| Seq | Timestamp | Type | Name | Duration |
|---|---|---|---|---|
| 0/0 | 2026/08/25 14:29 | flow | patch-triage |
30mArgs:null Results: {
"EnableConfigs": [
"ZSWAP",
"ZSWAP_DEFAULT_ON",
"ZSWAP_SHRINKER_DEFAULT_ON",
"SWAP",
"MEMCG",
"CGROUPS"
],
"FocusSymbols": [
"swap_writeback_dropbehind_folio",
"remove_mapping_reclaim",
"__swap_cache_alloc_folio"
],
"KMSANReasoning": "The patch modifies the lifecycle of folios in the swap cache, specifically introducing a \"dropbehind\" mechanism for zswap writeback. It changes how folios are allocated for the swap cache (returning them off-LRU) and manages their references during writeback.\n\nThese changes primarily involve page reference counting, LRU list management, and swap cache operations. The potential bugs introduced by these changes would be use-after-free, memory leaks (e.g., folios left off the LRU), or invalid page states. Such issues are effectively detected by KASAN, standard kernel memory debug options (like `CONFIG_DEBUG_VM`), and page reference tracking.\n\nThe patch does not introduce new data structures copied to user space, nor does it add complex parsing logic or conditional branching based on potentially uninitialized memory. The folios allocated are populated via decompression before being written to swap, and no uninitialized kernel memory is exposed. Thus, a dedicated KMSAN fuzzing session is not justified.",
"NeedsKMSAN": false,
"Reasoning": "The patch introduces a mechanism to drop swap cache folios after zswap writeback completes, avoiding unnecessary LRU pollution. It adds new functions `swap_writeback_dropbehind_folio` and `remove_mapping_reclaim`, and modifies `zswap_writeback_entry` to use this mechanism. This is a functional change in the core memory management subsystem (swap, zswap, page cache) that affects memory reclaim and swap behavior, which is reachable and worth fuzzing.",
"WorthFuzzing": true
} |
| 1/1 | 2026/08/25 14:29 | action | read-patch-diff |
0mArgs:null Results: {
"PatchDiff": "commit ae086299864049ed77698eafec0ec37660def15f\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Tue Aug 25 14:29:09 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/include/linux/swap.h b/include/linux/swap.h\nindex 8f0f68e245baa..29ec60dcae213 100644\n--- a/include/linux/swap.h\n+++ b/include/linux/swap.h\n@@ -374,6 +374,8 @@ extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,\n extern unsigned long shrink_all_memory(unsigned long nr_pages);\n extern int vm_swappiness;\n long remove_mapping(struct address_space *mapping, struct folio *folio);\n+long remove_mapping_reclaim(struct address_space *mapping, struct folio *folio,\n+\t\t\t struct mem_cgroup *target_memcg);\n \n #if defined(CONFIG_SYSFS) \u0026\u0026 defined(CONFIG_NUMA)\n extern int reclaim_register_node(struct node *node);\n@@ -465,6 +467,8 @@ void swap_put_entries_direct(swp_entry_t entry, int nr);\n */\n bool folio_free_swap(struct folio *folio);\n \n+void swap_writeback_dropbehind_folio(struct folio *folio);\n+\n /* Allocate / free (hibernation) exclusive entries */\n swp_entry_t swap_alloc_hibernation_slot(int type);\n void swap_free_hibernation_slot(swp_entry_t entry);\n@@ -475,6 +479,7 @@ static inline void put_swap_device(struct swap_info_struct *si)\n }\n \n #else /* CONFIG_SWAP */\n+static inline void swap_writeback_dropbehind_folio(struct folio *folio) {}\n static inline struct swap_info_struct *get_swap_device(swp_entry_t entry)\n {\n \treturn NULL;\ndiff --git a/mm/filemap.c b/mm/filemap.c\nindex d721986d5f465..040c97a121ded 100644\n--- a/mm/filemap.c\n+++ b/mm/filemap.c\n@@ -1686,6 +1686,8 @@ EXPORT_SYMBOL_GPL(folio_end_writeback_no_dropbehind);\n */\n void folio_end_writeback(struct folio *folio)\n {\n+\tbool swap_dropbehind;\n+\n \tVM_BUG_ON_FOLIO(!folio_test_writeback(folio), folio);\n \n \t/*\n@@ -1695,7 +1697,24 @@ void folio_end_writeback(struct folio *folio)\n \t * reused before the folio_wake_bit().\n \t */\n \tfolio_get(folio);\n+\n+\t/*\n+\t * Sample this before folio_end_writeback_no_dropbehind() clears\n+\t * PG_writeback: until then a racing swapin cannot remove the folio from\n+\t * the swap cache. Afterwards it can, and the drop below then finds a\n+\t * non-swapcache folio and puts it back on the LRU instead. The\n+\t * reference taken above keeps the folio alive across that window.\n+\t */\n+\tswap_dropbehind = folio_test_swapcache(folio) \u0026\u0026\n+\t\t\t folio_test_dropbehind(folio);\n+\n \tfolio_end_writeback_no_dropbehind(folio);\n+\n+\tif (swap_dropbehind) {\n+\t\tswap_writeback_dropbehind_folio(folio);\n+\t\treturn;\n+\t}\n+\n \tfolio_end_dropbehind(folio);\n \tfolio_put(folio);\n }\ndiff --git a/mm/page_io.c b/mm/page_io.c\nindex b23f494fcc83d..586c79c3bb3d2 100644\n--- a/mm/page_io.c\n+++ b/mm/page_io.c\n@@ -456,6 +456,13 @@ static void swap_writepage_bdev_async(struct folio *folio,\n \tbio-\u003ebi_end_io = end_swap_bio_write;\n \tbio_add_folio_nofail(bio, folio, folio_size(folio), 0);\n \n+\t/*\n+\t * Dropping the folio from the swap cache takes sleeping locks, so the\n+\t * completion must not run in interrupt context.\n+\t */\n+\tif (folio_test_dropbehind(folio))\n+\t\tbio_set_flag(bio, BIO_COMPLETE_IN_TASK);\n+\n \tbio_associate_blkg_from_page(bio, folio);\n \tcount_swpout_vm_event(folio);\n \tfolio_start_writeback(folio);\ndiff --git a/mm/swap.h b/mm/swap.h\nindex 77d2d14eda421..fc44daae1de1f 100644\n--- a/mm/swap.h\n+++ b/mm/swap.h\n@@ -304,9 +304,9 @@ bool swap_cache_has_folio(swp_entry_t entry);\n struct folio *swap_cache_get_folio(swp_entry_t entry);\n void *swap_cache_get_shadow(swp_entry_t entry);\n void swap_cache_del_folio(struct folio *folio);\n-struct folio *swap_cache_alloc_folio(swp_entry_t target_entry, gfp_t gfp_mask,\n-\t\t\t\t unsigned long orders, struct vm_fault *vmf,\n-\t\t\t\t struct mempolicy *mpol, pgoff_t ilx);\n+struct folio *__swap_cache_alloc_folio(swp_entry_t target_entry, gfp_t gfp_mask,\n+\t\t\t\t unsigned long orders, struct vm_fault *vmf,\n+\t\t\t\t struct mempolicy *mpol, pgoff_t ilx);\n /* Below helpers require the caller to lock and pass in the swap cluster. */\n void __swap_cache_add_folio(struct swap_cluster_info *ci,\n \t\t\t struct folio *folio, swp_entry_t entry);\ndiff --git a/mm/swap_state.c b/mm/swap_state.c\nindex 727a17ee78211..231fa87cbbe0c 100644\n--- a/mm/swap_state.c\n+++ b/mm/swap_state.c\n@@ -483,13 +483,11 @@ static struct folio *__swap_cache_alloc(struct swap_cluster_info *ci,\n \tnode_stat_mod_folio(folio, NR_FILE_PAGES, nr_pages);\n \tlruvec_stat_mod_folio(folio, NR_SWAPCACHE, nr_pages);\n \n-\t/* Caller will initiate read into locked new_folio */\n-\tfolio_add_lru(folio);\n \treturn folio;\n }\n \n /**\n- * swap_cache_alloc_folio - Allocate folio for swapped out slot in swap cache.\n+ * __swap_cache_alloc_folio - Allocate folio for swapped out slot in swap cache.\n * @targ_entry: swap entry indicating the target slot\n * @gfp: memory allocation flags\n * @orders: allocation orders, must be non zero\n@@ -501,13 +499,17 @@ static struct folio *__swap_cache_alloc(struct swap_cluster_info *ci,\n * doing IO (e.g. swap in or zswap writeback). The swap slot indicated by\n * @targ_entry must have a non-zero swap count (swapped out).\n *\n+ * The returned folio is locked and is NOT on the LRU. The caller must either\n+ * add it to the LRU with folio_add_lru() so page reclaim can find it, or free\n+ * it directly once done; a folio left off the LRU is unreclaimable and leaks.\n+ *\n * Context: Caller must protect the swap device with reference count or locks.\n * Return: Returns the folio if allocation succeeded and folio is in the swap\n * cache. Returns error code if failed due to race, OOM or invalid arguments.\n */\n-struct folio *swap_cache_alloc_folio(swp_entry_t targ_entry, gfp_t gfp,\n-\t\t\t\t unsigned long orders, struct vm_fault *vmf,\n-\t\t\t\t struct mempolicy *mpol, pgoff_t ilx)\n+struct folio *__swap_cache_alloc_folio(swp_entry_t targ_entry, gfp_t gfp,\n+\t\t\t\t unsigned long orders, struct vm_fault *vmf,\n+\t\t\t\t struct mempolicy *mpol, pgoff_t ilx)\n {\n \tint order, err;\n \tstruct folio *ret;\n@@ -535,6 +537,47 @@ struct folio *swap_cache_alloc_folio(swp_entry_t targ_entry, gfp_t gfp,\n \treturn ret;\n }\n \n+/**\n+ * swap_writeback_dropbehind_folio - drop a dropbehind swap cache folio\n+ * @folio: the off-LRU folio whose writeback has completed\n+ *\n+ * Context: task context, with the reference taken by folio_end_writeback()\n+ * donated to us.\n+ */\n+void swap_writeback_dropbehind_folio(struct folio *folio)\n+{\n+\tstruct mem_cgroup *memcg;\n+\n+\tfolio_lock(folio);\n+\n+\t/* The folio was allocated off the LRU and nothing re-adds it here. */\n+\tVM_WARN_ON_ONCE_FOLIO(folio_test_lru(folio), folio);\n+\n+\trcu_read_lock();\n+\tmemcg = folio_memcg(folio);\n+\tif (!mem_cgroup_tryget(memcg))\n+\t\tmemcg = NULL;\n+\trcu_read_unlock();\n+\n+\t/*\n+\t * Gate remove_mapping_reclaim() on folio_test_swapcache(): a racing\n+\t * swapin may have freed the swap slot (folio_free_swap()) and dropped the\n+\t * folio from the cache, and it must not run on a non-swapcache folio (it\n+\t * would trip __remove_mapping()'s mapping == folio_mapping() check).\n+\t */\n+\tif (!folio_test_swapcache(folio) || folio_test_writeback(folio) ||\n+\t !remove_mapping_reclaim(swap_address_space(folio-\u003eswap), folio, memcg)) {\n+\t\t/* Raced: the folio is now owned by the swapin; put it back. */\n+\t\tfolio_clear_dropbehind(folio);\n+\t\tfolio_add_lru(folio);\n+\t}\n+\n+\tmem_cgroup_put(memcg);\n+\n+\tfolio_unlock(folio);\n+\tfolio_put(folio);\n+}\n+\n /*\n * If we are the only user, then try to free up the swap cache.\n *\n@@ -643,12 +686,13 @@ static struct folio *swap_cache_read_folio(swp_entry_t entry, gfp_t gfp,\n \t\tfolio = swap_cache_get_folio(entry);\n \t\tif (folio)\n \t\t\treturn folio;\n-\t\tfolio = swap_cache_alloc_folio(entry, gfp, BIT(0), NULL, mpol, ilx);\n+\t\tfolio = __swap_cache_alloc_folio(entry, gfp, BIT(0), NULL, mpol, ilx);\n \t} while (PTR_ERR(folio) == -EEXIST);\n \n \tif (IS_ERR_OR_NULL(folio))\n \t\treturn NULL;\n \n+\tfolio_add_lru(folio);\n \tswap_read_folio(folio, plug);\n \tif (readahead) {\n \t\tfolio_set_readahead(folio);\n@@ -683,12 +727,13 @@ struct folio *swapin_sync(swp_entry_t entry, gfp_t gfp, unsigned long orders,\n \t\tfolio = swap_cache_get_folio(entry);\n \t\tif (folio)\n \t\t\treturn folio;\n-\t\tfolio = swap_cache_alloc_folio(entry, gfp, orders, vmf, mpol, ilx);\n+\t\tfolio = __swap_cache_alloc_folio(entry, gfp, orders, vmf, mpol, ilx);\n \t} while (PTR_ERR(folio) == -EEXIST);\n \n \tif (IS_ERR(folio))\n \t\treturn folio;\n \n+\tfolio_add_lru(folio);\n \tswap_read_folio(folio, NULL);\n \treturn folio;\n }\ndiff --git a/mm/vmscan.c b/mm/vmscan.c\nindex 848bd3e5eee2b..4cc3a3ed6db6e 100644\n--- a/mm/vmscan.c\n+++ b/mm/vmscan.c\n@@ -780,6 +780,22 @@ static int __remove_mapping(struct address_space *mapping, struct folio *folio,\n \treturn 0;\n }\n \n+static long __remove_mapping_unfreeze(struct address_space *mapping,\n+\t\t\t\t struct folio *folio, bool reclaimed,\n+\t\t\t\t struct mem_cgroup *target_memcg)\n+{\n+\tif (__remove_mapping(mapping, folio, reclaimed, target_memcg)) {\n+\t\t/*\n+\t\t * Unfreezing the refcount with 1 effectively\n+\t\t * drops the pagecache ref for us without requiring another\n+\t\t * atomic operation.\n+\t\t */\n+\t\tfolio_ref_unfreeze(folio, 1);\n+\t\treturn folio_nr_pages(folio);\n+\t}\n+\treturn 0;\n+}\n+\n /**\n * remove_mapping() - Attempt to remove a folio from its mapping.\n * @mapping: The address space.\n@@ -794,16 +810,28 @@ static int __remove_mapping(struct address_space *mapping, struct folio *folio,\n */\n long remove_mapping(struct address_space *mapping, struct folio *folio)\n {\n-\tif (__remove_mapping(mapping, folio, false, NULL)) {\n-\t\t/*\n-\t\t * Unfreezing the refcount with 1 effectively\n-\t\t * drops the pagecache ref for us without requiring another\n-\t\t * atomic operation.\n-\t\t */\n-\t\tfolio_ref_unfreeze(folio, 1);\n-\t\treturn folio_nr_pages(folio);\n-\t}\n-\treturn 0;\n+\treturn __remove_mapping_unfreeze(mapping, folio, false, NULL);\n+}\n+\n+/**\n+ * remove_mapping_reclaim() - Remove a folio from its mapping, as reclaim does.\n+ * @mapping: The address space.\n+ * @folio: The folio to remove.\n+ * @target_memcg: The memcg to charge the eviction shadow to; the caller must\n+ * keep it alive across the call.\n+ *\n+ * Like remove_mapping(), but stores a workingset eviction shadow the way page\n+ * reclaim does, so that a later refault can be detected and the folio\n+ * re-activated.\n+ * Return: The number of pages removed from the mapping. 0 if the folio\n+ * could not be removed.\n+ * Context: The caller should have a single refcount on the folio and\n+ * hold its lock.\n+ */\n+long remove_mapping_reclaim(struct address_space *mapping, struct folio *folio,\n+\t\t\t struct mem_cgroup *target_memcg)\n+{\n+\treturn __remove_mapping_unfreeze(mapping, folio, true, target_memcg);\n }\n \n /**\ndiff --git a/mm/zswap.c b/mm/zswap.c\nindex 761cd699e0a3e..d16822a516e8d 100644\n--- a/mm/zswap.c\n+++ b/mm/zswap.c\n@@ -1000,8 +1000,8 @@ static int zswap_writeback_entry(struct zswap_entry *entry,\n \t\treturn -EEXIST;\n \n \tmpol = get_task_policy(current);\n-\tfolio = swap_cache_alloc_folio(swpentry, GFP_KERNEL, BIT(0), NULL, mpol,\n-\t\t\t\t NO_INTERLEAVE_INDEX);\n+\tfolio = __swap_cache_alloc_folio(swpentry, GFP_KERNEL, BIT(0), NULL, mpol,\n+\t\t\t\t\t NO_INTERLEAVE_INDEX);\n \tput_swap_device(si);\n \n \t/*\n@@ -1045,12 +1045,26 @@ static int zswap_writeback_entry(struct zswap_entry *entry,\n \t/* folio is up to date */\n \tfolio_mark_uptodate(folio);\n \n-\t/* move it to the tail of the inactive list after end_writeback */\n-\tfolio_set_reclaim(folio);\n+\tfolio_set_dropbehind(folio);\n+\n+\t/*\n+\t * Drop our reference before starting writeback so the swap cache holds\n+\t * the only one: the drop in folio_end_writeback() needs that for\n+\t * remove_mapping_reclaim() to succeed, otherwise the folio is handed\n+\t * back to reclaim instead.\n+\t *\n+\t * Nothing can free the folio in the meantime: we hold the folio lock\n+\t * until writeback starts, PG_writeback then blocks swap cache removal,\n+\t * and folio_end_writeback() takes its own reference before clearing\n+\t * PG_writeback and donates it to the drop.\n+\t */\n+\tfolio_put(folio);\n \n \t/* start writeback */\n \t__swap_writepage(folio, NULL);\n \n+\treturn 0;\n+\n out:\n \tif (ret) {\n \t\tswap_cache_del_folio(folio);\n"
} |
| 2/1 | 2026/08/25 14:29 | agent | patch-evaluator |
25mModel:best-expensive Args: null Results: {
"EnableConfigs": [
"ZSWAP",
"ZSWAP_DEFAULT_ON",
"ZSWAP_SHRINKER_DEFAULT_ON",
"SWAP",
"MEMCG",
"CGROUPS"
],
"FocusSymbols": [
"swap_writeback_dropbehind_folio",
"remove_mapping_reclaim",
"__swap_cache_alloc_folio"
],
"Reasoning": "The patch introduces a mechanism to drop swap cache folios after zswap writeback completes, avoiding unnecessary LRU pollution. It adds new functions `swap_writeback_dropbehind_folio` and `remove_mapping_reclaim`, and modifies `zswap_writeback_entry` to use this mechanism. This is a functional change in the core memory management subsystem (swap, zswap, page cache) that affects memory reclaim and swap behavior, which is reachable and worth fuzzing.",
"WorthFuzzing": true
}Instruction: 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. Prompt: For your convenience, here is the diff of the changes:
commit ae086299864049ed77698eafec0ec37660def15f
Author: syz-cluster <triage@syzkaller.com>
Date: Tue Aug 25 14:29:09 2026 +0000
syz-cluster: applied patch under review
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 8f0f68e245baa..29ec60dcae213 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -374,6 +374,8 @@ extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
extern unsigned long shrink_all_memory(unsigned long nr_pages);
extern int vm_swappiness;
long remove_mapping(struct address_space *mapping, struct folio *folio);
+long remove_mapping_reclaim(struct address_space *mapping, struct folio *folio,
+ struct mem_cgroup *target_memcg);
#if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
extern int reclaim_register_node(struct node *node);
@@ -465,6 +467,8 @@ void swap_put_entries_direct(swp_entry_t entry, int nr);
*/
bool folio_free_swap(struct folio *folio);
+void swap_writeback_dropbehind_folio(struct folio *folio);
+
/* Allocate / free (hibernation) exclusive entries */
swp_entry_t swap_alloc_hibernation_slot(int type);
void swap_free_hibernation_slot(swp_entry_t entry);
@@ -475,6 +479,7 @@ static inline void put_swap_device(struct swap_info_struct *si)
}
#else /* CONFIG_SWAP */
+static inline void swap_writeback_dropbehind_folio(struct folio *folio) {}
static inline struct swap_info_struct *get_swap_device(swp_entry_t entry)
{
return NULL;
diff --git a/mm/filemap.c b/mm/filemap.c
index d721986d5f465..040c97a121ded 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1686,6 +1686,8 @@ EXPORT_SYMBOL_GPL(folio_end_writeback_no_dropbehind);
*/
void folio_end_writeback(struct folio *folio)
{
+ bool swap_dropbehind;
+
VM_BUG_ON_FOLIO(!folio_test_writeback(folio), folio);
/*
@@ -1695,7 +1697,24 @@ void folio_end_writeback(struct folio *folio)
* reused before the folio_wake_bit().
