1-pro-preview

null

null

							input: 17635
							output: 19
							thoughts: 906
						

**Analyzing a Memory Management Patch**

Alright, let's break this down. First, `vma_flags_t` is the key. It's a structure, essentially a bitmap, defined in `include/linux/mm_types.h`. This patch is replacing `vm_flags_t` with it in `mm/vmscan.c` and `mm/rmap.c`. That's the baseline.

Now, it's not just a straight swap. The patch is also introducing `const vma_flags_t *vma_flags` as a parameter to `lru_gen_set_refs` and `folio_update_gen`.  It's adding a new inline function, `is_exec_file_folio`, which checks if a folio is both file-backed and executable.  This is interesting. The logic is:
```c
static inline bool is_exec_file_folio(const struct folio *folio,
		const vma_flags_t *vma_flags)
{
	return vma_flags_test(vma_flags, VMA_EXEC_BIT) && folio_is_file_lru(folio);
}
```

The crucial part is how this new function is being used. It's being integrated into `lru_gen_set_refs`, which is called from `folio_check_references` and `walk_update_folio`. Looking at `folio_check_references`, the previous logic was a simple `(vm_flags & VM_EXEC) && folio_is_file_lru(folio)`. Now, it's calling `is_exec_file_folio`, and importantly, it activates these folios, which wasn't the case earlier:
```c
		if (is_exec_file_folio(folio, &vma_flags))
			return FOLIOREF_ACTIVATE;
```

In `lru_gen_set_refs`, we see the same principle - activate file-backed, executable folios:
```c
static bool lru_gen_set_refs(struct folio *folio, const vma_flags_t *vma_flags)
{
	/* see the comment on LRU_REFS_FLAGS */
	if (!folio_test_referenced(folio) && !folio_test_workingset(folio)) {
		/* Activate file-backed executable folios after first usage. */
		if (is_exec_file_folio(folio, vma_flags)) {
			set_mask_bits(&folio->flags.f, LRU_REFS_FLAGS, BIT(PG_workingset));
			return true;
		}

		set_mask_bits(&folio->flags.f, LRU_REFS_MASK, BIT(PG_referenced));
		return false;
	}
```

So, this *is* a functional change. It activates file-backed executable folios (after first usage) in reclaim paths. The commit message mentions this is a patch being applied from a fuzzing cluster, which suggests it targets a stability issue, probably involving the LRU algorithm.  Memory reclaim is a critical part of the kernel, and this touches both standard LRU and MGLRU logic, as shown from the modified functions: `lru_gen_set_refs`, `folio_check_references`, `shrink_active_list`, `folio_update_gen`, `walk_update_folio`, `walk_pte_range`, `walk_pmd_range_locked`, `lru_gen_look_around`.  Since `shrink_active_list`, for example, is there, this touches both MGLRU and active/inactive list reclaim. We should be able to get there by running memory pressure, so yes, this is definitely reachable.

Given that it modifies memory management, this is definitely worth fuzzing. The fact that the commit mentions "syz-cluster" means there's probably a real bug. I'll need to check if MGLRU (`CONFIG_LRU_GEN`) is enabled or needs a config, but I'm expecting this to be an active part of the kernel.

{
  "Expression": "config LRU_GEN"
}

{
  "Output": "mm/Kconfig=1389=config PTE_MARKER_UFFD_WP\n--\nmm/Kconfig-1399-# multi-gen LRU {\nmm/Kconfig:1400:config LRU_GEN\nmm/Kconfig-1401-\tbool \"Multi-Gen LRU\"\n--\nmm/Kconfig-1408-\nmm/Kconfig:1409:config LRU_GEN_ENABLED\nmm/Kconfig-1410-\tbool \"Enable by default\"\n--\nmm/Kconfig-1414-\nmm/Kconfig:1415:config LRU_GEN_STATS\nmm/Kconfig-1416-\tbool \"Full stats for debugging\"\n--\nmm/Kconfig-1423-\nmm/Kconfig:1424:config LRU_GEN_WALKS_MMU\nmm/Kconfig-1425-\tdef_bool y\n"
}

gemini-3.1-pro-preview

null

null

							input: 19704
							output: 33
							thoughts: 17
						

Here's a summary of my thought process:

**Diving into the Kernel Configuration Landscape**

Okay, so I need to understand something related to `LRU_GEN`. My immediate instinct is to check the `mm/Kconfig` file. This is where the core memory management configurations usually reside, and it's highly likely that a feature like `LRU_GEN` will have its defining options, dependencies, and help text there. I'm going straight for the source to get the definitive information on this. Time to dig in and see what `mm/Kconfig` reveals.

