AI Trajectory

null

{
  "EnableConfigs": [
    "LRU_GEN",
    "LRU_GEN_ENABLED",
    "MEMCG",
    "NUMA"
  ],
  "FocusSymbols": [
    "try_to_free_pages",
    "try_to_free_mem_cgroup_pages",
    "node_reclaim",
    "wakeup_kswapd"
  ],
  "KMSANReasoning": "The patch refactors the page reclaim throttling logic in `mm/vmscan.c` by introducing a new helper function `throttle_isolated`. It uses a local boolean variable `fatal` passed by reference to track if a fatal signal is pending. The variable `fatal` is unconditionally initialized at the beginning of `throttle_isolated` before any reads occur. The patch does not introduce any new data structures sent to user space, nor does it leave any fields uninitialized. Any potential bugs introduced by these changes (such as logic errors, use-after-free, or deadlocks) would be caught by standard KASAN, LOCKDEP, or other default sanitizers. There is no risk of uninitialized memory reads or info-leaks that would necessitate a dedicated KMSAN fuzzing session.",
  "NeedsKMSAN": false,
  "Reasoning": "The patch modifies memory reclaim logic in `mm/vmscan.c`. It introduces `throttle_isolated()` to throttle reclaimers when too many folios are isolated, and applies this logic to both the legacy LRU (`shrink_inactive_list`) and the Multi-Gen LRU (`evict_folios`). It also adds accounting for isolated folios in MGLRU. This is a core memory management change that affects how the kernel handles memory pressure and concurrent page reclaim.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit 5632d8ec239dfabbdcffffd55849db0352299a58\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Mon Aug 17 07:51:39 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/mm/vmscan.c b/mm/vmscan.c\nindex c1404a59523d6..886a53f563ab7 100644\n--- a/mm/vmscan.c\n+++ b/mm/vmscan.c\n@@ -1819,7 +1819,7 @@ bool folio_isolate_lru(struct folio *folio)\n  * the LRU list will go small and be scanned faster than necessary, leading to\n  * unnecessary swapping, thrashing and OOM.\n  */\n-static bool too_many_isolated(struct pglist_data *pgdat, int file,\n+static bool too_many_isolated(struct pglist_data *pgdat, bool file,\n \t\tstruct scan_control *sc)\n {\n \tunsigned long inactive, isolated;\n@@ -1856,6 +1856,37 @@ static bool too_many_isolated(struct pglist_data *pgdat, int file,\n \treturn too_many;\n }\n \n+/*\n+ * Throttle reclaim if too many isolated folios are piling up. If this makes\n+ * no progress, the caller is probably looping on unevictable folios, so give\n+ * up. Returns false to tell the caller to stop reclaiming, and sets @fatal\n+ * if the task received a fatal signal while waiting, so that the caller can\n+ * bail out faster.\n+ */\n+static bool throttle_isolated(struct pglist_data *pgdat, bool file,\n+\t\t\t      struct scan_control *sc, bool *fatal)\n+{\n+\tbool stalled = false;\n+\n+\t*fatal = false;\n+\twhile (unlikely(too_many_isolated(pgdat, file, sc))) {\n+\t\tif (stalled)\n+\t\t\treturn false;\n+\n+\t\t/* wait a bit for the reclaimer. */\n+\t\tstalled = true;\n+\t\treclaim_throttle(pgdat, VMSCAN_THROTTLE_ISOLATED);\n+\n+\t\t/* We are about to die and free our memory. Return now. */\n+\t\tif (fatal_signal_pending(current)) {\n+\t\t\t*fatal = true;\n+\t\t\treturn false;\n+\t\t}\n+\t}\n+\n+\treturn true;\n+}\n+\n /*\n  * move_folios_to_lru() moves folios from private @list to appropriate LRU list.\n  *\n@@ -1992,19 +2023,14 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,\n \tbool file = is_file_lru(lru);\n \tenum node_stat_item item;\n \tstruct pglist_data *pgdat = lruvec_pgdat(lruvec);\n-\tbool stalled = false;\n-\n-\twhile (unlikely(too_many_isolated(pgdat, file, sc))) {\n-\t\tif (stalled)\n-\t\t\treturn 0;\n-\n-\t\t/* wait a bit for the reclaimer. */\n-\t\tstalled = true;\n-\t\treclaim_throttle(pgdat, VMSCAN_THROTTLE_ISOLATED);\n+\tbool fatal;\n \n+\tif (!throttle_isolated(pgdat, file, sc, \u0026fatal)) {\n \t\t/* We are about to die and free our memory. Return now. */\n-\t\tif (fatal_signal_pending(current))\n+\t\tif (fatal)\n \t\t\treturn SWAP_CLUSTER_MAX;\n+\n+\t\treturn 0;\n \t}\n \n \tlru_add_drain();\n@@ -4883,6 +4909,25 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,\n \tbool skip_retry = false;\n \tstruct mem_cgroup *memcg = lruvec_memcg(lruvec);\n \tstruct pglist_data *pgdat = lruvec_pgdat(lruvec);\n+\tbool fatal;\n+\n+\t/*\n+\t * The type to isolate is unknown until isolation, so predict it for\n+\t * the throttling check. isolate_folios() may still fall back to the\n+\t * other type, which is fine for this heuristic.\n+\t */\n+\ttype = get_type_to_scan(lruvec, swappiness);\n+\tif (!throttle_isolated(pgdat, type, sc, \u0026fatal)) {\n+\t\t/*\n+\t\t * We are about to die and free our memory. Like the legacy\n+\t\t * path, pretend some pages were reclaimed so reclaim unwinds\n+\t\t * quickly instead of looping back into the throttle.\n+\t\t */\n+\t\tif (fatal)\n+\t\t\tsc-\u003enr_reclaimed += SWAP_CLUSTER_MAX;\n+\n+\t\treturn 0;\n+\t}\n \n \tlruvec_lock_irq(lruvec);\n \n@@ -4892,6 +4937,9 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,\n \tscanned = isolate_folios(nr_to_scan, lruvec, sc, swappiness,\n \t\t\t\t \u0026list, \u0026isolated, \u0026type, \u0026type_scanned);\n \tnr_isolated = isolated;\n+\tif (nr_isolated)\n+\t\t__mod_node_page_state(pgdat, NR_ISOLATED_ANON + type,\n+\t\t\t\t      nr_isolated);\n \n \t/* Scanning may have emptied the oldest gen, flush it */\n \tif (scanned)\n@@ -4954,6 +5002,10 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,\n \t\tgoto retry;\n \t}\n \n+\tif (nr_isolated)\n+\t\tmod_node_page_state(pgdat, NR_ISOLATED_ANON + type,\n+\t\t\t\t    -nr_isolated);\n+\n \tif (nr_isolated \u003e total_reclaimed)\n \t\tmod_lruvec_state(lruvec, PGROTATE_ANON + type,\n \t\t\t\t nr_isolated - total_reclaimed);\n"
}

best-expensive

null

{
  "EnableConfigs": [
    "LRU_GEN",
    "LRU_GEN_ENABLED",
    "MEMCG",
    "NUMA"
  ],
  "FocusSymbols": [
    "try_to_free_pages",
    "try_to_free_mem_cgroup_pages",
    "node_reclaim",
    "wakeup_kswapd"
  ],
  "Reasoning": "The patch modifies memory reclaim logic in `mm/vmscan.c`. It introduces `throttle_isolated()` to throttle reclaimers when too many folios are isolated, and applies this logic to both the legacy LRU (`shrink_inactive_list`) and the Multi-Gen LRU (`evict_folios`). It also adds accounting for isolated folios in MGLRU. This is a core memory management change that affects how the kernel handles memory pressure and concurrent page reclaim.",
  "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 5632d8ec239dfabbdcffffd55849db0352299a58
Author: syz-cluster <triage@syzkaller.com>
Date:   Mon Aug 17 07:51:39 2026 +0000

    syz-cluster: applied patch under review

diff --git a/mm/vmscan.c b/mm/vmscan.c
index c1404a59523d6..886a53f563ab7 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1819,7 +1819,7 @@ bool folio_isolate_lru(struct folio *folio)
  * the LRU list will go small and be scanned faster than necessary, leading to
  * unnecessary swapping, thrashing and OOM.
  */
-static bool too_many_isolated(struct pglist_data *pgdat, int file,
+static bool too_many_isolated(struct pglist_data *pgdat, bool file,
 		struct scan_control *sc)
 {
 	unsigned long inactive, isolated;
@@ -1856,6 +1856,37 @@ static bool too_many_isolated(struct pglist_data *pgdat, int file,
 	return too_many;
 }
 
+/*
+ * Throttle reclaim if too many isolated folios are piling up. If this makes
+ * no progress, the caller is probably looping on unevictable folios, so give
+ * up. Returns false to tell the caller to stop reclaiming, and sets @fatal
+ * if the task received a fatal signal while waiting, so that the caller can
+ * bail out faster.
+ */
+static bool throttle_isolated(struct pglist_data *pgdat, bool file,
+			      struct scan_control *sc, bool *fatal)
+{
+	bool stalled = false;
+
+	*fatal = false;
+	while (unlikely(too_many_isolated(pgdat, file, sc))) {
+		if (stalled)
+			return false;
+
+		/* wait a bit for the reclaimer. */
+		stalled = true;
+		reclaim_throttle(pgdat, VMSCAN_THROTTLE_ISOLATED);
+
+		/* We are about to die and free our memory. Return now. */
+		if (fatal_signal_pending(current)) {
+			*fatal = true;
+			return false;
+		}
+	}
+
+	return true;
+}
+
 /*
  * move_folios_to_lru() moves folios from private @list to appropriate LRU list.
  *
@@ -1992,19 +2023,14 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
 	bool file = is_file_lru(lru);
 	enum node_stat_item item;
 	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
-	bool stalled = false;
-
-	while (unlikely(too_many_isolated(pgdat, file, sc))) {
-		if (stalled)
-			return 0;
-
-		/* wait a bit for the reclaimer. */
-		stalled = true;
-		reclaim_throttle(pgdat, VMSCAN_THROTTLE_ISOLATED);
+	bool fatal;
 
+	if (!throttle_isolated(pgdat, file, sc, &fatal)) {
 		/* We are about to die and free our memory. Return now. */
-		if (fatal_signal_pending(current))
+		if (fatal)
 			return SWAP_CLUSTER_MAX;
+
+		return 0;
 	}
 
 	lru_add_drain();
@@ -4883,6 +4909,25 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
 	bool skip_retry = false;
 	struct mem_cgroup *memcg = lruvec_memcg(lruvec);
 	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
+	bool fatal;
+
+	/*
+	 * The type to isolate is unknown until isolation, so predict it for
+	 * the throttling check. isolate_folios() may still fall back to the
+	 * other type, which is fine for this heuristic.
+	 */
+	type = get_type_to_scan(lruvec, swappiness);
+	if (!throttle_isolated(pgdat, type, sc, &fatal)) {
+		/*
+		 * We are about to die and free our memory. Like the legacy
+		 * path, pretend some pages were reclaimed so reclaim unwinds
+		 * quickly instead of looping back into the throttle.
+		 */
+		if (fatal)
+			sc->nr_reclaimed += SWAP_CLUSTER_MAX;
+
+		return 0;
+	}
 
 	lruvec_lock_irq(lruvec);
 
@@ -4892,6 +4937,9 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
 	scanned = isolate_folios(nr_to_scan, lruvec, sc, swappiness,
 				 &list, &isolated, &type, &type_scanned);
 	nr_isolated = isolated;
+	if (nr_isolated)
+		__mod_node_page_state(pgdat, NR_ISOLATED_ANON + type,
+				      nr_isolated);
 
 	/* Scanning may have emptied the oldest gen, flush it */
 	if (scanned)
@@ -4954,6 +5002,10 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
 		goto retry;
 	}
 
+	if (nr_isolated)
+		mod_node_page_state(pgdat, NR_ISOLATED_ANON + type,
+				    -nr_isolated);
+
 	if (nr_isolated > total_reclaimed)
 		mod_lruvec_state(lruvec, PGROTATE_ANON + type,
 				 nr_isolated - total_reclaimed);

gemini-3.1-pro-preview

null

null

							input: 3259
							output: 30
							thoughts: 269
						

**My Initial Assessment of the Memory Management Patch**

Okay, so I'm looking at a patch that's deep within the `mm/vmscan.c` file – that screams core memory management changes. Specifically, it's messing with page reclaim, which means we're probably dealing with the Least Recently Used (LRU) lists, both the traditional legacy LRU and MGLRU. The patch introduces a `throttle_isolated()` function, which immediately catches my eye as a potential point of contention or performance bottleneck; it's used within `shrink_inactive_list()` (legacy LRU) and `evict_folios()` (MGLRU). Interesting. The additions of `__mod_node_page_state` calls for `NR_ISOLATED_ANON` and potentially other types during eviction within `evict_folios()` show that the isolation counter is adjusted.

