AI Trajectory

null

{
  "EnableConfigs": [
    "CGROUPS",
    "MEMCG",
    "MEMCG_V1"
  ],
  "FocusSymbols": [
    "count_shadow_nodes",
    "mod_memcg_state",
    "mod_lruvec_state",
    "reparent_memcg_state_local"
  ],
  "KMSANReasoning": "The patch series updates memory cgroup stat accounting and workingset shadow node counting:\n1. In `mm/memcontrol.c`, it simplifies and extends `get_non_dying_memcg_start()` across all cgroup hierarchies and adjusts RCU locking logic when offlining/reparenting memcgs. The out-parameter `rcu_locked` is unconditionally initialized on all execution paths before being passed to `get_non_dying_memcg_end()`.\n2. In `mm/workingset.c`, it updates `count_shadow_nodes()` to use `lruvec_page_state_local()` instead of `lruvec_lru_size()`.\n\nNo uninitialized stack or heap variables are read, no structs or buffers are copied to user space, and no memory allocations or uninitialized padding exposures are introduced. Potential risks (such as RCU lifetime issues, concurrency races, or use-after-free) are covered by KASAN and standard kernel debuggers. Therefore, dedicated KMSAN fuzzing is not required.",
  "NeedsKMSAN": false,
  "Reasoning": "The patch modifies memory cgroup stats handling and redirection for dying/offlining memcgs across all cgroup hierarchies (removing the v1-only restriction), as well as shadow node counting calculation in the workingset shrinker. This is core reachable memory management logic that should be fuzzed.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit c538b002b999cd1e3fef117ff6c636d69892a941\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Mon Aug 31 10:42:08 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/mm/memcontrol.c b/mm/memcontrol.c\nindex 8319ad8c5c23a..f454d02746e9f 100644\n--- a/mm/memcontrol.c\n+++ b/mm/memcontrol.c\n@@ -805,16 +805,21 @@ static long memcg_state_val_in_pages(int idx, long val)\n \treturn val \u003c 0 ? -res : res;\n }\n \n-#ifdef CONFIG_MEMCG_V1\n /*\n- * Used in mod_memcg_state() and mod_memcg_lruvec_state() to avoid race with\n- * reparenting of non-hierarchical state_locals.\n+ * Used in mod_memcg_state() and mod_memcg_lruvec_state() to avoid race\n+ * with reparenting of non-hierarchical state_locals.  Offlining a\n+ * memcg is rare, so do the redirection for all cgroup hierarchies.\n  */\n-static inline struct mem_cgroup *get_non_dying_memcg_start(struct mem_cgroup *memcg,\n-\t\t\t\t\t\t\t   bool *rcu_locked)\n+static inline struct mem_cgroup *\n+get_non_dying_memcg_start(struct mem_cgroup *memcg, bool *rcu_locked)\n {\n-\t/* Rebinding can cause this value to be changed at runtime */\n-\tif (cgroup_subsys_on_dfl(memory_cgrp_subsys)) {\n+\t/*\n+\t * Fast path: the caller holds a reference to @memcg, so reading\n+\t * its CSS_DYING flag without the RCU lock is safe.  The RCU lock\n+\t * is only needed to walk up to a non-dying ancestor, which\n+\t * happens only while a memcg is actually being offlined.\n+\t */\n+\tif (!memcg_is_dying(memcg)) {\n \t\t*rcu_locked = false;\n \t\treturn memcg;\n \t}\n@@ -835,17 +840,6 @@ static inline void get_non_dying_memcg_end(bool rcu_locked)\n \n \trcu_read_unlock();\n }\n-#else\n-static inline struct mem_cgroup *get_non_dying_memcg_start(struct mem_cgroup *memcg,\n-\t\t\t\t\t\t\t   bool *rcu_locked)\n-{\n-\treturn memcg;\n-}\n-\n-static inline void get_non_dying_memcg_end(bool rcu_locked)\n-{\n-}\n-#endif\n \n static void __mod_memcg_state(struct mem_cgroup *memcg,\n \t\t\t      enum memcg_stat_item idx, long val)\ndiff --git a/mm/workingset.c b/mm/workingset.c\nindex f351798e723ac..85a4e14e95d51 100644\n--- a/mm/workingset.c\n+++ b/mm/workingset.c\n@@ -693,10 +693,9 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,\n \n \t\tmem_cgroup_flush_stats_ratelimited(sc-\u003ememcg);\n \t\tlruvec = mem_cgroup_lruvec(sc-\u003ememcg, NODE_DATA(sc-\u003enid));\n-\n \t\tfor (pages = 0, i = 0; i \u003c NR_LRU_LISTS; i++)\n-\t\t\tpages += lruvec_lru_size(lruvec, i, MAX_NR_ZONES - 1);\n-\n+\t\t\tpages += lruvec_page_state_local(lruvec,\n+\t\t\t\t\t\t\t NR_LRU_BASE + i);\n \t\tpages += lruvec_page_state_local(\n \t\t\tlruvec, NR_SLAB_RECLAIMABLE_B) \u003e\u003e PAGE_SHIFT;\n \t\tpages += lruvec_page_state_local(\n"
}

core

null

{
  "EnableConfigs": [
    "CGROUPS",
    "MEMCG",
    "MEMCG_V1"
  ],
  "FocusSymbols": [
    "count_shadow_nodes",
    "mod_memcg_state",
    "mod_lruvec_state",
    "reparent_memcg_state_local"
  ],
  "Reasoning": "The patch modifies memory cgroup stats handling and redirection for dying/offlining memcgs across all cgroup hierarchies (removing the v1-only restriction), as well as shadow node counting calculation in the workingset shrinker. This is core reachable memory management logic that should be fuzzed.",
  "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).
- Code in vendor-specific PCIe switch, SmartNIC, or GPU drivers (e.g., mlxsw, pds_core, qed,
  ionic, amdgpu) that require physical PCIe hardware cards not emulated in standard QEMU.
- Driver .remove, .shutdown, or pci_unregister_driver teardown callbacks (e.g., igb_remove)
  that are executed only during PCI hot-unplug or sysfs driver unbind operations.

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

When returning WorthFuzzing=true, you MUST ALSO:
1. Extract any specific kernel functions that should be heavily fuzzed into FocusSymbols.
   Avoid listing generic hot-path functions to prevent skewed test distributions.
   Prefer non-static, non-inlined API entrypoint functions over internal static helper functions
   (which are inlined by the compiler and do not have distinct symbol addresses).
2. Identify any specific CONFIG_ options required to properly test this new/modified feature.
   Go and look into the Kconfig files and check for ifdefs around the code, do not make assumptions.
   Also check "depends on" lines in Kconfig to include any non-standard parent subsystem configs
   needed for Kbuild to compile the code statically into vmlinux. List them in the EnableConfigs
   output array, and DO NOT add a 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4").
Prefer calling several tools at the same time to save round-trips.


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

For your convenience, here is the diff of the changes:
commit c538b002b999cd1e3fef117ff6c636d69892a941
Author: syz-cluster <triage@syzkaller.com>
Date:   Mon Aug 31 10:42:08 2026 +0000

    syz-cluster: applied patch under review

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8319ad8c5c23a..f454d02746e9f 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -805,16 +805,21 @@ static long memcg_state_val_in_pages(int idx, long val)
 	return val < 0 ? -res : res;
 }
 
-#ifdef CONFIG_MEMCG_V1
 /*
- * Used in mod_memcg_state() and mod_memcg_lruvec_state() to avoid race with
- * reparenting of non-hierarchical state_locals.
+ * Used in mod_memcg_state() and mod_memcg_lruvec_state() to avoid race
+ * with reparenting of non-hierarchical state_locals.  Offlining a
+ * memcg is rare, so do the redirection for all cgroup hierarchies.
  */
-static inline struct mem_cgroup *get_non_dying_memcg_start(struct mem_cgroup *memcg,
-							   bool *rcu_locked)
+static inline struct mem_cgroup *
+get_non_dying_memcg_start(struct mem_cgroup *memcg, bool *rcu_locked)
 {
-	/* Rebinding can cause this value to be changed at runtime */
-	if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
+	/*
+	 * Fast path: the caller holds a reference to @memcg, so reading
+	 * its CSS_DYING flag without the RCU lock is safe.  The RCU lock
+	 * is only needed to walk up to a non-dying ancestor, which
+	 * happens only while a memcg is actually being offlined.
+	 */
+	if (!memcg_is_dying(memcg)) {
 		*rcu_locked = false;
 		return memcg;
 	}
@@ -835,17 +840,6 @@ static inline void get_non_dying_memcg_end(bool rcu_locked)
 
 	rcu_read_unlock();
 }
-#else
-static inline struct mem_cgroup *get_non_dying_memcg_start(struct mem_cgroup *memcg,
-							   bool *rcu_locked)
-{
-	return memcg;
-}
-
-static inline void get_non_dying_memcg_end(bool rcu_locked)
-{
-}
-#endif
 
 static void __mod_memcg_state(struct mem_cgroup *memcg,
 			      enum memcg_stat_item idx, long val)
diff --git a/mm/workingset.c b/mm/workingset.c
index f351798e723ac..85a4e14e95d51 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -693,10 +693,9 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
 
 		mem_cgroup_flush_stats_ratelimited(sc->memcg);
 		lruvec = mem_cgroup_lruvec(sc->memcg, NODE_DATA(sc->nid));
-
 		for (pages = 0, i = 0; i < NR_LRU_LISTS; i++)
-			pages += lruvec_lru_size(lruvec, i, MAX_NR_ZONES - 1);
-
+			pages += lruvec_page_state_local(lruvec,
+							 NR_LRU_BASE + i);
 		pages += lruvec_page_state_local(
 			lruvec, NR_SLAB_RECLAIMABLE_B) >> PAGE_SHIFT;
 		pages += lruvec_page_state_local(

gemini-3.7-flash

null

null

							input: 2857
							output: 34
							thoughts: 309
						

**Analyzing the Recent Code Changes**

Okay, let's dive into this diff. First, I need to understand the scope of these modifications. From what I see, we have changes in two key files: `mm/memcontrol.c` and `mm/workingset.c`. I'm already anticipating some of the implications here, given my familiarity with the memory management subsystem.

