AI Trajectory

null

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch only contains cosmetic changes (renaming FPI_TRYLOCK to FPI_NOLOCK, updating comments) and removes two VM_BUG_ON assertions. It does not functionally alter the execution flow or introduce new reachable logic.",
  "WorthFuzzing": false
}

null

{
  "PatchDiff": "commit de2a31086f50c60beba0e3aeccc45b087bfe4453\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Wed Jul 15 18:59:47 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/include/linux/gfp.h b/include/linux/gfp.h\nindex 4d57e9c0bf204d..872bc53f32ec87 100644\n--- a/include/linux/gfp.h\n+++ b/include/linux/gfp.h\n@@ -255,7 +255,6 @@ static inline void warn_if_node_offline(int this_node, gfp_t gfp_mask)\n static inline\n struct folio *__folio_alloc_node_noprof(gfp_t gfp, unsigned int order, int nid)\n {\n-\tVM_BUG_ON(nid \u003c 0 || nid \u003e= MAX_NUMNODES);\n \twarn_if_node_offline(nid, gfp);\n \n \treturn __folio_alloc_noprof(gfp, order, nid, NULL);\ndiff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c\nindex 24ea2d09cdbdba..dfd0f827e3b92c 100644\n--- a/kernel/cgroup/cpuset.c\n+++ b/kernel/cgroup/cpuset.c\n@@ -4193,7 +4193,7 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)\n  * nearest enclosing hardwalled ancestor cpuset.\n  *\n  * Scanning up parent cpusets requires callback_lock.  The\n- * __alloc_pages() routine only calls here with __GFP_HARDWALL bit\n+ * page allocator only calls here with __GFP_HARDWALL bit\n  * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the\n  * current tasks mems_allowed came up empty on the first pass over\n  * the zonelist.  So only GFP_KERNEL allocations, if all nodes in the\n@@ -4206,11 +4206,8 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)\n  * come before the __GFP_HARDWALL check, otherwise a dying task\n  * would be blocked on the fast path.\n  *\n- * The second pass through get_page_from_freelist() doesn't even call\n- * here for GFP_ATOMIC calls.  For those calls, the __alloc_pages()\n- * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set\n- * in alloc_flags.  That logic and the checks below have the combined\n- * affect that:\n+ * The second pass through get_page_from_freelist() doesn't even call here for\n+ * GFP_ATOMIC calls.  That, and the checks below have the combined affect that:\n  *\tin_interrupt - any node ok (current task context irrelevant)\n  *\tGFP_ATOMIC   - any node ok\n  *\ttsk_is_oom_victim   - any node ok\n@@ -4327,8 +4324,8 @@ void cpuset_nodes_allowed(struct cgroup *cgroup, nodemask_t *mask)\n  * should not be possible for the following code to return an\n  * offline node.  But if it did, that would be ok, as this routine\n  * is not returning the node where the allocation must be, only\n- * the node where the search should start.  The zonelist passed to\n- * __alloc_pages() will include all nodes.  If the slab allocator\n+ * the node where the search should start.  The zonelist used by\n+ * the allocator will include all nodes.  If the slab allocator\n  * is passed an offline node, it will fall back to the local node.\n  * See kmem_cache_alloc_node().\n  */\ndiff --git a/mm/page_alloc.c b/mm/page_alloc.c\nindex af635583913459..4c6815f84adc6b 100644\n--- a/mm/page_alloc.c\n+++ b/mm/page_alloc.c\n@@ -90,7 +90,7 @@ typedef int __bitwise fpi_t;\n #define FPI_TO_TAIL\t\t((__force fpi_t)BIT(1))\n \n /* Free the page without taking locks. Rely on trylock only. */\n-#define FPI_TRYLOCK\t\t((__force fpi_t)BIT(2))\n+#define FPI_NOLOCK\t\t((__force fpi_t)BIT(2))\n \n /* free_pages_prepare() has already been called for page(s) being freed. */\n #define FPI_PREPARED\t\t((__force fpi_t)BIT(3))\n@@ -1419,7 +1419,7 @@ static __always_inline bool __free_pages_prepare(struct page *page,\n \tpage_table_check_free(page, order);\n \tpgalloc_tag_sub(page, 1 \u003c\u003c order);\n \n-\tif (!PageHighMem(page) \u0026\u0026 !