Now, my immediate thought is "Where are the entry points?".  `shrink_inactive_list` and `evict_folios` are both static, meaning they're not directly exposed.  `throttle_isolated` is also static. So, I need to look upstream. What functions call these or are related to page reclaim that *aren't* static? Let's see... `shrink_node`? `shrink_lruvec`? `try_to_free_pages`? Is `kswapd` involved? I'm going to head to `mm/vmscan.c` and start tracing back to see where this all fits in.  That should give me the larger picture I need.

{
  "Expression": "evict_folios",
  "PathPrefix": "mm/vmscan.c"
}

{
  "Output": "mm/vmscan.c=4862=static int isolate_folios(unsigned long nr_to_scan, struct lruvec *lruvec,\n--\nmm/vmscan.c-4895-\nmm/vmscan.c:4896:static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,\nmm/vmscan.c-4897-\t\t\tstruct scan_control *sc, int swappiness)\n--\nmm/vmscan.c=5099=static bool try_to_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\n--\nmm/vmscan.c-5122-\t\tnr_batch = min(nr_to_scan, MIN_LRU_BATCH);\nmm/vmscan.c:5123:\t\tdelta = evict_folios(nr_batch, lruvec, sc, swappiness);\nmm/vmscan.c-5124-\t\tif (!delta)\n--\nmm/vmscan.c=5726=static int run_eviction(struct lruvec *lruvec, unsigned long seq, struct scan_control *sc,\n--\nmm/vmscan.c-5746-\t\tnr_batch = min(nr_to_reclaim - sc-\u003enr_reclaimed, MAX_LRU_BATCH);\nmm/vmscan.c:5747:\t\tif (!evict_folios(nr_batch, lruvec, sc, swappiness))\nmm/vmscan.c-5748-\t\t\treturn 0;\n"
}

gemini-3.1-pro-preview

null

null

							input: 4292
							output: 35
							thoughts: 50
						

Here's my thought process, as if I were analyzing this code:

**Analyzing the Eviction Path in the LRU Vector**

Okay, so I see that `evict_folios` is being called from both `try_to_shrink_lruvec` and `run_eviction`. That's a pretty clear indication that it's the core function for actually removing folios, which makes sense given the names. Now, I want to trace the call graph further upstream. My focus is understanding the triggers for folio eviction. I need to figure out where `try_to_shrink_lruvec` and `run_eviction` are being *called* from. That's the crucial link – those are the points in the system that are initiating the eviction process based on whatever conditions are in play. I need to understand those conditions to grasp the overall eviction policy. Are we dealing with memory pressure, aging of entries, or something else entirely? Time to dig deeper and find out.

{
  "Expression": "try_to_shrink_lruvec",
  "PathPrefix": "mm/vmscan.c"
}

{
  "Output": "mm/vmscan.c=5064=static bool should_abort_scan(struct lruvec *lruvec, struct scan_control *sc)\n--\nmm/vmscan.c-5098- */\nmm/vmscan.c:5099:static bool try_to_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\nmm/vmscan.c-5100-{\n--\nmm/vmscan.c=5144=static int shrink_one(struct lruvec *lruvec, struct scan_control *sc)\n--\nmm/vmscan.c-5163-\nmm/vmscan.c:5164:\tneed_rotate = try_to_shrink_lruvec(lruvec, sc);\nmm/vmscan.c-5165-\n--\nmm/vmscan.c=5255=static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\n--\nmm/vmscan.c-5267-\nmm/vmscan.c:5268:\tif (try_to_shrink_lruvec(lruvec, sc))\nmm/vmscan.c-5269-\t\tlru_gen_rotate_memcg(lruvec, MEMCG_LRU_YOUNG);\n"
}

gemini-3.1-pro-preview

null

null

							input: 4933
							output: 36
							thoughts: 40
						

**My Analysis of the `lru_gen_shrink_lruvec` Function**

Okay, so I'm looking at `lru_gen_shrink_lruvec`. It's clear that this function is responsible for shrinking something related to an LRU vector, and it's calling `try_to_shrink_lruvec` in the process. My immediate thought is, "Who's the caller here? What upstream function or process is triggering this whole shrinking operation?" I need to understand the control flow; knowing what initiates `lru_gen_shrink_lruvec` is crucial for understanding *why* the LRU vector is being shrunk, under what conditions, and what the overall system implications are. This is a critical point to pinpoint. Understanding the call stack is paramount for any effective system analysis.

{
  "Expression": "lru_gen_shrink_lruvec",
  "PathPrefix": "mm/vmscan.c"
}

{
  "Output": "mm/vmscan.c=5185=static void shrink_many(struct pglist_data *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-5254-\nmm/vmscan.c:5255:static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\nmm/vmscan.c-5256-{\n--\nmm/vmscan.c=5999=static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-6003-\nmm/vmscan.c:6004:static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\nmm/vmscan.c-6005-{\n--\nmm/vmscan.c=6016=static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\n--\nmm/vmscan.c-6027-\tif ((lru_gen_enabled() || lru_gen_switching()) \u0026\u0026 !root_reclaim(sc)) {\nmm/vmscan.c:6028:\t\tlru_gen_shrink_lruvec(lruvec, sc);\nmm/vmscan.c-6029-\n"
}

gemini-3.1-pro-preview

null

null

							input: 5539
							output: 31
							thoughts: 31
						

Here's my analysis of the situation, presented from my perspective as an expert:

**Investigating the `shrink_lruvec` Function's Callers**

Okay, so I see `shrink_lruvec` is calling `lru_gen_shrink_lruvec`. That's straightforward, and likely expected given the naming. My immediate question, though, is what *triggers* this call to `shrink_lruvec` in the first place? I need to understand the control flow. Is it invoked periodically based on a timer, triggered by a specific event within the LRU cache's operation, or something else entirely? To really understand the behavior and potential bottlenecks of the LRU cache, I have to trace back the call stack. Understanding *who* or *what* is calling `shrink_lruvec` is crucial to evaluating the performance and memory management strategy of the LRU implementation. Is the shrinking aggressive, or conservative? Are there any obvious candidates for optimization when reviewing where this function sits in the code? Let's trace this and understand the full implications.

{
  "Expression": "shrink_lruvec",
  "PathPrefix": "mm/vmscan.c"
}

{
  "Output": "mm/vmscan.c=5064=static bool should_abort_scan(struct lruvec *lruvec, struct scan_control *sc)\n--\nmm/vmscan.c-5098- */\nmm/vmscan.c:5099:static bool try_to_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\nmm/vmscan.c-5100-{\n--\nmm/vmscan.c=5144=static int shrink_one(struct lruvec *lruvec, struct scan_control *sc)\n--\nmm/vmscan.c-5163-\nmm/vmscan.c:5164:\tneed_rotate = try_to_shrink_lruvec(lruvec, sc);\nmm/vmscan.c-5165-\n--\nmm/vmscan.c=5185=static void shrink_many(struct pglist_data *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-5254-\nmm/vmscan.c:5255:static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\nmm/vmscan.c-5256-{\n--\nmm/vmscan.c-5267-\nmm/vmscan.c:5268:\tif (try_to_shrink_lruvec(lruvec, sc))\nmm/vmscan.c-5269-\t\tlru_gen_rotate_memcg(lruvec, MEMCG_LRU_YOUNG);\n--\nmm/vmscan.c=5999=static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-6003-\nmm/vmscan.c:6004:static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\nmm/vmscan.c-6005-{\n--\nmm/vmscan.c=6009=static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-6015-\nmm/vmscan.c:6016:static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\nmm/vmscan.c-6017-{\n--\nmm/vmscan.c-6027-\tif ((lru_gen_enabled() || lru_gen_switching()) \u0026\u0026 !root_reclaim(sc)) {\nmm/vmscan.c:6028:\t\tlru_gen_shrink_lruvec(lruvec, sc);\nmm/vmscan.c-6029-\n--\nmm/vmscan.c=6207=static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-6266-\nmm/vmscan.c:6267:\t\tshrink_lruvec(lruvec, sc);\nmm/vmscan.c-6268-\n--\nmm/vmscan.c=6862=unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,\n--\nmm/vmscan.c-6892-\t */\nmm/vmscan.c:6893:\tshrink_lruvec(lruvec, \u0026sc);\nmm/vmscan.c-6894-\n"
}

gemini-3.1-pro-preview

null

null

							input: 6732
							output: 33
							thoughts: 57
						

Okay, let's see what we have here.

**Deconstructing Memory Cgroup Shrinkage**

Right, `mem_cgroup_shrink_node` isn't static, interesting. Okay, so that means other parts of the kernel are calling it. I need to understand the call chain here, what's triggering that function. Let's see... looking at the code, `shrink_lruvec` is called within it. So, who else calls `shrink_lruvec`? Ah, yes, `shrink_node_memcgs` is one. Okay, and what is triggering *that* function, `shrink_node_memcgs`? I need to understand the broader context to understand the implications of this. I need to keep tracing the execution path.

{
  "Expression": "shrink_node_memcgs",
  "PathPrefix": "mm/vmscan.c"
}

{
  "Output": "mm/vmscan.c=6155=static inline bool should_continue_reclaim(struct pglist_data *pgdat,\n--\nmm/vmscan.c-6206-\nmm/vmscan.c:6207:static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)\nmm/vmscan.c-6208-{\n--\nmm/vmscan.c=6286=static void shrink_node(pg_data_t *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-6310-\nmm/vmscan.c:6311:\tshrink_node_memcgs(pgdat, sc);\nmm/vmscan.c-6312-\n"
}

gemini-3.1-pro-preview

null

null

							input: 7193
							output: 29
							thoughts: 24
						

Here's my understanding of the situation, given my expertise in this area:

**Deconstructing the Memory Shrinkage Process**

Okay, so I'm looking at `shrink_node`. This is clearly the core function responsible for, well, shrinking a node's memory footprint. My initial thought is, what specifically triggers this shrinkage? My analysis shows that `shrink_node` is calling `shrink_node_memcgs`. That makes sense; `memcgs` (memory cgroups) are a major player when it comes to memory management and resource limits. So, `shrink_node` is using `shrink_node_memcgs` to interact with and manage memory within the cgroup hierarchy. That's a reasonable modular design. But I need to go deeper. What are the calling functions which lead to the invocation of `shrink_node`? Identifying the call sites will give me a better understanding of the triggers or events in the system. That's where the real insights lie, understanding the circumstances when the system needs to shed memory from a node. Is it a periodic process? A response to memory pressure? Or triggered by something else entirely? Finding the callers is crucial to understanding the complete picture.

{
  "Expression": "shrink_node",
  "PathPrefix": "mm/vmscan.c"
}

{
  "Output": "mm/vmscan.c=1972=static void handle_reclaim_writeback(unsigned long nr_taken,\n--\nmm/vmscan.c-2010-/*\nmm/vmscan.c:2011: * shrink_inactive_list() is a helper for shrink_node().  It returns the number\nmm/vmscan.c-2012- * of reclaimed pages\n--\nmm/vmscan.c=5255=static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\n--\nmm/vmscan.c-5275-\nmm/vmscan.c:5276:static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *sc)\nmm/vmscan.c-5277-{\n--\nmm/vmscan.c=6004=static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\n--\nmm/vmscan.c-6008-\nmm/vmscan.c:6009:static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *sc)\nmm/vmscan.c-6010-{\n--\nmm/vmscan.c=6155=static inline bool should_continue_reclaim(struct pglist_data *pgdat,\n--\nmm/vmscan.c-6206-\nmm/vmscan.c:6207:static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)\nmm/vmscan.c-6208-{\n--\nmm/vmscan.c-6285-\nmm/vmscan.c:6286:static void shrink_node(pg_data_t *pgdat, struct scan_control *sc)\nmm/vmscan.c-6287-{\n--\nmm/vmscan.c-6293-\t\tmemset(\u0026sc-\u003enr, 0, sizeof(sc-\u003enr));\nmm/vmscan.c:6294:\t\tlru_gen_shrink_node(pgdat, sc);\nmm/vmscan.c-6295-\n--\nmm/vmscan.c-6310-\nmm/vmscan.c:6311:\tshrink_node_memcgs(pgdat, sc);\nmm/vmscan.c-6312-\n--\nmm/vmscan.c=6471=static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)\n--\nmm/vmscan.c-6549-\t\tlast_pgdat = zone-\u003ezone_pgdat;\nmm/vmscan.c:6550:\t\tshrink_node(zone-\u003ezone_pgdat, sc);\nmm/vmscan.c-6551-\t}\n--\nmm/vmscan.c=6816=unsigned long try_to_free_pages(struct zonelist *zonelist, int order,\n--\nmm/vmscan.c-6861-/* Only used by soft limit reclaim. Do not reuse for anything else. */\nmm/vmscan.c:6862:unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,\nmm/vmscan.c-6863-\t\t\t\t\t\tgfp_t gfp_mask, bool noswap,\n--\nmm/vmscan.c-6888-\t * here is not a good idea, since it limits the pages we can scan.\nmm/vmscan.c:6889:\t * if we don't reclaim here, the shrink_node from balance_pgdat\nmm/vmscan.c-6890-\t * will pick up pages from other mem cgroup's as well. We hack\n--\nmm/vmscan.c=7010=static bool pgdat_balanced(pg_data_t *pgdat, int order, int highest_zoneidx)\n--\nmm/vmscan.c-7034-\t\t * its own and needs kcompactd support. Once it's\nmm/vmscan.c:7035:\t\t * reclaimed a compaction gap, and kswapd_shrink_node\nmm/vmscan.c-7036-\t\t * has dropped order, simply ensure there are enough\n--\nmm/vmscan.c=7092=static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order,\n--\nmm/vmscan.c-7130- */\nmm/vmscan.c:7131:static bool kswapd_shrink_node(pg_data_t *pgdat,\nmm/vmscan.c-7132-\t\t\t       struct scan_control *sc)\n--\nmm/vmscan.c-7147-\t */\nmm/vmscan.c:7148:\tshrink_node(pgdat, sc);\nmm/vmscan.c-7149-\n--\nmm/vmscan.c=7204=static int balance_pgdat(pg_data_t *pgdat, int order, int highest_zoneidx)\n--\nmm/vmscan.c-7313-\nmm/vmscan.c:7314:\t\t/* Call soft limit reclaim before calling shrink_node. */\nmm/vmscan.c-7315-\t\tsc.nr_scanned = 0;\n--\nmm/vmscan.c-7325-\t\t */\nmm/vmscan.c:7326:\t\tif (kswapd_shrink_node(pgdat, \u0026sc))\nmm/vmscan.c-7327-\t\t\traise_priority = false;\n--\nmm/vmscan.c=7880=static unsigned long __node_reclaim(struct pglist_data *pgdat,\n--\nmm/vmscan.c-7907-\t\tdo {\nmm/vmscan.c:7908:\t\t\tshrink_node(pgdat, sc);\nmm/vmscan.c-7909-\t\t} while (sc-\u003enr_reclaimed \u003c nr_pages \u0026\u0026 --sc-\u003epriority \u003e= 0);\n"
}