It looks like the changes in `mm/memcontrol.c` are the more significant ones. Removing that `#ifdef CONFIG_MEMCG_V1` block around `get_non_dying_memcg_start()` and `get_non_dying_memcg_end()` is noteworthy. My immediate thought is that this consolidates some memcg (memory cgroup) behavior across v1 and v2. Specifically, the old `cgroup_subsys_on_dfl()` check has been replaced with `!memcg_is_dying(memcg)`. So, instead of being version-dependent, the new logic now checks if a memcg is "dying" to return the correct value. This affects how memcg state is tracked and how statistics are reparented. This has some implications for the consistency of these states across all cgroup versions. This potentially simplifies the code, but I need to make sure the behavior is consistent.

Moving on to `mm/workingset.c`, the change in `count_shadow_nodes()` appears less dramatic at first glance. It looks like `lruvec_lru_size()` has been replaced with `lruvec_page_state_local()`. This is probably an optimization, or maybe a change in the internal representation of the LRU. I know the internals of the LRU are complex, so I'll need to look at what `NR_LRU_BASE + i` corresponds to, as I know that `i` ranges from 0 to MAX_NR_ZONES - 1. But I suspect this could have implications for how the "working set" is calculated, potentially affecting the accuracy of the algorithm.

I need to dig into the surrounding code in both files now to get a better handle on the context of these changes. I'll need to see how `memcg_is_dying()` is implemented and used, and also understand the rationale behind replacing `lruvec_lru_size()`. I expect to see some performance improvements and simplification in both cases, but I need to ensure there are no regressions or unexpected side effects.

{
  "File": "mm/memcontrol.c",
  "FirstLine": 800,
  "LineCount": 70
}

{
  "Contents": " 800:\t\t/* Get the absolute value of (val * unit / PAGE_SIZE). */\n 801:\t\tres = mult_frac(abs(val), unit, PAGE_SIZE);\n 802:\t\t/* Round up zero values. */\n 803:\t\tres = res ? : 1;\n 804:\t\n 805:\t\treturn val \u003c 0 ? -res : res;\n 806:\t}\n 807:\t\n 808:\t/*\n 809:\t * Used in mod_memcg_state() and mod_memcg_lruvec_state() to avoid race\n 810:\t * with reparenting of non-hierarchical state_locals.  Offlining a\n 811:\t * memcg is rare, so do the redirection for all cgroup hierarchies.\n 812:\t */\n 813:\tstatic inline struct mem_cgroup *\n 814:\tget_non_dying_memcg_start(struct mem_cgroup *memcg, bool *rcu_locked)\n 815:\t{\n 816:\t\t/*\n 817:\t\t * Fast path: the caller holds a reference to @memcg, so reading\n 818:\t\t * its CSS_DYING flag without the RCU lock is safe.  The RCU lock\n 819:\t\t * is only needed to walk up to a non-dying ancestor, which\n 820:\t\t * happens only while a memcg is actually being offlined.\n 821:\t\t */\n 822:\t\tif (!memcg_is_dying(memcg)) {\n 823:\t\t\t*rcu_locked = false;\n 824:\t\t\treturn memcg;\n 825:\t\t}\n 826:\t\n 827:\t\trcu_read_lock();\n 828:\t\t*rcu_locked = true;\n 829:\t\n 830:\t\twhile (memcg_is_dying(memcg))\n 831:\t\t\tmemcg = parent_mem_cgroup(memcg);\n 832:\t\n 833:\t\treturn memcg;\n 834:\t}\n 835:\t\n 836:\tstatic inline void get_non_dying_memcg_end(bool rcu_locked)\n 837:\t{\n 838:\t\tif (!rcu_locked)\n 839:\t\t\treturn;\n 840:\t\n 841:\t\trcu_read_unlock();\n 842:\t}\n 843:\t\n 844:\tstatic void __mod_memcg_state(struct mem_cgroup *memcg,\n 845:\t\t\t\t      enum memcg_stat_item idx, long val)\n 846:\t{\n 847:\t\tint i = memcg_stats_index(idx);\n 848:\t\tint cpu;\n 849:\t\n 850:\t\tif (WARN_ONCE(BAD_STAT_IDX(i), \"%s: missing stat item %d\\n\", __func__, idx))\n 851:\t\t\treturn;\n 852:\t\n 853:\t\tcpu = get_cpu();\n 854:\t\n 855:\t\tthis_cpu_add(memcg-\u003evmstats_percpu-\u003estate[i], val);\n 856:\t\tval = memcg_state_val_in_pages(idx, val);\n 857:\t\tmemcg_rstat_updated(memcg, val, cpu);\n 858:\t\n 859:\t\ttrace_mod_memcg_state(memcg, idx, val);\n 860:\t\n 861:\t\tput_cpu();\n 862:\t}\n 863:\t\n 864:\t/**\n 865:\t * mod_memcg_state - update cgroup memory statistics\n 866:\t * @memcg: the memory cgroup\n 867:\t * @idx: the stat item - can be enum memcg_stat_item or enum node_stat_item\n 868:\t * @val: delta to add to the counter, can be negative\n 869:\t */\n"
}

gemini-3.7-flash

null

null

							input: 4795
							output: 31
							thoughts: 29
						

Here's my attempt at summarizing the thought process, as if I were thinking it:

**Digging into memcg Usage**

Okay, so I need to understand the implications of `get_non_dying_memcg_start`. My brain immediately heads to `mm/memcontrol.c`. That's where I expect to find the core memcg logic. Let's see how and where this function is actually being used within that file. I'm looking for the call sites – understanding *where* it's called will tell me a lot about its purpose and the specific scenarios it's designed to handle. This is the first step in unraveling its role in memory management within the context of control groups. I want the context of the call to give me an idea what problem is being solved.

{
  "Expression": "get_non_dying_memcg",
  "PathPrefix": "mm/"
}

{
  "Output": "mm/memcontrol.c=813=static inline struct mem_cgroup *\nmm/memcontrol.c:814:get_non_dying_memcg_start(struct mem_cgroup *memcg, bool *rcu_locked)\nmm/memcontrol.c-815-{\n--\nmm/memcontrol.c-835-\nmm/memcontrol.c:836:static inline void get_non_dying_memcg_end(bool rcu_locked)\nmm/memcontrol.c-837-{\n--\nmm/memcontrol.c=870=void mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx,\n--\nmm/memcontrol.c-877-\nmm/memcontrol.c:878:\tmemcg = get_non_dying_memcg_start(memcg, \u0026rcu_locked);\nmm/memcontrol.c-879-\t__mod_memcg_state(memcg, idx, val);\nmm/memcontrol.c:880:\tget_non_dying_memcg_end(rcu_locked);\nmm/memcontrol.c-881-}\n--\nmm/memcontrol.c=936=static void mod_memcg_lruvec_state(struct lruvec *lruvec,\n--\nmm/memcontrol.c-945-\tpn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);\nmm/memcontrol.c:946:\tmemcg = get_non_dying_memcg_start(pn-\u003ememcg, \u0026rcu_locked);\nmm/memcontrol.c-947-\tpn = memcg-\u003enodeinfo[pgdat-\u003enode_id];\n--\nmm/memcontrol.c-950-\nmm/memcontrol.c:951:\tget_non_dying_memcg_end(rcu_locked);\nmm/memcontrol.c-952-}\n"
}

gemini-3.7-flash

null

null

							input: 5527
							output: 35
							thoughts: 13
						

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

**Diving into `mm/workingset.c`**

Okay, time to dig into the workingset implementation. I need to refresh my mental model of how the kernel manages active memory regions. Let's see... I'm likely interested in how the kernel tracks page access, the criteria for moving pages between the active and inactive lists, and how the algorithm reacts to memory pressure. I anticipate I'll be looking for the fundamental data structures, like the `pgdat_t` and `zone_t` structures, and how they interact with the workingset code. Specifically, I'll be focused on any recent modifications that might be affecting performance or stability. I hope I don't run into a spaghetti mess in there! I need to ensure the system is behaving as expected, and I know that the workingset code is the place to start. I'm hoping it's well-commented.