*/
folio_get(folio);
+
+ /*
+ * Sample this before folio_end_writeback_no_dropbehind() clears
+ * PG_writeback: until then a racing swapin cannot remove the folio from
+ * the swap cache. Afterwards it can, and the drop below then finds a
+ * non-swapcache folio and puts it back on the LRU instead. The
+ * reference taken above keeps the folio alive across that window.
+ */
+ swap_dropbehind = folio_test_swapcache(folio) &&
+ folio_test_dropbehind(folio);
+
folio_end_writeback_no_dropbehind(folio);
+
+ if (swap_dropbehind) {
+ swap_writeback_dropbehind_folio(folio);
+ return;
+ }
+
folio_end_dropbehind(folio);
folio_put(folio);
}
diff --git a/mm/page_io.c b/mm/page_io.c
index b23f494fcc83d..586c79c3bb3d2 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -456,6 +456,13 @@ static void swap_writepage_bdev_async(struct folio *folio,
bio->bi_end_io = end_swap_bio_write;
bio_add_folio_nofail(bio, folio, folio_size(folio), 0);
+ /*
+ * Dropping the folio from the swap cache takes sleeping locks, so the
+ * completion must not run in interrupt context.
+ */
+ if (folio_test_dropbehind(folio))
+ bio_set_flag(bio, BIO_COMPLETE_IN_TASK);
+
bio_associate_blkg_from_page(bio, folio);
count_swpout_vm_event(folio);
folio_start_writeback(folio);
diff --git a/mm/swap.h b/mm/swap.h
index 77d2d14eda421..fc44daae1de1f 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -304,9 +304,9 @@ bool swap_cache_has_folio(swp_entry_t entry);
struct folio *swap_cache_get_folio(swp_entry_t entry);
void *swap_cache_get_shadow(swp_entry_t entry);
void swap_cache_del_folio(struct folio *folio);
-struct folio *swap_cache_alloc_folio(swp_entry_t target_entry, gfp_t gfp_mask,
- unsigned long orders, struct vm_fault *vmf,
- struct mempolicy *mpol, pgoff_t ilx);
+struct folio *__swap_cache_alloc_folio(swp_entry_t target_entry, gfp_t gfp_mask,
+ unsigned long orders, struct vm_fault *vmf,
+ struct mempolicy *mpol, pgoff_t ilx);
/* Below helpers require the caller to lock and pass in the swap cluster. */
void __swap_cache_add_folio(struct swap_cluster_info *ci,
struct folio *folio, swp_entry_t entry);
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 727a17ee78211..231fa87cbbe0c 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -483,13 +483,11 @@ static struct folio *__swap_cache_alloc(struct swap_cluster_info *ci,
node_stat_mod_folio(folio, NR_FILE_PAGES, nr_pages);
lruvec_stat_mod_folio(folio, NR_SWAPCACHE, nr_pages);
- /* Caller will initiate read into locked new_folio */
- folio_add_lru(folio);
return folio;
}
/**
- * swap_cache_alloc_folio - Allocate folio for swapped out slot in swap cache.
+ * __swap_cache_alloc_folio - Allocate folio for swapped out slot in swap cache.
* @targ_entry: swap entry indicating the target slot
* @gfp: memory allocation flags
* @orders: allocation orders, must be non zero
@@ -501,13 +499,17 @@ static struct folio *__swap_cache_alloc(struct swap_cluster_info *ci,
* doing IO (e.g. swap in or zswap writeback). The swap slot indicated by
* @targ_entry must have a non-zero swap count (swapped out).
*
+ * The returned folio is locked and is NOT on the LRU. The caller must either
+ * add it to the LRU with folio_add_lru() so page reclaim can find it, or free
+ * it directly once done; a folio left off the LRU is unreclaimable and leaks.
+ *
* Context: Caller must protect the swap device with reference count or locks.
* Return: Returns the folio if allocation succeeded and folio is in the swap
* cache. Returns error code if failed due to race, OOM or invalid arguments.
*/
-struct folio *swap_cache_alloc_folio(swp_entry_t targ_entry, gfp_t gfp,
- unsigned long orders, struct vm_fault *vmf,
- struct mempolicy *mpol, pgoff_t ilx)
+struct folio *__swap_cache_alloc_folio(swp_entry_t targ_entry, gfp_t gfp,
+ unsigned long orders, struct vm_fault *vmf,
+ struct mempolicy *mpol, pgoff_t ilx)
{
int order, err;
struct folio *ret;
@@ -535,6 +537,47 @@ struct folio *swap_cache_alloc_folio(swp_entry_t targ_entry, gfp_t gfp,
return ret;
}
+/**
+ * swap_writeback_dropbehind_folio - drop a dropbehind swap cache folio
+ * @folio: the off-LRU folio whose writeback has completed
+ *
+ * Context: task context, with the reference taken by folio_end_writeback()
+ * donated to us.
+ */
+void swap_writeback_dropbehind_folio(struct folio *folio)
+{
+ struct mem_cgroup *memcg;
+
+ folio_lock(folio);
+
+ /* The folio was allocated off the LRU and nothing re-adds it here. */
+ VM_WARN_ON_ONCE_FOLIO(folio_test_lru(folio), folio);
+
+ rcu_read_lock();
+ memcg = folio_memcg(folio);
+ if (!mem_cgroup_tryget(memcg))
+ memcg = NULL;
+ rcu_read_unlock();
+
+ /*
+ * Gate remove_mapping_reclaim() on folio_test_swapcache(): a racing
+ * swapin may have freed the swap slot (folio_free_swap()) and dropped the
+ * folio from the cache, and it must not run on a non-swapcache folio (it
+ * would trip __remove_mapping()'s mapping == folio_mapping() check).
+ */
+ if (!folio_test_swapcache(folio) || folio_test_writeback(folio) ||
+ !remove_mapping_reclaim(swap_address_space(folio->swap), folio, memcg)) {
+ /* Raced: the folio is now owned by the swapin; put it back. */
+ folio_clear_dropbehind(folio);
+ folio_add_lru(folio);
+ }
+
+ mem_cgroup_put(memcg);
+
+ folio_unlock(folio);
+ folio_put(folio);
+}
+
/*
* If we are the only user, then try to free up the swap cache.
*
@@ -643,12 +686,13 @@ static struct folio *swap_cache_read_folio(swp_entry_t entry, gfp_t gfp,
folio = swap_cache_get_folio(entry);
if (folio)
return folio;
- folio = swap_cache_alloc_folio(entry, gfp, BIT(0), NULL, mpol, ilx);
+ folio = __swap_cache_alloc_folio(entry, gfp, BIT(0), NULL, mpol, ilx);
} while (PTR_ERR(folio) == -EEXIST);
if (IS_ERR_OR_NULL(folio))
return NULL;
+ folio_add_lru(folio);
swap_read_folio(folio, plug);
if (readahead) {
folio_set_readahead(folio);
@@ -683,12 +727,13 @@ struct folio *swapin_sync(swp_entry_t entry, gfp_t gfp, unsigned long orders,
folio = swap_cache_get_folio(entry);
if (folio)
return folio;
- folio = swap_cache_alloc_folio(entry, gfp, orders, vmf, mpol, ilx);
+ folio = __swap_cache_alloc_folio(entry, gfp, orders, vmf, mpol, ilx);
} while (PTR_ERR(folio) == -EEXIST);
if (IS_ERR(folio))
return folio;
+ folio_add_lru(folio);
swap_read_folio(folio, NULL);
return folio;
}
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 848bd3e5eee2b..4cc3a3ed6db6e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -780,6 +780,22 @@ static int __remove_mapping(struct address_space *mapping, struct folio *folio,
return 0;
}
+static long __remove_mapping_unfreeze(struct address_space *mapping,
+ struct folio *folio, bool reclaimed,
+ struct mem_cgroup *target_memcg)
+{
+ if (__remove_mapping(mapping, folio, reclaimed, target_memcg)) {
+ /*
+ * Unfreezing the refcount with 1 effectively
+ * drops the pagecache ref for us without requiring another
+ * atomic operation.
+ */
+ folio_ref_unfreeze(folio, 1);
+ return folio_nr_pages(folio);
+ }
+ return 0;
+}
+
/**
* remove_mapping() - Attempt to remove a folio from its mapping.
* @mapping: The address space.
@@ -794,16 +810,28 @@ static int __remove_mapping(struct address_space *mapping, struct folio *folio,
*/
long remove_mapping(struct address_space *mapping, struct folio *folio)
{
- if (__remove_mapping(mapping, folio, false, NULL)) {
- /*
- * Unfreezing the refcount with 1 effectively
- * drops the pagecache ref for us without requiring another
- * atomic operation.
- */
- folio_ref_unfreeze(folio, 1);
- return folio_nr_pages(folio);
- }
- return 0;
+ return __remove_mapping_unfreeze(mapping, folio, false, NULL);
+}
+
+/**
+ * remove_mapping_reclaim() - Remove a folio from its mapping, as reclaim does.
+ * @mapping: The address space.
+ * @folio: The folio to remove.
+ * @target_memcg: The memcg to charge the eviction shadow to; the caller must
+ * keep it alive across the call.
+ *
+ * Like remove_mapping(), but stores a workingset eviction shadow the way page
+ * reclaim does, so that a later refault can be detected and the folio
+ * re-activated.
+ * Return: The number of pages removed from the mapping. 0 if the folio
+ * could not be removed.
+ * Context: The caller should have a single refcount on the folio and
+ * hold its lock.
+ */
+long remove_mapping_reclaim(struct address_space *mapping, struct folio *folio,
+ struct mem_cgroup *target_memcg)
+{
+ return __remove_mapping_unfreeze(mapping, folio, true, target_memcg);
}
/**
diff --git a/mm/zswap.c b/mm/zswap.c
index 761cd699e0a3e..d16822a516e8d 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1000,8 +1000,8 @@ static int zswap_writeback_entry(struct zswap_entry *entry,
return -EEXIST;
mpol = get_task_policy(current);
- folio = swap_cache_alloc_folio(swpentry, GFP_KERNEL, BIT(0), NULL, mpol,
- NO_INTERLEAVE_INDEX);
+ folio = __swap_cache_alloc_folio(swpentry, GFP_KERNEL, BIT(0), NULL, mpol,
+ NO_INTERLEAVE_INDEX);
put_swap_device(si);
/*
@@ -1045,12 +1045,26 @@ static int zswap_writeback_entry(struct zswap_entry *entry,
/* folio is up to date */
folio_mark_uptodate(folio);
- /* move it to the tail of the inactive list after end_writeback */
- folio_set_reclaim(folio);
+ folio_set_dropbehind(folio);
+
+ /*
+ * Drop our reference before starting writeback so the swap cache holds
+ * the only one: the drop in folio_end_writeback() needs that for
+ * remove_mapping_reclaim() to succeed, otherwise the folio is handed
+ * back to reclaim instead.
+ *
+ * Nothing can free the folio in the meantime: we hold the folio lock
+ * until writeback starts, PG_writeback then blocks swap cache removal,
+ * and folio_end_writeback() takes its own reference before clearing
+ * PG_writeback and donates it to the drop.