gemini-3.1-pro-preview

null

null

							input: 9013
							output: 33
							thoughts: 116
						

**My Initial Reclaim Analysis**

Okay, so I'm diving into this memory reclaim process. My immediate thought is to start with the key functions involved. I see `try_to_free_pages` – that's a non-static function, which is interesting, it seems directly involved in triggering the reclaim. Then there's `mem_cgroup_shrink_node`, also non-static; this suggests it plays a role in shrinking memory within cgroups, which will be vital for managing resources.

I need to quickly assess the core mechanics. `balance_pgdat`, while static, looks like the central loop within `kswapd`, which makes it a critical piece of the puzzle. I also note that `__node_reclaim` is static but linked to `node_reclaim`, so tracing those calls will provide the overview of overall node reclaim.

Therefore, my immediate plan is to focus my investigation on these critical points: `try_to_free_pages`, `try_to_free_mem_cgroup_pages`, `node_reclaim`, and `kswapd`. Examining their interactions should give me a good understanding of the reclaim strategy.

{
  "Expression": "try_to_free_pages",
  "PathPrefix": "mm/vmscan.c"
}

{
  "Output": "mm/vmscan.c=6563=static void snapshot_refaults(struct mem_cgroup *target_memcg, pg_data_t *pgdat)\n--\nmm/vmscan.c-6593- */\nmm/vmscan.c:6594:static unsigned long do_try_to_free_pages(struct zonelist *zonelist,\nmm/vmscan.c-6595-\t\t\t\t\t  struct scan_control *sc)\n--\nmm/vmscan.c=6736=static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,\n--\nmm/vmscan.c-6815-\nmm/vmscan.c:6816:unsigned long try_to_free_pages(struct zonelist *zonelist, int order,\nmm/vmscan.c-6817-\t\t\t\tgfp_t gfp_mask, const nodemask_t *nodemask)\n--\nmm/vmscan.c-6850-\nmm/vmscan.c:6851:\tnr_reclaimed = do_try_to_free_pages(zonelist, \u0026sc);\nmm/vmscan.c-6852-\n--\nmm/vmscan.c=6902=unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,\n--\nmm/vmscan.c-6933-\nmm/vmscan.c:6934:\tnr_reclaimed = do_try_to_free_pages(zonelist, \u0026sc);\nmm/vmscan.c-6935-\n--\nmm/vmscan.c=7700=unsigned long shrink_all_memory(unsigned long nr_to_reclaim)\n--\nmm/vmscan.c-7719-\nmm/vmscan.c:7720:\tnr_reclaimed = do_try_to_free_pages(zonelist, \u0026sc);\nmm/vmscan.c-7721-\n"
}

gemini-3.1-pro-preview

null

null

							input: 9916
							output: 29
							thoughts: 258
						

**My Assessment of the Memory Reclaim Patch**

Okay, so I'm looking at this memory reclaim patch, and the immediate entry points for direct reclaim jump out at me: `try_to_free_pages`, `try_to_free_mem_cgroup_pages`, `shrink_all_memory`, and `node_reclaim`. For the `kswapd` daemon, we're looking at the `kswapd` thread function itself as the entry point.

Given that this patch touches memory reclaim logic, fuzzing is an absolute must-do. The modifications are deep in `mm/vmscan.c` – that's core kernel code, easily reachable, and thus a prime target for fuzzing efforts. I see the patch introduces `throttle_isolated` and modifies `shrink_inactive_list` and `evict_folios`.

My focus is going to be on those key symbols: `try_to_free_pages`, `try_to_free_mem_cgroup_pages`, `shrink_all_memory`, `node_reclaim`, and `kswapd`.

Now, regarding `evict_folios`, I need to quickly determine if it's MGLRU-specific. Ah, yes, it's right there in the MGLRU section of `mm/vmscan.c`. A quick check. Is MGLRU enabled by default? I need to check `CONFIG_LRU_GEN`. I'll go look in `mm/Kconfig` to confirm the configuration.

{
  "Expression": "config LRU_GEN",
  "PathPrefix": "mm/Kconfig"
}

{
  "Output": "mm/Kconfig=1393=config PTE_MARKER_UFFD_WP\n--\nmm/Kconfig-1403-# multi-gen LRU {\nmm/Kconfig:1404:config LRU_GEN\nmm/Kconfig-1405-\tbool \"Multi-Gen LRU\"\n--\nmm/Kconfig-1412-\nmm/Kconfig:1413:config LRU_GEN_ENABLED\nmm/Kconfig-1414-\tbool \"Enable by default\"\n--\nmm/Kconfig-1418-\nmm/Kconfig:1419:config LRU_GEN_STATS\nmm/Kconfig-1420-\tbool \"Full stats for debugging\"\n--\nmm/Kconfig-1427-\nmm/Kconfig:1428:config LRU_GEN_WALKS_MMU\nmm/Kconfig-1429-\tdef_bool y\n"
}

gemini-3.1-pro-preview

null

null

							input: 10767
							output: 30
							thoughts: 101
						

**MGLRU Testing Plan**

Okay, so to really put MGLRU through its paces, I should enable both `LRU_GEN` and `LRU_GEN_ENABLED`. That makes sense. It allows for a more focused comparison, since the legacy LRU path, specifically the `shrink_inactive_list` function, has also been touched. Even though MGLRU isn't strictly necessary given the legacy changes, thorough testing of both is always the right call. It's the only way to be completely sure.

I can easily add those configurations to the EnableConfigs. No problem there.

Next, I need to take a look at `mm/vmscan.c`, specifically the `node_reclaim` function. That's the core of the reclaim process, so I should see how this affects it.

{
  "Expression": "node_reclaim",
  "PathPrefix": "mm/vmscan.c"
}

{
  "Output": "mm/vmscan.c=6286=static void shrink_node(pg_data_t *pgdat, struct scan_control *sc)\nmm/vmscan.c-6287-{\nmm/vmscan.c:6288:\tunsigned long nr_reclaimed, nr_scanned, nr_node_reclaimed;\nmm/vmscan.c-6289-\tstruct lruvec *target_lruvec;\n--\nmm/vmscan.c-6314-\nmm/vmscan.c:6315:\tnr_node_reclaimed = sc-\u003enr_reclaimed - nr_reclaimed;\nmm/vmscan.c-6316-\n--\nmm/vmscan.c-6319-\t\tvmpressure(sc-\u003egfp_mask, sc-\u003eorder, sc-\u003etarget_mem_cgroup, true,\nmm/vmscan.c:6320:\t\t\t   sc-\u003enr_scanned - nr_scanned, nr_node_reclaimed);\nmm/vmscan.c-6321-\nmm/vmscan.c:6322:\tif (nr_node_reclaimed)\nmm/vmscan.c-6323-\t\treclaimable = true;\n--\nmm/vmscan.c-6383-\nmm/vmscan.c:6384:\tif (should_continue_reclaim(pgdat, nr_node_reclaimed, sc))\nmm/vmscan.c-6385-\t\tgoto again;\n--\nmm/vmscan.c=7771=static const struct ctl_table vmscan_sysctl_table[] = {\n--\nmm/vmscan.c-7783-\t\t.procname\t= \"zone_reclaim_mode\",\nmm/vmscan.c:7784:\t\t.data\t\t= \u0026node_reclaim_mode,\nmm/vmscan.c:7785:\t\t.maxlen\t\t= sizeof(node_reclaim_mode),\nmm/vmscan.c-7786-\t\t.mode\t\t= 0644,\n--\nmm/vmscan.c=7803=module_init(kswapd_init)\n--\nmm/vmscan.c-7808- *\nmm/vmscan.c:7809: * If non-zero call node_reclaim when the number of free pages falls below\nmm/vmscan.c-7810- * the watermarks.\nmm/vmscan.c-7811- */\nmm/vmscan.c:7812:int node_reclaim_mode __read_mostly;\nmm/vmscan.c-7813-\n--\nmm/vmscan.c-7821-/*\nmm/vmscan.c:7822: * Percentage of pages in a zone that must be unmapped for node_reclaim to\nmm/vmscan.c-7823- * occur.\n--\nmm/vmscan.c=7848=static unsigned long node_pagecache_reclaimable(struct pglist_data *pgdat)\n--\nmm/vmscan.c-7858-\t */\nmm/vmscan.c:7859:\tif (node_reclaim_mode \u0026 RECLAIM_UNMAP)\nmm/vmscan.c-7860-\t\tnr_pagecache_reclaimable = node_page_state(pgdat, NR_FILE_PAGES);\n--\nmm/vmscan.c-7879- */\nmm/vmscan.c:7880:static unsigned long __node_reclaim(struct pglist_data *pgdat,\nmm/vmscan.c-7881-\t\t\t\t    unsigned long nr_pages,\n--\nmm/vmscan.c-7887-\nmm/vmscan.c:7888:\ttrace_mm_vmscan_node_reclaim_begin(pgdat-\u003enode_id, sc-\u003eorder,\nmm/vmscan.c-7889-\t\t\t\t\t   sc-\u003egfp_mask);\n--\nmm/vmscan.c-7917-\nmm/vmscan.c:7918:\ttrace_mm_vmscan_node_reclaim_end(sc-\u003enr_reclaimed, NULL);\nmm/vmscan.c-7919-\n--\nmm/vmscan.c-7922-\nmm/vmscan.c:7923:unsigned long node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order)\nmm/vmscan.c-7924-{\n--\nmm/vmscan.c-7932-\t\t.priority = NODE_RECLAIM_PRIORITY,\nmm/vmscan.c:7933:\t\t.may_writepage = !!(node_reclaim_mode \u0026 RECLAIM_WRITE),\nmm/vmscan.c:7934:\t\t.may_unmap = !!(node_reclaim_mode \u0026 RECLAIM_UNMAP),\nmm/vmscan.c-7935-\t\t.may_swap = 1,\n--\nmm/vmscan.c-7971-\nmm/vmscan.c:7972:\tret = __node_reclaim(pgdat, nr_pages, \u0026sc);\nmm/vmscan.c-7973-\tclear_bit_unlock(PGDAT_RECLAIM_LOCKED, \u0026pgdat-\u003eflags);\n--\nmm/vmscan.c-7984-\nmm/vmscan.c:7985:static unsigned long __node_reclaim(struct pglist_data *pgdat,\nmm/vmscan.c-7986-\t\t\t\t    unsigned long nr_pages,\n--\nmm/vmscan.c=8005=int user_proactive_reclaim(char *buf,\n--\nmm/vmscan.c-8097-\nmm/vmscan.c:8098:\t\t\treclaimed = __node_reclaim(pgdat, batch_size, \u0026sc);\nmm/vmscan.c-8099-\t\t\tclear_bit_unlock(PGDAT_RECLAIM_LOCKED, \u0026pgdat-\u003eflags);\n"
}

gemini-3.1-pro-preview

null

null

							input: 12573
							output: 31
							thoughts: 72
						

**Assessing Memory Reclamation Functions**

Okay, so I'm thinking about memory reclaim functions here. `node_reclaim` is a solid piece, always reliable. Then there's `shrink_all_memory` – that one's got a broad impact and I like its approach. `try_to_free_pages` is another good candidate for targeted page freeing, and `try_to_free_mem_cgroup_pages` is essential for cgroup management.

