AI Trajectory

null

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "KMSANReasoning": "",
  "NeedsKMSAN": false,
  "Reasoning": "The patch only modifies user-space selftest code in tools/testing/selftests/cgroup/test_memcontrol.c and does not alter the compiled kernel image (vmlinux) or any kernel modules.",
  "WorthFuzzing": false
}

null

{
  "PatchDiff": "commit 51fa932e9d970e8583f857bb6bc9052852e29db3\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Sun Sep 27 18:52:45 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c\nindex 0ed82347044ed..d3b9295aad759 100644\n--- a/tools/testing/selftests/cgroup/test_memcontrol.c\n+++ b/tools/testing/selftests/cgroup/test_memcontrol.c\n@@ -200,17 +200,20 @@ static int alloc_anon_50M_check(const char *cgroup, void *arg)\n \t\treturn -1;\n \n \tcurrent = cg_read_long(cgroup, \"memory.current\");\n-\tif (current \u003c size)\n+\tif (current \u003c size) {\n+\t\tfprintf(stderr, \"memory.current %ld \u003c expected %zu\\n\",\n+\t\t\tcurrent, size);\n \t\tgoto cleanup;\n+\t}\n \n-\tif (!values_close(size, current, 3))\n+\tif (!values_close_report(size, current, 3))\n \t\tgoto cleanup;\n \n \tanon = cg_read_key_long(cgroup, \"memory.stat\", \"anon \");\n \tif (anon \u003c 0)\n \t\tgoto cleanup;\n \n-\tif (!values_close(anon, current, 3))\n+\tif (!values_close_report(anon, current, 3))\n \t\tgoto cleanup;\n \n \tret = 0;\n@@ -219,7 +222,7 @@ static int alloc_anon_50M_check(const char *cgroup, void *arg)\n \treturn ret;\n }\n \n-static int alloc_pagecache_50M_check(const char *cgroup, void *arg)\n+static int __alloc_pagecache_50M_check(const char *cgroup, bool report)\n {\n \tsize_t size = MB(50);\n \tint ret = -1;\n@@ -234,14 +237,19 @@ static int alloc_pagecache_50M_check(const char *cgroup, void *arg)\n \t\tgoto cleanup;\n \n \tcurrent = cg_read_long(cgroup, \"memory.current\");\n-\tif (current \u003c size)\n+\tif (current \u003c size) {\n+\t\tif (report)\n+\t\t\tfprintf(stderr, \"memory.current %ld \u003c expected %zu\\n\",\n+\t\t\t\tcurrent, size);\n \t\tgoto cleanup;\n+\t}\n \n \tfile = cg_read_key_long(cgroup, \"memory.stat\", \"file \");\n \tif (file \u003c 0)\n \t\tgoto cleanup;\n \n-\tif (!values_close(file, current, 10))\n+\tif (report ? !values_close_report(file, current, 10) :\n+\t\t     !values_close(file, current, 10))\n \t\tgoto cleanup;\n \n \tret = 0;\n@@ -251,6 +259,20 @@ static int alloc_pagecache_50M_check(const char *cgroup, void *arg)\n \treturn ret;\n }\n \n+static int alloc_pagecache_50M_check(const char *cgroup, void *arg)\n+{\n+\treturn __alloc_pagecache_50M_check(cgroup, true);\n+}\n+\n+/*\n+ * Same as alloc_pagecache_50M_check(), but silent on failure, for callers\n+ * that expect the allocation to be held below 50M.