+ */
+ folio_put(folio);
/* start writeback */
__swap_writepage(folio, NULL);
+ return 0;
+
out:
if (ret) {
swap_cache_del_folio(folio);
|
| 3/2 | 2026/08/25 14:29 | llm | patch-evaluator |
2mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 6180 output: 28 thoughts: 526 Thoughts: **Fuzzing Target Identification: Memory Management Subsystem** Okay, here's what I'm thinking. This patch series is touching some pretty critical bits of the kernel's memory management. It's modifying headers and code in `swap.h`, `filemap.c`, `page_io.c`, `swap_state.c`, `vmscan.c`, and `zswap.c`. We're dealing with swap, zswap, and the page cache – that's a functional change, no question. This *definitely* needs fuzzing. Now, let's get specific about where to focus the fuzzing effort. I need to identify the key functions that have been added or modified. Alright, new functions: `remove_mapping_reclaim` and `swap_writeback_dropbehind_folio`. And then modified functions: `zswap_writeback_entry`, `folio_end_writeback`, and `swap_writepage_bdev_async`. Those are our main targets. Next, I have to determine the scope of these functions in the context of the fuzzing. Let me check if `zswap_writeback_entry` is static or non-static. Yup, it's static. Okay, let's check `swap_writeback_dropbehind_folio` and `remove_mapping_reclaim`. Hmm, both are non-static. So, they're exposed and can be called from other modules. `folio_end_writeback` is also non-static, so we have a few entry points to consider. One more thing: I need to quickly verify that we have the necessary kernel configurations to enable zswap and swap. It looks like we need `CONFIG_ZSWAP`, `CONFIG_SWAP`, and `CONFIG_MEMCG`. Time to double-check those configs and make sure they're all set appropriately for our testing environment. |
| 4/2 | 2026/08/25 14:31 | tool | grepper |
0mArgs:{
"Expression": "config ZSWAP",
"PathPrefix": "mm/Kconfig"
}Results: {
"Output": "mm/Kconfig=12=menuconfig SWAP\n--\nmm/Kconfig-21-\nmm/Kconfig:22:config ZSWAP\nmm/Kconfig-23-\tbool \"Compressed cache for swap pages\"\n--\nmm/Kconfig-34-\nmm/Kconfig:35:config ZSWAP_DEFAULT_ON\nmm/Kconfig-36-\tbool \"Enable the compressed cache for swap pages by default\"\n--\nmm/Kconfig-44-\nmm/Kconfig:45:config ZSWAP_SHRINKER_DEFAULT_ON\nmm/Kconfig-46-\tbool \"Shrink the zswap pool on memory pressure\"\n--\nmm/Kconfig=59=choice\n--\nmm/Kconfig-76-\nmm/Kconfig:77:config ZSWAP_COMPRESSOR_DEFAULT_DEFLATE\nmm/Kconfig-78-\tbool \"Deflate\"\n--\nmm/Kconfig-82-\nmm/Kconfig:83:config ZSWAP_COMPRESSOR_DEFAULT_LZO\nmm/Kconfig-84-\tbool \"LZO\"\n--\nmm/Kconfig-88-\nmm/Kconfig:89:config ZSWAP_COMPRESSOR_DEFAULT_842\nmm/Kconfig-90-\tbool \"842\"\n--\nmm/Kconfig-94-\nmm/Kconfig:95:config ZSWAP_COMPRESSOR_DEFAULT_LZ4\nmm/Kconfig-96-\tbool \"LZ4\"\n--\nmm/Kconfig-100-\nmm/Kconfig:101:config ZSWAP_COMPRESSOR_DEFAULT_LZ4HC\nmm/Kconfig-102-\tbool \"LZ4HC\"\n--\nmm/Kconfig-106-\nmm/Kconfig:107:config ZSWAP_COMPRESSOR_DEFAULT_ZSTD\nmm/Kconfig-108-\tbool \"zstd\"\n--\nmm/Kconfig=112=endchoice\nmm/Kconfig-113-\nmm/Kconfig:114:config ZSWAP_COMPRESSOR_DEFAULT\nmm/Kconfig-115- string\n"
} |
| 5/2 | 2026/08/25 14:31 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 7680 output: 27 thoughts: 18 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience, and written as if they were my own: **ZSWAP Dependency Deep Dive** Alright, so ZSWAP relies fundamentally on the existence and proper functioning of SWAP. That's the baseline assumption, but assumptions are the enemy of robust systems. My immediate thought is, let's not just *assume* that connection is solid. I need to explicitly verify the dependencies. We're talking about a core architectural relationship here, and any instability in SWAP, or an improperly configured dependency, could cascade and cause serious issues within ZSWAP's overall function. Time to dig into those ZSWAP dependencies and map out every point of integration to ensure stability and predict potential failure modes. Let's see how deep this rabbit hole goes. |
| 6/2 | 2026/08/25 14:31 | tool | grepper |
0mArgs:{
"Expression": "depends on.*",
"PathPrefix": "mm/Kconfig"
}Results: {
"Output": "mm/Kconfig=12=menuconfig SWAP\nmm/Kconfig-13-\tbool \"Support for paging of anonymous memory (swap)\"\nmm/Kconfig:14:\tdepends on MMU \u0026\u0026 BLOCK \u0026\u0026 !ARCH_NO_SWAP\nmm/Kconfig-15-\tdefault y\n--\nmm/Kconfig=22=config ZSWAP\nmm/Kconfig-23-\tbool \"Compressed cache for swap pages\"\nmm/Kconfig:24:\tdepends on SWAP\nmm/Kconfig-25-\tselect CRYPTO\n--\nmm/Kconfig=35=config ZSWAP_DEFAULT_ON\nmm/Kconfig-36-\tbool \"Enable the compressed cache for swap pages by default\"\nmm/Kconfig:37:\tdepends on ZSWAP\nmm/Kconfig-38-\thelp\n--\nmm/Kconfig=45=config ZSWAP_SHRINKER_DEFAULT_ON\nmm/Kconfig-46-\tbool \"Shrink the zswap pool on memory pressure\"\nmm/Kconfig:47:\tdepends on ZSWAP\nmm/Kconfig-48-\tdefault n\n--\nmm/Kconfig=59=choice\nmm/Kconfig-60-\tprompt \"Default compressor\"\nmm/Kconfig:61:\tdepends on ZSWAP\nmm/Kconfig-62-\tdefault ZSWAP_COMPRESSOR_DEFAULT_LZO\n--\nmm/Kconfig=114=config ZSWAP_COMPRESSOR_DEFAULT\nmm/Kconfig-115- string\nmm/Kconfig:116: depends on ZSWAP\nmm/Kconfig-117- default \"deflate\" if ZSWAP_COMPRESSOR_DEFAULT_DEFLATE\n--\nmm/Kconfig=130=menu \"Zsmalloc allocator options\"\nmm/Kconfig:131:\tdepends on ZSMALLOC\nmm/Kconfig-132-\n--\nmm/Kconfig=172=config KVFREE_RCU_BATCHED\nmm/Kconfig-173-\tdef_bool y\nmm/Kconfig:174:\tdepends on !SLUB_TINY \u0026\u0026 !TINY_RCU\nmm/Kconfig:175:\tdepends on !RCU_STRICT_GRACE_PERIOD\nmm/Kconfig-176-\nmm/Kconfig=177=config SLUB_TINY\nmm/Kconfig-178-\tbool \"Configure for minimal memory footprint\"\nmm/Kconfig:179:\tdepends on EXPERT \u0026\u0026 !COMPILE_TEST\nmm/Kconfig-180-\tselect SLAB_MERGE_DEFAULT\n--\nmm/Kconfig=204=config SLAB_FREELIST_RANDOM\nmm/Kconfig-205-\tbool \"Randomize slab freelist\"\nmm/Kconfig:206:\tdepends on !SLUB_TINY\nmm/Kconfig-207-\thelp\n--\nmm/Kconfig=212=config SLAB_FREELIST_HARDENED\nmm/Kconfig-213-\tbool \"Harden slab freelist metadata\"\nmm/Kconfig:214:\tdepends on !SLUB_TINY\nmm/Kconfig-215-\thelp\n--\nmm/Kconfig=221=config SLAB_BUCKETS\nmm/Kconfig-222-\tbool \"Support allocation from separate kmalloc buckets\"\nmm/Kconfig:223:\tdepends on !SLUB_TINY\nmm/Kconfig-224-\tdefault SLAB_FREELIST_HARDENED\n--\nmm/Kconfig=238=config SLUB_STATS\n--\nmm/Kconfig-240-\tbool \"Enable performance statistics\"\nmm/Kconfig:241:\tdepends on SYSFS \u0026\u0026 !SLUB_TINY\nmm/Kconfig-242-\thelp\n--\nmm/Kconfig=251=config KMALLOC_PARTITION_CACHES\nmm/Kconfig:252:\tdepends on !SLUB_TINY\nmm/Kconfig-253-\tbool \"Partitioned slab caches for normal kmalloc\"\n--\nmm/Kconfig=267=choice\nmm/Kconfig-268-\tprompt \"Partitioned slab cache mode\"\nmm/Kconfig:269:\tdepends on KMALLOC_PARTITION_CACHES\nmm/Kconfig-270-\tdefault KMALLOC_PARTITION_TYPED if CC_HAS_ALLOC_TOKEN\n--\nmm/Kconfig=287=config KMALLOC_PARTITION_TYPED\nmm/Kconfig-288-\tbool \"Type based slab cache selection for normal kmalloc\"\nmm/Kconfig:289:\tdepends on CC_HAS_ALLOC_TOKEN\nmm/Kconfig-290-\thelp\n--\nmm/Kconfig=358=config MMAP_ALLOW_UNINITIALIZED\nmm/Kconfig-359-\tbool \"Allow mmapped anonymous memory to be uninitialized\"\nmm/Kconfig:360:\tdepends on EXPERT \u0026\u0026 !MMU\nmm/Kconfig-361-\tdefault n\n--\nmm/Kconfig=380=config SELECT_MEMORY_MODEL\nmm/Kconfig-381-\tdef_bool y\nmm/Kconfig:382:\tdepends on ARCH_SELECT_MEMORY_MODEL\nmm/Kconfig-383-\nmm/Kconfig=384=choice\nmm/Kconfig-385-\tprompt \"Memory model\"\nmm/Kconfig:386:\tdepends on SELECT_MEMORY_MODEL\nmm/Kconfig-387-\tdefault SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT\n--\nmm/Kconfig=395=config FLATMEM_MANUAL\nmm/Kconfig-396-\tbool \"Flat Memory\"\nmm/Kconfig:397:\tdepends on !ARCH_SPARSEMEM_ENABLE || ARCH_FLATMEM_ENABLE\nmm/Kconfig-398-\thelp\n--\nmm/Kconfig=410=config SPARSEMEM_MANUAL\nmm/Kconfig-411-\tbool \"Sparse Memory\"\nmm/Kconfig:412:\tdepends on ARCH_SPARSEMEM_ENABLE\nmm/Kconfig-413-\thelp\n--\nmm/Kconfig=425=config SPARSEMEM\nmm/Kconfig-426-\tdef_bool y\nmm/Kconfig:427:\tdepends on (!SELECT_MEMORY_MODEL \u0026\u0026 ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL\nmm/Kconfig-428-\nmm/Kconfig=429=config FLATMEM\nmm/Kconfig-430-\tdef_bool y\nmm/Kconfig:431:\tdepends on !SPARSEMEM || FLATMEM_MANUAL\nmm/Kconfig-432-\n--\nmm/Kconfig=451=config SPARSEMEM_EXTREME\nmm/Kconfig-452-\tdef_bool y\nmm/Kconfig:453:\tdepends on SPARSEMEM \u0026\u0026 !SPARSEMEM_STATIC\nmm/Kconfig-454-\n--\nmm/Kconfig=458=config SPARSEMEM_VMEMMAP\nmm/Kconfig-459-\tdef_bool y\nmm/Kconfig:460:\tdepends on SPARSEMEM \u0026\u0026 SPARSEMEM_VMEMMAP_ENABLE\nmm/Kconfig-461-\thelp\n--\nmm/Kconfig=484=config HAVE_GUP_FAST\nmm/Kconfig:485:\tdepends on MMU\nmm/Kconfig-486-\tbool\n--\nmm/Kconfig=508=config EXCLUSIVE_SYSTEM_RAM\nmm/Kconfig-509-\tdef_bool y\nmm/Kconfig:510:\tdepends on !DEVMEM || STRICT_DEVMEM\nmm/Kconfig-511-\n--\nmm/Kconfig=523=menuconfig MEMORY_HOTPLUG\n--\nmm/Kconfig-525-\tselect MEMORY_ISOLATION\nmm/Kconfig:526:\tdepends on SPARSEMEM_VMEMMAP\nmm/Kconfig:527:\tdepends on ARCH_ENABLE_MEMORY_HOTPLUG\nmm/Kconfig:528:\tdepends on 64BIT\nmm/Kconfig-529-\tselect NUMA_KEEP_MEMINFO if NUMA\n--\nmm/Kconfig=591=config MEMORY_HOTREMOVE\n--\nmm/Kconfig-593-\tselect HAVE_BOOTMEM_INFO_NODE if X86_64\nmm/Kconfig:594:\tdepends on MEMORY_HOTPLUG\nmm/Kconfig-595-\tselect MIGRATION\n--\nmm/Kconfig=597=config MHP_MEMMAP_ON_MEMORY\nmm/Kconfig-598-\tdef_bool y\nmm/Kconfig:599:\tdepends on MEMORY_HOTPLUG \u0026\u0026 SPARSEMEM_VMEMMAP\nmm/Kconfig:600:\tdepends on ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE\nmm/Kconfig-601-\n--\nmm/Kconfig=604=config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE\n--\nmm/Kconfig-610-# Default to 4 for wider testing, though 8 might be more appropriate.\nmm/Kconfig:611:# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.\nmm/Kconfig-612-# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.\n--\nmm/Kconfig=618=config SPLIT_PTE_PTLOCKS\nmm/Kconfig-619-\tdef_bool y\nmm/Kconfig:620:\tdepends on MMU\nmm/Kconfig:621:\tdepends on SMP\nmm/Kconfig:622:\tdepends on NR_CPUS \u003e= 4\nmm/Kconfig:623:\tdepends on !ARM || CPU_CACHE_VIPT\nmm/Kconfig:624:\tdepends on !PARISC || PA20\nmm/Kconfig:625:\tdepends on !SPARC32\nmm/Kconfig:626:\tdepends on !UML\nmm/Kconfig-627-\n--\nmm/Kconfig=631=config SPLIT_PMD_PTLOCKS\nmm/Kconfig-632-\tdef_bool y\nmm/Kconfig:633:\tdepends on SPLIT_PTE_PTLOCKS \u0026\u0026 ARCH_ENABLE_SPLIT_PMD_PTLOCK\nmm/Kconfig-634-\n--\nmm/Kconfig=642=config BALLOON_MIGRATION\n--\nmm/Kconfig-644-\tdefault y\nmm/Kconfig:645:\tdepends on MIGRATION \u0026\u0026 BALLOON\nmm/Kconfig-646-\thelp\n--\nmm/Kconfig=654=config COMPACTION\n--\nmm/Kconfig-657-\tselect MIGRATION\nmm/Kconfig:658:\tdepends on MMU\nmm/Kconfig-659-\thelp\n--\nmm/Kconfig=669=config COMPACT_UNEVICTABLE_DEFAULT\nmm/Kconfig-670-\tint\nmm/Kconfig:671:\tdepends on COMPACTION\nmm/Kconfig-672-\tdefault 0 if PREEMPT_RT\n--\nmm/Kconfig=685=config NUMA_MIGRATION\n--\nmm/Kconfig-687-\tdefault y\nmm/Kconfig:688:\tdepends on NUMA \u0026\u0026 MMU\nmm/Kconfig-689-\tselect MIGRATION\n--\nmm/Kconfig=696=config MIGRATION\nmm/Kconfig-697-\tbool\nmm/Kconfig:698:\tdepends on MMU\nmm/Kconfig-699-\n--\nmm/Kconfig=740=config KSM\nmm/Kconfig-741-\tbool \"Enable KSM for page merging\"\nmm/Kconfig:742:\tdepends on MMU\nmm/Kconfig-743-\tselect XXHASH\n--\nmm/Kconfig=755=config DEFAULT_MMAP_MIN_ADDR\nmm/Kconfig-756-\tint \"Low address space to protect from user allocation\"\nmm/Kconfig:757:\tdepends on MMU\nmm/Kconfig-758-\tdefault 4096\n--\nmm/Kconfig=777=config MEMORY_FAILURE\nmm/Kconfig:778:\tdepends on MMU\nmm/Kconfig:779:\tdepends on ARCH_SUPPORTS_MEMORY_FAILURE\nmm/Kconfig-780-\tbool \"Enable recovery from hardware memory errors\"\n--\nmm/Kconfig=788=config HWPOISON_INJECT\nmm/Kconfig-789-\ttristate \"HWPoison pages injector\"\nmm/Kconfig:790:\tdepends on MEMORY_FAILURE \u0026\u0026 DEBUG_KERNEL \u0026\u0026 PROC_FS\nmm/Kconfig-791-\tselect PROC_PAGE_MONITOR\n--\nmm/Kconfig=793=config NOMMU_INITIAL_TRIM_EXCESS\nmm/Kconfig-794-\tint \"Turn on mmap() excess space trimming before booting\"\nmm/Kconfig:795:\tdepends on !MMU\nmm/Kconfig-796-\tdefault 1\n--\nmm/Kconfig=827=config PERSISTENT_HUGE_ZERO_FOLIO\nmm/Kconfig-828-\tbool \"Allocate a PMD sized folio for zeroing\"\nmm/Kconfig:829:\tdepends on TRANSPARENT_HUGEPAGE\nmm/Kconfig-830-\thelp\n--\nmm/Kconfig=846=menuconfig TRANSPARENT_HUGEPAGE\nmm/Kconfig-847-\tbool \"Transparent Hugepage Support\"\nmm/Kconfig:848:\tdepends on HAVE_ARCH_TRANSPARENT_HUGEPAGE \u0026\u0026 !PREEMPT_RT\nmm/Kconfig-849-\tselect COMPACTION\n--\nmm/Kconfig=982=config THP_SWAP\nmm/Kconfig-983-\tdef_bool y\nmm/Kconfig:984:\tdepends on ARCH_WANTS_THP_SWAP \u0026\u0026 SWAP \u0026\u0026 64BIT\nmm/Kconfig-985-\thelp\n--\nmm/Kconfig=1028=config ARCH_SUPPORTS_HUGE_PFNMAP\nmm/Kconfig-1029-\tdef_bool n\nmm/Kconfig:1030:\tdepends on TRANSPARENT_HUGEPAGE\nmm/Kconfig-1031-\nmm/Kconfig=1032=config ARCH_SUPPORTS_PMD_PFNMAP\nmm/Kconfig-1033-\tdef_bool y\nmm/Kconfig:1034:\tdepends on ARCH_SUPPORTS_HUGE_PFNMAP \u0026\u0026 HAVE_ARCH_TRANSPARENT_HUGEPAGE\nmm/Kconfig-1035-\nmm/Kconfig=1036=config ARCH_SUPPORTS_PUD_PFNMAP\nmm/Kconfig-1037-\tdef_bool y\nmm/Kconfig:1038:\tdepends on ARCH_SUPPORTS_HUGE_PFNMAP \u0026\u0026 HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD\nmm/Kconfig-1039-\n--\nmm/Kconfig=1050=config NEED_PER_CPU_KM\nmm/Kconfig:1051:\tdepends on !SMP || !MMU\nmm/Kconfig-1052-\tbool\n--\nmm/Kconfig=1067=config CMA\nmm/Kconfig-1068-\tbool \"Contiguous Memory