{
  "File": "mm/workingset.c",
  "FirstLine": 680,
  "LineCount": 40
}

{
  "Contents": " 680:\t\t * worst-case density of 1/8th. Below that, not all eligible\n 681:\t\t * refaults can be detected anymore.\n 682:\t\t *\n 683:\t\t * On 64-bit with 7 xa_nodes per page and 64 slots\n 684:\t\t * each, this will reclaim shadow entries when they consume\n 685:\t\t * ~1.8% of available memory:\n 686:\t\t *\n 687:\t\t * PAGE_SIZE / xa_nodes / node_entries * 8 / PAGE_SIZE\n 688:\t\t */\n 689:\t#ifdef CONFIG_MEMCG\n 690:\t\tif (sc-\u003ememcg) {\n 691:\t\t\tstruct lruvec *lruvec;\n 692:\t\t\tint i;\n 693:\t\n 694:\t\t\tmem_cgroup_flush_stats_ratelimited(sc-\u003ememcg);\n 695:\t\t\tlruvec = mem_cgroup_lruvec(sc-\u003ememcg, NODE_DATA(sc-\u003enid));\n 696:\t\t\tfor (pages = 0, i = 0; i \u003c NR_LRU_LISTS; i++)\n 697:\t\t\t\tpages += lruvec_page_state_local(lruvec,\n 698:\t\t\t\t\t\t\t\t NR_LRU_BASE + i);\n 699:\t\t\tpages += lruvec_page_state_local(\n 700:\t\t\t\tlruvec, NR_SLAB_RECLAIMABLE_B) \u003e\u003e PAGE_SHIFT;\n 701:\t\t\tpages += lruvec_page_state_local(\n 702:\t\t\t\tlruvec, NR_SLAB_UNRECLAIMABLE_B) \u003e\u003e PAGE_SHIFT;\n 703:\t\t} else\n 704:\t#endif\n 705:\t\t\tpages = node_present_pages(sc-\u003enid);\n 706:\t\n 707:\t\tmax_nodes = pages \u003e\u003e (XA_CHUNK_SHIFT - 3);\n 708:\t\n 709:\t\tif (nodes \u003c= max_nodes)\n 710:\t\t\treturn 0;\n 711:\t\treturn nodes - max_nodes;\n 712:\t}\n 713:\t\n 714:\tstatic enum lru_status shadow_lru_isolate(struct list_head *item,\n 715:\t\t\t\t\t\t  struct list_lru_one *lru,\n 716:\t\t\t\t\t\t  void *arg) __must_hold(lru-\u003elock)\n 717:\t{\n 718:\t\tstruct xa_node *node = container_of(item, struct xa_node, private_list);\n 719:\t\tstruct address_space *mapping;\n"
}

gemini-3.7-flash

null

null

							input: 6480
							output: 32
							thoughts: 859
						

**Patch Analysis for Fuzzing Eligibility**

Okay, let's break this down. I've got a patch here that's poking around in memory cgroup stat handling, specifically when a memcg is offlining, and also touching the workingset code. Hmm, looks like it's merging the v1 and v2 behavior, which is usually interesting. The key here is the `mod_memcg_state` / `mod_memcg_lruvec_state` hot path concern, I'll need to remember to circle back to that.

The instructions say I need to figure out if this is worth fuzzing. The criteria are pretty clear: it's *not* worth fuzzing if it's documentation, comments, decoration, unreachable code, or very specific drivers. However, if it touches reachable core kernel logic, drivers, or architectures, then it's a go.

This patch is definitely touching core memory management: `mm/memcontrol.c` and `mm/workingset.c`. In `mm/memcontrol.c`, it's altering how stats are handled when a memcg is dying, including removing an `#ifdef` for v1. This means it is directly modifying the critical path of memcg and page cache handling. Then, in `mm/workingset.c`, it's changing the `count_shadow_nodes` calculation to use `lruvec_page_state_local`. Given that, I'm confident in saying `WorthFuzzing=true`.

Now, the instructions tell me I need to identify the `FocusSymbols` and `EnableConfigs`. Let's get to it. Let's start with `count_shadow_nodes`. Okay, it's `static`. Damn. I need to be careful with this, as `static` functions do not have distinct symbol addresses, and these are likely inlined. I need to find the non-static entrypoints that call this, so let's start searching in `mm/workingset.c` and see where this is registered or used.

{
  "Expression": "count_shadow_nodes",
  "PathPrefix": "mm/workingset.c"
}

{
  "Output": "mm/workingset.c=629=void workingset_update_node(struct xa_node *node)\n--\nmm/workingset.c-655-\nmm/workingset.c:656:static unsigned long count_shadow_nodes(struct shrinker *shrinker,\nmm/workingset.c-657-\t\t\t\t\tstruct shrink_control *sc)\n--\nmm/workingset.c=797=static int __init workingset_init(void)\n--\nmm/workingset.c-833-\nmm/workingset.c:834:\tworkingset_shadow_shrinker-\u003ecount_objects = count_shadow_nodes;\nmm/workingset.c-835-\tworkingset_shadow_shrinker-\u003escan_objects = scan_shadow_nodes;\n"
}

gemini-3.7-flash

null

null

							input: 8023
							output: 33
							thoughts: 159
						

**Analyzing Memory Control Mechanisms**

Okay, let's break this down. My initial thought process is circling around memory management, specifically within the kernel, given those function names: `scan_shadow_nodes`, `workingset_update_node`, `workingset_refault`, `workingset_activation`. That tells me we're dealing with workingsets, perhaps shadow nodes, and likely some form of page fault or memory activation/deactivation.

Now, where are these mechanics implemented? My instinct immediately directs me towards `mm/memcontrol.c`. This is where I'd expect to find the core logic for memory control groups. Time to investigate what's actually *in* `mm/memcontrol.c`.

I need to focus on relevant functions within that file. Specifically, I'm thinking about `mod_memcg_state`, `mod_memcg_lruvec_state`, and `__mod_memcg_lruvec_state` and what calls `get_non_dying_memcg_start`, as they appear to be central to modifying memory control group state or LRU vector states. I need to cross-reference their declarations and definitions. I need to thoroughly understand their parameters, what their scope of function is, and how they relate to the bigger picture. Are there any relevant header files I should check to gain the entirety of their context? Let's check the source code itself, both declarations and definitions. That's the next step.

{
  "Expression": "mod_memcg_",
  "PathPrefix": "include/linux/memcontrol.h"
}

{
  "Output": "include/linux/memcontrol.h=923=void mem_cgroup_print_oom_group(struct mem_cgroup *memcg);\n--\ninclude/linux/memcontrol.h-925-/* idx can be of type enum memcg_stat_item or node_stat_item */\ninclude/linux/memcontrol.h:926:void mod_memcg_state(struct mem_cgroup *memcg,\ninclude/linux/memcontrol.h-927-\t\t     enum memcg_stat_item idx, int val);\ninclude/linux/memcontrol.h-928-\ninclude/linux/memcontrol.h:929:static inline void mod_memcg_page_state(struct page *page,\ninclude/linux/memcontrol.h-930-\t\t\t\t\tenum memcg_stat_item idx, int val)\n--\ninclude/linux/memcontrol.h-939-\tif (memcg)\ninclude/linux/memcontrol.h:940:\t\tmod_memcg_state(memcg, idx, val);\ninclude/linux/memcontrol.h-941-\trcu_read_unlock();\n--\ninclude/linux/memcontrol.h=1361=static inline void mem_cgroup_print_oom_group(struct mem_cgroup *memcg)\n--\ninclude/linux/memcontrol.h-1364-\ninclude/linux/memcontrol.h:1365:static inline void mod_memcg_state(struct mem_cgroup *memcg,\ninclude/linux/memcontrol.h-1366-\t\t\t\t   enum memcg_stat_item idx,\n--\ninclude/linux/memcontrol.h-1370-\ninclude/linux/memcontrol.h:1371:static inline void mod_memcg_page_state(struct page *page,\ninclude/linux/memcontrol.h-1372-\t\t\t\t\tenum memcg_stat_item idx, int val)\n"
}

gemini-3.7-flash

null

null

							input: 9011
							output: 34
							thoughts: 71
						

Here's my analysis of what I'm thinking, from a technical expert's perspective:

**Investigating `mm/memcontrol.c` for Memcg Lifecycle and Stats**

Okay, so I'm diving into `mm/memcontrol.c`, specifically focusing on the lifecycle and statistical aspects of memory control groups (memcgs). I'm deliberately *not* looking at the obvious, well-trodden paths like the "hot" execution paths or statically defined symbols right away. My goal is to get a broader view. I'm trying to identify any other interesting entry points or symbols in this file that might relate to how memcgs are created, destroyed, or how their memory usage is tracked *besides* the most obvious ones. I want to build a more holistic understanding of the code.

I figure reading around `mod_memcg_state` and `mod_memcg_lruvec_state` is a good starting point. Those look like key functions/structures for modifying or updating the state of a memcg, especially regarding LRU (Least Recently Used) data. I'm betting that understanding how these states are modified will illuminate other parts of the system. I'm anticipating that these modifications will likely reveal how the memory accounting and other stats are updated as well.