{
  "File": "mm/Kconfig",
  "FirstLine": 1399,
  "LineCount": 50
}

{
  "Contents": "1399:\t# multi-gen LRU {\n1400:\tconfig LRU_GEN\n1401:\t\tbool \"Multi-Gen LRU\"\n1402:\t\tdepends on MMU\n1403:\t\t# make sure folio-\u003eflags has enough spare bits\n1404:\t\tdepends on 64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP\n1405:\t\thelp\n1406:\t\t  A high performance LRU implementation to overcommit memory. See\n1407:\t\t  Documentation/admin-guide/mm/multigen_lru.rst for details.\n1408:\t\n1409:\tconfig LRU_GEN_ENABLED\n1410:\t\tbool \"Enable by default\"\n1411:\t\tdepends on LRU_GEN\n1412:\t\thelp\n1413:\t\t  This option enables the multi-gen LRU by default.\n1414:\t\n1415:\tconfig LRU_GEN_STATS\n1416:\t\tbool \"Full stats for debugging\"\n1417:\t\tdepends on LRU_GEN\n1418:\t\thelp\n1419:\t\t  Do not enable this option unless you plan to look at historical stats\n1420:\t\t  from evicted generations for debugging purpose.\n1421:\t\n1422:\t\t  This option has a per-memcg and per-node memory overhead.\n1423:\t\n1424:\tconfig LRU_GEN_WALKS_MMU\n1425:\t\tdef_bool y\n1426:\t\tdepends on LRU_GEN \u0026\u0026 ARCH_HAS_HW_PTE_YOUNG\n1427:\t# }\n1428:\t\n1429:\tconfig ARCH_SUPPORTS_PER_VMA_LOCK\n1430:\t       def_bool n\n1431:\t\n1432:\tconfig PER_VMA_LOCK\n1433:\t\tdef_bool y\n1434:\t\tdepends on ARCH_SUPPORTS_PER_VMA_LOCK \u0026\u0026 MMU \u0026\u0026 SMP\n1435:\t\thelp\n1436:\t\t  Allow per-vma locking during page fault handling.\n1437:\t\n1438:\t\t  This feature allows locking each virtual memory area separately when\n1439:\t\t  handling page faults instead of taking mmap_lock.\n1440:\t\n1441:\tconfig LOCK_MM_AND_FIND_VMA\n1442:\t\tbool\n1443:\t\tdepends on !STACK_GROWSUP\n1444:\t\n1445:\tconfig IOMMU_MM_DATA\n1446:\t\tbool\n1447:\t\n1448:\tconfig EXECMEM\n"
}

gemini-3.1-pro-preview

null

null

							input: 20569
							output: 34
							thoughts: 133
						

**Investigating LRU_GEN for Proper Testing**

Okay, so to really put this new `LRU_GEN` functionality through its paces, I need to enable both `LRU_GEN` and `LRU_GEN_ENABLED`. That seems obvious. The core of this patch touches `folio_check_references` and `shrink_active_list`, which, as I recall, are also fundamental components of the standard LRU reclaim process. Hmm, this is interesting. I'm seeing that `lru_gen_set_refs` gets called within `folio_check_references`. That would mean that the new `LRU_GEN` mechanism bleeds into the standard LRU. Wait, no, hang on, the definition of `lru_gen_set_refs` is conditional, depending on the `CONFIG_LRU_GEN` setting, so it *shouldn't* interfere when `LRU_GEN` isn't active. Just want to confirm that in my head. Let me just quickly double-check that interaction point in `mm/vmscan.c` around line 841. It's always good to be thorough when you're dealing with memory management.