Allocator\"\nmm/Kconfig:1069:\tdepends on MMU\nmm/Kconfig-1070-\tselect MIGRATION\n--\nmm/Kconfig=1082=config CMA_DEBUGFS\nmm/Kconfig-1083-\tbool \"CMA debugfs interface\"\nmm/Kconfig:1084:\tdepends on CMA \u0026\u0026 DEBUG_FS\nmm/Kconfig-1085-\thelp\n--\nmm/Kconfig=1088=config CMA_SYSFS\nmm/Kconfig-1089-\tbool \"CMA information through sysfs interface\"\nmm/Kconfig:1090:\tdepends on CMA \u0026\u0026 SYSFS\nmm/Kconfig-1091-\thelp\n--\nmm/Kconfig=1095=config CMA_AREAS\nmm/Kconfig-1096-\tint \"Maximum count of the CMA areas\"\nmm/Kconfig:1097:\tdepends on CMA\nmm/Kconfig-1098-\tdefault 20 if NUMA\n--\nmm/Kconfig=1142=config MEM_SOFT_DIRTY\nmm/Kconfig-1143-\tbool \"Track memory changes\"\nmm/Kconfig:1144:\tdepends on CHECKPOINT_RESTORE \u0026\u0026 HAVE_ARCH_SOFT_DIRTY \u0026\u0026 PROC_FS\nmm/Kconfig-1145-\tselect PROC_PAGE_MONITOR\n--\nmm/Kconfig=1157=config STACK_MAX_DEFAULT_SIZE_MB\n--\nmm/Kconfig-1160-\trange 8 2048\nmm/Kconfig:1161:\tdepends on STACK_GROWSUP \u0026\u0026 (!64BIT || COMPAT)\nmm/Kconfig-1162-\thelp\n--\nmm/Kconfig=1169=config DEFERRED_STRUCT_PAGE_INIT\nmm/Kconfig-1170-\tbool \"Defer initialisation of struct pages to kthreads\"\nmm/Kconfig:1171:\tdepends on SPARSEMEM\nmm/Kconfig:1172:\tdepends on !NEED_PER_CPU_KM\nmm/Kconfig:1173:\tdepends on 64BIT\nmm/Kconfig:1174:\tdepends on !KMSAN\nmm/Kconfig-1175-\tselect PADATA\n--\nmm/Kconfig=1193=config IDLE_PAGE_TRACKING\nmm/Kconfig-1194-\tbool \"Enable idle page tracking\"\nmm/Kconfig:1195:\tdepends on SYSFS \u0026\u0026 MMU\nmm/Kconfig-1196-\tselect PAGE_IDLE_FLAG\n--\nmm/Kconfig=1231=config ZONE_DMA32\nmm/Kconfig-1232-\tbool \"Support DMA32 zone\" if ARCH_HAS_ZONE_DMA_SET\nmm/Kconfig:1233:\tdepends on !X86_32\nmm/Kconfig-1234-\tdefault y if ARM64\n--\nmm/Kconfig=1236=config ZONE_DEVICE\nmm/Kconfig-1237-\tbool \"Device memory (pmem, HMM, etc...) hotplug support\"\nmm/Kconfig:1238:\tdepends on MEMORY_HOTPLUG\nmm/Kconfig:1239:\tdepends on MEMORY_HOTREMOVE\nmm/Kconfig:1240:\tdepends on SPARSEMEM_VMEMMAP\nmm/Kconfig-1241-\tselect XARRAY_MULTI\n--\nmm/Kconfig=1260=config HMM_MIRROR\nmm/Kconfig-1261-\tbool\nmm/Kconfig:1262:\tdepends on MMU\nmm/Kconfig-1263-\n--\nmm/Kconfig=1267=config DEVICE_PRIVATE\nmm/Kconfig-1268-\tbool \"Unaddressable device memory (GPU memory, ...)\"\nmm/Kconfig:1269:\tdepends on ZONE_DEVICE\nmm/Kconfig-1270-\tselect GET_FREE_REGION\n--\nmm/Kconfig=1306=config GUP_TEST\nmm/Kconfig-1307-\tbool \"Enable infrastructure for get_user_pages()-related unit tests\"\nmm/Kconfig:1308:\tdepends on DEBUG_FS\nmm/Kconfig-1309-\thelp\n--\nmm/Kconfig=1326=comment \"GUP_TEST needs to have DEBUG_FS enabled\"\nmm/Kconfig:1327:\tdepends on !GUP_TEST \u0026\u0026 !DEBUG_FS\nmm/Kconfig-1328-\n--\nmm/Kconfig=1332=config DMAPOOL_TEST\nmm/Kconfig-1333-\ttristate \"Enable a module to run time tests on dma_pool\"\nmm/Kconfig:1334:\tdepends on HAS_DMA\nmm/Kconfig-1335-\thelp\n--\nmm/Kconfig=1356=config SECRETMEM\n--\nmm/Kconfig-1358-\tbool \"Enable memfd_secret() system call\" if EXPERT\nmm/Kconfig:1359:\tdepends on ARCH_HAS_SET_DIRECT_MAP\nmm/Kconfig-1360-\thelp\n--\nmm/Kconfig=1365=config ANON_VMA_NAME\nmm/Kconfig-1366-\tbool \"Anonymous VMA name support\"\nmm/Kconfig:1367:\tdepends on PROC_FS \u0026\u0026 ADVISE_SYSCALLS \u0026\u0026 MMU\nmm/Kconfig-1368-\n--\nmm/Kconfig=1389=menuconfig USERFAULTFD\nmm/Kconfig-1390-\tbool \"Enable userfaultfd() system call\"\nmm/Kconfig:1391:\tdepends on MMU\nmm/Kconfig-1392-\thelp\n--\nmm/Kconfig=1397=config PTE_MARKER_UFFD_WP\n--\nmm/Kconfig-1399-\tdefault y\nmm/Kconfig:1400:\tdepends on HAVE_ARCH_USERFAULTFD_WP\nmm/Kconfig-1401-\n--\nmm/Kconfig=1409=config LRU_GEN\nmm/Kconfig-1410-\tbool \"Multi-Gen LRU\"\nmm/Kconfig:1411:\tdepends on MMU\nmm/Kconfig-1412-\t# make sure folio-\u003eflags has enough spare bits\nmm/Kconfig:1413:\tdepends on 64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP\nmm/Kconfig-1414-\thelp\n--\nmm/Kconfig=1418=config LRU_GEN_ENABLED\nmm/Kconfig-1419-\tbool \"Enable by default\"\nmm/Kconfig:1420:\tdepends on LRU_GEN\nmm/Kconfig-1421-\thelp\n--\nmm/Kconfig=1424=config LRU_GEN_STATS\nmm/Kconfig-1425-\tbool \"Full stats for debugging\"\nmm/Kconfig:1426:\tdepends on LRU_GEN\nmm/Kconfig-1427-\thelp\n--\nmm/Kconfig=1433=config LRU_GEN_WALKS_MMU\nmm/Kconfig-1434-\tdef_bool y\nmm/Kconfig:1435:\tdepends on LRU_GEN \u0026\u0026 ARCH_HAS_HW_PTE_YOUNG\nmm/Kconfig-1436-# }\n--\nmm/Kconfig=1441=config PER_VMA_LOCK\nmm/Kconfig-1442-\tdef_bool y\nmm/Kconfig:1443:\tdepends on ARCH_SUPPORTS_PER_VMA_LOCK \u0026\u0026 MMU \u0026\u0026 SMP\nmm/Kconfig-1444-\thelp\n--\nmm/Kconfig=1450=config LOCK_MM_AND_FIND_VMA\nmm/Kconfig-1451-\tbool\nmm/Kconfig:1452:\tdepends on !STACK_GROWSUP\nmm/Kconfig-1453-\n--\nmm/Kconfig=1463=config NUMA_EMU\nmm/Kconfig-1464-\tbool \"NUMA emulation\"\nmm/Kconfig:1465:\tdepends on NUMA_MEMBLKS\nmm/Kconfig:1466:\tdepends on X86 || GENERIC_ARCH_NUMA\nmm/Kconfig-1467-\thelp\n--\nmm/Kconfig=1481=config PT_RECLAIM\nmm/Kconfig-1482-\tdef_bool y\nmm/Kconfig:1483:\tdepends on MMU_GATHER_RCU_TABLE_FREE \u0026\u0026 !HAVE_ARCH_TLB_REMOVE_TABLE\nmm/Kconfig-1484-\thelp\n--\nmm/Kconfig=1500=config LAZY_MMU_MODE_KUNIT_TEST\nmm/Kconfig-1501-\ttristate \"KUnit tests for the lazy MMU mode\" if !KUNIT_ALL_TESTS\nmm/Kconfig:1502:\tdepends on ARCH_HAS_LAZY_MMU_MODE\nmm/Kconfig:1503:\tdepends on KUNIT\nmm/Kconfig-1504-\tdefault KUNIT_ALL_TESTS\n"
} |
| 7/2 | 2026/08/25 14:31 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 14041 output: 27 thoughts: 15 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience: **Memory Management Deep Dive - Initial Assessment** Alright, ZSWAP is officially online and operational. Excellent, we're making progress. Now, my immediate next step is to drill down into the MEMCG (Memory Control Groups) metrics and behaviors. We have ZSWAP, but *how* is it performing in the context of our existing memory hierarchy and workload isolation? I need to understand if the configuration is optimal for this deployment. My focus will be on tracking the key MEMCG parameters, especially swap usage, page fault rates, and reclaim statistics for each relevant cgroup. I'll need to correlate these with performance data from other monitoring tools to assess any possible bottlenecks or regressions now that ZSWAP is active. This investigation will probably involve visualizing the relevant metrics over time, and possibly adjusting the settings of the cgroups to see if we can achieve better overall performance, which is what I always aim for. |
| 8/2 | 2026/08/25 14:31 | tool | grepper |
0mArgs:{
"Expression": "config MEMCG",
"PathPrefix": "init/Kconfig"
}Results: {
"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"
} |
| 9/2 | 2026/08/25 14:31 | llm | patch-evaluator |
4mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 14517 output: 28 thoughts: 17 Thoughts: Okay, here's my take on those thoughts, framed as my own: **Investigating the Dependency: MEMCG and CGROUPS** Alright, let's get down to brass tacks. I'm looking at MEMCG, and it's ringing a bell. I know it's intrinsically linked to CGROUPS – they're practically symbiotic in the Linux kernel. So, my immediate thought is, before I dig any deeper into MEMCG's behavior or troubleshoot any issues, I *absolutely* need to confirm my understanding and the current state of CGROUPS. Everything downstream from here hinges on that foundational layer. Time to get a handle on the CGROUPS situation. That's where I need to focus my initial analysis. |
| 10/2 | 2026/08/25 14:36 | tool | grepper |
0mArgs:{
"Expression": "config CGROUPS",
"PathPrefix": "init/Kconfig"
}Results: {
"Output": "init/Kconfig=1045=config SLAB_OBJ_EXT\n--\ninit/Kconfig-1047-\ninit/Kconfig:1048:menuconfig CGROUPS\ninit/Kconfig-1049-\tbool \"Control Group support\"\n"
} |
| 11/2 | 2026/08/25 14:36 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 14796 output: 27 thoughts: 185 Thoughts: **My Initial Assessment of the Code Changes** Okay, so we're dealing with `ZSWAP`, `SWAP`, and `MEMCG` – those are the key areas impacted by this change. My initial task is to get a handle on what's been touched. Time to look into the configuration options to see what else has been added or modified in the relevant modules. I've got the affected files: `mm/filemap.c`, `mm/page_io.c`, `mm/swap.h`, `mm/swap_state.c`, `mm/vmscan.c`, and `mm/zswap.c`. Alright, so `mm/zswap.c` is clearly conditional on `CONFIG_ZSWAP`, making sense. `mm/swap_state.c` and `mm/page_io.c` are tied to `CONFIG_SWAP`. `mm/vmscan.c` and `mm/filemap.c` are always compiled. Now, let's double-check the `mm/Makefile` to confirm the build dependencies and any other potentially relevant configurations I haven't spotted yet. |
| 12/2 | 2026/08/25 14:36 | tool | grepper |
0mArgs:{
"Expression": "zswap\\.o",
"PathPrefix": "mm/Makefile"
}Results: {
"Output": "mm/Makefile=78=obj-$(CONFIG_SWAP)\t+= page_io.o swap_state.o swapfile.o\nmm/Makefile:79:obj-$(CONFIG_ZSWAP)\t+= zswap.o\nmm/Makefile-80-obj-$(CONFIG_HAS_DMA)\t+= dmapool.o\n"
} |
| 13/2 | 2026/08/25 14:36 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 15345 output: 28 thoughts: 11 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: **Analyzing `swap_state.o`** Alright, time to dive into `swap_state.o`. I'm immediately thinking about its likely role; the name screams "context switching" or at least some part of the process. I need to figure out precisely *what* functionality it provides within the larger architecture. Is it the core state management, or just a small piece that interfaces with some hardware registers? Is this part of a monolithic kernel implementation or something more modular? Are we talking about user-space swapping, kernel-level, or both? I'll start by disassembling it. I'm looking for key instructions – `mov` to specific registers, likely those associated with the Program Status Word, stack manipulations, perhaps some `syscall` instructions that would tie into the operating system's swap primitives. I'll be searching for any hints of interrupt handling logic. I'll need to identify any data structures that hold process state. Are there pointers to task control blocks, or perhaps a more elegant descriptor structure? I’ll look for any dependencies on other object files or libraries. This is a very common clue as to whether or not it's a stand-alone function, or if it has some dependencies on other parts of the system. I also want to identify how it gets called. Is it part of a scheduled interrupt, a trap, or is it triggered directly by some software event? Understanding the call paths is critical. The calling convention of the function is going to be extremely important here. I anticipate seeing assembly related to saving and restoring register contexts, managing the page tables, and possibly dealing with cache coherence. This function is likely performance-critical, so I expect the code to be optimized – hand-coded assembly is a real possibility. I’ll keep a close eye for any potential optimization issues or areas of concern, such as race conditions or subtle memory leaks. Let's see what we've got. |
| 14/2 | 2026/08/25 14:37 | tool | grepper |
0mArgs:{
"Expression": "swap_state\\.o",
"PathPrefix": "mm/Makefile"
}Results: {
"Output": "mm/Makefile=76=endif\nmm/Makefile-77-\nmm/Makefile:78:obj-$(CONFIG_SWAP)\t+= page_io.o swap_state.o swapfile.o\nmm/Makefile-79-obj-$(CONFIG_ZSWAP)\t+= zswap.o\n"
} |
| 15/2 | 2026/08/25 14:37 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 15887 output: 27 thoughts: 33 Thoughts: **Checking Swap Configuration for Memory Management** Okay, so I'm diving into this memory management stuff again. Right, `CONFIG_SWAP` and `CONFIG_ZSWAP` are definitely necessary, I know that. But where are the relevant definitions? I need to quickly check the dependency settings for these. My next step is to look at the `MEMCG` configuration option, right? That's in the `mm/Makefile`. That should give me the information I need to sort this out. |
| 16/2 | 2026/08/25 14:37 | tool | grepper |
0mArgs:{
"Expression": "memcontrol\\.o",
"PathPrefix": "mm/Makefile"
}Results: {
"Output": "mm/Makefile=27=KCOV_INSTRUMENT_kmemleak.o := n\nmm/Makefile:28:KCOV_INSTRUMENT_memcontrol.o := n\nmm/Makefile-29-KCOV_INSTRUMENT_memcontrol-v1.o := n\n--\nmm/Makefile=104=obj-$(CONFIG_MEMCG_V1) += memcontrol-v1.o\nmm/Makefile:105:obj-$(CONFIG_MEMCG) += memcontrol.o vmpressure.o\nmm/Makefile-106-ifdef CONFIG_BPF_SYSCALL\nmm/Makefile:107:obj-$(CONFIG_MEMCG) += bpf_memcontrol.o\nmm/Makefile-108-endif\n"
} |
| 17/2 | 2026/08/25 14:37 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 16243 output: 33 thoughts: 152 Thoughts: **My Thought Process on Identifying Focus Symbols** Okay, so we're dealing with memory control groups, and it looks like `CONFIG_MEMCG` is definitely relevant – that's the baseline. Now, I need to pinpoint the appropriate focus symbols. Let's see... I've got to find the key API entry points for this memory reclaim and swap writeback scenario. Alright, initial candidates: `swap_writeback_dropbehind_folio` and `remove_mapping_reclaim` seem promising, those look like potential entry points. I also see `zswap_writeback_entry`, but that's static. Hmm, tricky. The instructions do mention preferring non-static, non-inlined API functions over internals. Hold on a second, though, even though `zswap_writeback_entry` is static, it's *not* inlined. It must be called from somewhere else, possibly as a callback. I need to investigate where `zswap_writeback_entry` is actually invoked. That will clarify if it's a suitable candidate. |