{
  "File": "mm/memcontrol.c",
  "FirstLine": 870,
  "LineCount": 90
}

{
  "Contents": " 870:\tvoid mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx,\n 871:\t\t\t       int val)\n 872:\t{\n 873:\t\tbool rcu_locked = false;\n 874:\t\n 875:\t\tif (mem_cgroup_disabled())\n 876:\t\t\treturn;\n 877:\t\n 878:\t\tmemcg = get_non_dying_memcg_start(memcg, \u0026rcu_locked);\n 879:\t\t__mod_memcg_state(memcg, idx, val);\n 880:\t\tget_non_dying_memcg_end(rcu_locked);\n 881:\t}\n 882:\t\n 883:\t#ifdef CONFIG_MEMCG_V1\n 884:\t/* idx can be of type enum memcg_stat_item or node_stat_item. */\n 885:\tunsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx)\n 886:\t{\n 887:\t\tlong x;\n 888:\t\tint i = memcg_stats_index(idx);\n 889:\t\n 890:\t\tif (WARN_ONCE(BAD_STAT_IDX(i), \"%s: missing stat item %d\\n\", __func__, idx))\n 891:\t\t\treturn 0;\n 892:\t\n 893:\t\tx = READ_ONCE(memcg-\u003evmstats-\u003estate_local[i]);\n 894:\t#ifdef CONFIG_SMP\n 895:\t\tif (x \u003c 0)\n 896:\t\t\tx = 0;\n 897:\t#endif\n 898:\t\treturn x;\n 899:\t}\n 900:\t\n 901:\tvoid reparent_memcg_state_local(struct mem_cgroup *memcg,\n 902:\t\t\t\t\tstruct mem_cgroup *parent, int idx)\n 903:\t{\n 904:\t\tunsigned long value = memcg_page_state_local(memcg, idx);\n 905:\t\n 906:\t\t__mod_memcg_state(memcg, idx, -value);\n 907:\t\t__mod_memcg_state(parent, idx, value);\n 908:\t}\n 909:\t#endif\n 910:\t\n 911:\tstatic void __mod_memcg_lruvec_state(struct mem_cgroup_per_node *pn,\n 912:\t\t\t\t\t     enum node_stat_item idx, long val)\n 913:\t{\n 914:\t\tstruct mem_cgroup *memcg = pn-\u003ememcg;\n 915:\t\tint i = memcg_stats_index(idx);\n 916:\t\tint cpu;\n 917:\t\n 918:\t\tif (WARN_ONCE(BAD_STAT_IDX(i), \"%s: missing stat item %d\\n\", __func__, idx))\n 919:\t\t\treturn;\n 920:\t\n 921:\t\tcpu = get_cpu();\n 922:\t\n 923:\t\t/* Update memcg */\n 924:\t\tthis_cpu_add(memcg-\u003evmstats_percpu-\u003estate[i], val);\n 925:\t\n 926:\t\t/* Update lruvec */\n 927:\t\tthis_cpu_add(pn-\u003elruvec_stats_percpu-\u003estate[i], val);\n 928:\t\n 929:\t\tval = memcg_state_val_in_pages(idx, val);\n 930:\t\tmemcg_rstat_updated(memcg, val, cpu);\n 931:\t\ttrace_mod_memcg_lruvec_state(memcg, idx, val);\n 932:\t\n 933:\t\tput_cpu();\n 934:\t}\n 935:\t\n 936:\tstatic void mod_memcg_lruvec_state(struct lruvec *lruvec,\n 937:\t\t\t\t\t     enum node_stat_item idx,\n 938:\t\t\t\t\t     int val)\n 939:\t{\n 940:\t\tstruct pglist_data *pgdat = lruvec_pgdat(lruvec);\n 941:\t\tstruct mem_cgroup_per_node *pn;\n 942:\t\tstruct mem_cgroup *memcg;\n 943:\t\tbool rcu_locked = false;\n 944:\t\n 945:\t\tpn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);\n 946:\t\tmemcg = get_non_dying_memcg_start(pn-\u003ememcg, \u0026rcu_locked);\n 947:\t\tpn = memcg-\u003enodeinfo[pgdat-\u003enode_id];\n 948:\t\n 949:\t\t__mod_memcg_lruvec_state(pn, idx, val);\n 950:\t\n 951:\t\tget_non_dying_memcg_end(rcu_locked);\n 952:\t}\n 953:\t\n 954:\t/**\n 955:\t * mod_lruvec_state - update lruvec memory statistics\n 956:\t * @lruvec: the lruvec\n 957:\t * @idx: the stat item\n 958:\t * @val: delta to add to the counter, can be negative\n 959:\t *\n"
}

gemini-3.7-flash

null

null

							input: 10820
							output: 34
							thoughts: 32
						

Okay, let's dive into this. Here's my thought process as I start to investigate the `mod_memcg_lruvec_state` function within the `mm/memcontrol.c` file.

**Investigating `mod_memcg_lruvec_state` and Related Functions**

Alright, so someone's asked me to look into `mod_memcg_lruvec_state` and understand its role in memory control, specifically within the memcg (memory control group) subsystem. My first instinct, as always, is to get a handle on its call sites. Where is this function *used*? Understanding its callers will immediately tell me what parts of the kernel are interacting with the LRU (Least Recently Used) state of a memcg. I'll need to figure out which other functions are available in the `mm/memcontrol.c` file and how they might relate to LRU management. Are there functions for updating, querying, or otherwise manipulating the LRU state? Knowing the landscape of functions within that file will give me a comprehensive view. This will give me a good lay of the land, making sure to track the interactions with memory and related features. My goal is to paint a complete picture of the LRU state manipulation within the memcg system.

{
  "File": "mm/memcontrol.c",
  "FirstLine": 955,
  "LineCount": 50
}

{
  "Contents": " 955:\t * mod_lruvec_state - update lruvec memory statistics\n 956:\t * @lruvec: the lruvec\n 957:\t * @idx: the stat item\n 958:\t * @val: delta to add to the counter, can be negative\n 959:\t *\n 960:\t * The lruvec is the intersection of the NUMA node and a cgroup. This\n 961:\t * function updates the all three counters that are affected by a\n 962:\t * change of state at this level: per-node, per-cgroup, per-lruvec.\n 963:\t */\n 964:\tvoid mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,\n 965:\t\t\t\tint val)\n 966:\t{\n 967:\t\t/* Update node */\n 968:\t\tmod_node_page_state(lruvec_pgdat(lruvec), idx, val);\n 969:\t\n 970:\t\t/* Update memcg and lruvec */\n 971:\t\tif (!mem_cgroup_disabled())\n 972:\t\t\tmod_memcg_lruvec_state(lruvec, idx, val);\n 973:\t}\n 974:\t\n 975:\tvoid lruvec_stat_mod_folio(struct folio *folio, enum node_stat_item idx,\n 976:\t\t\t\t     int val)\n 977:\t{\n 978:\t\tstruct mem_cgroup *memcg;\n 979:\t\tpg_data_t *pgdat = folio_pgdat(folio);\n 980:\t\tstruct lruvec *lruvec;\n 981:\t\n 982:\t\trcu_read_lock();\n 983:\t\tmemcg = folio_memcg(folio);\n 984:\t\t/* Untracked pages have no memcg, no lruvec. Update only the node */\n 985:\t\tif (!memcg) {\n 986:\t\t\trcu_read_unlock();\n 987:\t\t\tmod_node_page_state(pgdat, idx, val);\n 988:\t\t\treturn;\n 989:\t\t}\n 990:\t\n 991:\t\tlruvec = mem_cgroup_lruvec(memcg, pgdat);\n 992:\t\tmod_lruvec_state(lruvec, idx, val);\n 993:\t\trcu_read_unlock();\n 994:\t}\n 995:\tEXPORT_SYMBOL(lruvec_stat_mod_folio);\n 996:\t\n 997:\tvoid mod_lruvec_kmem_state(void *p, enum node_stat_item idx, int val)\n 998:\t{\n 999:\t\tpg_data_t *pgdat = page_pgdat(virt_to_page(p));\n1000:\t\tstruct mem_cgroup *memcg;\n1001:\t\tstruct lruvec *lruvec;\n1002:\t\n1003:\t\trcu_read_lock();\n1004:\t\tmemcg = mem_cgroup_from_virt(p);\n"
}

gemini-3.7-flash

null

null

							input: 11995
							output: 29
							thoughts: 76
						

Okay, let's dive into this. Here's how I'd approach this memcg offlining/dying situation:

**Investigating memcg Offlining Triggers**

Right, so I need to figure out what precisely causes a memory cgroup (memcg) to offline or die. My initial thought is to zero in on the core code responsible for managing memory control groups. I know the likely suspects are within `mm/memcontrol.c`.

My instinct is to start by looking for the functions involved in these states. I'm going to focus on `mem_cgroup_css_offline` as a primary trigger, and also need to consider related functions like `mem_cgroup_css_released` and `mem_cgroup_css_free`. These seem like the key players.

