AI Trajectory

null

{
  "EnableConfigs": [
    "EROFS_FS",
    "EXT4_FS",
    "NFS_FS",
    "NTFS_FS",
    "NTFS_FS_WOF_COMPRESSION",
    "SQUASHFS"
  ],
  "FocusSymbols": [
    "__filemap_get_folio_mpol",
    "squashfs_copy_cache",
    "ext4_generic_write_inline_data",
    "ntfs_read_wof_compressed_block"
  ],
  "KMSANReasoning": "The patch removes the deprecated FGP_NOFS flag from the page cache folio acquisition APIs and adjusts call sites across various filesystems (EROFS, EXT4, NFS, NTFS, SquashFS) to rely on mapping GFP masks or scoped memalloc_nofs_save()/memalloc_nofs_restore() contexts.\n\nThese changes strictly pertain to memory allocation reclaim flags (GFP/FGP flags) and filesystem recursion/deadlock prevention. They do not introduce or modify any kernel-to-user copies, buffer initializations, stack/heap allocations of uninitialized data, or control flow branching on uninitialized variables. Any potential regressions (e.g., reclaim recursion or locking issues) fall under the purview of LOCKDEP and standard kernel sanitizers, not KMSAN. Therefore, a dedicated KMSAN fuzzing session is not warranted.",
  "NeedsKMSAN": false,
  "Reasoning": "The patch removes the FGP_NOFS flag from core page cache APIs (__filemap_get_folio_mpol) and adjusts folio allocation flags and reclaim context across several filesystems (ext4, squashfs, erofs, ntfs, and nfs). It alters memory allocation flags and introduces scoped NOFS contexts (memalloc_nofs_save/restore) in reachable filesystem I/O and caching paths, making it worth fuzzing for memory reclaim and locking issues.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit e24356d7ac65e0f9bdedf6731f6aa3822d90747f\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Sun Aug 30 04:42:42 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/fs/erofs/internal.h b/fs/erofs/internal.h\nindex 65974e57aebfb..84b3cdc8e88f1 100644\n--- a/fs/erofs/internal.h\n+++ b/fs/erofs/internal.h\n@@ -327,7 +327,7 @@ static inline struct folio *erofs_grab_folio_nowait(struct address_space *as,\n \t\t\t\t\t\t    pgoff_t index)\n {\n \treturn __filemap_get_folio(as, index,\n-\t\t\tFGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,\n+\t\t\tFGP_LOCK | FGP_CREAT | FGP_NOWAIT,\n \t\t\treadahead_gfp_mask(as) \u0026 ~__GFP_RECLAIM);\n }\n \ndiff --git a/fs/ext4/inline.c b/fs/ext4/inline.c\nindex ceee69a66482b..1884abb096140 100644\n--- a/fs/ext4/inline.c\n+++ b/fs/ext4/inline.c\n@@ -601,9 +601,7 @@ static int ext4_convert_inline_data_to_extent(struct address_space *mapping,\n \t\tgoto out;\n \t}\n \n-\t/* We cannot recurse into the filesystem as the transaction is already\n-\t * started */\n-\tfolio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN | FGP_NOFS,\n+\tfolio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN,\n \t\t\tmapping_gfp_mask(mapping));\n \tif (IS_ERR(folio)) {\n \t\tret = PTR_ERR(folio);\n@@ -734,7 +732,7 @@ int ext4_generic_write_inline_data(struct address_space *mapping,\n \t\tgoto out_release_bh;\n \t}\n \n-\tfolio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN | FGP_NOFS,\n+\tfolio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN,\n \t\t\t\t\tmapping_gfp_mask(mapping));\n \tif (IS_ERR(folio)) {\n \t\tret = PTR_ERR(folio);\ndiff --git a/fs/nfs/dir.c b/fs/nfs/dir.c\nindex 49394123bd096..e34125a8a2e28 100644\n--- a/fs/nfs/dir.c\n+++ b/fs/nfs/dir.c\n@@ -447,7 +447,7 @@ static struct folio *nfs_readdir_folio_get_next(struct address_space *mapping,\n \tstruct folio *folio;\n \n \tfolio = __filemap_get_folio(mapping, index,\n-\t\t\tFGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,\n+\t\t\tFGP_LOCK | FGP_CREAT | FGP_NOWAIT,\n \t\t\tmapping_gfp_mask(mapping));\n \tif (IS_ERR(folio))\n \t\treturn NULL;\ndiff --git a/fs/ntfs/inode.c b/fs/ntfs/inode.c\nindex 32edb4045178a..36a0d6b26c02e 100644\n--- a/fs/ntfs/inode.c\n+++ b/fs/ntfs/inode.c\n@@ -3676,7 +3676,7 @@ static s64 __ntfs_inode_resident_attr_pwrite(struct inode *vi,\n \tmark_mft_record_dirty(ctx-\u003entfs_ino);\n \n \t/* Keep the first page clean and uptodate */\n-\tfolio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN | FGP_NOFS,\n+\tfolio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN,\n \t\t\t\t   mapping_gfp_mask(mapping));\n \tif (IS_ERR(folio)) {\n \t\terr = PTR_ERR(folio);\ndiff --git a/fs/ntfs/wof.c b/fs/ntfs/wof.c\nindex 8f84c2212eeec..c981b4a3b6959 100644\n--- a/fs/ntfs/wof.c\n+++ b/fs/ntfs/wof.c\n@@ -464,10 +464,9 @@ static int ntfs_wof_collect_dest(struct address_space *mapping,\n \t\t\tfolio = target;\n \t\t\tis_target = true;\n \t\t} else {\n-\t\t\tfolio = __filemap_get_folio(\n-\t\t\t\tmapping, index,\n-\t\t\t\tFGP_LOCK | FGP_CREAT | FGP_NOFS | FGP_NOWAIT,\n-\t\t\t\tGFP_NOFS);\n+\t\t\tfolio = __filemap_get_folio(mapping, index,\n+\t\t\t\t\tFGP_LOCK | FGP_CREAT | FGP_NOWAIT,\n+\t\t\t\t\tmapping_gfp_mask(mapping));\n \t\t\tif (IS_ERR(folio))\n \t\t\t\treturn PTR_ERR(folio);\n \t\t\tis_target = false;\ndiff --git a/fs/squashfs/file.c b/fs/squashfs/file.c\nindex d83594ce91d23..34c550a266bcf 100644\n--- a/fs/squashfs/file.c\n+++ b/fs/squashfs/file.c\n@@ -398,6 +398,7 @@ void squashfs_copy_cache(struct folio *folio,\n \tstruct squashfs_sb_info *msblk = inode-\u003ei_sb-\u003es_fs_info;\n \tint i, mask = (1 \u003c\u003c (msblk-\u003eblock_log - PAGE_SHIFT)) - 1;\n \tint start_index = folio-\u003eindex \u0026 ~mask, end_index = start_index | mask;\n+\tunsigned int nofs = memalloc_nofs_save();\n \n \t/*\n \t * Loop copying datablock into pages.  As the datablock likely covers\n@@ -415,7 +416,7 @@ void squashfs_copy_cache(struct folio *folio,\n \n \t\tpush_folio = (i == folio-\u003eindex) ? folio :\n \t\t\t__filemap_get_folio(mapping, i,\n-\t\t\t\t\tFGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,\n+\t\t\t\t\tFGP_LOCK | FGP_CREAT | FGP_NOWAIT,\n \t\t\t\t\tmapping_gfp_mask(mapping));\n \n \t\tif (IS_ERR(push_folio))\n@@ -430,6 +431,8 @@ void squashfs_copy_cache(struct folio *folio,\n \t\tif (i != folio-\u003eindex)\n \t\t\tfolio_put(push_folio);\n \t}\n+\n+\tmemalloc_nofs_restore(nofs);\n }\n \n /* Read datablock stored packed inside a fragment (tail-end packed block) */\ndiff --git a/include/linux/pagemap.h b/include/linux/pagemap.h\nindex 0adfa6605653d..bff8b7264fb02 100644\n--- a/include/linux/pagemap.h\n+++ b/include/linux/pagemap.h\n@@ -697,7 +697,6 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping,\n  *   folio is already in cache.  