| 18/2 | 2026/08/25 14:37 | tool | grepper |
0mArgs:{
"Expression": "zswap_writeback_entry",
"PathPrefix": "mm/zswap.c"
}Results: {
"Output": "mm/zswap.c=924=static bool zswap_decompress(struct zswap_entry *entry, struct folio *folio)\n--\nmm/zswap.c-986- */\nmm/zswap.c:987:static int zswap_writeback_entry(struct zswap_entry *entry,\nmm/zswap.c-988-\t\t\t\t swp_entry_t swpentry)\n--\nmm/zswap.c=1102=static enum lru_status shrink_memcg_cb(struct list_head *item, struct list_lru_one *l,\n--\nmm/zswap.c-1125-\t * 1. We extract the swp_entry_t to the stack, allowing\nmm/zswap.c:1126:\t * zswap_writeback_entry() to pin the swap entry and\nmm/zswap.c-1127-\t * then validate the zswap entry against that swap entry's\n--\nmm/zswap.c-1160-\nmm/zswap.c:1161:\twriteback_result = zswap_writeback_entry(entry, swpentry);\nmm/zswap.c-1162-\n"
} |
| 19/2 | 2026/08/25 14:37 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 16967 output: 32 thoughts: 54 Thoughts: **My Analysis of the Memory Reclamation Process** Okay, so I'm looking at `shrink_memcg_cb`. Right, this is a callback function – specifically, it's used with `list_lru_shrink_cb`. My brain immediately makes the connection: This is part of the memory management and reclaim process within a cgroup context. And I see that `shrink_memcg_cb` calls `zswap_writeback_entry`. That suggests this callback is involved in writing memory pages to zswap when a memcg is under memory pressure, which means it is attempting to free up memory. Since the pages will have to go somewhere, let me check `folio_end_writeback`. This is probably where the details are regarding the actual action of the writeback and how it interacts with the underlying page structure, and therefore it is the crucial part that ensures the memory is actually written back, potentially to the swap device. |
| 20/2 | 2026/08/25 14:37 | tool | grepper |
0mArgs:{
"Expression": "folio_end_writeback",
"PathPrefix": "mm/filemap.c"
}Results: {
"Output": "mm/filemap.c=1645=EXPORT_SYMBOL_GPL(folio_end_dropbehind);\n--\nmm/filemap.c-1647-/**\nmm/filemap.c:1648: * folio_end_writeback_no_dropbehind - End writeback against a folio.\nmm/filemap.c-1649- * @folio: The folio.\n--\nmm/filemap.c-1655- */\nmm/filemap.c:1656:void folio_end_writeback_no_dropbehind(struct folio *folio)\nmm/filemap.c-1657-{\n--\nmm/filemap.c-1671-\nmm/filemap.c:1672:\tif (__folio_end_writeback(folio))\nmm/filemap.c-1673-\t\tfolio_wake_bit(folio, PG_writeback);\n--\nmm/filemap.c-1676-}\nmm/filemap.c:1677:EXPORT_SYMBOL_GPL(folio_end_writeback_no_dropbehind);\nmm/filemap.c-1678-\nmm/filemap.c-1679-/**\nmm/filemap.c:1680: * folio_end_writeback - End writeback against a folio.\nmm/filemap.c-1681- * @folio: The folio.\n--\nmm/filemap.c-1686- */\nmm/filemap.c:1687:void folio_end_writeback(struct folio *folio)\nmm/filemap.c-1688-{\n--\nmm/filemap.c-1701-\t/*\nmm/filemap.c:1702:\t * Sample this before folio_end_writeback_no_dropbehind() clears\nmm/filemap.c-1703-\t * PG_writeback: until then a racing swapin cannot remove the folio from\n--\nmm/filemap.c-1710-\nmm/filemap.c:1711:\tfolio_end_writeback_no_dropbehind(folio);\nmm/filemap.c-1712-\n--\nmm/filemap.c-1720-}\nmm/filemap.c:1721:EXPORT_SYMBOL(folio_end_writeback);\nmm/filemap.c-1722-\n"
} |
| 21/2 | 2026/08/25 14:37 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 17849 output: 35 thoughts: 74 Thoughts: Okay, here's my understanding, tailored for an expert audience: **Analyzing Potential Focus Symbols in Memory Management** Alright, I'm zeroing in on a few promising candidates for tracking, likely for performance analysis or debugging purposes. First, `folio_end_writeback` feels like a solid choice – it's a critical point in the writeback process, a good place to begin. Then, `swap_writeback_dropbehind_folio` looks equally relevant, specifically tied to swap I/O and folio operations, which could be very telling. And, let's add `remove_mapping_reclaim` to the list; handling page reclamation is always a complex area that merits close inspection. Now, regarding `__swap_cache_alloc_folio`, I'm a bit curious. It's not declared static, which suggests it might be callable from outside its compilation unit. But, whether it's actually *exported* is the key question. I need to quickly check the symbols table to verify if it's visible, as this will influence its utility in our analysis. |
| 22/2 | 2026/08/25 14:37 | tool | grepper |
0mArgs:{
"Expression": "__swap_cache_alloc_folio",
"PathPrefix": "mm/swap_state.c"
}Results: {
"Output": "mm/swap_state.c=403=static struct folio *__swap_cache_alloc(struct swap_cluster_info *ci,\n--\nmm/swap_state.c-489-/**\nmm/swap_state.c:490: * __swap_cache_alloc_folio - Allocate folio for swapped out slot in swap cache.\nmm/swap_state.c-491- * @targ_entry: swap entry indicating the target slot\n--\nmm/swap_state.c-509- */\nmm/swap_state.c:510:struct folio *__swap_cache_alloc_folio(swp_entry_t targ_entry, gfp_t gfp,\nmm/swap_state.c-511-\t\t\t\t unsigned long orders, struct vm_fault *vmf,\n--\nmm/swap_state.c=679=static struct folio *swap_cache_read_folio(swp_entry_t entry, gfp_t gfp,\n--\nmm/swap_state.c-688-\t\t\treturn folio;\nmm/swap_state.c:689:\t\tfolio = __swap_cache_alloc_folio(entry, gfp, BIT(0), NULL, mpol, ilx);\nmm/swap_state.c-690-\t} while (PTR_ERR(folio) == -EEXIST);\n--\nmm/swap_state.c=721=struct folio *swapin_sync(swp_entry_t entry, gfp_t gfp, unsigned long orders,\n--\nmm/swap_state.c-729-\t\t\treturn folio;\nmm/swap_state.c:730:\t\tfolio = __swap_cache_alloc_folio(entry, gfp, orders, vmf, mpol, ilx);\nmm/swap_state.c-731-\t} while (PTR_ERR(folio) == -EEXIST);\n"
} |
| 23/2 | 2026/08/25 14:37 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 18654 output: 32 thoughts: 63 Thoughts: **Focusing on a Key Symbol for Analysis** Okay, so I'm looking at `__swap_cache_alloc_folio`. The key thing here is that it's *not* exported, which immediately flags it as something interesting internally within the kernel. It’s non-static, however, meaning it's potentially accessible within a larger compilation unit. The fact that it's used within `mm/zswap.c` narrows my focus considerably. Zswap is memory compression, so this likely has something to do with the interaction of memory management and compressed swap. This makes `__swap_cache_alloc_folio` a prime candidate to dissect and understand further. I'm thinking, "Is this the allocation function for swapcache folios?" Given that context, I'll go ahead and check `remove_mapping_reclaim` next. This seems like a reasonable next step given the relationship with the memory management subsystem. |
| 24/2 | 2026/08/25 14:37 | tool | grepper |
0mArgs:{
"Expression": "remove_mapping_reclaim",
"PathPrefix": "mm/vmscan.c"
}Results: {
"Output": "mm/vmscan.c=811=long remove_mapping(struct address_space *mapping, struct folio *folio)\n--\nmm/vmscan.c-816-/**\nmm/vmscan.c:817: * remove_mapping_reclaim() - Remove a folio from its mapping, as reclaim does.\nmm/vmscan.c-818- * @mapping: The address space.\n--\nmm/vmscan.c-830- */\nmm/vmscan.c:831:long remove_mapping_reclaim(struct address_space *mapping, struct folio *folio,\nmm/vmscan.c-832-\t\t\t struct mem_cgroup *target_memcg)\n"
} |
| 25/2 | 2026/08/25 14:37 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 19125 output: 36 thoughts: 29 Thoughts: Here's my take on those thoughts, from an expert's perspective: **Debugging Memory Reclamation in the Block Layer** Okay, so `remove_mapping_reclaim` isn't static. That immediately piques my interest. It implies that this function is visible and potentially used outside of the compilation unit it's defined in. That's good to know for context. I need to understand its relationship to other functions, especially in the context of reclaiming memory associated with a block device. Since this is related to removing and reclaiming, my next obvious step is to dig into `swap_writepage_bdev_async`. This function handles asynchronous writes to block devices during swap operations. It's likely involved in freeing up pages, and `remove_mapping_reclaim` could very well be part of that cycle. Understanding how these two interact will give me a better grasp of the memory management and reclaiming process when writing back swap pages. I'm looking for the call chain and how the reclaim operation is initiated. Knowing the context will help me with any potential bug-hunting or optimization efforts in this area. |
| 26/2 | 2026/08/25 14:37 | tool | grepper |
0mArgs:{
"Expression": "swap_writepage_bdev_async",
"PathPrefix": "mm/page_io.c"
}Results: {
"Output": "mm/page_io.c=429=static void swap_writepage_bdev_sync(struct folio *folio,\n--\nmm/page_io.c-448-\nmm/page_io.c:449:static void swap_writepage_bdev_async(struct folio *folio,\nmm/page_io.c-450-\t\tstruct swap_info_struct *sis)\n--\nmm/page_io.c=473=void __swap_writepage(struct folio *folio, struct swap_iocb **swap_plug)\n--\nmm/page_io.c-492-\telse\nmm/page_io.c:493:\t\tswap_writepage_bdev_async(folio, sis);\nmm/page_io.c-494-}\n"
} |
| 27/2 | 2026/08/25 14:37 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 19627 output: 32 thoughts: 204 Thoughts: **My Analysis of Swap Writeback and ZSWAP Configuration** Okay, so `swap_writepage_bdev_async` is a static function, which immediately narrows down my focus. I need to look closely at the related symbols. My attention goes to: `swap_writeback_dropbehind_folio`, `remove_mapping_reclaim`, `__swap_cache_alloc_folio`, and `folio_end_writeback`. These are the key functions I need to understand in relation to the swap writeback process. Next, I need to consider the relevant configuration options. I'm focusing on `ZSWAP`, `SWAP`, and `MEMCG`. I need to verify a point here. I want to be certain about the allocator that `ZSWAP` uses. Does it *require* `ZSMALLOC`, or a similar allocator? Checking `mm/Kconfig`, I can see: `config ZSWAP` `depends on SWAP` `select CRYPTO` `select ZPOOL` Ah, it depends on `SWAP`, and selects `CRYPTO` and `ZPOOL`. So it doesn't strictly *require* `ZSMALLOC`, but `ZSMALLOC` (or similar) is a commonly used allocator for it. That makes sense. Finally, I need to make a recommendation about enabling `ZSWAP_DEFAULT_ON`. Given the current context, and my understanding of its dependencies, enabling `ZSWAP_DEFAULT_ON` would be a good default. It seems like the correct choice. |
| 28/2 | 2026/08/25 14:37 | tool | grepper |
0mArgs:{
"Expression": "config ZSWAP_DEFAULT_ON",
"PathPrefix": "mm/Kconfig"
}Results: {
"Output": "mm/Kconfig=22=config ZSWAP\n--\nmm/Kconfig-34-\nmm/Kconfig:35:config ZSWAP_DEFAULT_ON\nmm/Kconfig-36-\tbool \"Enable the compressed cache for swap pages by default\"\n"
} |
| 29/2 | 2026/08/25 14:37 | llm | patch-evaluator |
1mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 20270 output: 27 thoughts: 80 Thoughts: Okay, let's see, my initial thought is to quickly verify if `ZSWAP_COMPRESSOR_DEFAULT_LZO` is enabled by default. Ah, yes, confirmed, it's set. Good, that's what I expected. Now, shifting gears, I need to understand the relationship between `CONFIG_MEMCG` and `CONFIG_CGROUPS`. Is `MEMCG` sufficient on its own, or does it depend on `CGROUPS`? No, wait... let's not assume. I should check the direct dependencies of `MEMCG` to be sure. It's best to be precise here; I'll trace through the dependencies to be absolutely certain. |
| 30/2 | 2026/08/25 14:39 | tool | grepper |
0mArgs:{
"Expression": "depends on.*",
"PathPrefix": "init/Kconfig"
}Results: {