\n+ */\n+static int alloc_pagecache_50M_check_quiet(const char *cgroup, void *arg)\n+{\n+\treturn __alloc_pagecache_50M_check(cgroup, false);\n+}\n+\n /*\n  * This test create a memory cgroup, allocates\n  * some anonymous memory and some pagecache\n@@ -578,16 +600,16 @@ static int test_memcg_protection(const char *root, bool min)\n \tif (cg_run(parent[2], alloc_anon, (void *)MB(148)))\n \t\tgoto cleanup;\n \n-\tif (!values_close(cg_read_long(parent[1], \"memory.current\"), MB(50), 3))\n+\tif (!values_close_report(cg_read_long(parent[1], \"memory.current\"), MB(50), 3))\n \t\tgoto cleanup;\n \n \tfor (i = 0; i \u003c ARRAY_SIZE(children); i++)\n \t\tc[i] = cg_read_long(children[i], \"memory.current\");\n \n-\tif (!values_close(c[0], MB(29), 15))\n+\tif (!values_close_report(c[0], MB(29), 15))\n \t\tgoto cleanup;\n \n-\tif (!values_close(c[1], MB(21), 20))\n+\tif (!values_close_report(c[1], MB(21), 20))\n \t\tgoto cleanup;\n \n \tif (c[3] != 0)\n@@ -603,7 +625,7 @@ static int test_memcg_protection(const char *root, bool min)\n \t}\n \n \tcurrent = min ? MB(50) : MB(30);\n-\tif (!values_close(cg_read_long(parent[1], \"memory.current\"), current, 3))\n+\tif (!values_close_report(cg_read_long(parent[1], \"memory.current\"), current, 3))\n \t\tgoto cleanup;\n \n \tif (!reclaim_until(children[0], MB(10)))\n@@ -691,7 +713,7 @@ static int alloc_pagecache_max_30M(const char *cgroup, void *arg)\n \t\tgoto cleanup;\n \n \tcurrent = cg_read_long(cgroup, \"memory.current\");\n-\tif (!values_close(current, MB(30), 5))\n+\tif (!values_close_report(current, MB(30), 5))\n \t\tgoto cleanup;\n \n \tret = 0;\n@@ -732,7 +754,7 @@ static int test_memcg_high(const char *root)\n \tif (cg_run(memcg, alloc_anon, (void *)MB(31)))\n \t\tgoto cleanup;\n \n-\tif (!cg_run(memcg, alloc_pagecache_50M_check, NULL))\n+\tif (!cg_run(memcg, alloc_pagecache_50M_check_quiet, NULL))\n \t\tgoto cleanup;\n \n \tif (cg_run(memcg, alloc_pagecache_max_30M, NULL))\n@@ -1006,12 +1028,12 @@ static int alloc_anon_50M_check_swap(const char *cgroup, void *arg)\n \t\treturn -1;\n \n \tmem_current = cg_read_long(cgroup, \"memory.current\");\n-\tif (!mem_current || !values_close(mem_current, mem_max, 3))\n+\tif (!mem_current || !values_close_report(mem_current, mem_max, 3))\n \t\tgoto cleanup;\n \n \tswap_current = cg_read_long(cgroup, \"memory.swap.current\");\n \tif (!swap_current ||\n-\t    !values_close(mem_current + swap_current, size, 3))\n+\t    !values_close_report(mem_current + swap_current, size, 3))\n \t\tgoto cleanup;\n \n \tret = 0;\n"
}