{
  "File": "mm/vmscan.c",
  "FirstLine": 830,
  "LineCount": 50
}

{
  "Contents": " 830:\t\n 831:\tenum folio_references {\n 832:\t\tFOLIOREF_RECLAIM,\n 833:\t\tFOLIOREF_KEEP,\n 834:\t\tFOLIOREF_ACTIVATE,\n 835:\t};\n 836:\t\n 837:\t#ifdef CONFIG_LRU_GEN\n 838:\t/*\n 839:\t * Only used on a mapped folio in the eviction (rmap walk) path, where promotion\n 840:\t * needs to be done by taking the folio off the LRU list and then adding it back\n 841:\t * with PG_active set. In contrast, the aging (page table walk) path uses\n 842:\t * folio_update_gen().\n 843:\t */\n 844:\tstatic bool lru_gen_set_refs(struct folio *folio, const vma_flags_t *vma_flags)\n 845:\t{\n 846:\t\t/* see the comment on LRU_REFS_FLAGS */\n 847:\t\tif (!folio_test_referenced(folio) \u0026\u0026 !folio_test_workingset(folio)) {\n 848:\t\t\t/* Activate file-backed executable folios after first usage. */\n 849:\t\t\tif (is_exec_file_folio(folio, vma_flags)) {\n 850:\t\t\t\tset_mask_bits(\u0026folio-\u003eflags.f, LRU_REFS_FLAGS, BIT(PG_workingset));\n 851:\t\t\t\treturn true;\n 852:\t\t\t}\n 853:\t\n 854:\t\t\tset_mask_bits(\u0026folio-\u003eflags.f, LRU_REFS_MASK, BIT(PG_referenced));\n 855:\t\t\treturn false;\n 856:\t\t}\n 857:\t\n 858:\t\t/* Promote on second access */\n 859:\t\tif (folio_lru_refs(folio) \u003e 1)\n 860:\t\t\tset_mask_bits(\u0026folio-\u003eflags.f, LRU_REFS_FLAGS, BIT(PG_workingset));\n 861:\t\telse\n 862:\t\t\tfolio_mark_accessed(folio);\n 863:\t\treturn true;\n 864:\t}\n 865:\t#else\n 866:\tstatic bool lru_gen_set_refs(struct folio *folio, const vma_flags_t *vma_flags)\n 867:\t{\n 868:\t\treturn false;\n 869:\t}\n 870:\t#endif /* CONFIG_LRU_GEN */\n 871:\t\n 872:\tstatic enum folio_references folio_check_references(struct folio *folio,\n 873:\t\t\t\t\t\t\t  struct scan_control *sc)\n 874:\t{\n 875:\t\tint referenced_ptes, referenced_folio;\n 876:\t\tvma_flags_t vma_flags;\n 877:\t\n 878:\t\treferenced_ptes = folio_referenced(folio, 1, sc-\u003etarget_mem_cgroup,\n 879:\t\t\t\t\t\t   \u0026vma_flags);\n"
}

gemini-3.1-pro-preview

null

null

							input: 21797
							output: 22
							thoughts: 744
						

**Analyzing the Potential Impact of this Patch**

Okay, so I've been digging into this patch. I see that `lru_gen_set_refs` is definitely part of `CONFIG_LRU_GEN`, which is MGLRU, but `folio_check_references` is also used in standard LRU reclaim. That's immediately interesting. Then I see that `folio_check_references` directly calls `is_exec_file_folio`, and that `shrink_active_list` *also* utilizes `is_exec_file_folio`. So, this patch isn't just touching MGLRU; it's got implications for the standard LRU reclaim path as well. Hmm, definitely something to prioritize for fuzzing.

Now, let's identify the key functions we need to focus on. I've got: `folio_check_references`, `shrink_active_list`, `folio_update_gen`, `walk_update_folio`, `walk_pte_range`, `walk_pmd_range_locked`, `lru_gen_look_around`, `folio_referenced`, and `folio_referenced_one`.

Wait, let's refine this list. `folio_referenced` and `folio_referenced_one` are in `mm/rmap.c`, while `folio_check_references` and `shrink_active_list` are in `mm/vmscan.c`. Then the MGLRU code: `folio_update_gen`, `walk_update_folio`, `walk_pte_range`, `walk_pmd_range_locked`, `lru_gen_look_around` are also in `mm/vmscan.c`.

Okay, let's check function visibility. `folio_check_references` and `shrink_active_list` are static. `folio_referenced` is exported/global. `folio_update_gen` is static. `walk_update_folio` is static. `lru_gen_look_around` is global.

So, for fuzzing, I'm thinking the following functions. Since `FocusSymbols` is about functions to target, I can fuzz the static ones if the code path is hit.

*   `folio_referenced`
*   `folio_check_references`
*   `shrink_active_list`
*   `folio_update_gen`
*   `walk_update_folio`
*   `lru_gen_look_around`
*   `walk_pte_range`
*   `walk_pmd_range_locked`

Are these hot paths? Memory reclaim functions aren't necessarily *hot*, unless there's memory pressure. But `folio_referenced` is called during reclaim. `lru_gen_look_around` is called during page fault (from `do_set_pte` or similar), so definitely could be frequently hit. Let me double-check where `lru_gen_look_around` is called...