(fpi_flags \u0026 FPI_TRYLOCK)) {\n+\tif (!PageHighMem(page) \u0026\u0026 !(fpi_flags \u0026 FPI_NOLOCK)) {\n \t\tdebug_check_no_locks_freed(page_address(page),\n \t\t\t\t\t   PAGE_SIZE \u003c\u003c order);\n \t\tdebug_check_no_obj_freed(page_address(page),\n@@ -1558,7 +1558,7 @@ static void free_one_page(struct zone *zone, struct page *page,\n \tstruct llist_head *llhead;\n \tunsigned long flags;\n \n-\tif (unlikely(fpi_flags \u0026 FPI_TRYLOCK)) {\n+\tif (unlikely(fpi_flags \u0026 FPI_NOLOCK)) {\n \t\tif (!spin_trylock_irqsave(\u0026zone-\u003elock, flags)) {\n \t\t\tadd_page_to_zone_llist(zone, page, order);\n \t\t\treturn;\n@@ -1569,7 +1569,7 @@ static void free_one_page(struct zone *zone, struct page *page,\n \n \t/* The lock succeeded. Process deferred pages. */\n \tllhead = \u0026zone-\u003etrylock_free_pages;\n-\tif (unlikely(!llist_empty(llhead) \u0026\u0026 !(fpi_flags \u0026 FPI_TRYLOCK))) {\n+\tif (unlikely(!llist_empty(llhead) \u0026\u0026 !(fpi_flags \u0026 FPI_NOLOCK))) {\n \t\tstruct llist_node *llnode;\n \t\tstruct page *p, *tmp;\n \n@@ -2882,7 +2882,7 @@ static bool free_frozen_page_commit(struct zone *zone,\n \tif (pcp-\u003efree_count \u003c (batch \u003c\u003c CONFIG_PCP_BATCH_SCALE_MAX))\n \t\tpcp-\u003efree_count += (1 \u003c\u003c order);\n \n-\tif (unlikely(fpi_flags \u0026 FPI_TRYLOCK)) {\n+\tif (unlikely(fpi_flags \u0026 FPI_NOLOCK)) {\n \t\t/*\n \t\t * Do not attempt to take a zone lock. Let pcp-\u003ecount get\n \t\t * over high mark temporarily.\n@@ -2979,7 +2979,7 @@ static void __free_frozen_pages(struct page *page, unsigned int order,\n \t\tmigratetype = MIGRATE_MOVABLE;\n \t}\n \n-\tif (unlikely((fpi_flags \u0026 FPI_TRYLOCK) \u0026\u0026 IS_ENABLED(CONFIG_PREEMPT_RT)\n+\tif (unlikely((fpi_flags \u0026 FPI_NOLOCK) \u0026\u0026 IS_ENABLED(CONFIG_PREEMPT_RT)\n \t\t     \u0026\u0026 (in_nmi() || in_hardirq()))) {\n \t\tadd_page_to_zone_llist(zone, page, order);\n \t\treturn;\n@@ -3002,7 +3002,7 @@ void free_frozen_pages(struct page *page, unsigned int order)\n \n void free_frozen_pages_nolock(struct page *page, unsigned int order)\n {\n-\t__free_frozen_pages(page, order, FPI_TRYLOCK);\n+\t__free_frozen_pages(page, order, FPI_NOLOCK);\n }\n \n /*\n@@ -5399,7 +5399,7 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,\n \tif (memcg_kmem_online() \u0026\u0026 (gfp \u0026 __GFP_ACCOUNT) \u0026\u0026 page \u0026\u0026\n \t    unlikely(__memcg_kmem_charge_page(page, gfp, order) != 0)) {\n \t\t__free_frozen_pages(page, order,\n-\t\t\t\t    alloc_flags \u0026 ALLOC_NOLOCK ? FPI_TRYLOCK : 0);\n+\t\t\t\t    alloc_flags \u0026 ALLOC_NOLOCK ? FPI_NOLOCK : 0);\n \t\tpage = NULL;\n \t}\n \n@@ -5427,7 +5427,6 @@ struct page *alloc_pages_node_noprof(int nid, gfp_t gfp_mask, unsigned int order\n \tif (nid == NUMA_NO_NODE)\n \t\tnid = numa_mem_id();\n \n-\tVM_BUG_ON(nid \u003c 0 || nid \u003e= MAX_NUMNODES);\n \twarn_if_node_offline(nid, gfp_mask);\n \n \treturn __alloc_pages_noprof(gfp_mask, order, nid, NULL, ALLOC_DEFAULT);\n@@ -5522,7 +5521,7 @@ EXPORT_SYMBOL(__free_pages);\n  */\n void free_pages_nolock(struct page *page, unsigned int order)\n {\n-\t___free_pages(page, order, FPI_TRYLOCK);\n+\t___free_pages(page, order, FPI_NOLOCK);\n }\n \n /**\n@@ -7983,7 +7982,8 @@ struct page *alloc_frozen_pages_nolock_noprof(gfp_t gfp_flags, int nid, unsigned\n }\n /**\n  * alloc_pages_nolock - opportunistic reentrant allocation from any context\n- * @gfp_flags: GFP flags. Only __GFP_ACCOUNT allowed.\n+ * @gfp_flags: GFP flags. Only __GFP_ACCOUNT, plus some flags that get set\n+ *             internally regardless (see %gfp_nolock) are allowed.\n  * @nid: node to allocate from\n  * @order: allocation order size\n  *\n"
}