Now, a crucial question pops up regarding `shrink_all_memory`: is it readily available when and where I need it? Is it exported properly? I need to quickly verify its reachability. I'll need to double check the visibility of this crucial function.

{
  "Expression": "shrink_all_memory",
  "PathPrefix": "mm/vmscan.c"
}

{
  "Output": "mm/vmscan.c=7686=bool kswapd_test_hopeless(pg_data_t *pgdat)\n--\nmm/vmscan.c-7699- */\nmm/vmscan.c:7700:unsigned long shrink_all_memory(unsigned long nr_to_reclaim)\nmm/vmscan.c-7701-{\n"
}

gemini-3.1-pro-preview

null

null

							input: 12936
							output: 29
							thoughts: 17
						

Okay, here's my summary, presented as a stream of thought:

**Checking for Hibernation Interference**

Alright, I'm thinking about this issue... it's definitely related to hibernation, that much is clear. My immediate instinct is to check the activity of `kswapd`. It's the kernel thread responsible for managing memory swapping, and it's a prime suspect whenever hibernation-related issues pop up. I need to see if it's behaving as expected or if something is bottlenecking there. Let's dig in and see what `kswapd` is up to.

{
  "Expression": "kswapd",
  "PathPrefix": "mm/vmscan.c"
}

{
  "Output": "\nFull output is too long, showing 500 out of 524 lines.\nUse more precise expression if possible.\n\nmm/vmscan.c-5- *  Swap reorganised 29.12.95, Stephen Tweedie.\nmm/vmscan.c:6: *  kswapd added: 7.1.96  sct\nmm/vmscan.c:7: *  Removed kswapd_ctl limits, and swap out as many pages as needed\nmm/vmscan.c-8- *  to bring the system back to freepages.high: 2.4.97, Rik van Riel.\nmm/vmscan.c:9: *  Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com).\nmm/vmscan.c-10- *  Multiqueue VM started 5.8.00, Rik van Riel.\n--\nmm/vmscan.c=447=static int reclaimer_offset(struct scan_control *sc)\n--\nmm/vmscan.c-452-\nmm/vmscan.c:453:\tif (current_is_kswapd())\nmm/vmscan.c-454-\t\treturn 0;\n--\nmm/vmscan.c=483=static bool skip_throttle_noprogress(pg_data_t *pgdat)\n--\nmm/vmscan.c-488-\t/*\nmm/vmscan.c:489:\t * If kswapd is disabled, reschedule if necessary but do not\nmm/vmscan.c-490-\t * throttle as the system is likely near OOM.\nmm/vmscan.c-491-\t */\nmm/vmscan.c:492:\tif (kswapd_test_hopeless(pgdat))\nmm/vmscan.c-493-\t\treturn true;\n--\nmm/vmscan.c=511=void reclaim_throttle(pg_data_t *pgdat, enum vmscan_throttle_state reason)\n--\nmm/vmscan.c-517-\t/*\nmm/vmscan.c:518:\t * Do not throttle user workers, kthreads other than kswapd or\nmm/vmscan.c-519-\t * workqueues. They may be required for reclaim to make\n--\nmm/vmscan.c-521-\t */\nmm/vmscan.c:522:\tif (!current_is_kswapd() \u0026\u0026\nmm/vmscan.c-523-\t    current-\u003eflags \u0026 (PF_USER_WORKER|PF_KTHREAD)) {\n--\nmm/vmscan.c=966=static struct folio *alloc_demote_folio(struct folio *src,\n--\nmm/vmscan.c-975-\t * make sure we allocate from the target node first also trying to\nmm/vmscan.c:976:\t * demote or reclaim pages from the target node via kswapd if we are\nmm/vmscan.c-977-\t * low on free memory on target node. If we don't do this and if\n--\nmm/vmscan.c=1058=static unsigned int shrink_folio_list(struct list_head *folio_list,\n--\nmm/vmscan.c-1121-\t\t * The number of dirty pages determines if a node is marked\nmm/vmscan.c:1122:\t\t * reclaim_congested. kswapd will stall and start writing\nmm/vmscan.c-1123-\t\t * folios if the tail of the LRU is all dirty unqueued folios.\n--\nmm/vmscan.c-1190-\t\t\t/* Case 1 above */\nmm/vmscan.c:1191:\t\t\tif (current_is_kswapd() \u0026\u0026\nmm/vmscan.c-1192-\t\t\t    folio_test_reclaim(folio) \u0026\u0026\n--\nmm/vmscan.c=1589=unsigned int reclaim_clean_pages_from_list(struct zone *zone,\n--\nmm/vmscan.c-1614-\t * We should be safe here since we are only dealing with file pages and\nmm/vmscan.c:1615:\t * we are not kswapd and therefore cannot write dirty file pages. But\nmm/vmscan.c-1616-\t * call memalloc_noreclaim_save() anyway, just in case these conditions\n--\nmm/vmscan.c=1822=static bool too_many_isolated(struct pglist_data *pgdat, bool file,\n--\nmm/vmscan.c-1827-\nmm/vmscan.c:1828:\tif (current_is_kswapd())\nmm/vmscan.c-1829-\t\treturn false;\n--\nmm/vmscan.c=3893=static struct lru_gen_mm_walk *set_mm_walk(struct pglist_data *pgdat, bool force_alloc)\n--\nmm/vmscan.c-3896-\nmm/vmscan.c:3897:\tif (pgdat \u0026\u0026 current_is_kswapd()) {\nmm/vmscan.c-3898-\t\tVM_WARN_ON_ONCE(walk);\n--\nmm/vmscan.c-3901-\t} else if (!walk \u0026\u0026 force_alloc) {\nmm/vmscan.c:3902:\t\tVM_WARN_ON_ONCE(current_is_kswapd());\nmm/vmscan.c-3903-\n--\nmm/vmscan.c=3913=static void clear_mm_walk(void)\n--\nmm/vmscan.c-3921-\nmm/vmscan.c:3922:\tif (!current_is_kswapd())\nmm/vmscan.c-3923-\t\tkfree(walk);\n--\nmm/vmscan.c=4235=static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-4240-\nmm/vmscan.c:4241:\tVM_WARN_ON_ONCE(!current_is_kswapd());\nmm/vmscan.c-4242-\n--\nmm/vmscan.c=5064=static bool should_abort_scan(struct lruvec *lruvec, struct scan_control *sc)\n--\nmm/vmscan.c-5075-\t/* check the order to exclude compaction-induced reclaim */\nmm/vmscan.c:5076:\tif (!current_is_kswapd() || sc-\u003eorder)\nmm/vmscan.c-5077-\t\treturn false;\n--\nmm/vmscan.c-5089-\nmm/vmscan.c:5090:\t/* kswapd should abort if all eligible zones are safe */\nmm/vmscan.c-5091-\treturn true;\n--\nmm/vmscan.c=5276=static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-5298-\nmm/vmscan.c:5299:\tif (current_is_kswapd())\nmm/vmscan.c-5300-\t\tsc-\u003enr_reclaimed = 0;\n--\nmm/vmscan.c-5306-\nmm/vmscan.c:5307:\tif (current_is_kswapd())\nmm/vmscan.c-5308-\t\tsc-\u003enr_reclaimed += reclaimed;\n--\nmm/vmscan.c-5314-\tif (sc-\u003enr_reclaimed \u003e reclaimed)\nmm/vmscan.c:5315:\t\tkswapd_try_clear_hopeless(pgdat, sc-\u003eorder, sc-\u003ereclaim_idx);\nmm/vmscan.c-5316-}\n--\nmm/vmscan.c=6016=static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)\n--\nmm/vmscan.c-6045-\t * DEF_PRIORITY on the assumption that the fact we are direct\nmm/vmscan.c:6046:\t * reclaiming implies that kswapd is not keeping up and it is best to\nmm/vmscan.c-6047-\t * do a batch of work at once. For memcg reclaim one check is made to\n--\nmm/vmscan.c-6050-\t */\nmm/vmscan.c:6051:\tproportional_reclaim = (!cgroup_reclaim(sc) \u0026\u0026 !current_is_kswapd() \u0026\u0026\nmm/vmscan.c-6052-\t\t\t\tsc-\u003epriority == DEF_PRIORITY);\n--\nmm/vmscan.c-6075-\t\t/*\nmm/vmscan.c:6076:\t\t * For kswapd and memcg, reclaim at least the number of pages\nmm/vmscan.c-6077-\t\t * requested. Ensure that the anon and file LRUs are scanned\n--\nmm/vmscan.c=6207=static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-6221-\t *\nmm/vmscan.c:6222:\t * For kswapd, reliable forward progress is more important\nmm/vmscan.c-6223-\t * than a quick return to idle. Always do full walks.\nmm/vmscan.c-6224-\t */\nmm/vmscan.c:6225:\tif (current_is_kswapd() || sc-\u003ememcg_full_walk)\nmm/vmscan.c-6226-\t\tpartial = NULL;\n--\nmm/vmscan.c=6286=static void shrink_node(pg_data_t *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-6324-\nmm/vmscan.c:6325:\tif (current_is_kswapd()) {\nmm/vmscan.c-6326-\t\t/*\n--\nmm/vmscan.c-6337-\t\t *\nmm/vmscan.c:6338:\t\t * Once a node is flagged PGDAT_WRITEBACK, kswapd will\nmm/vmscan.c-6339-\t\t * count the number of pages under pages flagged for\n--\nmm/vmscan.c-6346-\t\t/*\nmm/vmscan.c:6347:\t\t * If kswapd scans pages marked for immediate\nmm/vmscan.c-6348-\t\t * reclaim and under writeback (nr_immediate), it\n--\nmm/vmscan.c-6367-\nmm/vmscan.c:6368:\t\tif (current_is_kswapd())\nmm/vmscan.c-6369-\t\t\tset_bit(LRUVEC_NODE_CONGESTED, \u0026target_lruvec-\u003eflags);\n--\nmm/vmscan.c-6373-\t * Stall direct reclaim for IO completions if the lruvec is\nmm/vmscan.c:6374:\t * node is congested. Allow kswapd to continue until it\nmm/vmscan.c-6375-\t * starts encountering unqueued dirty pages or cycling through\n--\nmm/vmscan.c-6377-\t */\nmm/vmscan.c:6378:\tif (!current_is_kswapd() \u0026\u0026 current_may_throttle() \u0026\u0026\nmm/vmscan.c-6379-\t    !sc-\u003ehibernation_mode \u0026\u0026\n--\nmm/vmscan.c-6390-\t * sleep. On reclaim progress, reset the failure counter. A\nmm/vmscan.c:6391:\t * successful direct reclaim run will revive a dormant kswapd.\nmm/vmscan.c-6392-\t */\nmm/vmscan.c-6393-\tif (reclaimable)\nmm/vmscan.c:6394:\t\tkswapd_try_clear_hopeless(pgdat, sc-\u003eorder, sc-\u003ereclaim_idx);\nmm/vmscan.c-6395-\telse if (sc-\u003ecache_trim_mode)\n--\nmm/vmscan.c=6433=static void consider_reclaim_throttle(pg_data_t *pgdat, struct scan_control *sc)\n--\nmm/vmscan.c-6449-\t/*\nmm/vmscan.c:6450:\t * Do not throttle kswapd or cgroup reclaim on NOPROGRESS as it will\nmm/vmscan.c-6451-\t * throttle on VMSCAN_THROTTLE_WRITEBACK if there are too many pages\n--\nmm/vmscan.c-6454-\t */\nmm/vmscan.c:6455:\tif (current_is_kswapd() || cgroup_reclaim(sc))\nmm/vmscan.c-6456-\t\treturn;\n--\nmm/vmscan.c=6691=static bool allow_direct_reclaim(pg_data_t *pgdat)\n--\nmm/vmscan.c-6698-\nmm/vmscan.c:6699:\tif (kswapd_test_hopeless(pgdat))\nmm/vmscan.c-6700-\t\treturn true;\n--\nmm/vmscan.c-6715-\nmm/vmscan.c:6716:\t/* kswapd must be awake if processes are being throttled */\nmm/vmscan.c:6717:\tif (!wmark_ok \u0026\u0026 waitqueue_active(\u0026pgdat-\u003ekswapd_wait)) {\nmm/vmscan.c:6718:\t\tif (READ_ONCE(pgdat-\u003ekswapd_highest_zoneidx) \u003e ZONE_NORMAL)\nmm/vmscan.c:6719:\t\t\tWRITE_ONCE(pgdat-\u003ekswapd_highest_zoneidx, ZONE_NORMAL);\nmm/vmscan.c-6720-\nmm/vmscan.c:6721:\t\twake_up_interruptible(\u0026pgdat-\u003ekswapd_wait);\nmm/vmscan.c-6722-\t}\n--\nmm/vmscan.c-6729- * and the PFMEMALLOC reserve for the preferred node is getting dangerously\nmm/vmscan.c:6730: * depleted. kswapd will continue to make progress and wake the processes\nmm/vmscan.c-6731- * when the low watermark is reached.\n--\nmm/vmscan.c=6736=static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,\n--\nmm/vmscan.c-6766-\t * Throttling is based on the first usable node and throttled processes\nmm/vmscan.c:6767:\t * wait on a queue until kswapd makes progress and wakes them. There\nmm/vmscan.c-6768-\t * is an affinity then between processes waking up and where reclaim\n--\nmm/vmscan.c-6796-\t * transaction in the case of a filesystem like ext[3|4]. In this case,\nmm/vmscan.c:6797:\t * it is not safe to block on pfmemalloc_wait as kswapd could be\nmm/vmscan.c-6798-\t * blocked waiting on the same lock. Instead, throttle for up to a\n--\nmm/vmscan.c-6804-\telse\nmm/vmscan.c:6805:\t\t/* Throttle until kswapd wakes the process */\nmm/vmscan.c-6806-\t\twait_event_killable(zone-\u003ezone_pgdat-\u003epfmemalloc_wait,\n--\nmm/vmscan.c=6943=unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,\n--\nmm/vmscan.c-6952-\nmm/vmscan.c:6953:static void kswapd_age_node(struct pglist_data *pgdat, struct scan_control *sc)\nmm/vmscan.c-6954-{\n--\nmm/vmscan.c=7010=static bool pgdat_balanced(pg_data_t *pgdat, int order, int highest_zoneidx)\n--\nmm/vmscan.c-7032-\t\t *\nmm/vmscan.c:7033:\t\t * However, kswapd usually cannot accomplish this on\nmm/vmscan.c-7034-\t\t * its own and needs kcompactd support. Once it's\nmm/vmscan.c:7035:\t\t * reclaimed a compaction gap, and kswapd_shrink_node\nmm/vmscan.c-7036-\t\t * has dropped order, simply ensure there are enough\n--\nmm/vmscan.c-7067-\t * need balancing by definition. This can happen if a zone-restricted\nmm/vmscan.c:7068:\t * allocation tries to wake a remote kswapd.\nmm/vmscan.c-7069-\t */\n--\nmm/vmscan.c=7077=static void clear_pgdat_congested(pg_data_t *pgdat)\n--\nmm/vmscan.c-7086-/*\nmm/vmscan.c:7087: * Prepare kswapd for sleeping. This verifies that there are no processes\nmm/vmscan.c-7088- * waiting in throttle_direct_reclaim() and that watermarks have been met.\nmm/vmscan.c-7089- *\nmm/vmscan.c:7090: * Returns true if kswapd is ready to sleep\nmm/vmscan.c-7091- */\nmm/vmscan.c:7092:static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order,\nmm/vmscan.c-7093-\t\t\t\tint highest_zoneidx)\n--\nmm/vmscan.c-7097-\t * soon as allow_direct_reclaim() is true. But there is a potential\nmm/vmscan.c:7098:\t * race between when kswapd checks the watermarks and a process gets\nmm/vmscan.c-7099-\t * throttled. There is also a potential race if processes get\nmm/vmscan.c:7100:\t * throttled, kswapd wakes, a large process exits thereby balancing the\nmm/vmscan.c:7101:\t * zones, which causes kswapd to exit balance_pgdat() before reaching\nmm/vmscan.c:7102:\t * the wake up checks. If kswapd is going to sleep, no process should\nmm/vmscan.c-7103-\t * be sleeping on pfmemalloc_wait, so wake them now if necessary. If\nmm/vmscan.c:7104:\t * the wake up is premature, processes will wake kswapd and get\nmm/vmscan.c-7105-\t * throttled again. The difference from wake ups in balance_pgdat() is\n--\nmm/vmscan.c-7111-\t/* Hopeless node, leave it to direct reclaim */\nmm/vmscan.c:7112:\tif (kswapd_test_hopeless(pgdat))\nmm/vmscan.c-7113-\t\treturn true;\n--\nmm/vmscan.c-7123-/*\nmm/vmscan.c:7124: * kswapd shrinks a node of pages that are at or below the highest usable\nmm/vmscan.c-7125- * zone that is currently unbalanced.