My next step is a code search. I'm going to jump right into `mm/memcontrol.c` and search for the string "css_offline". This should quickly reveal all the call sites and related logic surrounding the offline process, allowing me to understand the conditions that lead to memcg deactivation. I expect this approach will quickly uncover the crucial mechanisms at play.

{
  "Expression": "css_offline",
  "PathPrefix": "mm/memcontrol.c"
}

{
  "Output": "mm/memcontrol.c=4205=static int mem_cgroup_css_online(struct cgroup_subsys_state *css)\n--\nmm/memcontrol.c-4281-\nmm/memcontrol.c:4282:static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)\nmm/memcontrol.c-4283-{\n--\nmm/memcontrol.c-4285-\nmm/memcontrol.c:4286:\tmemcg1_css_offline(memcg);\nmm/memcontrol.c-4287-\n--\nmm/memcontrol.c=5088=struct cgroup_subsys memory_cgrp_subsys = {\n--\nmm/memcontrol.c-5090-\t.css_online = mem_cgroup_css_online,\nmm/memcontrol.c:5091:\t.css_offline = mem_cgroup_css_offline,\nmm/memcontrol.c-5092-\t.css_released = mem_cgroup_css_released,\n"
}

gemini-3.7-flash

null

null

							input: 12628
							output: 26
							thoughts: 51
						

**Investigating Memory Control Configuration**

Okay, so I need to figure out the specific configuration options needed for `mm/memcontrol.c` and `mm/workingset.c`. Right, that means I should dive into the build system and configuration files to see what's controlling their inclusion. Let's start with `mm/Makefile`. That should give me a good handle on dependencies and how these files are compiled. From there, I'll need to check `init/Kconfig` – that's where the actual configuration options are defined. I'm assuming `CONFIG_MEMCG` is going to be central to this, but I need to confirm the dependencies and how this option influences the compilation of those specific source files. This should give me the information I need to understand which configuration options are relevant to make those modules work correctly.

{
  "Expression": "memcontrol\\.o",
  "PathPrefix": "mm/"
}

{
  "Output": "mm/Makefile=27=KCOV_INSTRUMENT_kmemleak.o := n\nmm/Makefile:28:KCOV_INSTRUMENT_memcontrol.o := n\nmm/Makefile-29-KCOV_INSTRUMENT_memcontrol-v1.o := n\n--\nmm/Makefile=104=obj-$(CONFIG_MEMCG_V1) += memcontrol-v1.o\nmm/Makefile:105:obj-$(CONFIG_MEMCG) += memcontrol.o vmpressure.o\nmm/Makefile-106-ifdef CONFIG_BPF_SYSCALL\nmm/Makefile:107:obj-$(CONFIG_MEMCG) += bpf_memcontrol.o\nmm/Makefile-108-endif\n"
}

gemini-3.7-flash

null

null

							input: 13072
							output: 27
							thoughts: 17
						

Here's a summary of my thought process, as requested:

**Checking Kernel Configuration**

Okay, first things first, let's dive into the kernel configuration. I need to refresh my understanding of how memory control groups are set up, so I'm going to jump straight into the source. Specifically, I'm going to check the `CONFIG_MEMCG` option. I know it's a fundamental part of managing resources in the kernel, and I need to see how it's defined and potentially configured in `init/Kconfig`. This should give me a solid foundation to understand the memory cgroup subsystem, its dependencies, and any default settings that might be in place. I'm expecting to find the standard configuration syntax, dependencies, and a detailed description that I can quickly scan for a quick overview. From there, I can decide where to go next based on what I uncover.

{
  "Expression": "config MEMCG",
  "PathPrefix": "init/Kconfig"
}

{
  "Output": "init/Kconfig=1074=config CGROUP_FAVOR_DYNMODS\n--\ninit/Kconfig-1083-\ninit/Kconfig:1084:config MEMCG\ninit/Kconfig-1085-\tbool \"Memory controller\"\n--\ninit/Kconfig-1092-\ninit/Kconfig:1093:config MEMCG_NMI_UNSAFE\ninit/Kconfig-1094-\tbool\n--\ninit/Kconfig-1099-\ninit/Kconfig:1100:config MEMCG_NMI_SAFETY_REQUIRES_ATOMIC\ninit/Kconfig-1101-\tbool\n--\ninit/Kconfig-1106-\ninit/Kconfig:1107:config MEMCG_V1\ninit/Kconfig-1108-\tbool \"Legacy cgroup v1 memory controller\"\n"
}

gemini-3.7-flash

null

null

							input: 13530
							output: 33
							thoughts: 27
						

Here's my take on the `init/Kconfig` file, specifically the sections around `CONFIG_MEMCG` and `CONFIG_MEMCG_V1`, given my expertise:

**Diving into the Kernel Configuration for Memory Control Groups**

Okay, time to get a good handle on how memory control groups are configured in this kernel. Let's see what the Kconfig file has to say about `CONFIG_MEMCG` and `CONFIG_MEMCG_V1`. My initial thought is to trace the conditional logic. Where does `CONFIG_MEMCG` fit within the overall system? What dependencies does it have? Are there any obvious conflicts or deprecations related to the different memory cgroup versions, particularly focusing on how `CONFIG_MEMCG_V1` is handled relative to the newer capabilities or default? I need to understand if this is a monolithic option or if there are finer-grained choices that become available when `CONFIG_MEMCG` is enabled. For instance, are there sub-options that control specific memory accounting or throttling features? Are there any architectural dependencies specified? And how does the file handle the user's default choice? What kind of help text provides a comprehensive understanding of what's what, and will it be clear and concise? I'm anticipating some legacy support and a potential transition path, so I'll be looking for clues on how the kernel handles backwards compatibility. Ultimately, I'm trying to gain a clear picture of the design space and potential gotchas when working with memory control groups within this particular kernel configuration.

{
  "File": "init/Kconfig",
  "FirstLine": 1080,
  "LineCount": 40
}

{
  "Contents": "1080:\t\t  hot path operations such as forks and exits more expensive.\n1081:\t\n1082:\t\t  Say N if unsure.\n1083:\t\n1084:\tconfig MEMCG\n1085:\t\tbool \"Memory controller\"\n1086:\t\tselect PAGE_COUNTER\n1087:\t\tselect EVENTFD\n1088:\t\tselect SLAB_OBJ_EXT\n1089:\t\tselect VM_EVENT_COUNTERS\n1090:\t\thelp\n1091:\t\t  Provides control over the memory footprint of tasks in a cgroup.\n1092:\t\n1093:\tconfig MEMCG_NMI_UNSAFE\n1094:\t\tbool\n1095:\t\tdepends on MEMCG\n1096:\t\tdepends on HAVE_NMI\n1097:\t\tdepends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS \u0026\u0026 !ARCH_HAVE_NMI_SAFE_CMPXCHG\n1098:\t\tdefault y\n1099:\t\n1100:\tconfig MEMCG_NMI_SAFETY_REQUIRES_ATOMIC\n1101:\t\tbool\n1102:\t\tdepends on MEMCG\n1103:\t\tdepends on HAVE_NMI\n1104:\t\tdepends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS \u0026\u0026 ARCH_HAVE_NMI_SAFE_CMPXCHG\n1105:\t\tdefault y\n1106:\t\n1107:\tconfig MEMCG_V1\n1108:\t\tbool \"Legacy cgroup v1 memory controller\"\n1109:\t\tdepends on MEMCG\n1110:\t\tdefault n\n1111:\t\thelp\n1112:\t\t  Legacy cgroup v1 memory controller which has been deprecated by\n1113:\t\t  cgroup v2 implementation. The v1 is there for legacy applications\n1114:\t\t  which haven't migrated to the new cgroup v2 interface yet. If you\n1115:\t\t  do not have any such application then you are completely fine leaving\n1116:\t\t  this option disabled.\n1117:\t\n1118:\t\t  Please note that feature set of the legacy memory controller is likely\n1119:\t\t  going to shrink due to deprecation process. New deployments with v1\n"
}

gemini-3.7-flash

null

null

							input: 14497
							output: 34
							thoughts: 85
						

**My Initial Thoughts on MEMCG and its Dependencies**

Okay, so I'm focusing on `MEMCG`. I know that I need the `MEMCG` config option enabled for both the `mm/memcontrol.c` file and that conditional `ifdef` in `mm/workingset.c`. But a quick question pops into my head: is `MEMCG` actually contingent on `CGROUPS` being enabled? This feels like a question I should absolutely know the answer to, especially given my background. Let me quickly check `init/Kconfig`. That's where the dependencies are laid out, so I can confirm whether `MEMCG` is directly tied to an `if CGROUPS` block or if it has any other dependencies that might be relevant.