gemini-3.1-pro-preview

null

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch only contains cosmetic changes (renaming FPI_TRYLOCK to FPI_NOLOCK, updating comments) and removes two VM_BUG_ON assertions. It does not functionally alter the execution flow or introduce new reachable logic.",
  "WorthFuzzing": false
}

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 de2a31086f50c60beba0e3aeccc45b087bfe4453
Author: syz-cluster <triage@syzkaller.com>
Date:   Wed Jul 15 18:59:47 2026 +0000

    syz-cluster: applied patch under review

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 4d57e9c0bf204d..872bc53f32ec87 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -255,7 +255,6 @@ static inline void warn_if_node_offline(int this_node, gfp_t gfp_mask)
 static inline
 struct folio *__folio_alloc_node_noprof(gfp_t gfp, unsigned int order, int nid)
 {
-	VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES);
 	warn_if_node_offline(nid, gfp);
 
 	return __folio_alloc_noprof(gfp, order, nid, NULL);
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 24ea2d09cdbdba..dfd0f827e3b92c 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -4193,7 +4193,7 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
  * nearest enclosing hardwalled ancestor cpuset.
  *
  * Scanning up parent cpusets requires callback_lock.  The
- * __alloc_pages() routine only calls here with __GFP_HARDWALL bit
+ * page allocator only calls here with __GFP_HARDWALL bit
  * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
  * current tasks mems_allowed came up empty on the first pass over
  * the zonelist.  So only GFP_KERNEL allocations, if all nodes in the
@@ -4206,11 +4206,8 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
  * come before the __GFP_HARDWALL check, otherwise a dying task
  * would be blocked on the fast path.
  *
- * The second pass through get_page_from_freelist() doesn't even call
- * here for GFP_ATOMIC calls.  For those calls, the __alloc_pages()
- * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
- * in alloc_flags.  That logic and the checks below have the combined
- * affect that:
+ * The second pass through get_page_from_freelist() doesn't even call here for
+ * GFP_ATOMIC calls.  That, and the checks below have the combined affect that:
  *	in_interrupt - any node ok (current task context irrelevant)
  *	GFP_ATOMIC   - any node ok
  *	tsk_is_oom_victim   - any node ok
@@ -4327,8 +4324,8 @@ void cpuset_nodes_allowed(struct cgroup *cgroup, nodemask_t *mask)
  * should not be possible for the following code to return an
  * offline node.  But if it did, that would be ok, as this routine
  * is not returning the node where the allocation must be, only
- * the node where the search should start.  The zonelist passed to
- * __alloc_pages() will include all nodes.  If the slab allocator
+ * the node where the search should start.  The zonelist used by
+ * the allocator will include all nodes.  If the slab allocator
  * is passed an offline node, it will fall back to the local node.
  * See kmem_cache_alloc_node().
  */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index af635583913459..4c6815f84adc6b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -90,7 +90,7 @@ typedef int __bitwise fpi_t;
 #define FPI_TO_TAIL		((__force fpi_t)BIT(1))
 