"Output": "\nFull output is too long, showing 500 out of 585 lines.\nUse more precise expression if possible.\n\ninit/Kconfig=63=config RUSTC_VERSION\n--\ninit/Kconfig-67-\t It does not depend on `RUST` since that one may need to use the version\ninit/Kconfig:68:\t in a `depends on`.\ninit/Kconfig-69-\n--\ninit/Kconfig=111=config GCC_ASM_GOTO_OUTPUT_BROKEN\ninit/Kconfig-112-\tbool\ninit/Kconfig:113:\tdepends on CC_IS_GCC\ninit/Kconfig-114-\tdefault y if GCC_VERSION \u003c 110500\n--\ninit/Kconfig=118=config CC_HAS_ASM_GOTO_OUTPUT\ninit/Kconfig-119-\tdef_bool y\ninit/Kconfig:120:\tdepends on !GCC_ASM_GOTO_OUTPUT_BROKEN\ninit/Kconfig:121:\tdepends on $(success,echo 'int foo(int x) { asm goto (\"\": \"=r\"(x) ::: bar); return x; bar: return 0; }' | $(CC) -x c - -c -o /dev/null)\ninit/Kconfig-122-\ninit/Kconfig=123=config CC_HAS_ASM_GOTO_TIED_OUTPUT\ninit/Kconfig:124:\tdepends on CC_HAS_ASM_GOTO_OUTPUT\ninit/Kconfig-125-\t# Detect buggy gcc and clang, fixed in gcc-11 clang-14.\n--\ninit/Kconfig=228=config BROKEN_ON_SMP\ninit/Kconfig-229-\tbool\ninit/Kconfig:230:\tdepends on BROKEN || !SMP\ninit/Kconfig-231-\tdefault y\n--\ninit/Kconfig=241=config COMPILE_TEST\ninit/Kconfig-242-\tbool \"Compile also drivers which will not load\"\ninit/Kconfig:243:\tdepends on HAS_IOMEM\ninit/Kconfig-244-\thelp\n--\ninit/Kconfig=272=config UAPI_HEADER_TEST\ninit/Kconfig-273-\tbool \"Compile test UAPI headers\"\ninit/Kconfig:274:\tdepends on HEADERS_INSTALL\ninit/Kconfig-275-\thelp\n--\ninit/Kconfig=292=config LOCALVERSION_AUTO\n--\ninit/Kconfig-294-\tdefault y\ninit/Kconfig:295:\tdepends on !COMPILE_TEST\ninit/Kconfig-296-\thelp\n--\ninit/Kconfig=346=choice\n--\ninit/Kconfig-348-\tdefault KERNEL_GZIP\ninit/Kconfig:349:\tdepends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_ZSTD || HAVE_KERNEL_UNCOMPRESSED\ninit/Kconfig-350-\thelp\n--\ninit/Kconfig=368=config KERNEL_GZIP\ninit/Kconfig-369-\tbool \"Gzip\"\ninit/Kconfig:370:\tdepends on HAVE_KERNEL_GZIP\ninit/Kconfig-371-\thelp\n--\ninit/Kconfig=375=config KERNEL_BZIP2\ninit/Kconfig-376-\tbool \"Bzip2\"\ninit/Kconfig:377:\tdepends on HAVE_KERNEL_BZIP2\ninit/Kconfig-378-\thelp\n--\ninit/Kconfig=385=config KERNEL_LZMA\ninit/Kconfig-386-\tbool \"LZMA\"\ninit/Kconfig:387:\tdepends on HAVE_KERNEL_LZMA\ninit/Kconfig-388-\thelp\n--\ninit/Kconfig=393=config KERNEL_XZ\ninit/Kconfig-394-\tbool \"XZ\"\ninit/Kconfig:395:\tdepends on HAVE_KERNEL_XZ\ninit/Kconfig-396-\thelp\n--\ninit/Kconfig=409=config KERNEL_LZO\ninit/Kconfig-410-\tbool \"LZO\"\ninit/Kconfig:411:\tdepends on HAVE_KERNEL_LZO\ninit/Kconfig-412-\thelp\n--\ninit/Kconfig=417=config KERNEL_LZ4\ninit/Kconfig-418-\tbool \"LZ4\"\ninit/Kconfig:419:\tdepends on HAVE_KERNEL_LZ4\ninit/Kconfig-420-\thelp\n--\ninit/Kconfig=429=config KERNEL_ZSTD\ninit/Kconfig-430-\tbool \"ZSTD\"\ninit/Kconfig:431:\tdepends on HAVE_KERNEL_ZSTD\ninit/Kconfig-432-\thelp\n--\ninit/Kconfig=439=config KERNEL_UNCOMPRESSED\ninit/Kconfig-440-\tbool \"None\"\ninit/Kconfig:441:\tdepends on HAVE_KERNEL_UNCOMPRESSED\ninit/Kconfig-442-\thelp\n--\ninit/Kconfig=485=config SYSVIPC_SYSCTL\ninit/Kconfig-486-\tbool\ninit/Kconfig:487:\tdepends on SYSVIPC\ninit/Kconfig:488:\tdepends on SYSCTL\ninit/Kconfig-489-\tdefault y\n--\ninit/Kconfig=491=config SYSVIPC_COMPAT\ninit/Kconfig-492-\tdef_bool y\ninit/Kconfig:493:\tdepends on COMPAT \u0026\u0026 SYSVIPC\ninit/Kconfig-494-\ninit/Kconfig=495=config POSIX_MQUEUE\ninit/Kconfig-496-\tbool \"POSIX Message Queues\"\ninit/Kconfig:497:\tdepends on NET\ninit/Kconfig-498-\thelp\n--\ninit/Kconfig=511=config POSIX_MQUEUE_SYSCTL\ninit/Kconfig-512-\tbool\ninit/Kconfig:513:\tdepends on POSIX_MQUEUE\ninit/Kconfig:514:\tdepends on SYSCTL\ninit/Kconfig-515-\tdefault y\n--\ninit/Kconfig=529=config CROSS_MEMORY_ATTACH\ninit/Kconfig-530-\tbool \"Enable process_vm_readv/writev syscalls\"\ninit/Kconfig:531:\tdepends on MMU\ninit/Kconfig-532-\tdefault y\n--\ninit/Kconfig=539=config AUDIT\ninit/Kconfig-540-\tbool \"Auditing support\"\ninit/Kconfig:541:\tdepends on NET\ninit/Kconfig-542-\thelp\n--\ninit/Kconfig=551=config AUDITSYSCALL\ninit/Kconfig-552-\tdef_bool y\ninit/Kconfig:553:\tdepends on AUDIT \u0026\u0026 HAVE_ARCH_AUDITSYSCALL\ninit/Kconfig-554-\tselect FSNOTIFY\n--\ninit/Kconfig=572=config TICK_CPU_ACCOUNTING\ninit/Kconfig-573-\tbool \"Simple tick based cputime accounting\"\ninit/Kconfig:574:\tdepends on !S390 \u0026\u0026 !NO_HZ_FULL\ninit/Kconfig-575-\thelp\n--\ninit/Kconfig=582=config VIRT_CPU_ACCOUNTING_NATIVE\ninit/Kconfig-583-\tbool \"Deterministic task and CPU time accounting\"\ninit/Kconfig:584:\tdepends on HAVE_VIRT_CPU_ACCOUNTING \u0026\u0026 !NO_HZ_FULL\ninit/Kconfig-585-\tselect VIRT_CPU_ACCOUNTING\n--\ninit/Kconfig=595=config VIRT_CPU_ACCOUNTING_GEN\ninit/Kconfig-596-\tbool \"Full dynticks CPU time accounting\"\ninit/Kconfig:597:\tdepends on HAVE_CONTEXT_TRACKING_USER\ninit/Kconfig:598:\tdepends on HAVE_VIRT_CPU_ACCOUNTING_GEN\ninit/Kconfig:599:\tdepends on GENERIC_CLOCKEVENTS\ninit/Kconfig-600-\tselect VIRT_CPU_ACCOUNTING\n--\ninit/Kconfig=616=config IRQ_TIME_ACCOUNTING\ninit/Kconfig-617-\tbool \"Fine granularity task level IRQ time accounting\"\ninit/Kconfig:618:\tdepends on HAVE_IRQ_TIME_ACCOUNTING \u0026\u0026 !VIRT_CPU_ACCOUNTING_NATIVE\ninit/Kconfig-619-\thelp\n--\ninit/Kconfig=627=config HAVE_SCHED_AVG_IRQ\ninit/Kconfig-628-\tdef_bool y\ninit/Kconfig:629:\tdepends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING\ninit/Kconfig:630:\tdepends on SMP\ninit/Kconfig-631-\ninit/Kconfig=632=config SCHED_HW_PRESSURE\n--\ninit/Kconfig-635-\tdefault y if ARM64\ninit/Kconfig:636:\tdepends on SMP\ninit/Kconfig:637:\tdepends on CPU_FREQ_THERMAL\ninit/Kconfig-638-\thelp\n--\ninit/Kconfig=651=config BSD_PROCESS_ACCT\ninit/Kconfig-652-\tbool \"BSD Process Accounting (DEPRECATED)\"\ninit/Kconfig:653:\tdepends on MULTIUSER\ninit/Kconfig-654-\tdefault n\n--\ninit/Kconfig=668=config BSD_PROCESS_ACCT_V3\ninit/Kconfig-669-\tbool \"BSD Process Accounting version 3 file format\"\ninit/Kconfig:670:\tdepends on BSD_PROCESS_ACCT\ninit/Kconfig-671-\tdefault n\n--\ninit/Kconfig=680=config TASKSTATS\ninit/Kconfig-681-\tbool \"Export task/process statistics through netlink\"\ninit/Kconfig:682:\tdepends on NET\ninit/Kconfig:683:\tdepends on MULTIUSER\ninit/Kconfig-684-\tdefault n\n--\ninit/Kconfig=694=config TASK_DELAY_ACCT\ninit/Kconfig-695-\tbool \"Enable per-task delay accounting\"\ninit/Kconfig:696:\tdepends on TASKSTATS\ninit/Kconfig-697-\tselect SCHED_INFO\n--\ninit/Kconfig=706=config TASK_XACCT\ninit/Kconfig-707-\tbool \"Enable extended accounting over taskstats\"\ninit/Kconfig:708:\tdepends on TASKSTATS\ninit/Kconfig-709-\thelp\n--\ninit/Kconfig=715=config TASK_IO_ACCOUNTING\ninit/Kconfig-716-\tbool \"Enable per-task storage I/O accounting\"\ninit/Kconfig:717:\tdepends on TASK_XACCT\ninit/Kconfig-718-\thelp\n--\ninit/Kconfig=744=config PSI_DEFAULT_DISABLED\n--\ninit/Kconfig-746-\tdefault n\ninit/Kconfig:747:\tdepends on PSI\ninit/Kconfig-748-\thelp\n--\ninit/Kconfig=766=config CPU_ISOLATION\ninit/Kconfig-767-\tbool \"CPU isolation\"\ninit/Kconfig:768:\tdepends on SMP\ninit/Kconfig-769-\tdefault y\n--\ninit/Kconfig=792=config IKCONFIG_PROC\ninit/Kconfig-793-\tbool \"Enable access to .config through /proc/config.gz\"\ninit/Kconfig:794:\tdepends on IKCONFIG \u0026\u0026 PROC_FS\ninit/Kconfig-795-\thelp\n--\ninit/Kconfig=799=config IKHEADERS\ninit/Kconfig-800-\ttristate \"Enable kernel headers through /sys/kernel/kheaders.tar.xz\"\ninit/Kconfig:801:\tdepends on SYSFS\ninit/Kconfig-802-\thelp\n--\ninit/Kconfig=808=config LOG_BUF_SHIFT\n--\ninit/Kconfig-811-\tdefault 17\ninit/Kconfig:812:\tdepends on PRINTK\ninit/Kconfig-813-\thelp\n--\ninit/Kconfig=827=config LOG_CPU_MAX_BUF_SHIFT\ninit/Kconfig-828-\tint \"CPU kernel log buffer size contribution (13 =\u003e 8 KB, 17 =\u003e 128KB)\"\ninit/Kconfig:829:\tdepends on SMP\ninit/Kconfig-830-\trange 0 21\n--\ninit/Kconfig-832-\tdefault 12\ninit/Kconfig:833:\tdepends on PRINTK\ninit/Kconfig-834-\thelp\n--\ninit/Kconfig=863=config PRINTK_INDEX\ninit/Kconfig-864-\tbool \"Printk indexing debugfs interface\"\ninit/Kconfig:865:\tdepends on PRINTK \u0026\u0026 DEBUG_FS\ninit/Kconfig-866-\thelp\n--\ninit/Kconfig=888=config UCLAMP_TASK\ninit/Kconfig-889-\tbool \"Enable utilization clamping for RT/FAIR tasks\"\ninit/Kconfig:890:\tdepends on CPU_FREQ_GOV_SCHEDUTIL\ninit/Kconfig-891-\thelp\n--\ninit/Kconfig=906=config UCLAMP_BUCKETS_COUNT\n--\ninit/Kconfig-909-\tdefault 5\ninit/Kconfig:910:\tdepends on UCLAMP_TASK\ninit/Kconfig-911-\thelp\n--\ninit/Kconfig=937=config SCHED_PROXY_EXEC\n--\ninit/Kconfig-939-\t# Avoid some build failures w/ PREEMPT_RT until it can be fixed\ninit/Kconfig:940:\tdepends on !PREEMPT_RT\ninit/Kconfig-941-\t# Need to investigate how to inform sched_ext of split contexts\ninit/Kconfig:942:\tdepends on !SCHED_CLASS_EXT\ninit/Kconfig-943-\t# Not particularly useful until we get to multi-rq proxying\ninit/Kconfig:944:\tdepends on EXPERT\ninit/Kconfig-945-\thelp\n--\ninit/Kconfig=1014=config NUMA_BALANCING\ninit/Kconfig-1015-\tbool \"Memory placement aware NUMA scheduler\"\ninit/Kconfig:1016:\tdepends on ARCH_SUPPORTS_NUMA_BALANCING\ninit/Kconfig:1017:\tdepends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY\ninit/Kconfig:1018:\tdepends on SMP \u0026\u0026 NUMA_MIGRATION \u0026\u0026 !PREEMPT_RT\ninit/Kconfig-1019-\thelp\n--\ninit/Kconfig=1026=config SCHED_CACHE\n--\ninit/Kconfig-1028-\tdefault y\ninit/Kconfig:1029:\tdepends on SMP\ninit/Kconfig-1030-\thelp\n--\ninit/Kconfig=1037=config NUMA_BALANCING_DEFAULT_ENABLED\n--\ninit/Kconfig-1039-\tdefault y\ninit/Kconfig:1040:\tdepends on NUMA_BALANCING\ninit/Kconfig-1041-\thelp\n--\ninit/Kconfig=1086=config MEMCG_NMI_UNSAFE\ninit/Kconfig-1087-\tbool\ninit/Kconfig:1088:\tdepends on MEMCG\ninit/Kconfig:1089:\tdepends on HAVE_NMI\ninit/Kconfig:1090:\tdepends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS \u0026\u0026 !ARCH_HAVE_NMI_SAFE_CMPXCHG\ninit/Kconfig-1091-\tdefault y\n--\ninit/Kconfig=1093=config MEMCG_NMI_SAFETY_REQUIRES_ATOMIC\ninit/Kconfig-1094-\tbool\ninit/Kconfig:1095:\tdepends on MEMCG\ninit/Kconfig:1096:\tdepends on HAVE_NMI\ninit/Kconfig:1097:\tdepends on !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS \u0026\u0026 ARCH_HAVE_NMI_SAFE_CMPXCHG\ninit/Kconfig-1098-\tdefault y\n--\ninit/Kconfig=1100=config MEMCG_V1\ninit/Kconfig-1101-\tbool \"Legacy cgroup v1 memory controller\"\ninit/Kconfig:1102:\tdepends on MEMCG\ninit/Kconfig-1103-\tdefault n\n--\ninit/Kconfig=1117=config BLK_CGROUP\ninit/Kconfig-1118-\tbool \"IO controller\"\ninit/Kconfig:1119:\tdepends on BLOCK\ninit/Kconfig-1120-\tdefault n\n--\ninit/Kconfig=1139=config CGROUP_WRITEBACK\ninit/Kconfig-1140-\tbool\ninit/Kconfig:1141:\tdepends on MEMCG \u0026\u0026 BLK_CGROUP\ninit/Kconfig-1142-\tdefault y\n--\ninit/Kconfig=1159=config FAIR_GROUP_SCHED\ninit/Kconfig-1160-\tbool \"Group scheduling for SCHED_OTHER\"\ninit/Kconfig:1161:\tdepends on CGROUP_SCHED\ninit/Kconfig-1162-\tselect GROUP_SCHED_WEIGHT\n--\ninit/Kconfig=1165=config CFS_BANDWIDTH\ninit/Kconfig-1166-\tbool \"CPU bandwidth provisioning for FAIR_GROUP_SCHED\"\ninit/Kconfig:1167:\tdepends on FAIR_GROUP_SCHED\ninit/Kconfig-1168-\tselect GROUP_SCHED_BANDWIDTH\n--\ninit/Kconfig=1177=config RT_GROUP_SCHED\ninit/Kconfig-1178-\tbool \"Group scheduling for SCHED_RR/FIFO\"\ninit/Kconfig:1179:\tdepends on CGROUP_SCHED\ninit/Kconfig-1180-\tdefault n\n--\ninit/Kconfig=1188=config RT_GROUP_SCHED_DEFAULT_DISABLED\ninit/Kconfig-1189-\tbool \"Require boot parameter to enable group scheduling for SCHED_RR/FIFO\"\ninit/Kconfig:1190:\tdepends on RT_GROUP_SCHED\ninit/Kconfig-1191-\tdefault n\n--\ninit/Kconfig=1199=config EXT_GROUP_SCHED\ninit/Kconfig-1200-\tbool\ninit/Kconfig:1201:\tdepends on SCHED_CLASS_EXT \u0026\u0026 CGROUP_SCHED\ninit/Kconfig-1202-\tselect GROUP_SCHED_WEIGHT\n--\ninit/Kconfig=1208=config EXT_SUB_SCHED\ninit/Kconfig-1209- def_bool y\ninit/Kconfig:1210: depends on SCHED_CLASS_EXT \u0026\u0026 CGROUPS\ninit/Kconfig-1211-\ninit/Kconfig=1212=config SCHED_MM_CID\ninit/Kconfig-1213-\tdef_bool y\ninit/Kconfig:1214:\tdepends on SMP \u0026\u0026 RSEQ\ninit/Kconfig-1215-\ninit/Kconfig=1216=config UCLAMP_TASK_GROUP\ninit/Kconfig-1217-\tbool \"Utilization clamping per group of tasks\"\ninit/Kconfig:1218:\tdepends on CGROUP_SCHED\ninit/Kconfig:1219:\tdepends on UCLAMP_TASK\ninit/Kconfig-1220-\tdefault n\n--\ninit/Kconfig=1285=config CGROUP_HUGETLB\ninit/Kconfig-1286-\tbool \"HugeTLB controller\"\ninit/Kconfig:1287:\tdepends on HUGETLB_PAGE\ninit/Kconfig-1288-\tselect PAGE_COUNTER\n--\ninit/Kconfig=1301=config CPUSETS\ninit/Kconfig-1302-\tbool \"Cpuset controller\"\ninit/Kconfig:1303:\tdepends on SMP\ninit/Kconfig-1304-\tselect UNION_FIND\n--\ninit/Kconfig=1314=config CPUSETS_V1\ninit/Kconfig-1315-\tbool \"Legacy cgroup v1 cpusets controller\"\ninit/Kconfig:1316:\tdepends on CPUSETS\ninit/Kconfig-1317-\tdefault n\n--\ninit/Kconfig=1328=config PROC_PID_CPUSET\ninit/Kconfig-1329-\tbool \"Include legacy /proc/\u003cpid\u003e/cpuset file\"\ninit/Kconfig:1330:\tdepends on CPUSETS_V1\ninit/Kconfig-1331-\tdefault y\n--\ninit/Kconfig=1345=config CGROUP_PERF\ninit/Kconfig-1346-\tbool \"Perf controller\"\ninit/Kconfig:1347:\tdepends on PERF_EVENTS\ninit/Kconfig-1348-\thelp\n--\ninit/Kconfig=1356=config CGROUP_BPF\ninit/Kconfig-1357-\tbool \"Support for eBPF programs attached to cgroups\"\ninit/Kconfig:1358:\tdepends on BPF_SYSCALL\ninit/Kconfig-1359-\tselect SOCK_CGROUP_DATA\n--\ninit/Kconfig-1363-\ninit/Kconfig:1364:\t In which context these programs are accessed depends on the type\ninit/Kconfig-1365-\t of attachment. For instance, programs that are attached using\n--\ninit/Kconfig=1383=config CGROUP_DEBUG\n--\ninit/Kconfig-1385-\tdefault n\ninit/Kconfig:1386:\tdepends on DEBUG_KERNEL\ninit/Kconfig-1387-\thelp\n--\ninit/Kconfig=1401=menuconfig NAMESPACES\ninit/Kconfig-1402-\tbool \"Namespaces support\" if EXPERT\ninit/Kconfig:1403:\tdepends on MULTIUSER\ninit/Kconfig-1404-\tdefault !EXPERT\n--\ninit/Kconfig=1430=config IPC_NS\ninit/Kconfig-1431-\tbool \"IPC namespace\"\ninit/Kconfig:1432:\tdepends on (SYSVIPC || POSIX_MQUEUE)\ninit/Kconfig-1433-\tdefault y\n--\ninit/Kconfig=1460=config NET_NS\ninit/Kconfig-1461-\tbool \"Network namespace\"\ninit/Kconfig:1462:\tdepends on NET\ninit/Kconfig-1463-\tdefault y\n--\ninit/Kconfig=1470=config CHECKPOINT_RESTORE\ninit/Kconfig-1471-\tbool \"Checkpoint/restore support\"\ninit/Kconfig:1472:\tdepends on PROC_FS\ninit/Kconfig-1473-\tselect PROC_CHILDREN\n--\ninit/Kconfig=1541=config BOOT_CONFIG_FORCE\ninit/Kconfig-1542-\tbool \"Force unconditional bootconfig processing\"\ninit/Kconfig:1543:\tdepends on BOOT_CONFIG\ninit/Kconfig-1544-\tdefault y if BOOT_CONFIG_EMBED\n--\ninit/Kconfig=1554=config BOOT_CONFIG_EMBED\ninit/Kconfig-1555-\tbool \"Embed bootconfig file in the kernel\"\ninit/Kconfig:1556:\tdepends on BOOT_CONFIG\ninit/Kconfig-1557-\thelp\n--\ninit/Kconfig=1565=config BOOT_CONFIG_EMBED_FILE\ninit/Kconfig-1566-\tstring \"Embedded bootconfig file path\"\ninit/Kconfig:1567:\tdepends on BOOT_CONFIG_EMBED\ninit/Kconfig-1568-\thelp\n--\ninit/Kconfig=1591=config INITRAMFS_PRESERVE_MTIME\ninit/Kconfig-1592-\tbool \"Preserve cpio archive mtimes in initramfs\"\ninit/Kconfig:1593:\tdepends on BLK_DEV_INITRD\ninit/Kconfig-1594-\tdefault y\n--\ninit/Kconfig=1602=config INITRAMFS_TEST\ninit/Kconfig-1603-\tbool \"Test initramfs cpio archive extraction\" if !KUNIT_ALL_TESTS\ninit/Kconfig:1604:\tdepends on BLK_DEV_INITRD \u0026\u0026 KUNIT=y\ninit/Kconfig-1605-\tdefault KUNIT_ALL_TESTS\n--\ninit/Kconfig=1638=config LD_DEAD_CODE_DATA_ELIMINATION\ninit/Kconfig-1639-\tbool \"Dead code and data elimination (EXPERIMENTAL)\"\ninit/Kconfig:1640:\tdepends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION\ninit/Kconfig:1641:\tdepends on EXPERT\ninit/Kconfig:1642:\tdepends on $(cc-option,-ffunction-sections -fdata-sections)\ninit/Kconfig:1643:\tdepends on $(ld-option,--gc-sections)\ninit/Kconfig-1644-\thelp\n--\ninit/Kconfig=1656=config LD_ORPHAN_WARN\ninit/Kconfig-1657-\tdef_bool y\ninit/Kconfig:1658:\tdepends on ARCH_WANT_LD_ORPHAN_WARN\ninit/Kconfig:1659:\tdepends on $(ld-option,--orphan-handling=warn)\ninit/Kconfig:1660:\tdepends on $(ld-option,--orphan-handling=error)\ninit/Kconfig-1661-\ninit/Kconfig=1662=config LD_ORPHAN_WARN_LEVEL\ninit/Kconfig-1663-\tstring\ninit/Kconfig:1664:\tdepends on LD_ORPHAN_WARN\ninit/Kconfig-1665-\tdefault \"error\" if WERROR\n--\ninit/Kconfig=1714=config UID16\ninit/Kconfig-1715-\tbool \"Enable 16-bit UID system calls\" if EXPERT\ninit/Kconfig:1716:\tdepends on HAVE_UID16 \u0026\u0026 MULTIUSER\ninit/Kconfig-1717-\tdefault y\n--\ninit/Kconfig=1786=config PRINTK_RINGBUFFER_KUNIT_TEST\ninit/Kconfig-1787-\ttristate \"KUnit Test for the printk ringbuffer\" if !KUNIT_ALL_TESTS\ninit/Kconfig:1788:\tdepends on PRINTK \u0026\u0026 KUNIT\ninit/Kconfig-1789-\tdefault KUNIT_ALL_TESTS\n--\ninit/Kconfig=1808=config ELF_CORE\ninit/Kconfig:1809:\tdepends on COREDUMP\ninit/Kconfig-1810-\tdefault y\n--\ninit/Kconfig=1816=config PCSPKR_PLATFORM\ninit/Kconfig-1817-\tbool \"Enable PC-Speaker support\" if EXPERT\ninit/Kconfig:1818:\tdepends on HAVE_PCSPKR_PLATFORM\ninit/Kconfig-1819-\tselect I8253_LOCK\n--\ninit/Kconfig=1832=config FUTEX\ninit/Kconfig-1833-\tbool \"Enable futex support\" if EXPERT\ninit/Kconfig:1834:\tdepends on !