\nmm/vmscan.c-7126- *\nmm/vmscan.c:7127: * Returns true if kswapd scanned at least the requested number of pages to\nmm/vmscan.c-7128- * reclaim or if the lack of progress was due to pages under writeback.\n--\nmm/vmscan.c-7130- */\nmm/vmscan.c:7131:static bool kswapd_shrink_node(pg_data_t *pgdat,\nmm/vmscan.c-7132-\t\t\t       struct scan_control *sc)\n--\nmm/vmscan.c=7186=clear_reclaim_active(pg_data_t *pgdat, int highest_zoneidx)\n--\nmm/vmscan.c-7191-/*\nmm/vmscan.c:7192: * For kswapd, balance_pgdat() will reclaim pages across a node from zones\nmm/vmscan.c-7193- * that are eligible for use by the caller until at least one zone is\n--\nmm/vmscan.c-7195- *\nmm/vmscan.c:7196: * Returns the order kswapd finished reclaiming at.\nmm/vmscan.c-7197- *\nmm/vmscan.c:7198: * kswapd scans the zones in the highmem-\u003enormal-\u003edma direction.  It skips\nmm/vmscan.c-7199- * zones which have free_pages \u003e high_wmark_pages(zone), but once a zone is\n--\nmm/vmscan.c=7204=static int balance_pgdat(pg_data_t *pgdat, int order, int highest_zoneidx)\n--\nmm/vmscan.c-7230-\t * place so that parallel allocations that are near the watermark will\nmm/vmscan.c:7231:\t * stall or direct reclaim until kswapd is finished.\nmm/vmscan.c-7232-\t */\n--\nmm/vmscan.c-7259-\t\t * go ahead if all eligible zones for the original allocation\nmm/vmscan.c:7260:\t\t * request are balanced to avoid excessive reclaim from kswapd.\nmm/vmscan.c-7261-\t\t */\n--\nmm/vmscan.c-7277-\t\t * on the grounds that the normal reclaim should be enough to\nmm/vmscan.c:7278:\t\t * re-evaluate if boosting is required when kswapd next wakes.\nmm/vmscan.c-7279-\t\t */\n--\nmm/vmscan.c-7311-\t\t */\nmm/vmscan.c:7312:\t\tkswapd_age_node(pgdat, \u0026sc);\nmm/vmscan.c-7313-\n--\nmm/vmscan.c-7325-\t\t */\nmm/vmscan.c:7326:\t\tif (kswapd_shrink_node(pgdat, \u0026sc))\nmm/vmscan.c-7327-\t\t\traise_priority = false;\n--\nmm/vmscan.c-7337-\nmm/vmscan.c:7338:\t\t/* Check if kswapd should be suspending */\nmm/vmscan.c-7339-\t\t__fs_reclaim_release(_THIS_IP_);\n--\nmm/vmscan.c-7376-\t * watermark_high at this point. We need to avoid increasing the\nmm/vmscan.c:7377:\t * failure count to prevent the kswapd thread from stopping.\nmm/vmscan.c-7378-\t */\nmm/vmscan.c-7379-\tif (!sc.nr_reclaimed \u0026\u0026 !boosted) {\nmm/vmscan.c:7380:\t\tint fail_cnt = atomic_inc_return(\u0026pgdat-\u003ekswapd_failures);\nmm/vmscan.c:7381:\t\t/* kswapd context, low overhead to trace every failure */\nmm/vmscan.c:7382:\t\ttrace_mm_vmscan_kswapd_reclaim_fail(pgdat-\u003enode_id, fail_cnt);\nmm/vmscan.c-7383-\t}\n--\nmm/vmscan.c-7418-\t/*\nmm/vmscan.c:7419:\t * Return the order kswapd stopped reclaiming at as\nmm/vmscan.c:7420:\t * prepare_kswapd_sleep() takes it into account. If another caller\nmm/vmscan.c:7421:\t * entered the allocator slow path while kswapd was awake, order will\nmm/vmscan.c-7422-\t * remain at the higher level.\n--\nmm/vmscan.c-7427-/*\nmm/vmscan.c:7428: * The pgdat-\u003ekswapd_highest_zoneidx is used to pass the highest zone index to\nmm/vmscan.c:7429: * be reclaimed by kswapd from the waker. If the value is MAX_NR_ZONES which is\nmm/vmscan.c:7430: * not a valid index then either kswapd runs for first time or kswapd couldn't\nmm/vmscan.c-7431- * sleep after previous reclaim attempt (node is still unbalanced). In that\nmm/vmscan.c:7432: * case return the zone index of the previous kswapd reclaim cycle.\nmm/vmscan.c-7433- */\nmm/vmscan.c:7434:static enum zone_type kswapd_highest_zoneidx(pg_data_t *pgdat,\nmm/vmscan.c-7435-\t\t\t\t\t   enum zone_type prev_highest_zoneidx)\nmm/vmscan.c-7436-{\nmm/vmscan.c:7437:\tenum zone_type curr_idx = READ_ONCE(pgdat-\u003ekswapd_highest_zoneidx);\nmm/vmscan.c-7438-\n--\nmm/vmscan.c-7441-\nmm/vmscan.c:7442:static void kswapd_try_to_sleep(pg_data_t *pgdat, int alloc_order, int reclaim_order,\nmm/vmscan.c-7443-\t\t\t\tunsigned int highest_zoneidx)\n--\nmm/vmscan.c-7450-\nmm/vmscan.c:7451:\tprepare_to_wait(\u0026pgdat-\u003ekswapd_wait, \u0026wait, TASK_INTERRUPTIBLE);\nmm/vmscan.c-7452-\n--\nmm/vmscan.c-7459-\t */\nmm/vmscan.c:7460:\tif (prepare_kswapd_sleep(pgdat, reclaim_order, highest_zoneidx)) {\nmm/vmscan.c-7461-\t\t/*\n--\nmm/vmscan.c-7463-\t\t * isolate pages from and skips them in the future scanning.\nmm/vmscan.c:7464:\t\t * When kswapd is going to sleep, it is reasonable to assume\nmm/vmscan.c-7465-\t\t * that pages and compaction may succeed so reset the cache.\n--\nmm/vmscan.c-7477-\t\t/*\nmm/vmscan.c:7478:\t\t * If woken prematurely then reset kswapd_highest_zoneidx and\nmm/vmscan.c-7479-\t\t * order. The values will either be from a wakeup request or\n--\nmm/vmscan.c-7482-\t\tif (remaining) {\nmm/vmscan.c:7483:\t\t\tWRITE_ONCE(pgdat-\u003ekswapd_highest_zoneidx,\nmm/vmscan.c:7484:\t\t\t\t\tkswapd_highest_zoneidx(pgdat,\nmm/vmscan.c-7485-\t\t\t\t\t\t\thighest_zoneidx));\nmm/vmscan.c-7486-\nmm/vmscan.c:7487:\t\t\tif (READ_ONCE(pgdat-\u003ekswapd_order) \u003c reclaim_order)\nmm/vmscan.c:7488:\t\t\t\tWRITE_ONCE(pgdat-\u003ekswapd_order, reclaim_order);\nmm/vmscan.c-7489-\t\t}\nmm/vmscan.c-7490-\nmm/vmscan.c:7491:\t\tfinish_wait(\u0026pgdat-\u003ekswapd_wait, \u0026wait);\nmm/vmscan.c:7492:\t\tprepare_to_wait(\u0026pgdat-\u003ekswapd_wait, \u0026wait, TASK_INTERRUPTIBLE);\nmm/vmscan.c-7493-\t}\n--\nmm/vmscan.c-7499-\tif (!remaining \u0026\u0026\nmm/vmscan.c:7500:\t    prepare_kswapd_sleep(pgdat, reclaim_order, highest_zoneidx)) {\nmm/vmscan.c:7501:\t\ttrace_mm_vmscan_kswapd_sleep(pgdat-\u003enode_id);\nmm/vmscan.c-7502-\n--\nmm/vmscan.c-7507-\t\t * watermarks being breached while under pressure, we reduce the\nmm/vmscan.c:7508:\t\t * per-cpu vmstat threshold while kswapd is awake and restore\nmm/vmscan.c-7509-\t\t * them before going back to sleep.\n--\nmm/vmscan.c-7522-\t}\nmm/vmscan.c:7523:\tfinish_wait(\u0026pgdat-\u003ekswapd_wait, \u0026wait);\nmm/vmscan.c-7524-}\n--\nmm/vmscan.c-7538- */\nmm/vmscan.c:7539:static int kswapd(void *p)\nmm/vmscan.c-7540-{\n--\nmm/vmscan.c-7548-\t * and that if we need more memory we should get access to it\nmm/vmscan.c:7549:\t * regardless (see \"__alloc_pages()\"). \"kswapd\" should\nmm/vmscan.c-7550-\t * never get caught in the normal page freeing logic.\n--\nmm/vmscan.c-7560-\nmm/vmscan.c:7561:\tWRITE_ONCE(pgdat-\u003ekswapd_order, 0);\nmm/vmscan.c:7562:\tWRITE_ONCE(pgdat-\u003ekswapd_highest_zoneidx, MAX_NR_ZONES);\nmm/vmscan.c-7563-\tatomic_set(\u0026pgdat-\u003enr_writeback_throttled, 0);\n--\nmm/vmscan.c-7566-\nmm/vmscan.c:7567:\t\talloc_order = reclaim_order = READ_ONCE(pgdat-\u003ekswapd_order);\nmm/vmscan.c:7568:\t\thighest_zoneidx = kswapd_highest_zoneidx(pgdat,\nmm/vmscan.c-7569-\t\t\t\t\t\t\thighest_zoneidx);\nmm/vmscan.c-7570-\nmm/vmscan.c:7571:kswapd_try_sleep:\nmm/vmscan.c:7572:\t\tkswapd_try_to_sleep(pgdat, alloc_order, reclaim_order,\nmm/vmscan.c-7573-\t\t\t\t\thighest_zoneidx);\n--\nmm/vmscan.c-7575-\t\t/* Read the new order and highest_zoneidx */\nmm/vmscan.c:7576:\t\talloc_order = READ_ONCE(pgdat-\u003ekswapd_order);\nmm/vmscan.c:7577:\t\thighest_zoneidx = kswapd_highest_zoneidx(pgdat,\nmm/vmscan.c-7578-\t\t\t\t\t\t\thighest_zoneidx);\nmm/vmscan.c:7579:\t\tWRITE_ONCE(pgdat-\u003ekswapd_order, 0);\nmm/vmscan.c:7580:\t\tWRITE_ONCE(pgdat-\u003ekswapd_highest_zoneidx, MAX_NR_ZONES);\nmm/vmscan.c-7581-\n--\nmm/vmscan.c-7593-\t\t * Reclaim begins at the requested order but if a high-order\nmm/vmscan.c:7594:\t\t * reclaim fails then kswapd falls back to reclaiming for\nmm/vmscan.c:7595:\t\t * order-0. If that happens, kswapd will consider sleeping\nmm/vmscan.c-7596-\t\t * for the order it finished reclaiming at (reclaim_order)\n--\nmm/vmscan.c-7599-\t\t */\nmm/vmscan.c:7600:\t\ttrace_mm_vmscan_kswapd_wake(pgdat-\u003enode_id, highest_zoneidx,\nmm/vmscan.c-7601-\t\t\t\t\t\talloc_order);\n--\nmm/vmscan.c-7604-\t\tif (reclaim_order \u003c alloc_order)\nmm/vmscan.c:7605:\t\t\tgoto kswapd_try_sleep;\nmm/vmscan.c-7606-\t}\n--\nmm/vmscan.c-7614- * A zone is low on free memory or too fragmented for high-order memory.  If\nmm/vmscan.c:7615: * kswapd should reclaim (direct reclaim is deferred), wake it up for the zone's\nmm/vmscan.c:7616: * pgdat.  It will wake up kcompactd after reclaiming memory.  If kswapd reclaim\nmm/vmscan.c-7617- * has failed or is not needed, still wake up kcompactd if only compaction is\n--\nmm/vmscan.c-7619- */\nmm/vmscan.c:7620:void wakeup_kswapd(struct zone *zone, gfp_t gfp_flags, int order,\nmm/vmscan.c-7621-\t\t   enum zone_type highest_zoneidx)\n--\nmm/vmscan.c-7632-\tpgdat = zone-\u003ezone_pgdat;\nmm/vmscan.c:7633:\tcurr_idx = READ_ONCE(pgdat-\u003ekswapd_highest_zoneidx);\nmm/vmscan.c-7634-\nmm/vmscan.c-7635-\tif (curr_idx == MAX_NR_ZONES || curr_idx \u003c highest_zoneidx)\nmm/vmscan.c:7636:\t\tWRITE_ONCE(pgdat-\u003ekswapd_highest_zoneidx, highest_zoneidx);\nmm/vmscan.c-7637-\nmm/vmscan.c:7638:\tif (READ_ONCE(pgdat-\u003ekswapd_order) \u003c order)\nmm/vmscan.c:7639:\t\tWRITE_ONCE(pgdat-\u003ekswapd_order, order);\nmm/vmscan.c-7640-\nmm/vmscan.c:7641:\tif (!waitqueue_active(\u0026pgdat-\u003ekswapd_wait))\nmm/vmscan.c-7642-\t\treturn;\n--\nmm/vmscan.c-7644-\t/* Hopeless node, leave it to direct reclaim if possible */\nmm/vmscan.c:7645:\tif (kswapd_test_hopeless(pgdat) ||\nmm/vmscan.c-7646-\t    (pgdat_balanced(pgdat, order, highest_zoneidx) \u0026\u0026\n--\nmm/vmscan.c-7659-\nmm/vmscan.c:7660:\ttrace_mm_vmscan_wakeup_kswapd(pgdat-\u003enode_id, highest_zoneidx, order,\nmm/vmscan.c-7661-\t\t\t\t      gfp_flags);\nmm/vmscan.c:7662:\twake_up_interruptible(\u0026pgdat-\u003ekswapd_wait);\nmm/vmscan.c-7663-}\nmm/vmscan.c-7664-\nmm/vmscan.c:7665:void kswapd_clear_hopeless(pg_data_t *pgdat, enum kswapd_clear_hopeless_reason reason)\nmm/vmscan.c-7666-{\nmm/vmscan.c-7667-\t/* Only trace actual resets, not redundant zero-to-zero */\nmm/vmscan.c:7668:\tif (atomic_xchg(\u0026pgdat-\u003ekswapd_failures, 0))\nmm/vmscan.c:7669:\t\ttrace_mm_vmscan_kswapd_clear_hopeless(pgdat-\u003enode_id, reason);\nmm/vmscan.c-7670-}\n--\nmm/vmscan.c-7672-/*\nmm/vmscan.c:7673: * Reset kswapd_failures only when the node is balanced. Without this\nmm/vmscan.c-7674- * check, successful direct reclaim (e.g., from cgroup memory.high\nmm/vmscan.c:7675: * throttling) can keep resetting kswapd_failures even when the node\nmm/vmscan.c:7676: * cannot be balanced, causing kswapd to run endlessly.\nmm/vmscan.c-7677- */\nmm/vmscan.c:7678:void kswapd_try_clear_hopeless(struct pglist_data *pgdat,\nmm/vmscan.c-7679-\t\t\t       unsigned int order, int highest_zoneidx)\n--\nmm/vmscan.c-7681-\tif (pgdat_balanced(pgdat, order, highest_zoneidx))\nmm/vmscan.c:7682:\t\tkswapd_clear_hopeless(pgdat, current_is_kswapd() ?\nmm/vmscan.c-7683-\t\t\tKSWAPD_CLEAR_HOPELESS_KSWAPD : KSWAPD_CLEAR_HOPELESS_DIRECT);\n--\nmm/vmscan.c-7685-\nmm/vmscan.c:7686:bool kswapd_test_hopeless(pg_data_t *pgdat)\nmm/vmscan.c-7687-{\nmm/vmscan.c:7688:\treturn atomic_read(\u0026pgdat-\u003ekswapd_failures) \u003e= MAX_RECLAIM_RETRIES;\nmm/vmscan.c-7689-}\n--\nmm/vmscan.c=7700=unsigned long shrink_all_memory(unsigned long nr_to_reclaim)\n--\nmm/vmscan.c-7730-/*\nmm/vmscan.c:7731: * This kswapd start function will be called by init and node-hot-add.\nmm/vmscan.c-7732- */\nmm/vmscan.c:7733:void __meminit kswapd_run(int nid)\nmm/vmscan.c-7734-{\n--\nmm/vmscan.c-7736-\nmm/vmscan.c:7737:\tpgdat_kswapd_lock(pgdat);\nmm/vmscan.c:7738:\tif (!pgdat-\u003ekswapd) {\nmm/vmscan.c:7739:\t\tpgdat-\u003ekswapd = kthread_create_on_node(kswapd, pgdat, nid, \"kswapd%d\", nid);\nmm/vmscan.c:7740:\t\tif (IS_ERR(pgdat-\u003ekswapd)) {\nmm/vmscan.c-7741-\t\t\t/* failure at boot is fatal */\nmm/vmscan.c:7742:\t\t\tpr_err(\"Failed to start kswapd on node %d, ret=%pe\\n\",\nmm/vmscan.c:7743:\t\t\t\t   nid, pgdat-\u003ekswapd);\nmm/vmscan.c-7744-\t\t\tBUG_ON(system_state \u003c SYSTEM_RUNNING);\nmm/vmscan.c:7745:\t\t\tpgdat-\u003ekswapd = NULL;\nmm/vmscan.c-7746-\t\t} else {\nmm/vmscan.c:7747:\t\t\twake_up_process(pgdat-\u003ekswapd);\nmm/vmscan.c-7748-\t\t}\nmm/vmscan.c-7749-\t}\nmm/vmscan.c:7750:\tpgdat_kswapd_unlock(pgdat);\nmm/vmscan.c-7751-}\n--\nmm/vmscan.c-7756- */\nmm/vmscan.c:7757:void __meminit kswapd_stop(int nid)\nmm/vmscan.c-7758-{\nmm/vmscan.c-7759-\tpg_data_t *pgdat = NODE_DATA(nid);\n\n"
}