core

null

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch only modifies user-space selftest code in tools/testing/selftests/cgroup/test_memcontrol.c and does not alter the compiled kernel image (vmlinux) or any kernel modules.",
  "WorthFuzzing": false
}

You are an expert Linux kernel maintainer and security engineer.
Your job is to review a provided patch series and evaluate whether it warrants fuzzing with syzkaller.

IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on internal assumptions. You must actively use your code access
tools to inspect the actual source code, callers, and surrounding context.

================================================================================
1. CORE TRIAGE PHILOSOPHY
================================================================================
The goal of patch fuzzing is to discover crashes, regressions, exposed latent bugs,
and newly triggered assertions introduced by the patch series.

- REACHABILITY IS THE PRIMARY GATE:
  Fuzzing can only discover bugs in code that can actually execute in standard virtualized
  environments (GCE or QEMU, utilizing software-emulated devices like USB gadgets, netdev, tun/tap).
  If the modified code is structurally unreachable (see Section 2), it MUST NOT be fuzzed,
  regardless of whether it adds assertions or complex logic.

- DO NOT BLINDLY TRUST "NO FUNCTIONAL CHANGE" (NFCI) OR "REFACTORING" CLAIMS:
  Patch authors routinely label changes as "cleanups", "refactorings", or state
  "No functional change intended". Do NOT take these claims at face value.
  Code refactorings that rearrange logic, introduce helper functions, or alter state management
  in core subsystems frequently introduce subtle semantic shifts or uncover latent kernel bugs.
  If reachable executable code is modified or refactored, it MUST be fuzzed.

- NEW OR MODIFIED ASSERTIONS IN REACHABLE CODE MUST BE FUZZED:
  When a patch introduces or modifies runtime checks or assertions (e.g., WARN_ON*, VM_WARN_ON*,
  BUG_ON*, lockdep_assert*) in reachable code paths, it enforces new or stricter invariants.
  Even if the author believes the invariant always holds, fuzzing is essential to verify whether
  an unusual sequence of operations can violate it.

================================================================================
2. WHEN TO RETURN WorthFuzzing=false (NEGATIVE CRITERIA)
================================================================================
Return WorthFuzzing=false ONLY IF all modified code falls strictly into one or more of these categories:

- Non-kernel and non-executable changes:
  * Modifications to Documentation/, comments, or spelling fixes.
  * User-space directories, self-tests, samples, or scripts (e.g., tools/, samples/, scripts/, usr/)
    that do not affect the compiled kernel image (vmlinux) or kernel modules.
  * Purely decorative logging (e.g., message strings in pr_err, printk, dev_info) or tracepoints
    that do not alter control flow or data structures.
  * Build system or Kconfig changes that do not alter compiled C logic.
- Structurally unreachable hardware:
  * Vendor-specific PCIe switches, SmartNICs, or GPU drivers (e.g., mlxsw, pds_core, qed,
    ionic, amdgpu) requiring physical ASIC/PCIe cards not emulated in standard QEMU.
- Unreachable execution paths:
  * Driver teardown callbacks (.remove, .shutdown, pci_unregister_driver) executed only during
    physical PCI hot-unplug or manual sysfs driver unbinding.
  * Code paths exclusive to architectures other than the target architecture.

================================================================================
3. WHEN TO RETURN WorthFuzzing=true (POSITIVE CRITERIA)
================================================================================
Return WorthFuzzing=true whenever the patch touches reachable executable code, including:
- Core Subsystems:
  * Any logic modifications in memory management (mm/), synchronization/locking (kernel/locking/),
    BPF, scheduler, core networking, VFS, or syscall handling.
- Refactorings and Code Cleanups:
  * Any restructuring of reachable data structures, helper abstractions, or algorithm flows.
- Runtime Assertions and Defensive Checks:
  * Any introduction or alteration of assertions (WARN_ON*, VM_WARN_ON*, BUG_ON*, etc.) in reachable paths.
- Reachable Drivers and Protocols:
  * Drivers accessible via virtual buses (virtio, USB gadget, loopback, netlink, binder, sockets, etc.).

================================================================================
4. EXTRACTING FocusSymbols (PREVENTING DILUTION)
================================================================================
When WorthFuzzing=true, you must extract specific kernel functions into FocusSymbols to guide the fuzzer:

- AVOID UBIQUITOUS LIFECYCLE HOT-PATHS:
  Do NOT list generic, ubiquitous functions called by almost every program in the corpus
  (including, but not limited to: general memory allocators and deallocators, page fault
  and trap handlers, or core synchronization primitives; this is not an exhaustive list).
  Listing ubiquitous functions causes the fuzzer to classify thousands of unrelated tests as "focused",
  which severely dilutes fuzzing effort away from the actual changes.

- TARGET SPECIFIC FEATURE LOGIC AND ENTRYPOINTS:
  List functions that specifically implement the logic being added or altered, or direct API entrypoints
  for the subsystem feature under review.

- HANDLING STATIC INLINE FUNCTIONS IN HEADERS (.h):
  Compiler-inlined static functions (such as static inlines in mm/*.h or include/linux/*.h) lack
  distinct symbol addresses in vmlinux and cannot be targeted directly by symbol coverage filters.
  If the changes are primarily in static inline helpers, identify non-static, feature-specific caller
  functions in .c files that exercise them (avoiding ubiquitous lifecycle wrappers).