(SPARC32 \u0026\u0026 SMP)\ninit/Kconfig-1835-\tdefault y\n--\ninit/Kconfig=1842=config FUTEX_PI\ninit/Kconfig-1843-\tbool\ninit/Kconfig:1844:\tdepends on FUTEX \u0026\u0026 RT_MUTEXES\ninit/Kconfig-1845-\tdefault y\n--\ninit/Kconfig=1847=config FUTEX_PRIVATE_HASH\ninit/Kconfig-1848-\tbool\ninit/Kconfig:1849:\tdepends on FUTEX \u0026\u0026 !BASE_SMALL \u0026\u0026 MMU\ninit/Kconfig-1850-\tdefault y\n--\ninit/Kconfig=1852=config FUTEX_MPOL\ninit/Kconfig-1853-\tbool\ninit/Kconfig:1854:\tdepends on FUTEX \u0026\u0026 NUMA\ninit/Kconfig-1855-\tdefault y\n--\ninit/Kconfig=1897=config SHMEM\n--\ninit/Kconfig-1899-\tdefault y\ninit/Kconfig:1900:\tdepends on MMU\ninit/Kconfig-1901-\thelp\n--\ninit/Kconfig=1925=config GCOV_PROFILE_URING\ninit/Kconfig-1926-\tbool \"Enable GCOV profiling on the io_uring subsystem\"\ninit/Kconfig:1927:\tdepends on IO_URING \u0026\u0026 GCOV_KERNEL\ninit/Kconfig-1928-\thelp\n--\ninit/Kconfig=1938=config IO_URING_MOCK_FILE\n--\ninit/Kconfig-1940-\tdefault n\ninit/Kconfig:1941:\tdepends on IO_URING\ninit/Kconfig-1942-\thelp\n--\ninit/Kconfig=1981=config RSEQ\n--\ninit/Kconfig-1983-\tdefault y\n\n"
} |
| 31/2 | 2026/08/25 14:39 | llm | patch-evaluator |
3mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 27944 output: 27 thoughts: 45 Thoughts: Okay, here's my interpretation of those thoughts, presented as a first-person summary, keeping in mind my expertise: **My Initial Assessment of MEMCG Dependency** Alright, so the MEMCG subsystem… it seems straightforward, right? No overly complex prerequisite modules or exotic hardware dependencies. Just the usual suspects: `HAVE_NMI` and the like. It's built into the kernel, relying on the availability of common functionalities. *But wait a second...* I have a nagging feeling. Is it actually nested within the `CGROUPS` framework? My memory is a bit hazy on that specific point. It’s certainly a core component these days. I need to confirm if it *is* indeed a sub-module of `CGROUPS` to be certain. Let’s double-check the configuration options – `init/Kconfig` is the best place to start. That'll quickly clarify the dependency tree and remove any ambiguity. I need to refresh my memory on the exact configuration details. |
| 32/2 | 2026/08/25 14:42 | tool | grepper |
0mArgs:{
"Expression": "config MEMCG",
"PathPrefix": "init/Kconfig"
}Results: {
"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"
} |
| 33/2 | 2026/08/25 14:42 | llm | patch-evaluator |
3mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 28457 output: 29 thoughts: 18 Thoughts: Here's my take on those thoughts: **Checking CGROUP Configuration** Okay, so I need to verify something related to `MEMCG`. My immediate thought is, "Is `MEMCG` enabled within the `menuconfig CGROUPS` settings?" That seems like the logical first step, the foundational check. I need to confirm if it's even configured before I go any further down this rabbit hole. It's a fundamental part of the configuration, so checking its presence here is the best place to start. I'm going to start there and go from there. |
| 34/2 | 2026/08/25 14:45 | tool | grepper |
0mArgs:{
"Expression": "menuconfig CGROUPS",
"PathPrefix": "init/Kconfig"
}Results: {
"Output": "init/Kconfig=1045=config SLAB_OBJ_EXT\n--\ninit/Kconfig-1047-\ninit/Kconfig:1048:menuconfig CGROUPS\ninit/Kconfig-1049-\tbool \"Control Group support\"\n"
} |
| 35/2 | 2026/08/25 14:45 | llm | patch-evaluator |
3mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 28703 output: 37 thoughts: 1405 Thoughts: **My Analysis of Zswap Configuration and Focus Symbols** Okay, so we're looking at configuring Zswap and identifying key functions for fuzzing. Seems straightforward. First, I need to ensure the right configs are in place. Yes, `CGROUPS` is essential, no question about it. Let's pull together the necessary configurations: `ZSWAP`, `SWAP`, `MEMCG`, and `CGROUPS`. I need to ensure they are all present. Right, and I should remember that `ZSWAP` depends on `SWAP`, and `MEMCG` depends on `CGROUPS`, so the order matters. Thus, `ZSWAP`, `SWAP`, `MEMCG`, `CGROUPS` is the correct set. Let's consider whether to enable `ZSWAP` by default. Yes, `ZSWAP_DEFAULT_ON` is important to ensure Zswap is actually used by default. Now, let's keep `ZSWAP_COMPRESSOR_DEFAULT_LZO` in mind. It's a default. Next, I need to identify the key functions for fuzzing. I've got a list of potential candidates: `swap_writeback_dropbehind_folio`, `remove_mapping_reclaim`, `__swap_cache_alloc_folio`, and `folio_end_writeback`. Let's confirm that `__swap_cache_alloc_folio` is indeed non-static, which is an important criterion. Yes, it's non-static in `mm/swap_state.c` and is declared in `mm/swap.h`. `swap_writeback_dropbehind_folio` is non-static in `mm/swap_state.c` and declared in `include/linux/swap.h`. `remove_mapping_reclaim` is non-static in `mm/vmscan.c` and declared in `include/linux/swap.h`. And `folio_end_writeback` is non-static in `mm/filemap.c` and exported. Hmm, there's `zswap_writeback_entry`, which is static but it triggers dropbehind. Since it's static we can't use it. But, it is called by `shrink_memcg_cb`, which is static, so that's not useful either. What about `zswap_shrinker_scan`? That's static as well. Let's trace the call paths. `folio_end_writeback` is an entry point, called when writeback completes. `swap_writeback_dropbehind_folio` is called from `folio_end_writeback`. Then, `remove_mapping_reclaim` is called from `swap_writeback_dropbehind_folio`. Finally, `__swap_cache_alloc_folio` is called from `zswap_writeback_entry`, `swap_cache_read_folio`, and `swapin_sync`. So, the current potential focus symbols are: - `swap_writeback_dropbehind_folio` - `remove_mapping_reclaim` - `__swap_cache_alloc_folio` - `folio_end_writeback` Now, let's look at the config and instruction details. The configs will be: - `ZSWAP` - `ZSWAP_DEFAULT_ON` - `SWAP` - `MEMCG` - `CGROUPS` The instructions dictate to avoid generic hot-path functions. `folio_end_writeback` is a generic hot-path function and should be excluded. It's called for every page writeback completion. Let's exclude it to avoid skewed test distributions. This leaves me with: `swap_writeback_dropbehind_folio`, `remove_mapping_reclaim`, and `__swap_cache_alloc_folio`. I'll consider how hot each is. `swap_writeback_dropbehind_folio` is specific to this new feature, and `remove_mapping_reclaim` is specific to this new feature (and page reclaim), so those seem okay. `remove_mapping_reclaim` is called during page reclaim and swap writeback dropbehind. It's somewhat hot during memory pressure, but not as hot as `folio_end_writeback`. It's fine to include. `__swap_cache_alloc_folio` is called during swapin and zswap writeback. It's fine to include. `swap_writeback_dropbehind_folio` is called only for dropbehind swap cache folios (zswap writeback). It's fine to include. I need to confirm all the config names. Let me double check: - `Z |
| 36/2 | 2026/08/25 14:49 | tool | grepper |
0mArgs:{
"Expression": "config ZSWAP_SHRINKER_DEFAULT_ON",
"PathPrefix": "mm/Kconfig"
}Results: {
"Output": "mm/Kconfig=35=config ZSWAP_DEFAULT_ON\n--\nmm/Kconfig-44-\nmm/Kconfig:45:config ZSWAP_SHRINKER_DEFAULT_ON\nmm/Kconfig-46-\tbool \"Shrink the zswap pool on memory pressure\"\n"
} |
| 37/2 | 2026/08/25 14:49 | llm | patch-evaluator |
5mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 31254 output: 208 thoughts: 220 Thoughts: **My Assessment of the Zswap Shrinker Addition** Okay, so we *do* need `ZSWAP_SHRINKER_DEFAULT_ON`. The shrinker is essential for triggering zswap writeback, so that's a key configuration to enable by default. That feels right, and it makes the most sense. I'm thinking we're going to want to have a look at a few other configs to make sure everything lines up. I'm going to want to confirm that we've got: `ZSWAP`, `ZSWAP_DEFAULT_ON`, and of course `ZSWAP_SHRINKER_DEFAULT_ON`. Then, of course, the obvious ones: `SWAP`, `MEMCG`, and `CGROUPS`. Gotta make sure all the building blocks are in place for this to work as expected. Now, looking at the code, this patch is introducing a way to drop swap cache folios *after* the zswap writeback is complete. It's designed to prevent unnecessary pollution of the LRU, which is a significant optimization. That's good. They're adding `swap_writeback_dropbehind_folio` and `remove_mapping_reclaim` functions, and they're modifying `zswap_writeback_entry` to leverage this new mechanism. This is a functional change, a core modification to how the memory management subsystem deals with swap, zswap, and the page cache. It fundamentally alters memory reclaim and swap behavior, so it is absolutely reachable and definitely worth fuzzing. It's a prime target for that kind of thorough testing. Let's call `set-results` and see what we can do to make this happen. |
| 38/2 | 2026/08/25 14:54 | tool | set-results |
0mArgs:{
"EnableConfigs": [
"ZSWAP",
"ZSWAP_DEFAULT_ON",
"ZSWAP_SHRINKER_DEFAULT_ON",
"SWAP",
"MEMCG",
"CGROUPS"
],
"FocusSymbols": [
"swap_writeback_dropbehind_folio",
"remove_mapping_reclaim",
"__swap_cache_alloc_folio"
],
"Reasoning": "The patch introduces a mechanism to drop swap cache folios after zswap writeback completes, avoiding unnecessary LRU pollution. It adds new functions `swap_writeback_dropbehind_folio` and `remove_mapping_reclaim`, and modifies `zswap_writeback_entry` to use this mechanism. This is a functional change in the core memory management subsystem (swap, zswap, page cache) that affects memory reclaim and swap behavior, which is reachable and worth fuzzing.",
"WorthFuzzing": true
}Results: {
"EnableConfigs": [
"ZSWAP",
"ZSWAP_DEFAULT_ON",
"ZSWAP_SHRINKER_DEFAULT_ON",
"SWAP",
"MEMCG",
"CGROUPS"
],
"FocusSymbols": [
"swap_writeback_dropbehind_folio",
"remove_mapping_reclaim",
"__swap_cache_alloc_folio"
],
"Reasoning": "The patch introduces a mechanism to drop swap cache folios after zswap writeback completes, avoiding unnecessary LRU pollution. It adds new functions `swap_writeback_dropbehind_folio` and `remove_mapping_reclaim`, and modifies `zswap_writeback_entry` to use this mechanism. This is a functional change in the core memory management subsystem (swap, zswap, page cache) that affects memory reclaim and swap behavior, which is reachable and worth fuzzing.",
"WorthFuzzing": true
} |
| 39/1 | 2026/08/25 14:54 | action | If |
5mArgs:{
"WorthFuzzing": true
}Results: null |
| 40/2 | 2026/08/25 14:54 | agent | kmsan-evaluator |
5mModel:best-expensive Args: null Results: {
"KMSANReasoning": "The patch modifies the lifecycle of folios in the swap cache, specifically introducing a \"dropbehind\" mechanism for zswap writeback. It changes how folios are allocated for the swap cache (returning them off-LRU) and manages their references during writeback.\n\nThese changes primarily involve page reference counting, LRU list management, and swap cache operations. The potential bugs introduced by these changes would be use-after-free, memory leaks (e.g., folios left off the LRU), or invalid page states. Such issues are effectively detected by KASAN, standard kernel memory debug options (like `CONFIG_DEBUG_VM`), and page reference tracking.\n\nThe patch does not introduce new data structures copied to user space, nor does it add complex parsing logic or conditional branching based on potentially uninitialized memory. The folios allocated are populated via decompression before being written to swap, and no uninitialized kernel memory is exposed. Thus, a dedicated KMSAN fuzzing session is not justified.",
"NeedsKMSAN": false
}Instruction: 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.