gemini-3.1-pro-preview

null

null

							input: 23155
							output: 29
							thoughts: 406
						

**Analyzing Memory Reclaim Paths for Fuzzing**

Okay, so I'm thinking about how to trigger interesting memory reclaim paths using syzkaller. I know `kswapd` is a thread function, so I can't call it directly. But `wakeup_kswapd` is callable, which is a good starting point to control the `kswapd` thread.

Now, the main functions I should focus on are `try_to_free_pages`, `try_to_free_mem_cgroup_pages`, and `node_reclaim`, so I should inspect those functions in `mm/vmscan.c` more closely. Wait, `try_to_free_pages` is actually called by `__alloc_pages_slowpath` in `mm/page_alloc.c`... That's a key detail! `try_to_free_mem_cgroup_pages` is likely called by functions related to memcg limits. I think `memory_high_write` or similar in `mm/memcontrol.c` are probably involved. `node_reclaim` is also critical, and it's called by `get_page_from_freelist` in `mm/page_alloc.c`.

So the most effective fuzzing strategy is clear: I need to target memory allocation and memcg limits to hit these reclaim paths. The patch I'm examining modifies `throttle_isolated`, and that's called when too many pages are being isolated, and this situation happens when multiple threads are concurrently reclaiming memory. Thus, fuzzing with many threads allocating memory or hitting memcg limits is the way to go here.

My focus should be on these key symbols: `try_to_free_pages`, `try_to_free_mem_cgroup_pages`, `node_reclaim`, and `shrink_all_memory`. It's worth double-checking that `try_to_free_pages` is exported or reachable. It's called by `__alloc_pages_slowpath`, which is right at the core of page allocation. `try_to_free_mem_cgroup_pages` is definitely tied to memcg reclaim. Time to go back to `mm/vmscan.c` and take another look at `throttle_isolated`.

{
  "Expression": "throttle_isolated",
  "PathPrefix": "mm/vmscan.c"
}

{
  "Output": "mm/vmscan.c=1822=static bool too_many_isolated(struct pglist_data *pgdat, bool file,\n--\nmm/vmscan.c-1853-\tif (!too_many)\nmm/vmscan.c:1854:\t\twake_throttle_isolated(pgdat);\nmm/vmscan.c-1855-\n--\nmm/vmscan.c-1865- */\nmm/vmscan.c:1866:static bool throttle_isolated(struct pglist_data *pgdat, bool file,\nmm/vmscan.c-1867-\t\t\t      struct scan_control *sc, bool *fatal)\n--\nmm/vmscan.c=2014=static unsigned long shrink_inactive_list(unsigned long nr_to_scan,\n--\nmm/vmscan.c-2027-\nmm/vmscan.c:2028:\tif (!throttle_isolated(pgdat, file, sc, \u0026fatal)) {\nmm/vmscan.c-2029-\t\t/* We are about to die and free our memory. Return now. */\n--\nmm/vmscan.c=4896=static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,\n--\nmm/vmscan.c-4919-\ttype = get_type_to_scan(lruvec, swappiness);\nmm/vmscan.c:4920:\tif (!throttle_isolated(pgdat, type, sc, \u0026fatal)) {\nmm/vmscan.c-4921-\t\t/*\n"
}

gemini-3.1-pro-preview

null

null

							input: 24482
							output: 23
							thoughts: 441
						

**My Analysis of the Patch**

Okay, so `wake_throttle_isolated` is showing up in the output. That means this patch isn't *introducing* it; it's either pre-existing or being added in a different part of the series. Good, that clarifies things.