================================================================================
5. IDENTIFYING EnableConfigs
================================================================================
Identify any specific CONFIG_ options required to properly compile and reach the modified code:
- Inspect Kconfig files and #ifdef guards; do not make assumptions.
- Check "depends on" lines in Kconfig to include any non-standard parent subsystem configs needed.
- Strip any 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4").
Prefer calling several tools at the same time to save round-trips.


Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.

Target architecture: amd64

For your convenience, here is the diff of the changes:
commit 51fa932e9d970e8583f857bb6bc9052852e29db3
Author: syz-cluster <triage@syzkaller.com>
Date:   Sun Sep 27 18:52:45 2026 +0000

    syz-cluster: applied patch under review

diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
index 0ed82347044ed..d3b9295aad759 100644
--- a/tools/testing/selftests/cgroup/test_memcontrol.c
+++ b/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -200,17 +200,20 @@ static int alloc_anon_50M_check(const char *cgroup, void *arg)
 		return -1;
 
 	current = cg_read_long(cgroup, "memory.current");
-	if (current < size)
+	if (current < size) {
+		fprintf(stderr, "memory.current %ld < expected %zu\n",
+			current, size);
 		goto cleanup;
+	}
 
-	if (!values_close(size, current, 3))
+	if (!values_close_report(size, current, 3))
 		goto cleanup;
 
 	anon = cg_read_key_long(cgroup, "memory.stat", "anon ");
 	if (anon < 0)
 		goto cleanup;
 
-	if (!values_close(anon, current, 3))
+	if (!values_close_report(anon, current, 3))
 		goto cleanup;
 
 	ret = 0;
@@ -219,7 +222,7 @@ static int alloc_anon_50M_check(const char *cgroup, void *arg)
 	return ret;
 }
 
-static int alloc_pagecache_50M_check(const char *cgroup, void *arg)
+static int __alloc_pagecache_50M_check(const char *cgroup, bool report)
 {
 	size_t size = MB(50);
 	int ret = -1;
@@ -234,14 +237,19 @@ static int alloc_pagecache_50M_check(const char *cgroup, void *arg)
 		goto cleanup;
 
 	current = cg_read_long(cgroup, "memory.current");
-	if (current < size)
+	if (current < size) {
+		if (report)
+			fprintf(stderr, "memory.current %ld < expected %zu\n",
+				current, size);
 		goto cleanup;
+	}
 
 	file = cg_read_key_long(cgroup, "memory.stat", "file ");
 	if (file < 0)
 		goto cleanup;
 
-	if (!values_close(file, current, 10))
+	if (report ? !values_close_report(file, current, 10) :
+		     !values_close(file, current, 10))
 		goto cleanup;
 
 	ret = 0;
@@ -251,6 +259,20 @@ static int alloc_pagecache_50M_check(const char *cgroup, void *arg)
 	return ret;
 }
 
+static int alloc_pagecache_50M_check(const char *cgroup, void *arg)
+{
+	return __alloc_pagecache_50M_check(cgroup, true);
+}
+
+/*
+ * Same as alloc_pagecache_50M_check(), but silent on failure, for callers
+ * that expect the allocation to be held below 50M.
+ */
+static int alloc_pagecache_50M_check_quiet(const char *cgroup, void *arg)
+{
+	return __alloc_pagecache_50M_check(cgroup, false);
+}
+
 /*
  * This test create a memory cgroup, allocates
  * some anonymous memory and some pagecache
@@ -578,16 +600,16 @@ static int test_memcg_protection(const char *root, bool min)
 	if (cg_run(parent[2], alloc_anon, (void *)MB(148)))
 		goto cleanup;
 
-	if (!values_close(cg_read_long(parent[1], "memory.current"), MB(50), 3))
+	if (!values_close_report(cg_read_long(parent[1], "memory.current"), MB(50), 3))
 		goto cleanup;
 
 	for (i = 0; i < ARRAY_SIZE(children); i++)
 		c[i] = cg_read_long(children[i], "memory.current");
 
-	if (!values_close(c[0], MB(29), 15))
+	if (!values_close_report(c[0], MB(29), 15))
 		goto cleanup;
 