 /* Free the page without taking locks. Rely on trylock only. */
-#define FPI_TRYLOCK		((__force fpi_t)BIT(2))
+#define FPI_NOLOCK		((__force fpi_t)BIT(2))
 
 /* free_pages_prepare() has already been called for page(s) being freed. */
 #define FPI_PREPARED		((__force fpi_t)BIT(3))
@@ -1419,7 +1419,7 @@ static __always_inline bool __free_pages_prepare(struct page *page,
 	page_table_check_free(page, order);
 	pgalloc_tag_sub(page, 1 << order);
 
-	if (!PageHighMem(page) && !(fpi_flags & FPI_TRYLOCK)) {
+	if (!PageHighMem(page) && !(fpi_flags & FPI_NOLOCK)) {
 		debug_check_no_locks_freed(page_address(page),
 					   PAGE_SIZE << order);
 		debug_check_no_obj_freed(page_address(page),
@@ -1558,7 +1558,7 @@ static void free_one_page(struct zone *zone, struct page *page,
 	struct llist_head *llhead;
 	unsigned long flags;
 
-	if (unlikely(fpi_flags & FPI_TRYLOCK)) {
+	if (unlikely(fpi_flags & FPI_NOLOCK)) {
 		if (!spin_trylock_irqsave(&zone->lock, flags)) {
 			add_page_to_zone_llist(zone, page, order);
 			return;
@@ -1569,7 +1569,7 @@ static void free_one_page(struct zone *zone, struct page *page,
 
 	/* The lock succeeded. Process deferred pages. */
 	llhead = &zone->trylock_free_pages;
-	if (unlikely(!llist_empty(llhead) && !(fpi_flags & FPI_TRYLOCK))) {
+	if (unlikely(!llist_empty(llhead) && !(fpi_flags & FPI_NOLOCK))) {
 		struct llist_node *llnode;
 		struct page *p, *tmp;
 
@@ -2882,7 +2882,7 @@ static bool free_frozen_page_commit(struct zone *zone,
 	if (pcp->free_count < (batch << CONFIG_PCP_BATCH_SCALE_MAX))
 		pcp->free_count += (1 << order);
 
-	if (unlikely(fpi_flags & FPI_TRYLOCK)) {
+	if (unlikely(fpi_flags & FPI_NOLOCK)) {
 		/*
 		 * Do not attempt to take a zone lock. Let pcp->count get
 		 * over high mark temporarily.
@@ -2979,7 +2979,7 @@ static void __free_frozen_pages(struct page *page, unsigned int order,
 		migratetype = MIGRATE_MOVABLE;
 	}
 
-	if (unlikely((fpi_flags & FPI_TRYLOCK) && IS_ENABLED(CONFIG_PREEMPT_RT)
+	if (unlikely((fpi_flags & FPI_NOLOCK) && IS_ENABLED(CONFIG_PREEMPT_RT)
 		     && (in_nmi() || in_hardirq()))) {
 		add_page_to_zone_llist(zone, page, order);
 		return;
@@ -3002,7 +3002,7 @@ void free_frozen_pages(struct page *page, unsigned int order)
 
 void free_frozen_pages_nolock(struct page *page, unsigned int order)
 {
-	__free_frozen_pages(page, order, FPI_TRYLOCK);
+	__free_frozen_pages(page, order, FPI_NOLOCK);
 }
 