Let's focus on the actual changes here. The core of this patch seems to be refactoring the throttling logic related to isolated folios. They've moved the logic into a new function, `throttle_isolated`, and crucially, they're now applying it to MGLRU's `evict_folios`. This is a pretty significant functional change because now the MGLRU code path will also throttle when there are too many isolated folios. It also includes fatal signal handling during the throttling process. This is a noticeable impact on how memory reclaim behaves.

This boils down to:

*   Refactoring: Separating out the throttling logic.
*   Functional Change: Applying this throttling to MGLRU, which is significant, plus a change in how fatal signals are handled.

I need to confirm the required configuration options to enable this functionality. I'll need to check the Kconfig files, specifically `init/Kconfig` or `mm/Kconfig`, to verify that `MEMCG`, `LRU_GEN`, and `LRU_GEN_ENABLED` are set correctly.

{
  "Expression": "config MEMCG",
  "PathPrefix": ""
}

{
  "Output": "init/Kconfig=1067=config CGROUP_FAVOR_DYNMODS\n--\ninit/Kconfig-1076-\ninit/Kconfig:1077:config MEMCG\ninit/Kconfig-1078-\tbool \"Memory controller\"\n--\ninit/Kconfig-1085-\ninit/Kconfig:1086:config MEMCG_NMI_UNSAFE\ninit/Kconfig-1087-\tbool\n--\ninit/Kconfig-1092-\ninit/Kconfig:1093:config MEMCG_NMI_SAFETY_REQUIRES_ATOMIC\ninit/Kconfig-1094-\tbool\n--\ninit/Kconfig-1099-\ninit/Kconfig:1100:config MEMCG_V1\ninit/Kconfig-1101-\tbool \"Legacy cgroup v1 memory controller\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 25464
							output: 31
							thoughts: 80
						

**My Initial Assessment of the Memory Management Landscape**

Okay, so I'm looking at memory management configurations, specifically `MEMCG`. My immediate thought is to zero in on a few crucial symbols: `try_to_free_pages`, `try_to_free_mem_cgroup_pages`, `node_reclaim`, `shrink_all_memory`, and `wakeup_kswapd`. These are the key players in this memory game.

Given that I'm working with `shrink_all_memory`, my first move is to determine if its behavior is contingent on any specific configuration settings. It's vital to know if its execution and outcomes are directly impacted by the setup. I need to understand whether this function is universally active or if it's selectively enabled or disabled based on the environment. Understanding this dependency will be key to deciphering its overall role within this configuration.

{
  "Expression": "shrink_all_memory",
  "PathPrefix": "mm/vmscan.c"
}

{
  "Output": "mm/vmscan.c=7686=bool kswapd_test_hopeless(pg_data_t *pgdat)\n--\nmm/vmscan.c-7699- */\nmm/vmscan.c:7700:unsigned long shrink_all_memory(unsigned long nr_to_reclaim)\nmm/vmscan.c-7701-{\n"
}

gemini-3.1-pro-preview

null

null

							input: 25864
							output: 35
							thoughts: 34
						

**Checking Hibernation-Related Code in vmscan.c**

Okay, let's dive in. I need to take a look at `mm/vmscan.c`. Specifically, I'm interested in a certain section, so I'll zero in on the vicinity of line 7700. My immediate thought is to see if this particular piece of code is guarded by a `#ifdef CONFIG_HIBERNATION` preprocessor directive. I'm trying to determine if the logic I'm investigating is conditionally compiled based on the system's hibernation configuration. This is likely related to the problem I'm trying to solve. Understanding the conditional compilation will help pinpoint how the system behaves under different circumstances.

{
  "File": "mm/vmscan.c",
  "FirstLine": 7690,
  "LineCount": 30
}

{
  "Contents": "7690:\t\n7691:\t#ifdef CONFIG_HIBERNATION\n7692:\t/*\n7693:\t * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of\n7694:\t * freed pages.\n7695:\t *\n7696:\t * Rather than trying to age LRUs the aim is to preserve the overall\n7697:\t * LRU order by reclaiming preferentially\n7698:\t * inactive \u003e active \u003e active referenced \u003e active mapped\n7699:\t */\n7700:\tunsigned long shrink_all_memory(unsigned long nr_to_reclaim)\n7701:\t{\n7702:\t\tstruct scan_control sc = {\n7703:\t\t\t.nr_to_reclaim = nr_to_reclaim,\n7704:\t\t\t.gfp_mask = GFP_HIGHUSER_MOVABLE,\n7705:\t\t\t.reclaim_idx = MAX_NR_ZONES - 1,\n7706:\t\t\t.priority = DEF_PRIORITY,\n7707:\t\t\t.may_writepage = 1,\n7708:\t\t\t.may_unmap = 1,\n7709:\t\t\t.may_swap = 1,\n7710:\t\t\t.hibernation_mode = 1,\n7711:\t\t};\n7712:\t\tstruct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);\n7713:\t\tunsigned long nr_reclaimed;\n7714:\t\tunsigned int noreclaim_flag;\n7715:\t\n7716:\t\tfs_reclaim_acquire(sc.gfp_mask);\n7717:\t\tnoreclaim_flag = memalloc_noreclaim_save();\n7718:\t\tset_task_reclaim_state(current, \u0026sc.reclaim_state);\n7719:\t\n"
}

gemini-3.1-pro-preview

null

null

							input: 26574
							output: 30
							thoughts: 118
						

**My Approach to Hibernation Memory Management**

Okay, so I'm looking at how we're handling memory reclaim during hibernation, and it's all tucked away under `CONFIG_HIBERNATION`. That's the key. Now, the question is, how do we best handle the memory shrinking aspect? I see two primary paths forward.

Option one: We could explicitly add `HIBERNATION` to `EnableConfigs`, but I'm leaning toward a simpler approach. I think we can probably just omit the `shrink_all_memory` call altogether. This would mean relying primarily on the built-in mechanisms, namely `try_to_free_pages` and `try_to_free_mem_cgroup_pages`. Those seem to be the typical, most-often-used paths in most systems. That would provide good support for the general cases.

While I'm here, I should make sure that `node_reclaim` is behaving correctly in this context, too. It’s obviously dependent on `CONFIG_NUMA`, so I’ll make sure to double-check that interaction as well. Gotta be thorough.

{
  "Expression": "node_reclaim",
  "PathPrefix": "mm/vmscan.c"
}

{
  "Output": "mm/vmscan.c=6286=static void shrink_node(pg_data_t *pgdat, struct scan_control *sc)\nmm/vmscan.c-6287-{\nmm/vmscan.c:6288:\tunsigned long nr_reclaimed, nr_scanned, nr_node_reclaimed;\nmm/vmscan.c-6289-\tstruct lruvec *target_lruvec;\n--\nmm/vmscan.c-6314-\nmm/vmscan.c:6315:\tnr_node_reclaimed = sc-\u003enr_reclaimed - nr_reclaimed;\nmm/vmscan.c-6316-\n--\nmm/vmscan.c-6319-\t\tvmpressure(sc-\u003egfp_mask, sc-\u003eorder, sc-\u003etarget_mem_cgroup, true,\nmm/vmscan.c:6320:\t\t\t   sc-\u003enr_scanned - nr_scanned, nr_node_reclaimed);\nmm/vmscan.c-6321-\nmm/vmscan.c:6322:\tif (nr_node_reclaimed)\nmm/vmscan.c-6323-\t\treclaimable = true;\n--\nmm/vmscan.c-6383-\nmm/vmscan.c:6384:\tif (should_continue_reclaim(pgdat, nr_node_reclaimed, sc))\nmm/vmscan.c-6385-\t\tgoto again;\n--\nmm/vmscan.c=7771=static const struct ctl_table vmscan_sysctl_table[] = {\n--\nmm/vmscan.c-7783-\t\t.procname\t= \"zone_reclaim_mode\",\nmm/vmscan.c:7784:\t\t.data\t\t= \u0026node_reclaim_mode,\nmm/vmscan.c:7785:\t\t.maxlen\t\t= sizeof(node_reclaim_mode),\nmm/vmscan.c-7786-\t\t.mode\t\t= 0644,\n--\nmm/vmscan.c=7803=module_init(kswapd_init)\n--\nmm/vmscan.c-7808- *\nmm/vmscan.c:7809: * If non-zero call node_reclaim when the number of free pages falls below\nmm/vmscan.c-7810- * the watermarks.\nmm/vmscan.c-7811- */\nmm/vmscan.c:7812:int node_reclaim_mode __read_mostly;\nmm/vmscan.c-7813-\n--\nmm/vmscan.c-7821-/*\nmm/vmscan.c:7822: * Percentage of pages in a zone that must be unmapped for node_reclaim to\nmm/vmscan.c-7823- * occur.\n--\nmm/vmscan.c=7848=static unsigned long node_pagecache_reclaimable(struct pglist_data *pgdat)\n--\nmm/vmscan.c-7858-\t */\nmm/vmscan.c:7859:\tif (node_reclaim_mode \u0026 RECLAIM_UNMAP)\nmm/vmscan.c-7860-\t\tnr_pagecache_reclaimable = node_page_state(pgdat, NR_FILE_PAGES);\n--\nmm/vmscan.c-7879- */\nmm/vmscan.c:7880:static unsigned long __node_reclaim(struct pglist_data *pgdat,\nmm/vmscan.c-7881-\t\t\t\t    unsigned long nr_pages,\n--\nmm/vmscan.c-7887-\nmm/vmscan.c:7888:\ttrace_mm_vmscan_node_reclaim_begin(pgdat-\u003enode_id, sc-\u003eorder,\nmm/vmscan.c-7889-\t\t\t\t\t   sc-\u003egfp_mask);\n--\nmm/vmscan.c-7917-\nmm/vmscan.c:7918:\ttrace_mm_vmscan_node_reclaim_end(sc-\u003enr_reclaimed, NULL);\nmm/vmscan.c-7919-\n--\nmm/vmscan.c-7922-\nmm/vmscan.c:7923:unsigned long node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order)\nmm/vmscan.c-7924-{\n--\nmm/vmscan.c-7932-\t\t.priority = NODE_RECLAIM_PRIORITY,\nmm/vmscan.c:7933:\t\t.may_writepage = !!(node_reclaim_mode \u0026 RECLAIM_WRITE),\nmm/vmscan.c:7934:\t\t.may_unmap = !!(node_reclaim_mode \u0026 RECLAIM_UNMAP),\nmm/vmscan.c-7935-\t\t.may_swap = 1,\n--\nmm/vmscan.c-7971-\nmm/vmscan.c:7972:\tret = __node_reclaim(pgdat, nr_pages, \u0026sc);\nmm/vmscan.c-7973-\tclear_bit_unlock(PGDAT_RECLAIM_LOCKED, \u0026pgdat-\u003eflags);\n--\nmm/vmscan.c-7984-\nmm/vmscan.c:7985:static unsigned long __node_reclaim(struct pglist_data *pgdat,\nmm/vmscan.c-7986-\t\t\t\t    unsigned long nr_pages,\n--\nmm/vmscan.c=8005=int user_proactive_reclaim(char *buf,\n--\nmm/vmscan.c-8097-\nmm/vmscan.c:8098:\t\t\treclaimed = __node_reclaim(pgdat, batch_size, \u0026sc);\nmm/vmscan.c-8099-\t\t\tclear_bit_unlock(PGDAT_RECLAIM_LOCKED, \u0026pgdat-\u003eflags);\n"
}

gemini-3.1-pro-preview

null

null

							input: 28463
							output: 29
							thoughts: 119
						

**My Current Focus: NUMA and Memory Management**

Okay, so `node_reclaim` relies on `CONFIG_NUMA`, which makes perfect sense in the context of Non-Uniform Memory Access. I need to make sure `NUMA` is properly enabled. Therefore, I need to add `NUMA` to my `EnableConfigs` list. That list is growing, it's now:

*   `LRU_GEN`
*   `LRU_GEN_ENABLED`
*   `MEMCG`
*   `NUMA`

Now, I need to really dig into what's happening. The key symbols I'm focusing on are: `try_to_free_pages`, `try_to_free_mem_cgroup_pages`, `node_reclaim`, and `wakeup_kswapd`. My goal is to understand how these pieces fit together, especially concerning NUMA architectures. I'm especially keen to check and confirm if `wakeup_kswapd` is exported, as that's a key function in the process.

no matches

{
  "Expression": "EXPORT_SYMBOL.*wakeup_kswapd",
  "PathPrefix": ""
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 28853
							output: 31
							thoughts: 41
						

Okay, here's my take on those thoughts, tailored for an expert audience:

**Analyzing Memory Management: Unraveling the 'Not-Static, But Not-Exported' Mystery**

Right, so this thing I'm looking at isn't *exported* – that's the first clue. But it's also *not* static, which immediately piques my interest. It has to be called from *somewhere* within the kernel, and the hint points directly to `mm/page_alloc.c`. My immediate thought is, "Okay, let's trace this back to the caller."