If the folio was allocated, unlock it\n  *   before returning so the caller can do the same dance.\n  * * %FGP_WRITE - The folio will be written to by the caller.\n- * * %FGP_NOFS - __GFP_FS will get cleared in gfp.\n  * * %FGP_NOWAIT - Don't block on the folio lock.\n  * * %FGP_STABLE - Wait for the folio to be stable (finished writeback)\n  * * %FGP_DONTCACHE - Uncached buffered IO\n@@ -710,11 +709,10 @@ typedef unsigned int __bitwise fgf_t;\n #define FGP_LOCK\t\t((__force fgf_t)0x00000002)\n #define FGP_CREAT\t\t((__force fgf_t)0x00000004)\n #define FGP_WRITE\t\t((__force fgf_t)0x00000008)\n-#define FGP_NOFS\t\t((__force fgf_t)0x00000010)\n-#define FGP_NOWAIT\t\t((__force fgf_t)0x00000020)\n-#define FGP_FOR_MMAP\t\t((__force fgf_t)0x00000040)\n-#define FGP_STABLE\t\t((__force fgf_t)0x00000080)\n-#define FGP_DONTCACHE\t\t((__force fgf_t)0x00000100)\n+#define FGP_NOWAIT\t\t((__force fgf_t)0x00000010)\n+#define FGP_FOR_MMAP\t\t((__force fgf_t)0x00000020)\n+#define FGP_STABLE\t\t((__force fgf_t)0x00000040)\n+#define FGP_DONTCACHE\t\t((__force fgf_t)0x00000080)\n #define FGF_GET_ORDER(fgf)\t(((__force unsigned)fgf) \u003e\u003e 26)\t/* top 6 bits */\n \n #define FGP_WRITEBEGIN\t\t(FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE)\n@@ -929,7 +927,7 @@ static inline struct page *grab_cache_page_nowait(struct address_space *mapping,\n \t\t\t\tpgoff_t index)\n {\n \treturn pagecache_get_page(mapping, index,\n-\t\t\tFGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,\n+\t\t\tFGP_LOCK | FGP_CREAT | FGP_NOWAIT,\n \t\t\tmapping_gfp_mask(mapping));\n }\n \ndiff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h\nindex d7c6a942aa7e0..f76be1141b064 100644\n--- a/include/linux/sched/mm.h\n+++ b/include/linux/sched/mm.h\n@@ -372,13 +372,26 @@ static inline void memalloc_noio_restore(unsigned int flags)\n }\n \n /**\n- * memalloc_nofs_save - Marks implicit GFP_NOFS allocation scope.\n+ * memalloc_nofs_save - Prevent recursion into the filesystem.\n  *\n- * This functions marks the beginning of the GFP_NOFS allocation scope.\n- * All further allocations will implicitly drop __GFP_FS flag and so\n- * they are safe for the FS critical section from the allocation recursion\n- * point of view. Use memalloc_nofs_restore to end the scope with flags\n- * returned by this function.\n+ * All memory allocations between calling this function and calling\n+ * memalloc_nofs_restore() will be prevented from calling into filesystems\n+ * to reclaim memory.  Clean page cache memory can still be reclaimed,\n+ * but (for example) inodes will not be.\n+ *\n+ * The primary reason to do this is that the caller has taken a lock\n+ * which would be needed by FS reclaim.  While we could theoretically\n+ * call into a different filesystem in this case, it can be a deep call\n+ * stack so it is better to avoid all filesystems.\n+ *\n+ * Filesystems often choose to incorporate a call to this function as part\n+ * of starting a journal transaction.  While not a lock in the normal\n+ * sense, it has much the same effect as nested journal transactions\n+ * are either prohibited or expensive.\n+ *\n+ * Also call this function if you need to allocate memory while holding\n+ * a file folio locked.  