{
  "Expression": "menuconfig CGROUPS|if CGROUPS",
  "PathPrefix": "init/Kconfig"
}

{
  "Output": "init/Kconfig=1052=config SLAB_OBJ_EXT\n--\ninit/Kconfig-1054-\ninit/Kconfig:1055:menuconfig CGROUPS\ninit/Kconfig-1056-\tbool \"Control Group support\"\n--\ninit/Kconfig-1068-\ninit/Kconfig:1069:if CGROUPS\ninit/Kconfig-1070-\n"
}

gemini-3.7-flash

null

null

							input: 14894
							output: 31
							thoughts: 157
						

**My Initial Thoughts on Memory CGroups**

Okay, so I'm digging into `MEMCG`, which I know lives under the `CGROUPS` umbrella. First things first, let's see if there are any other configuration options or related functions I should be aware of. Gotta get the lay of the land, you know?

Now, let's think about potential symbols to focus on. What makes the most sense in terms of what's relevant to this area? Here are a few thoughts:

*   `mod_memcg_state`: This seems like a pretty core state variable, so it's a good place to start looking.
*   `mod_lruvec_state`: LRU (Least Recently Used) is crucial for memory management, so this likely relates to the state of the LRU vector within the cgroup. Definitely relevant.
*   `lruvec_stat_mod_folio`: This is very specific but looks like it handles updating folio stats within the LRU, also important.
*   `count_shadow_nodes` (or perhaps `workingset_update_node` or `workingset_refault`): Shadow nodes are interesting, so this count seems important. I'm also thinking updates and refaults in the working set are relevant, so I need to check these as well.
*   `mem_cgroup_css_offline`: This is probably the cgroup subsystem state offline.

If `MEMCG_V1` is enabled I need to check `reparent_memcg_state_local`. I need to figure out if it is static, which would be interesting.

{
  "Expression": "reparent_memcg_state_local",
  "PathPrefix": "mm/"
}

{
  "Output": "mm/memcontrol-v1.c=2209=void reparent_memcg1_state_local(struct mem_cgroup *memcg, struct mem_cgroup *parent)\n--\nmm/memcontrol-v1.c-2213-\tfor (i = 0; i \u003c ARRAY_SIZE(memcg1_stats); i++)\nmm/memcontrol-v1.c:2214:\t\treparent_memcg_state_local(memcg, parent, memcg1_stats[i]);\nmm/memcontrol-v1.c-2215-}\n--\nmm/memcontrol-v1.h=71=void reparent_memcg1_lruvec_state_local(struct mem_cgroup *memcg, struct mem_cgroup *parent);\nmm/memcontrol-v1.h-72-\nmm/memcontrol-v1.h:73:void reparent_memcg_state_local(struct mem_cgroup *memcg,\nmm/memcontrol-v1.h-74-\t\t\t\tstruct mem_cgroup *parent, int idx);\n--\nmm/memcontrol.c=885=unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx)\n--\nmm/memcontrol.c-900-\nmm/memcontrol.c:901:void reparent_memcg_state_local(struct mem_cgroup *memcg,\nmm/memcontrol.c-902-\t\t\t\tstruct mem_cgroup *parent, int idx)\n"
}

gemini-3.7-flash

null

null

							input: 15815
							output: 147
							thoughts: 442
						

**Focus Symbol Refinement for Memcg Fuzzing**

Okay, let's take a look at refining our focus symbols for memcg fuzzing. The guidance is clear: we need to isolate specific kernel functions that are critical to fuzz. We want to avoid generic hot-path functions to maintain a balanced test distribution. We're aiming for non-static, non-inlined API entrypoints – functions that have distinct symbol addresses, not buried inlined helpers.

Alright, let's run through the candidate functions we identified: `reparent_memcg1_state_local`, `reparent_memcg_state_local`, `mod_memcg_state`, `mod_lruvec_state`, `mod_lruvec_kmem_state`, and `count_shadow_nodes`.

I need to analyze if `mod_memcg_state` and `mod_lruvec_state` qualify as hot-path candidates. While they get some action during allocations and freeing, those are not the main areas we want to focus on. Specifically, memcg reparenting, cgroup teardown, and shadow shrinker are the most important. `reparent_memcg_state_local` is the crucial one for v1 offlining. For v2, or general cgroup offlining, the key functions are `mem_cgroup_css_offline` and `memcg1_css_offline`. And finally, `count_shadow_nodes` is something we might consider, located in `mm/workingset.c`.

Now, let's make sure our `EnableConfigs` are on point: `CGROUPS`, `MEMCG`, and `MEMCG_V1`.

Crucially, should we enable `MEMCG_V1` to hit both v1 and v2 paths? Yes, absolutely. `MEMCG_V1` enables testing `reparent_memcg_state_local`, which calls `__mod_memcg_state`, while v2 also brings `get_non_dying_memcg_start` into the picture.

Okay, let's take one last pass to confirm all of this and format the results neatly using `set-results`.

{
  "EnableConfigs": [
    "CGROUPS",
    "MEMCG",
    "MEMCG_V1"
  ],
  "FocusSymbols": [
    "count_shadow_nodes",
    "mod_memcg_state",
    "mod_lruvec_state",
    "reparent_memcg_state_local"
  ],
  "Reasoning": "The patch modifies memory cgroup stats handling and redirection for dying/offlining memcgs across all cgroup hierarchies (removing the v1-only restriction), as well as shadow node counting calculation in the workingset shrinker. This is core reachable memory management logic that should be fuzzed.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "CGROUPS",
    "MEMCG",
    "MEMCG_V1"
  ],
  "FocusSymbols": [
    "count_shadow_nodes",
    "mod_memcg_state",
    "mod_lruvec_state",
    "reparent_memcg_state_local"
  ],
  "Reasoning": "The patch modifies memory cgroup stats handling and redirection for dying/offlining memcgs across all cgroup hierarchies (removing the v1-only restriction), as well as shadow node counting calculation in the workingset shrinker. This is core reachable memory management logic that should be fuzzed.",
  "WorthFuzzing": true
}

{
  "WorthFuzzing": true
}

null

core

null

{
  "KMSANReasoning": "The patch series updates memory cgroup stat accounting and workingset shadow node counting:\n1. In `mm/memcontrol.c`, it simplifies and extends `get_non_dying_memcg_start()` across all cgroup hierarchies and adjusts RCU locking logic when offlining/reparenting memcgs. The out-parameter `rcu_locked` is unconditionally initialized on all execution paths before being passed to `get_non_dying_memcg_end()`.\n2. In `mm/workingset.c`, it updates `count_shadow_nodes()` to use `lruvec_page_state_local()` instead of `lruvec_lru_size()`.\n\nNo uninitialized stack or heap variables are read, no structs or buffers are copied to user space, and no memory allocations or uninitialized padding exposures are introduced. Potential risks (such as RCU lifetime issues, concurrency races, or use-after-free) are covered by KASAN and standard kernel debuggers. Therefore, dedicated KMSAN fuzzing is not required.",
  "NeedsKMSAN": false
}

You are an expert Linux kernel security engineer specializing in kernel memory
error detectors (KASAN and KMSAN). Your job is to review the provided patch series and
determine if the code changes justify spawning a dedicated KMSAN (KernelMemorySanitizer)
fuzzing session in addition to standard KASAN fuzzing.

CRITICAL DISTINCTION BETWEEN KASAN AND KMSAN:
- Standard KASAN kernel builds (upstream-apparmor-kasan.config) already enable
  a comprehensive suite of debugging tools and sanitizers, including KASAN
  (out-of-bounds accesses, use-after-free, double free, invalid free), LOCKDEP
  (locking bugs and deadlocks), UB-sanitizers, and memory corruption checks.
- KMSAN (KernelMemorySanitizer) detects reads of UNINITIALIZED memory (stack, heap,
  or page allocations) and kernel-to-user memory info-leaks.

Rule: THERE IS NO SENSE IN RUNNING A KMSAN SESSION IF A BUG CAN BE CAUGHT BY KASAN,
LOCKDEP, OR OTHER STANDARD BUG DETECTORS.
A dedicated KMSAN fuzzing session incurs significant resource costs. You must ONLY
set NeedsKMSAN=true if the code changes introduce or expose UNINITIALIZED MEMORY risks
that are detected ONLY by KMSAN.

Look holistically at the patch series and surrounding code. Even if no direct
uninitialized field accesses or new buffer allocations are added in the diff itself,
a patch may alter control flow, bounds checking, or data length calculations in ways
that change how the rest of the code operates on existing buffers (e.g. allowing
uninitialized stack/heap memory to be read, copied to user space, or used in control
flow). Do not hesitate to use your code access tools to inspect the surrounding code,
called functions, and callers.

Set NeedsKMSAN=true ONLY IF the patch introduces or modifies:
1. Kernel structures sent to user space (via copy_to_user, put_user, netlink skb
   attributes, ioctl output arguments, socket options, or BPF buffers) where fields
   or structure padding might not be fully initialized/zeroed.
2. Conditional logic or branching that depends on potentially uninitialized variables
   or struct fields.
3. Allocation or initialization of complex data structures where uninitialized fields
   could be read later in reachable code paths.
4. Bounds checks, lengths, or logic in a way that allows surrounding code to access
   uninitialized bytes of existing buffers.