The fact that it's called from within page_alloc is interesting, this is a core component. The next logical step is to dive into the call graph and follow the path this code is following. The key now is understanding how this internal, non-static function integrates with the page allocation/deallocation process. Let's start by digging into `try_to_free_pages`. That's where the rubber meets the road, so to speak. Understanding this module is key to understanding the kernel.

no matches

{
  "Expression": "EXPORT_SYMBOL.*try_to_free_pages",
  "PathPrefix": ""
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 29174
							output: 36
							thoughts: 35
						

Okay, here's my interpretation of those thoughts, presented as a first-person summary, keeping in mind my expertise:

**Checking a Memory Allocation Function's Dependencies**

Alright, I'm digging into something here. Looks like there's some code that isn't being directly exported, meaning it's only being called internally within the kernel. It's called from `mm/page_alloc.c`, so it's clearly related to memory management and page allocation. I need to understand the relationship between this code and other parts of the system.

The function I need to look at is `try_to_free_mem_cgroup_pages`. I'll need to figure out what it's trying to accomplish, and the implications of it. Perhaps it's part of a mechanism for reclaiming memory within a memory cgroup, or maybe it's handling some edge case related to freeing pages. I need to understand its role within the larger memory management strategy to determine if it has any relevance to the problem I'm trying to solve. I'll need to trace its call sites to find out precisely where and when it gets invoked.

no matches

{
  "Expression": "EXPORT_SYMBOL.*try_to_free_mem_cgroup_pages",
  "PathPrefix": ""
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 29501
							output: 192
							thoughts: 716
						

**My Assessment of the Memory Reclaim Patch**

Okay, so I've taken a look at this patch, and my initial thought is that it's addressing a critical area within the memory management subsystem. The fact that it's touching `mm/vmscan.c` immediately signals that we're dealing with the core of how the kernel handles memory pressure and reclamation.

Specifically, it seems the patch introduces a mechanism to throttle reclaimers when a substantial number of folios are in an isolated state. This is especially relevant to Multi-Gen LRU (MGLRU), as the code now *correctly* accounts for these isolated pages. The introduction of `throttle_isolated` and its integration into both `shrink_inactive_list` (for the legacy LRU) and `evict_folios` (for MGLRU) implies a fundamental improvement in how the kernel responds to situations where concurrent reclaim is causing problems, potentially preventing Out-of-Memory (OOM) conditions and thrashing. I am also thinking that `__mod_node_page_state` and `mod_node_page_state` are important, here.

This is a functional change. It seems like the patch's purpose is to manage memory reclaim in a more efficient manner, particularly when faced with a high number of concurrent threads vying for memory. I believe this will make our systems more robust. It's likely trying to avoid a scenario where the LRU list becomes too small, resulting in the system swapping unnecessarily and further exacerbating the memory pressure.

Considering the potential impact on memory management, especially in NUMA or MEMCG environments, I'm confident that this is something that needs a thorough fuzzing campaign to ensure stability and catch any subtle regressions. This change will likely interact with: `try_to_free_pages`, `try_to_free_mem_cgroup_pages`, `node_reclaim`, and `wakeup_kswapd`.

So, yeah, let's call `set-results`.

{
  "EnableConfigs": [
    "LRU_GEN",
    "LRU_GEN_ENABLED",
    "MEMCG",
    "NUMA"
  ],
  "FocusSymbols": [
    "try_to_free_pages",
    "try_to_free_mem_cgroup_pages",
    "node_reclaim",
    "wakeup_kswapd"
  ],
  "Reasoning": "The patch modifies memory reclaim logic in `mm/vmscan.c`. It introduces `throttle_isolated()` to throttle reclaimers when too many folios are isolated, and applies this logic to both the legacy LRU (`shrink_inactive_list`) and the Multi-Gen LRU (`evict_folios`). It also adds accounting for isolated folios in MGLRU. This is a core memory management change that affects how the kernel handles memory pressure and concurrent page reclaim.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "LRU_GEN",
    "LRU_GEN_ENABLED",
    "MEMCG",
    "NUMA"
  ],
  "FocusSymbols": [
    "try_to_free_pages",
    "try_to_free_mem_cgroup_pages",
    "node_reclaim",
    "wakeup_kswapd"
  ],
  "Reasoning": "The patch modifies memory reclaim logic in `mm/vmscan.c`. It introduces `throttle_isolated()` to throttle reclaimers when too many folios are isolated, and applies this logic to both the legacy LRU (`shrink_inactive_list`) and the Multi-Gen LRU (`evict_folios`). It also adds accounting for isolated folios in MGLRU. This is a core memory management change that affects how the kernel handles memory pressure and concurrent page reclaim.",
  "WorthFuzzing": true
}

{
  "WorthFuzzing": true
}

null

best-expensive

null

{
  "KMSANReasoning": "The patch refactors the page reclaim throttling logic in `mm/vmscan.c` by introducing a new helper function `throttle_isolated`. It uses a local boolean variable `fatal` passed by reference to track if a fatal signal is pending. The variable `fatal` is unconditionally initialized at the beginning of `throttle_isolated` before any reads occur. The patch does not introduce any new data structures sent to user space, nor does it leave any fields uninitialized. Any potential bugs introduced by these changes (such as logic errors, use-after-free, or deadlocks) would be caught by standard KASAN, LOCKDEP, or other default sanitizers. There is no risk of uninitialized memory reads or info-leaks that would necessitate a dedicated KMSAN fuzzing session.",
  "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 5632d8ec239dfabbdcffffd55849db0352299a58
Author: syz-cluster <triage@syzkaller.com>
Date:   Mon Aug 17 07:51:39 2026 +0000

    syz-cluster: applied patch under review

diff --git a/mm/vmscan.c b/mm/vmscan.c
index c1404a59523d6..886a53f563ab7 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1819,7 +1819,7 @@ bool folio_isolate_lru(struct folio *folio)
  * the LRU list will go small and be scanned faster than necessary, leading to
  * unnecessary swapping, thrashing and OOM.
  */
-static bool too_many_isolated(struct pglist_data *pgdat, int file,
+static bool too_many_isolated(struct pglist_data *pgdat, bool file,
 		struct scan_control *sc)
 {
 	unsigned long inactive, isolated;
@@ -1856,6 +1856,37 @@ static bool too_many_isolated(struct pglist_data *pgdat, int file,
 	return too_many;
 }
 
+/*
+ * Throttle reclaim if too many isolated folios are piling up. If this makes
+ * no progress, the caller is probably looping on unevictable folios, so give
+ * up. Returns false to tell the caller to stop reclaiming, and sets @fatal
+ * if the task received a fatal signal while waiting, so that the caller can
+ * bail out faster.
+ */
+static bool throttle_isolated(struct pglist_data *pgdat, bool file,
+			      struct scan_control *sc, bool *fatal)
+{
+	bool stalled = false;
+
+	*fatal = false;
+	while (unlikely(too_many_isolated(pgdat, file, sc))) {
+		if (stalled)
+			return false;
+
+		/* wait a bit for the reclaimer. */
+		stalled = true;
+		reclaim_throttle(pgdat, VMSCAN_THROTTLE_ISOLATED);
+
+		/* We are about to die and free our memory. Return now. */
+		if (fatal_signal_pending(current)) {
+			*fatal = true;
+			return false;
+		}
+	}
+
+	return true;
+}
+
 /*
  * move_folios_to_lru() moves folios from private @list to appropriate LRU list.
  *
@@ -1992,19 +2023,14 @@ static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
 	bool file = is_file_lru(lru);
 	enum node_stat_item item;
 	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
-	bool stalled = false;
-
-	while (unlikely(too_many_isolated(pgdat, file, sc))) {
-		if (stalled)
-			return 0;
-
-		/* wait a bit for the reclaimer. */
-		stalled = true;
-		reclaim_throttle(pgdat, VMSCAN_THROTTLE_ISOLATED);
+	bool fatal;
 
+	if (!throttle_isolated(pgdat, file, sc, &fatal)) {
 		/* We are about to die and free our memory. Return now. */
-		if (fatal_signal_pending(current))
+		if (fatal)
 			return SWAP_CLUSTER_MAX;
+
+		return 0;
 	}
 
 	lru_add_drain();
@@ -4883,6 +4909,25 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
 	bool skip_retry = false;
 	struct mem_cgroup *memcg = lruvec_memcg(lruvec);
 	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
+	bool fatal;
+
+	/*
+	 * The type to isolate is unknown until isolation, so predict it for
+	 * the throttling check. isolate_folios() may still fall back to the
+	 * other type, which is fine for this heuristic.
+	 */
+	type = get_type_to_scan(lruvec, swappiness);
+	if (!throttle_isolated(pgdat, type, sc, &fatal)) {
+		/*
+		 * We are about to die and free our memory. Like the legacy
+		 * path, pretend some pages were reclaimed so reclaim unwinds
+		 * quickly instead of looping back into the throttle.
+		 */
+		if (fatal)
+			sc->nr_reclaimed += SWAP_CLUSTER_MAX;
+
+		return 0;
+	}
 
 	lruvec_lock_irq(lruvec);
 
@@ -4892,6 +4937,9 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
 	scanned = isolate_folios(nr_to_scan, lruvec, sc, swappiness,
 				 &list, &isolated, &type, &type_scanned);
 	nr_isolated = isolated;
+	if (nr_isolated)
+		__mod_node_page_state(pgdat, NR_ISOLATED_ANON + type,
+				      nr_isolated);
 
 	/* Scanning may have emptied the oldest gen, flush it */
 	if (scanned)
@@ -4954,6 +5002,10 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
 		goto retry;
 	}
 
+	if (nr_isolated)
+		mod_node_page_state(pgdat, NR_ISOLATED_ANON + type,
+				    -nr_isolated);
+
 	if (nr_isolated > total_reclaimed)
 		mod_lruvec_state(lruvec, PGROTATE_ANON + type,
 				 nr_isolated - total_reclaimed);

gemini-3.1-pro-preview

null

null

							input: 3256
							output: 187
							thoughts: 960
						

**Analyzing the Patch for Uninitialized Memory Risks**

Okay, so this patch in `mm/vmscan.c` looks like it's refactoring the isolated page throttling logic. My main concern is always uninitialized memory, which can lead to nasty bugs. Let's break down the `fatal` variable. They've moved the `too_many_isolated` check into a new `throttle_isolated` function and now they're passing a `bool fatal` by reference. I need to make *absolutely* sure `fatal` is always initialized before it's read.

Looking at `throttle_isolated`, the very first thing it does is set `*fatal = false`. Good, that's reassuring. It seems like it's always initialized, whether or not the function returns `true` or `false`. Then, in both `shrink_inactive_list` and `evict_folios`, `fatal` is only read if `throttle_isolated` returns `false`, which is where the return happens immediately after the `fatal` variable is set.

Okay, so I think `fatal` is fine, but I should look deeper just in case. Now that I think about it, the patch focuses on page reclaim and throttling, not on data copying or complex structs. The `fatal` variable is local and explicitly initialized. I'm reasonably confident that this is *not* a KMSAN situation. KASAN and standard bug detectors should be sufficient to catch any subtle issues like use-after-free, out-of-bounds, or concurrency problems.

Just to be absolutely certain, I'll quickly check the `evict_folios` changes. They are updating statistics for isolated pages, which should also be fine. No red flags there either. All good. No KMSAN needed here.

{
  "KMSANReasoning": "The patch refactors the page reclaim throttling logic in `mm/vmscan.c` by introducing a new helper function `throttle_isolated`. It uses a local boolean variable `fatal` passed by reference to track if a fatal signal is pending. The variable `fatal` is unconditionally initialized at the beginning of `throttle_isolated` before any reads occur. The patch does not introduce any new data structures sent to user space, nor does it leave any fields uninitialized. Any potential bugs introduced by these changes (such as logic errors, use-after-free, or deadlocks) would be caught by standard KASAN, LOCKDEP, or other default sanitizers. There is no risk of uninitialized memory reads or info-leaks that would necessitate a dedicated KMSAN fuzzing session.",
  "NeedsKMSAN": false
}

{
  "KMSANReasoning": "The patch refactors the page reclaim throttling logic in `mm/vmscan.c` by introducing a new helper function `throttle_isolated`. It uses a local boolean variable `fatal` passed by reference to track if a fatal signal is pending. The variable `fatal` is unconditionally initialized at the beginning of `throttle_isolated` before any reads occur. The patch does not introduce any new data structures sent to user space, nor does it leave any fields uninitialized. Any potential bugs introduced by these changes (such as logic errors, use-after-free, or deadlocks) would be caught by standard KASAN, LOCKDEP, or other default sanitizers. There is no risk of uninitialized memory reads or info-leaks that would necessitate a dedicated KMSAN fuzzing session.",
  "NeedsKMSAN": false
}