{
  "Expression": "lru_gen_look_around"
}

{
  "Output": "Documentation/mm/multigen_lru.rst=187=can incur the highest CPU cost in the reclaim path.\nDocumentation/mm/multigen_lru.rst-188-\nDocumentation/mm/multigen_lru.rst:189:``lru_gen_look_around()`` exploits spatial locality to reduce the\nDocumentation/mm/multigen_lru.rst-190-trips into the rmap. It scans the adjacent PTEs of a young PTE and\n--\nDocumentation/mm/multigen_lru.rst=199=in the set.\nDocumentation/mm/multigen_lru.rst-200-\nDocumentation/mm/multigen_lru.rst:201:In the eviction path, specifically, in ``lru_gen_look_around()``, if a\nDocumentation/mm/multigen_lru.rst-202-PMD has a sufficient number of hot pages, its address is placed in the\n--\ninclude/linux/mmzone.h=689=void lru_gen_init_lruvec(struct lruvec *lruvec);\ninclude/linux/mmzone.h:690:bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw, unsigned int nr);\ninclude/linux/mmzone.h-691-\n--\ninclude/linux/mmzone.h=708=static inline void lru_gen_init_lruvec(struct lruvec *lruvec)\n--\ninclude/linux/mmzone.h-711-\ninclude/linux/mmzone.h:712:static inline bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw,\ninclude/linux/mmzone.h-713-\t\tunsigned int nr)\n--\nmm/rmap.c=917=static bool folio_referenced_one(struct folio *folio,\n--\nmm/rmap.c-981-\t\tif (lru_gen_enabled() \u0026\u0026 !lru_gen_switching() \u0026\u0026 pvmw.pte) {\nmm/rmap.c:982:\t\t\tif (lru_gen_look_around(\u0026pvmw, nr))\nmm/rmap.c-983-\t\t\t\treferenced++;\n--\nmm/vmscan.c=2720=static bool __maybe_unused seq_is_valid(struct lruvec *lruvec)\n--\nmm/vmscan.c-2749- * walk_pmd_range(); the eviction also report them when walking the rmap\nmm/vmscan.c:2750: * in lru_gen_look_around().\nmm/vmscan.c-2751- *\n--\nmm/vmscan.c=4002=static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long seq,\n--\nmm/vmscan.c-4021-\t * If the hardware doesn't automatically set the accessed bit, fallback\nmm/vmscan.c:4022:\t * to lru_gen_look_around(), which only clears the accessed bit in a\nmm/vmscan.c-4023-\t * handful of PTEs. Spreading the work out over a period of time usually\n--\nmm/vmscan.c=4141=static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-4187- */\nmm/vmscan.c:4188:bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw, unsigned int nr)\nmm/vmscan.c-4189-{\n"
}

gemini-3.1-pro-preview

null

null

							input: 24116
							output: 22
							thoughts: 370
						

**Analyzing the Memory Management Patch**

Okay, so I'm looking at this patch and tracing the changes. It seems `lru_gen_look_around` is being called from `folio_referenced_one`, which is in `mm/rmap.c`. Right, so this is definitely part of the memory reclaim path. The core of this patch seems to be updating `folio_referenced` to use `vma_flags_t` and pass it down to `folio_check_references` and `shrink_active_list`. Interesting. And I see a change in `lru_gen_set_refs` too, which now activates file-backed executable folios after their initial use.

Let's quickly check the configuration options. I see `LRU_GEN` and `LRU_GEN_ENABLED`. These are obviously related to the MGLRU component, which makes sense. Hmm, but what about the standard LRU functionality? Ah, right, that's always on; it doesn't need any special config. So, including those MGLRU-specific options, `LRU_GEN` and `LRU_GEN_ENABLED`, will ensure that both paths are properly tested. Smart move.

Okay, let's verify that `vma_flags_t` is defined in `include/linux/mm_types.h`. Yep, it's there, as expected. This patch looks functionally sound. It's clearly modifying the memory reclaim logic, affecting things at the folio level.

Now, let's nail down the key symbols involved. I need to keep these in mind: `folio_referenced`, `folio_check_references`, `shrink_active_list`, `folio_update_gen`, `walk_update_folio`, `lru_gen_look_around`, and `lru_gen_set_refs`.

Wait, just a second... is `lru_gen_set_refs` inline or static? Let me double-check. Okay, it's static, which explains why it's defined in `mm/vmscan.c`. Alright, let's take a closer look at `mm/vmscan.c` and make sure I fully understand that static function.