Set NeedsKMSAN=false IF:
- The code changes primarily risk out-of-bounds access, array overflows, NULL pointer
  dereferences, locking deadlocks, or use-after-free bugs (these are already caught
  by KASAN, LOCKDEP, or standard bug detectors).
- All stack/heap structures touched or introduced by the patch are fully zeroed
  or initialized (e.g. using = {0}, memset, kzalloc) before being read or copied.
- The patch does not introduce any risk of uninitialized memory usage or info-leaks.

Use your code access tools to inspect the surrounding code if necessary, then provide
detailed KMSANReasoning contrasting KASAN vs KMSAN applicability for this patch.
Prefer calling several tools at the same time to save round-trips.


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

For your convenience, here is the diff of the changes:
commit c538b002b999cd1e3fef117ff6c636d69892a941
Author: syz-cluster <triage@syzkaller.com>
Date:   Mon Aug 31 10:42:08 2026 +0000

    syz-cluster: applied patch under review

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8319ad8c5c23a..f454d02746e9f 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -805,16 +805,21 @@ static long memcg_state_val_in_pages(int idx, long val)
 	return val < 0 ? -res : res;
 }
 
-#ifdef CONFIG_MEMCG_V1
 /*
- * Used in mod_memcg_state() and mod_memcg_lruvec_state() to avoid race with
- * reparenting of non-hierarchical state_locals.
+ * Used in mod_memcg_state() and mod_memcg_lruvec_state() to avoid race
+ * with reparenting of non-hierarchical state_locals.  Offlining a
+ * memcg is rare, so do the redirection for all cgroup hierarchies.
  */
-static inline struct mem_cgroup *get_non_dying_memcg_start(struct mem_cgroup *memcg,
-							   bool *rcu_locked)
+static inline struct mem_cgroup *
+get_non_dying_memcg_start(struct mem_cgroup *memcg, bool *rcu_locked)
 {
-	/* Rebinding can cause this value to be changed at runtime */
-	if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
+	/*
+	 * Fast path: the caller holds a reference to @memcg, so reading
+	 * its CSS_DYING flag without the RCU lock is safe.  The RCU lock
+	 * is only needed to walk up to a non-dying ancestor, which
+	 * happens only while a memcg is actually being offlined.
+	 */
+	if (!memcg_is_dying(memcg)) {
 		*rcu_locked = false;
 		return memcg;
 	}
@@ -835,17 +840,6 @@ static inline void get_non_dying_memcg_end(bool rcu_locked)
 
 	rcu_read_unlock();
 }
-#else
-static inline struct mem_cgroup *get_non_dying_memcg_start(struct mem_cgroup *memcg,
-							   bool *rcu_locked)
-{
-	return memcg;
-}
-
-static inline void get_non_dying_memcg_end(bool rcu_locked)
-{
-}
-#endif
 
 static void __mod_memcg_state(struct mem_cgroup *memcg,
 			      enum memcg_stat_item idx, long val)
diff --git a/mm/workingset.c b/mm/workingset.c
index f351798e723ac..85a4e14e95d51 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -693,10 +693,9 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
 
 		mem_cgroup_flush_stats_ratelimited(sc->memcg);
 		lruvec = mem_cgroup_lruvec(sc->memcg, NODE_DATA(sc->nid));
-
 		for (pages = 0, i = 0; i < NR_LRU_LISTS; i++)
-			pages += lruvec_lru_size(lruvec, i, MAX_NR_ZONES - 1);
-
+			pages += lruvec_page_state_local(lruvec,
+							 NR_LRU_BASE + i);
 		pages += lruvec_page_state_local(
 			lruvec, NR_SLAB_RECLAIMABLE_B) >> PAGE_SHIFT;
 		pages += lruvec_page_state_local(

gemini-3.7-flash

null

null

							input: 2854
							output: 37
							thoughts: 256
						

**Analyzing This Patch for Uninitialized Memory Risks**

Okay, let's dive into this patch and see if it introduces any uninitialized memory risks that would necessitate KMSAN testing. My initial impression is that the changes are primarily focused on memory control groups and workingset management, which are areas where subtle bugs can have significant consequences. I'll need to meticulously examine each modification.

First, I see the patch touches `mm/memcontrol.c`. The removal of the `#ifdef CONFIG_MEMCG_V1` conditional around `get_non_dying_memcg_start()` immediately catches my attention. The direct check for `!memcg_is_dying(memcg)` instead of the previous `cgroup_subsys_on_dfl(memory_cgrp_subsys)` conditional indicates a shift in how memcg death is handled or detected. This change in control flow is a classic area to trigger problems. I'll need to understand the implications of this change, especially regarding race conditions, and if the memory backing the cgroup is guaranteed to be zeroed when the new code executes. I need to understand if the removal of the conditional alters any memory allocation guarantees or assumptions. The modification of RCU locking logic for memcg ancestor walk during offlining/dying is also concerning, particularly in multi-threaded environments. I'll need to understand the new logic, the locking strategy, and potential for use-after-free conditions.

Second, the change in `mm/workingset.c` in `count_shadow_nodes()` appears to be a modification of how lruvec size is calculated. Replacing `lruvec_lru_size(lruvec, i, MAX_NR_ZONES - 1)` with `lruvec_page_state_local(lruvec, NR_LRU_BASE + i)` is potentially subtle. I'll need to determine if this change affects the intended behavior of the function, particularly related to the allocation or usage of memory, or if it can lead to under-counting of allocated pages. Are we inadvertently using uninitialized memory here?

Given the potential for subtle memory-related bugs in both files, I will need to inspect the surrounding code context. I'll likely use `read-file` or `grepper` to understand the bigger picture and identify any potential vulnerabilities. My primary focus will be on ensuring that no uninitialized memory is read or written. Any divergence in execution paths based on the death of a memcg needs to be verified.

{
  "Expression": "get_non_dying_memcg_start",
  "PathPrefix": "mm/memcontrol.c"
}

{
  "Output": "mm/memcontrol.c=813=static inline struct mem_cgroup *\nmm/memcontrol.c:814:get_non_dying_memcg_start(struct mem_cgroup *memcg, bool *rcu_locked)\nmm/memcontrol.c-815-{\n--\nmm/memcontrol.c=870=void mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx,\n--\nmm/memcontrol.c-877-\nmm/memcontrol.c:878:\tmemcg = get_non_dying_memcg_start(memcg, \u0026rcu_locked);\nmm/memcontrol.c-879-\t__mod_memcg_state(memcg, idx, val);\n--\nmm/memcontrol.c=936=static void mod_memcg_lruvec_state(struct lruvec *lruvec,\n--\nmm/memcontrol.c-945-\tpn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);\nmm/memcontrol.c:946:\tmemcg = get_non_dying_memcg_start(pn-\u003ememcg, \u0026rcu_locked);\nmm/memcontrol.c-947-\tpn = memcg-\u003enodeinfo[pgdat-\u003enode_id];\n"
}

gemini-3.7-flash

null

null

							input: 4023
							output: 34
							thoughts: 55
						

Okay, let's dive into this.

**Examining Memory Control in mm/memcontrol.c**

Alright, I need to refresh my memory on how these memory control functions, `get_non_dying_memcg_start()` and `get_non_dying_memcg_end()`, are actually implemented. Given my familiarity with memory management in this area, the most efficient approach is to go straight to the source. Specifically, I should focus on `mm/memcontrol.c`, and I'll jump to the relevant section around lines 800 to 860. That should give me a clear picture of their functionality within the context of the memory cgroup subsystem, particularly focusing on how they handle dying memory control groups. This will allow me to assess their role in whatever problem I'm trying to solve.

{
  "File": "mm/memcontrol.c",
  "FirstLine": 800,
  "LineCount": 60
}

{
  "Contents": " 800:\t\t/* Get the absolute value of (val * unit / PAGE_SIZE). */\n 801:\t\tres = mult_frac(abs(val), unit, PAGE_SIZE);\n 802:\t\t/* Round up zero values. */\n 803:\t\tres = res ? : 1;\n 804:\t\n 805:\t\treturn val \u003c 0 ? -res : res;\n 806:\t}\n 807:\t\n 808:\t/*\n 809:\t * Used in mod_memcg_state() and mod_memcg_lruvec_state() to avoid race\n 810:\t * with reparenting of non-hierarchical state_locals.  Offlining a\n 811:\t * memcg is rare, so do the redirection for all cgroup hierarchies.\n 812:\t */\n 813:\tstatic inline struct mem_cgroup *\n 814:\tget_non_dying_memcg_start(struct mem_cgroup *memcg, bool *rcu_locked)\n 815:\t{\n 816:\t\t/*\n 817:\t\t * Fast path: the caller holds a reference to @memcg, so reading\n 818:\t\t * its CSS_DYING flag without the RCU lock is safe.  The RCU lock\n 819:\t\t * is only needed to walk up to a non-dying ancestor, which\n 820:\t\t * happens only while a memcg is actually being offlined.\n 821:\t\t */\n 822:\t\tif (!memcg_is_dying(memcg)) {\n 823:\t\t\t*rcu_locked = false;\n 824:\t\t\treturn memcg;\n 825:\t\t}\n 826:\t\n 827:\t\trcu_read_lock();\n 828:\t\t*rcu_locked = true;\n 829:\t\n 830:\t\twhile (memcg_is_dying(memcg))\n 831:\t\t\tmemcg = parent_mem_cgroup(memcg);\n 832:\t\n 833:\t\treturn memcg;\n 834:\t}\n 835:\t\n 836:\tstatic inline void get_non_dying_memcg_end(bool rcu_locked)\n 837:\t{\n 838:\t\tif (!rcu_locked)\n 839:\t\t\treturn;\n 840:\t\n 841:\t\trcu_read_unlock();\n 842:\t}\n 843:\t\n 844:\tstatic void __mod_memcg_state(struct mem_cgroup *memcg,\n 845:\t\t\t\t      enum memcg_stat_item idx, long val)\n 846:\t{\n 847:\t\tint i = memcg_stats_index(idx);\n 848:\t\tint cpu;\n 849:\t\n 850:\t\tif (WARN_ONCE(BAD_STAT_IDX(i), \"%s: missing stat item %d\\n\", __func__, idx))\n 851:\t\t\treturn;\n 852:\t\n 853:\t\tcpu = get_cpu();\n 854:\t\n 855:\t\tthis_cpu_add(memcg-\u003evmstats_percpu-\u003estate[i], val);\n 856:\t\tval = memcg_state_val_in_pages(idx, val);\n 857:\t\tmemcg_rstat_updated(memcg, val, cpu);\n 858:\t\n 859:\t\ttrace_mod_memcg_state(memcg, idx, val);\n"
}