-	if (!values_close(c[1], MB(21), 20))
+	if (!values_close_report(c[1], MB(21), 20))
 		goto cleanup;
 
 	if (c[3] != 0)
@@ -603,7 +625,7 @@ static int test_memcg_protection(const char *root, bool min)
 	}
 
 	current = min ? MB(50) : MB(30);
-	if (!values_close(cg_read_long(parent[1], "memory.current"), current, 3))
+	if (!values_close_report(cg_read_long(parent[1], "memory.current"), current, 3))
 		goto cleanup;
 
 	if (!reclaim_until(children[0], MB(10)))
@@ -691,7 +713,7 @@ static int alloc_pagecache_max_30M(const char *cgroup, void *arg)
 		goto cleanup;
 
 	current = cg_read_long(cgroup, "memory.current");
-	if (!values_close(current, MB(30), 5))
+	if (!values_close_report(current, MB(30), 5))
 		goto cleanup;
 
 	ret = 0;
@@ -732,7 +754,7 @@ static int test_memcg_high(const char *root)
 	if (cg_run(memcg, alloc_anon, (void *)MB(31)))
 		goto cleanup;
 
-	if (!cg_run(memcg, alloc_pagecache_50M_check, NULL))
+	if (!cg_run(memcg, alloc_pagecache_50M_check_quiet, NULL))
 		goto cleanup;
 
 	if (cg_run(memcg, alloc_pagecache_max_30M, NULL))
@@ -1006,12 +1028,12 @@ static int alloc_anon_50M_check_swap(const char *cgroup, void *arg)
 		return -1;
 
 	mem_current = cg_read_long(cgroup, "memory.current");
-	if (!mem_current || !values_close(mem_current, mem_max, 3))
+	if (!mem_current || !values_close_report(mem_current, mem_max, 3))
 		goto cleanup;
 
 	swap_current = cg_read_long(cgroup, "memory.swap.current");
 	if (!swap_current ||
-	    !values_close(mem_current + swap_current, size, 3))
+	    !values_close_report(mem_current + swap_current, size, 3))
 		goto cleanup;
 
 	ret = 0;

gemini-3.8-flash

null

null

							input: 4575
							output: 77
							thoughts: 485
						

**Fuzzing Verdict: WorthFuzzing = False**

Okay, let's break this down. The patch diff I'm seeing is laser-focused; it's *only* touching `tools/testing/selftests/cgroup/test_memcontrol.c`. Time to run it against the criteria.

Alright, the negative criteria are pretty clear: does this change fall neatly into a category where fuzzing is pointless? Let's see... the relevant rule is "User-space directories, self-tests, samples, or scripts (e.g., tools/, samples/, scripts/, usr/) that do not affect the compiled kernel image (vmlinux) or kernel modules." Bingo! This file is nestled right there in `tools/testing/selftests/cgroup/`, which means it's a user-space selftest. It doesn't touch the kernel image or modules at all.

Just to be absolutely certain, I'm verifying no other files were altered in this commit. Let's see...Yep, the diff confirms it:
`diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c`

So, it's pretty clear-cut. Based on this, WorthFuzzing has to be false. FocusSymbols and EnableConfigs should both be empty.

The reasoning for the verdict needs to be concise and accurate. It's going to state that the patch solely modifies userspace selftest code:  `tools/testing/selftests/cgroup/test_memcontrol.c`, and that this does not impact the compiled kernel image (vmlinux) or any kernel modules.

I'm confident in this, so time to call `set-results`.

{
  "EnableConfigs": [],
  "FocusSymbols": [],
  "Reasoning": "The patch only modifies user-space selftest code in tools/testing/selftests/cgroup/test_memcontrol.c and does not alter the compiled kernel image (vmlinux) or any kernel modules.",
  "WorthFuzzing": false
}

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch only modifies user-space selftest code in tools/testing/selftests/cgroup/test_memcontrol.c and does not alter the compiled kernel image (vmlinux) or any kernel modules.",
  "WorthFuzzing": false
}

{
  "WorthFuzzing": false
}

null