{
  "Expression": "lru_gen_set_refs"
}

{
  "Output": "include/linux/mmzone.h=422=enum lruvec_flags {\n--\ninclude/linux/mmzone.h-509- * For folios accessed multiple times through page tables, folio_update_gen()\ninclude/linux/mmzone.h:510: * from a page table walk or lru_gen_set_refs() from a rmap walk sets\ninclude/linux/mmzone.h-511- * PG_referenced after the accessed bit is cleared for the first time.\n--\nmm/vmscan.c=831=enum folio_references {\n--\nmm/vmscan.c-843- */\nmm/vmscan.c:844:static bool lru_gen_set_refs(struct folio *folio, const vma_flags_t *vma_flags)\nmm/vmscan.c-845-{\n--\nmm/vmscan.c-865-#else\nmm/vmscan.c:866:static bool lru_gen_set_refs(struct folio *folio, const vma_flags_t *vma_flags)\nmm/vmscan.c-867-{\n--\nmm/vmscan.c=872=static enum folio_references folio_check_references(struct folio *folio,\n--\nmm/vmscan.c-900-\nmm/vmscan.c:901:\t\treturn lru_gen_set_refs(folio, \u0026vma_flags) ? FOLIOREF_ACTIVATE : FOLIOREF_KEEP;\nmm/vmscan.c-902-\t}\n--\nmm/vmscan.c=3446=static void walk_update_folio(struct lru_gen_mm_walk *walk, struct vm_area_struct *vma,\n--\nmm/vmscan.c-3462-\t\t\tupdate_batch_size(walk, folio, old_gen, new_gen);\nmm/vmscan.c:3463:\t} else if (lru_gen_set_refs(folio, \u0026vma-\u003eflags)) {\nmm/vmscan.c-3464-\t\told_gen = folio_lru_gen(folio);\n"
}

gemini-3.1-pro-preview

null

null

							input: 25514
							output: 167
							thoughts: 256
						

**My Analysis of the Patch's Reach and Significance**

Alright, let's break this down. First, `lru_gen_set_refs` is definitely static, so I can see what functions interact with it. I'll need to focus on: `folio_check_references`, `shrink_active_list`, `folio_update_gen`, `walk_update_folio`, `lru_gen_look_around`, and of course, `lru_gen_set_refs` itself.

Hold on, I see `folio_referenced` is also modified, I need to include that in the list as well.

Now, what about the configurations? This patch touches `mm/vmscan.c` and `mm/rmap.c`, which tells me it's deeply involved in memory management. Memory reclaim is always enabled, so that's a given. MGLRU, however, is gated by `CONFIG_LRU_GEN`. So, I'll need to consider `LRU_GEN` and `LRU_GEN_ENABLED` as the critical configs for enabling this particular functionality.

Let me double-check my logic. It looks like this patch changes how VMA flags are passed and checked during memory reclaim. This affects both the standard LRU and MGLRU. The main point is to trigger file-backed executable folios after their first use to prevent IO thrashing. This is a significant functional change within core memory management, which makes it highly reachable. This is *definitely* worth fuzzing.

Time to feed this into the `set-results` tool now.

{
  "EnableConfigs": [
    "LRU_GEN",
    "LRU_GEN_ENABLED"
  ],
  "FocusSymbols": [
    "folio_referenced",
    "folio_check_references",
    "shrink_active_list",
    "folio_update_gen",
    "walk_update_folio",
    "lru_gen_look_around",
    "lru_gen_set_refs"
  ],
  "Reasoning": "The patch modifies memory reclaim logic (both standard LRU and MGLRU) to activate file-backed executable folios after their first usage, preventing IO thrashing. It also changes how VMA flags are passed and evaluated during reclaim. This is a functional change to core memory management and is highly reachable.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "LRU_GEN",
    "LRU_GEN_ENABLED"
  ],
  "FocusSymbols": [
    "folio_referenced",
    "folio_check_references",
    "shrink_active_list",
    "folio_update_gen",
    "walk_update_folio",
    "lru_gen_look_around",
    "lru_gen_set_refs"
  ],
  "Reasoning": "The patch modifies memory reclaim logic (both standard LRU and MGLRU) to activate file-backed executable folios after their first usage, preventing IO thrashing. It also changes how VMA flags are passed and evaluated during reclaim. This is a functional change to core memory management and is highly reachable.",
  "WorthFuzzing": true
}