Prompt: For your convenience, here is the diff of the changes:
commit ae086299864049ed77698eafec0ec37660def15f
Author: syz-cluster <triage@syzkaller.com>
Date: Tue Aug 25 14:29:09 2026 +0000
syz-cluster: applied patch under review
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 8f0f68e245baa..29ec60dcae213 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -374,6 +374,8 @@ extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem,
extern unsigned long shrink_all_memory(unsigned long nr_pages);
extern int vm_swappiness;
long remove_mapping(struct address_space *mapping, struct folio *folio);
+long remove_mapping_reclaim(struct address_space *mapping, struct folio *folio,
+ struct mem_cgroup *target_memcg);
#if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
extern int reclaim_register_node(struct node *node);
@@ -465,6 +467,8 @@ void swap_put_entries_direct(swp_entry_t entry, int nr);
*/
bool folio_free_swap(struct folio *folio);
+void swap_writeback_dropbehind_folio(struct folio *folio);
+
/* Allocate / free (hibernation) exclusive entries */
swp_entry_t swap_alloc_hibernation_slot(int type);
void swap_free_hibernation_slot(swp_entry_t entry);
@@ -475,6 +479,7 @@ static inline void put_swap_device(struct swap_info_struct *si)
}
#else /* CONFIG_SWAP */
+static inline void swap_writeback_dropbehind_folio(struct folio *folio) {}
static inline struct swap_info_struct *get_swap_device(swp_entry_t entry)
{
return NULL;
diff --git a/mm/filemap.c b/mm/filemap.c
index d721986d5f465..040c97a121ded 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1686,6 +1686,8 @@ EXPORT_SYMBOL_GPL(folio_end_writeback_no_dropbehind);
*/
void folio_end_writeback(struct folio *folio)
{
+ bool swap_dropbehind;
+
VM_BUG_ON_FOLIO(!folio_test_writeback(folio), folio);
/*
@@ -1695,7 +1697,24 @@ void folio_end_writeback(struct folio *folio)
* reused before the folio_wake_bit().
*/
folio_get(folio);
+
+ /*
+ * Sample this before folio_end_writeback_no_dropbehind() clears
+ * PG_writeback: until then a racing swapin cannot remove the folio from
+ * the swap cache. Afterwards it can, and the drop below then finds a
+ * non-swapcache folio and puts it back on the LRU instead. The
+ * reference taken above keeps the folio alive across that window.
+ */
+ swap_dropbehind = folio_test_swapcache(folio) &&
+ folio_test_dropbehind(folio);
+
folio_end_writeback_no_dropbehind(folio);
+
+ if (swap_dropbehind) {
+ swap_writeback_dropbehind_folio(folio);
+ return;
+ }
+
folio_end_dropbehind(folio);
folio_put(folio);
}
diff --git a/mm/page_io.c b/mm/page_io.c
index b23f494fcc83d..586c79c3bb3d2 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -456,6 +456,13 @@ static void swap_writepage_bdev_async(struct folio *folio,
bio->bi_end_io = end_swap_bio_write;
bio_add_folio_nofail(bio, folio, folio_size(folio), 0);
+ /*
+ * Dropping the folio from the swap cache takes sleeping locks, so the
+ * completion must not run in interrupt context.
+ */
+ if (folio_test_dropbehind(folio))
+ bio_set_flag(bio, BIO_COMPLETE_IN_TASK);
+
bio_associate_blkg_from_page(bio, folio);
count_swpout_vm_event(folio);
folio_start_writeback(folio);
diff --git a/mm/swap.h b/mm/swap.h
index 77d2d14eda421..fc44daae1de1f 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -304,9 +304,9 @@ bool swap_cache_has_folio(swp_entry_t entry);
struct folio *swap_cache_get_folio(swp_entry_t entry);
void *swap_cache_get_shadow(swp_entry_t entry);
void swap_cache_del_folio(struct folio *folio);
-struct folio *swap_cache_alloc_folio(swp_entry_t target_entry, gfp_t gfp_mask,
- unsigned long orders, struct vm_fault *vmf,
- struct mempolicy *mpol, pgoff_t ilx);
+struct folio *__swap_cache_alloc_folio(swp_entry_t target_entry, gfp_t gfp_mask,
+ unsigned long orders, struct vm_fault *vmf,
+ struct mempolicy *mpol, pgoff_t ilx);
/* Below helpers require the caller to lock and pass in the swap cluster. */
void __swap_cache_add_folio(struct swap_cluster_info *ci,
struct folio *folio, swp_entry_t entry);
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 727a17ee78211..231fa87cbbe0c 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -483,13 +483,11 @@ static struct folio *__swap_cache_alloc(struct swap_cluster_info *ci,
node_stat_mod_folio(folio, NR_FILE_PAGES, nr_pages);
lruvec_stat_mod_folio(folio, NR_SWAPCACHE, nr_pages);
- /* Caller will initiate read into locked new_folio */
- folio_add_lru(folio);
return folio;
}
/**
- * swap_cache_alloc_folio - Allocate folio for swapped out slot in swap cache.
+ * __swap_cache_alloc_folio - Allocate folio for swapped out slot in swap cache.
* @targ_entry: swap entry indicating the target slot
* @gfp: memory allocation flags
* @orders: allocation orders, must be non zero
@@ -501,13 +499,17 @@ static struct folio *__swap_cache_alloc(struct swap_cluster_info *ci,
* doing IO (e.g. swap in or zswap writeback). The swap slot indicated by
* @targ_entry must have a non-zero swap count (swapped out).
*
+ * The returned folio is locked and is NOT on the LRU. The caller must either
+ * add it to the LRU with folio_add_lru() so page reclaim can find it, or free
+ * it directly once done; a folio left off the LRU is unreclaimable and leaks.
+ *
* Context: Caller must protect the swap device with reference count or locks.
* Return: Returns the folio if allocation succeeded and folio is in the swap
* cache. Returns error code if failed due to race, OOM or invalid arguments.
*/
-struct folio *swap_cache_alloc_folio(swp_entry_t targ_entry, gfp_t gfp,
- unsigned long orders, struct vm_fault *vmf,
- struct mempolicy *mpol, pgoff_t ilx)
+struct folio *__swap_cache_alloc_folio(swp_entry_t targ_entry, gfp_t gfp,
+ unsigned long orders, struct vm_fault *vmf,
+ struct mempolicy *mpol, pgoff_t ilx)
{
int order, err;
struct folio *ret;
@@ -535,6 +537,47 @@ struct folio *swap_cache_alloc_folio(swp_entry_t targ_entry, gfp_t gfp,
return ret;
}
+/**
+ * swap_writeback_dropbehind_folio - drop a dropbehind swap cache folio
+ * @folio: the off-LRU folio whose writeback has completed
+ *
+ * Context: task context, with the reference taken by folio_end_writeback()
+ * donated to us.
+ */
+void swap_writeback_dropbehind_folio(struct folio *folio)
+{
+ struct mem_cgroup *memcg;
+
+ folio_lock(folio);
+
+ /* The folio was allocated off the LRU and nothing re-adds it here. */
+ VM_WARN_ON_ONCE_FOLIO(folio_test_lru(folio), folio);
+
+ rcu_read_lock();
+ memcg = folio_memcg(folio);
+ if (!mem_cgroup_tryget(memcg))
+ memcg = NULL;
+ rcu_read_unlock();
+
+ /*
+ * Gate remove_mapping_reclaim() on folio_test_swapcache(): a racing
+ * swapin may have freed the swap slot (folio_free_swap()) and dropped the
+ * folio from the cache, and it must not run on a non-swapcache folio (it
+ * would trip __remove_mapping()'s mapping == folio_mapping() check).
+ */
+ if (!folio_test_swapcache(folio) || folio_test_writeback(folio) ||
+ !remove_mapping_reclaim(swap_address_space(folio->swap), folio, memcg)) {
+ /* Raced: the folio is now owned by the swapin; put it back. */
+ folio_clear_dropbehind(folio);
+ folio_add_lru(folio);
+ }
+
+ mem_cgroup_put(memcg);
+
+ folio_unlock(folio);
+ folio_put(folio);
+}
+
/*
* If we are the only user, then try to free up the swap cache.
*
@@ -643,12 +686,13 @@ static struct folio *swap_cache_read_folio(swp_entry_t entry, gfp_t gfp,
folio = swap_cache_get_folio(entry);
if (folio)
return folio;
- folio = swap_cache_alloc_folio(entry, gfp, BIT(0), NULL, mpol, ilx);
+ folio = __swap_cache_alloc_folio(entry, gfp, BIT(0), NULL, mpol, ilx);
} while (PTR_ERR(folio) == -EEXIST);
if (IS_ERR_OR_NULL(folio))
return NULL;
+ folio_add_lru(folio);
swap_read_folio(folio, plug);
if (readahead) {
folio_set_readahead(folio);
@@ -683,12 +727,13 @@ struct folio *swapin_sync(swp_entry_t entry, gfp_t gfp, unsigned long orders,
folio = swap_cache_get_folio(entry);
if (folio)
return folio;
- folio = swap_cache_alloc_folio(entry, gfp, orders, vmf, mpol, ilx);
+ folio = __swap_cache_alloc_folio(entry, gfp, orders, vmf, mpol, ilx);
} while (PTR_ERR(folio) == -EEXIST);
if (IS_ERR(folio))
return folio;
+ folio_add_lru(folio);
swap_read_folio(folio, NULL);
return folio;
}
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 848bd3e5eee2b..4cc3a3ed6db6e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -780,6 +780,22 @@ static int __remove_mapping(struct address_space *mapping, struct folio *folio,
return 0;
}
+static long __remove_mapping_unfreeze(struct address_space *mapping,
+ struct folio *folio, bool reclaimed,
+ struct mem_cgroup *target_memcg)
+{
+ if (__remove_mapping(mapping, folio, reclaimed, target_memcg)) {
+ /*
+ * Unfreezing the refcount with 1 effectively
+ * drops the pagecache ref for us without requiring another
+ * atomic operation.
+ */
+ folio_ref_unfreeze(folio, 1);
+ return folio_nr_pages(folio);
+ }
+ return 0;
+}
+
/**
* remove_mapping() - Attempt to remove a folio from its mapping.
* @mapping: The address space.
@@ -794,16 +810,28 @@ static int __remove_mapping(struct address_space *mapping, struct folio *folio,
*/
long remove_mapping(struct address_space *mapping, struct folio *folio)
{
- if (__remove_mapping(mapping, folio, false, NULL)) {
- /*
- * Unfreezing the refcount with 1 effectively
- * drops the pagecache ref for us without requiring another
- * atomic operation.
- */
- folio_ref_unfreeze(folio, 1);
- return folio_nr_pages(folio);
- }
- return 0;
+ return __remove_mapping_unfreeze(mapping, folio, false, NULL);
+}
+
+/**
+ * remove_mapping_reclaim() - Remove a folio from its mapping, as reclaim does.
+ * @mapping: The address space.
+ * @folio: The folio to remove.
+ * @target_memcg: The memcg to charge the eviction shadow to; the caller must
+ * keep it alive across the call.
+ *
+ * Like remove_mapping(), but stores a workingset eviction shadow the way page
+ * reclaim does, so that a later refault can be detected and the folio
+ * re-activated.
+ * Return: The number of pages removed from the mapping. 0 if the folio
+ * could not be removed.
+ * Context: The caller should have a single refcount on the folio and
+ * hold its lock.
+ */
+long remove_mapping_reclaim(struct address_space *mapping, struct folio *folio,
+ struct mem_cgroup *target_memcg)
+{
+ return __remove_mapping_unfreeze(mapping, folio, true, target_memcg);
}
/**
diff --git a/mm/zswap.c b/mm/zswap.c
index 761cd699e0a3e..d16822a516e8d 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1000,8 +1000,8 @@ static int zswap_writeback_entry(struct zswap_entry *entry,
return -EEXIST;
mpol = get_task_policy(current);
- folio = swap_cache_alloc_folio(swpentry, GFP_KERNEL, BIT(0), NULL, mpol,
- NO_INTERLEAVE_INDEX);
+ folio = __swap_cache_alloc_folio(swpentry, GFP_KERNEL, BIT(0), NULL, mpol,
+ NO_INTERLEAVE_INDEX);
put_swap_device(si);
/*
@@ -1045,12 +1045,26 @@ static int zswap_writeback_entry(struct zswap_entry *entry,
/* folio is up to date */
folio_mark_uptodate(folio);
- /* move it to the tail of the inactive list after end_writeback */
- folio_set_reclaim(folio);
+ folio_set_dropbehind(folio);
+
+ /*
+ * Drop our reference before starting writeback so the swap cache holds
+ * the only one: the drop in folio_end_writeback() needs that for
+ * remove_mapping_reclaim() to succeed, otherwise the folio is handed
+ * back to reclaim instead.
+ *
+ * Nothing can free the folio in the meantime: we hold the folio lock
+ * until writeback starts, PG_writeback then blocks swap cache removal,
+ * and folio_end_writeback() takes its own reference before clearing
+ * PG_writeback and donates it to the drop.
+ */
+ folio_put(folio);
/* start writeback */
__swap_writepage(folio, NULL);
+ return 0;
+
out:
if (ret) {
swap_cache_del_folio(folio);
|
| 41/3 | 2026/08/25 14:54 | llm | kmsan-evaluator |
5mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 6177 output: 230 thoughts: 1320 Thoughts: **KMSAN Fuzzing Session Justification: Analysis of Swap Cache Patch Series** Okay, let's break this down. We have a patch series touching the swap, page cache, and zswap memory management code. The core of the changes revolve around this new `swap_writeback_dropbehind_folio` function and modifications to folio handling during writeback, specifically the allocation and management of folios within the swap cache. My initial thought is to analyze for uninitialized memory risks that KMSAN *might* uniquely catch. The patch introduces `__swap_cache_alloc_folio`, modifies how folios are marked as "dropbehind", and alters the lifecycle in the swap cache. It's essentially about how folios are allocated, added to the LRU (or not), and managed during zswap writeback. The patch does *not* introduce new structures going to user space, nor does it have any logic that would conditionally execute based on uninitialized data. There aren't any new complex data structures with uninitialized fields. There are no changes to any boundary checks or variable lengths that would expose uninitialized bytes. The primary concerns I have are likely going to be the usual suspects: use-after-free conditions, memory leaks (e.g., folios being left off the LRU or being double-freed), or potential locking issues. These are precisely the types of bugs that KASAN, LOCKDEP, and standard kernel debugging tools are designed to catch. Let's do a deep dive and confirm no uninitialized memory could be read. The important section is that `zswap_writeback_entry` now calls `__swap_cache_alloc_folio`. This function is responsible for allocating the folio for the swap or zswap entry. The folio memory is populated by decompressing the zswap entry into it. If the decompression fails, then the folio is deleted from swap cache, otherwise, it marks it up-to-date and writes it back. Crucially, there's no scenario where uninitialized memory is *exposed* to user space, or where control flow depends on uninitialized memory within the allocation and writeback path. The code carefully populates the folio with the decompressed data. The primary concerns I see are use-after-free bugs (e.g., dropping a reference early and then accessing the folio), memory leaks, or bad page state issues - all of which would be flagged by standard VM debugging tools or KASAN. In summary, the patch series modifies the folio lifecycle in the swap cache, introduces a "dropbehind" mechanism, and changes how folios are allocated (off-LRU) and managed during zswap writeback. The potential bugs are primarily use-after-free, memory leaks, and page state issues - all of which are detectable by KASAN, standard kernel memory debug options, and page reference tracking. The changes do not introduce new user-space data structures nor parsing logic or conditional branching based on potentially uninitialized memory. KMSAN is not justified here. We're looking at reference counting, LRU list management, and the overall swap cache lifecycle. Therefore, KASAN and the standard VM debug tools are sufficient for this patch. I think this is a pretty straightforward call. No need for a KMSAN session. |
| 42/3 | 2026/08/25 14:59 | tool | set-results |
0mArgs:{
"KMSANReasoning": "The patch modifies the lifecycle of folios in the swap cache, specifically introducing a \"dropbehind\" mechanism for zswap writeback. It changes how folios are allocated for the swap cache (returning them off-LRU) and manages their references during writeback.\n\nThese changes primarily involve page reference counting, LRU list management, and swap cache operations. The potential bugs introduced by these changes would be use-after-free, memory leaks (e.g., folios left off the LRU), or invalid page states. Such issues are effectively detected by KASAN, standard kernel memory debug options (like `CONFIG_DEBUG_VM`), and page reference tracking.\n\nThe patch does not introduce new data structures copied to user space, nor does it add complex parsing logic or conditional branching based on potentially uninitialized memory. The folios allocated are populated via decompression before being written to swap, and no uninitialized kernel memory is exposed. Thus, a dedicated KMSAN fuzzing session is not justified.",
"NeedsKMSAN": false
}Results: {
"KMSANReasoning": "The patch modifies the lifecycle of folios in the swap cache, specifically introducing a \"dropbehind\" mechanism for zswap writeback. It changes how folios are allocated for the swap cache (returning them off-LRU) and manages their references during writeback.\n\nThese changes primarily involve page reference counting, LRU list management, and swap cache operations. The potential bugs introduced by these changes would be use-after-free, memory leaks (e.g., folios left off the LRU), or invalid page states. Such issues are effectively detected by KASAN, standard kernel memory debug options (like `CONFIG_DEBUG_VM`), and page reference tracking.\n\nThe patch does not introduce new data structures copied to user space, nor does it add complex parsing logic or conditional branching based on potentially uninitialized memory. The folios allocated are populated via decompression before being written to swap, and no uninitialized kernel memory is exposed. Thus, a dedicated KMSAN fuzzing session is not justified.",
"NeedsKMSAN": false
} |
| Total Calls | Total Tokens | Avg Tokens | Total Duration (Seconds) | Avg Duration (Seconds) |
|---|
| Total Calls | Total Duration (Seconds) | Avg Duration (Seconds) |
|---|