 /*
@@ -5399,7 +5399,7 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order,
 	if (memcg_kmem_online() && (gfp & __GFP_ACCOUNT) && page &&
 	    unlikely(__memcg_kmem_charge_page(page, gfp, order) != 0)) {
 		__free_frozen_pages(page, order,
-				    alloc_flags & ALLOC_NOLOCK ? FPI_TRYLOCK : 0);
+				    alloc_flags & ALLOC_NOLOCK ? FPI_NOLOCK : 0);
 		page = NULL;
 	}
 
@@ -5427,7 +5427,6 @@ struct page *alloc_pages_node_noprof(int nid, gfp_t gfp_mask, unsigned int order
 	if (nid == NUMA_NO_NODE)
 		nid = numa_mem_id();
 
-	VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES);
 	warn_if_node_offline(nid, gfp_mask);
 
 	return __alloc_pages_noprof(gfp_mask, order, nid, NULL, ALLOC_DEFAULT);
@@ -5522,7 +5521,7 @@ EXPORT_SYMBOL(__free_pages);
  */
 void free_pages_nolock(struct page *page, unsigned int order)
 {
-	___free_pages(page, order, FPI_TRYLOCK);
+	___free_pages(page, order, FPI_NOLOCK);
 }
 
 /**
@@ -7983,7 +7982,8 @@ struct page *alloc_frozen_pages_nolock_noprof(gfp_t gfp_flags, int nid, unsigned
 }
 /**
  * alloc_pages_nolock - opportunistic reentrant allocation from any context
- * @gfp_flags: GFP flags. Only __GFP_ACCOUNT allowed.
+ * @gfp_flags: GFP flags. Only __GFP_ACCOUNT, plus some flags that get set
+ *             internally regardless (see %gfp_nolock) are allowed.
  * @nid: node to allocate from
  * @order: allocation order size
  *

gemini-3.1-pro-preview

null

null

							input: 4191
							output: 80
							thoughts: 1125
						

**Patch Analysis: Not Worth Fuzzing**

Alright, let's break down this patch. I see changes in `include/linux/gfp.h`, `kernel/cgroup/cpuset.c`, and `mm/page_alloc.c`. My initial scan suggests these are mostly housekeeping, but let's be thorough.

First, in `include/linux/gfp.h`, it looks like a `VM_BUG_ON` assertion is being removed from `__folio_alloc_node_noprof`. This is the kind of thing that *could* raise a flag, but let's see.

Next, `kernel/cgroup/cpuset.c` only has comment modifications, so that's a non-issue.

Finally, in `mm/page_alloc.c`, I see a renaming from `FPI_TRYLOCK` to `FPI_NOLOCK`, and another instance of that `VM_BUG_ON` removal in `alloc_pages_node_noprof`.

Okay, digging in deeper, after a more thorough review, all the changes boil down to: 1) a constant rename, and 2) removing the `VM_BUG_ON` assertion in two places.

The `VM_BUG_ON` removal is interesting, but it's important to remember what `VM_BUG_ON` *does*. It's an assertion that, if triggered, will halt execution, but only in debug builds. Removing it means a potential panic condition is gone, but it doesn't fundamentally change the logic's *execution path*. In non-debug builds, it's just a no-op, and removing it makes no functional difference.

The renaming of `FPI_TRYLOCK` to `FPI_NOLOCK` is clearly a cosmetic change – a find and replace.

So, realistically, we have a cosmetic change, and the removal of a debugging assertion. This doesn't introduce any new attack surfaces, logic flaws, or new features.

Therefore, my conclusion is that this patch doesn't warrant fuzzing. The functional risk is negligible. I'm going to set `WorthFuzzing=false`.

{
  "EnableConfigs": [],
  "FocusSymbols": [],
  "Reasoning": "The patch only contains cosmetic changes (renaming FPI_TRYLOCK to FPI_NOLOCK, updating comments) and removes two VM_BUG_ON assertions. It does not functionally alter the execution flow or introduce new reachable logic.",
  "WorthFuzzing": false
}

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch only contains cosmetic changes (renaming FPI_TRYLOCK to FPI_NOLOCK, updating comments) and removes two VM_BUG_ON assertions. It does not functionally alter the execution flow or introduce new reachable logic.",
  "WorthFuzzing": false
}