gemini-3.7-flash

null

null

							input: 5215
							output: 35
							thoughts: 15
						

Here's my take on the thoughts, rendered as a first-person summary, keeping in mind the user's expertise:

**Diving into the Memory Management Nuances**

Okay, so we've been deep in the weeds on this, and I'm itching to see how the memory management is *really* working in this context. Specifically, let's turn our attention to `mm/workingset.c`. I need to understand how the working set model is implemented here. I'm especially interested in how it interacts with the other memory management subsystems, like the page replacement algorithms, and how the various parameters are tuned. I want to see if they're making smart choices about resident set size limits, or if they are just doing the bare minimum. What are the key data structures used to track the working set? Are they efficient? Do they scale well? I'm hoping to get a clearer picture of the tradeoffs they've made, and see if there are opportunities for optimization, or perhaps areas where they've gone down an unproductive path. I'll be particularly interested in identifying any potential bottlenecks or areas where contention might arise, especially under heavy load. I'm looking for the elegance (or lack thereof) of the implementation. Let's see what gems we find.

{
  "File": "mm/workingset.c",
  "FirstLine": 685,
  "LineCount": 40
}

{
  "Contents": " 685:\t\t * ~1.8% of available memory:\n 686:\t\t *\n 687:\t\t * PAGE_SIZE / xa_nodes / node_entries * 8 / PAGE_SIZE\n 688:\t\t */\n 689:\t#ifdef CONFIG_MEMCG\n 690:\t\tif (sc-\u003ememcg) {\n 691:\t\t\tstruct lruvec *lruvec;\n 692:\t\t\tint i;\n 693:\t\n 694:\t\t\tmem_cgroup_flush_stats_ratelimited(sc-\u003ememcg);\n 695:\t\t\tlruvec = mem_cgroup_lruvec(sc-\u003ememcg, NODE_DATA(sc-\u003enid));\n 696:\t\t\tfor (pages = 0, i = 0; i \u003c NR_LRU_LISTS; i++)\n 697:\t\t\t\tpages += lruvec_page_state_local(lruvec,\n 698:\t\t\t\t\t\t\t\t NR_LRU_BASE + i);\n 699:\t\t\tpages += lruvec_page_state_local(\n 700:\t\t\t\tlruvec, NR_SLAB_RECLAIMABLE_B) \u003e\u003e PAGE_SHIFT;\n 701:\t\t\tpages += lruvec_page_state_local(\n 702:\t\t\t\tlruvec, NR_SLAB_UNRECLAIMABLE_B) \u003e\u003e PAGE_SHIFT;\n 703:\t\t} else\n 704:\t#endif\n 705:\t\t\tpages = node_present_pages(sc-\u003enid);\n 706:\t\n 707:\t\tmax_nodes = pages \u003e\u003e (XA_CHUNK_SHIFT - 3);\n 708:\t\n 709:\t\tif (nodes \u003c= max_nodes)\n 710:\t\t\treturn 0;\n 711:\t\treturn nodes - max_nodes;\n 712:\t}\n 713:\t\n 714:\tstatic enum lru_status shadow_lru_isolate(struct list_head *item,\n 715:\t\t\t\t\t\t  struct list_lru_one *lru,\n 716:\t\t\t\t\t\t  void *arg) __must_hold(lru-\u003elock)\n 717:\t{\n 718:\t\tstruct xa_node *node = container_of(item, struct xa_node, private_list);\n 719:\t\tstruct address_space *mapping;\n 720:\t\tint ret;\n 721:\t\n 722:\t\t/*\n 723:\t\t * Page cache insertions and deletions synchronously maintain\n 724:\t\t * the shadow node LRU under the i_pages lock and the\n"
}

gemini-3.7-flash

null

null

							input: 6198
							output: 252
							thoughts: 538
						

**My Analysis of Potential KMSAN Issues**

Okay, let's break down these changes and see if they introduce any uninitialized memory risks, a key concern when assessing the need for Kernel Memory Sanitizer (KMSAN). I'm focusing on the potential for reading uninitialized memory, passing it to user-space, or any other KMSAN-relevant issues.

First, I'm looking at `mm/memcontrol.c`. Specifically, I'm examining the `get_non_dying_memcg_start()` function and how it interacts with `rcu_locked`. From what I see, `*rcu_locked` is always explicitly initialized, regardless of the control flow. The code paths ensure `rcu_locked` gets a definite boolean value before it's used elsewhere, specifically in `mod_memcg_state` and `mod_memcg_lruvec_state`. So, no uninitialized reads there. The changes appear to optimize the handling of non-hierarchical state locals during memcg death, but this seems related to RCU synchronization and concurrency concerns, not uninitialized memory itself. This involves locking and RCU pointer traversal, not KMSAN-relevant data issues.

Moving on to `mm/workingset.c`, the change involves replacing `lruvec_lru_size` with `lruvec_page_state_local`. This function reads memcg vmstats per-cpu counters. There's nothing here that looks like allocating new buffers, copying to user-space, padding, or introducing uninitialized fields. It's just reading existing counter data.

So, in terms of uninitialized memory, here’s my assessment:

*   Are there uninitialized stack variables being passed or read? No, `rcu_locked` is fully initialized in all return paths.
*   Are any structs being sent to userspace? Nope.
*   Does it allocate or copy uninitialized memory? No.
*   Does it change buffer bounds or parsing lengths? No, this appears unrelated.

Any potential bugs that *do* exist are likely to be race conditions, deadlocks, problems with RCU lifetimes, or incorrect counter values. All of these fall into the category of concurrency issues, logic errors, or might be detected by other tools like KASAN or LOCKDEP, but not KMSAN.

Therefore, I'm comfortable concluding that this change doesn't introduce any new risks related to uninitialized memory. `NeedsKMSAN` should indeed be `false`. I'll double-check everything, of course, and document the clear reasoning for my assessment.

{
  "KMSANReasoning": "The patch series updates memory cgroup stat accounting and workingset shadow node counting:\n1. In `mm/memcontrol.c`, it simplifies and extends `get_non_dying_memcg_start()` across all cgroup hierarchies and adjusts RCU locking logic when offlining/reparenting memcgs. The out-parameter `rcu_locked` is unconditionally initialized on all execution paths before being passed to `get_non_dying_memcg_end()`.\n2. In `mm/workingset.c`, it updates `count_shadow_nodes()` to use `lruvec_page_state_local()` instead of `lruvec_lru_size()`.\n\nNo uninitialized stack or heap variables are read, no structs or buffers are copied to user space, and no memory allocations or uninitialized padding exposures are introduced. Potential risks (such as RCU lifetime issues, concurrency races, or use-after-free) are covered by KASAN and standard kernel debuggers. Therefore, dedicated KMSAN fuzzing is not required.",
  "NeedsKMSAN": false
}

{
  "KMSANReasoning": "The patch series updates memory cgroup stat accounting and workingset shadow node counting:\n1. In `mm/memcontrol.c`, it simplifies and extends `get_non_dying_memcg_start()` across all cgroup hierarchies and adjusts RCU locking logic when offlining/reparenting memcgs. The out-parameter `rcu_locked` is unconditionally initialized on all execution paths before being passed to `get_non_dying_memcg_end()`.\n2. In `mm/workingset.c`, it updates `count_shadow_nodes()` to use `lruvec_page_state_local()` instead of `lruvec_lru_size()`.\n\nNo uninitialized stack or heap variables are read, no structs or buffers are copied to user space, and no memory allocations or uninitialized padding exposures are introduced. Potential risks (such as RCU lifetime issues, concurrency races, or use-after-free) are covered by KASAN and standard kernel debuggers. Therefore, dedicated KMSAN fuzzing is not required.",
  "NeedsKMSAN": false
}