High order allocations (such as those requested\n+ * by slab) can trigger compaction which will attempt to lock the folio.\n  *\n  * Context: This function is safe to be used from any context.\n  * Return: The saved flags to be passed to memalloc_nofs_restore.\n@@ -389,10 +402,12 @@ static inline unsigned int memalloc_nofs_save(void)\n }\n \n /**\n- * memalloc_nofs_restore - Ends the implicit GFP_NOFS scope.\n+ * memalloc_nofs_restore - End filesystem reclaim scope.\n  * @flags: Flags to restore.\n  *\n- * Ends the implicit GFP_NOFS scope started by memalloc_nofs_save function.\n+ * Ends the implicit memory allocation scope started by\n+ * memalloc_nofs_save().  This may not enable access to filesystem reclaim\n+ * if it was already disabled at the time memalloc_nofs_save() was called.\n  * Always make sure that the given flags is the return value from the\n  * pairing memalloc_nofs_save call.\n  */\ndiff --git a/mm/filemap.c b/mm/filemap.c\nindex 6afec636881fb..e6580291f2185 100644\n--- a/mm/filemap.c\n+++ b/mm/filemap.c\n@@ -1994,8 +1994,6 @@ struct folio *__filemap_get_folio_mpol(struct address_space *mapping,\n \n \t\tif ((fgp_flags \u0026 FGP_WRITE) \u0026\u0026 mapping_can_writeback(mapping))\n \t\t\tgfp |= __GFP_WRITE;\n-\t\tif (fgp_flags \u0026 FGP_NOFS)\n-\t\t\tgfp \u0026= ~__GFP_FS;\n \t\tif (fgp_flags \u0026 FGP_NOWAIT) {\n \t\t\tgfp \u0026= ~GFP_KERNEL;\n \t\t\tgfp |= GFP_NOWAIT;\ndiff --git a/mm/readahead.c b/mm/readahead.c\nindex 6e5563290287e..9c116d4ba963a 100644\n--- a/mm/readahead.c\n+++ b/mm/readahead.c\n@@ -227,17 +227,7 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,\n \tgfp_t gfp_mask = readahead_gfp_mask(mapping);\n \tunsigned long mark = ULONG_MAX, i = 0;\n \tunsigned int min_nrpages = mapping_min_folio_nrpages(mapping);\n-\n-\t/*\n-\t * Partway through the readahead operation, we will have added\n-\t * locked pages to the page cache, but will not yet have submitted\n-\t * them for I/O.  Adding another page may need to allocate memory,\n-\t * which can trigger memory reclaim.  Telling the VM we're in\n-\t * the middle of a filesystem operation will cause it to not\n-\t * touch file-backed pages, preventing a deadlock.  Most (all?)\n-\t * filesystems already specify __GFP_NOFS in their mapping's\n-\t * gfp_mask, but let's be explicit here.\n-\t */\n+\t/* Allocating with locked folios */\n \tunsigned int nofs = memalloc_nofs_save();\n \n \tlockdep_assert_held(\u0026mapping-\u003einvalidate_lock);\n@@ -512,7 +502,7 @@ void page_cache_ra_order(struct readahead_control *ractl,\n \n \tra-\u003eorder = new_order;\n \n-\t/* See comment in page_cache_ra_unbounded() */\n+\t/* Allocating with locked folios */\n \tnofs = memalloc_nofs_save();\n \tfilemap_invalidate_lock_shared(mapping);\n \t/*\n"
}

core

null

{
  "EnableConfigs": [
    "EROFS_FS",
    "EXT4_FS",
    "NFS_FS",
    "NTFS_FS",
    "NTFS_FS_WOF_COMPRESSION",
    "SQUASHFS"
  ],
  "FocusSymbols": [
    "__filemap_get_folio_mpol",
    "squashfs_copy_cache",
    "ext4_generic_write_inline_data",
    "ntfs_read_wof_compressed_block"
  ],
  "Reasoning": "The patch removes the FGP_NOFS flag from core page cache APIs (__filemap_get_folio_mpol) and adjusts folio allocation flags and reclaim context across several filesystems (ext4, squashfs, erofs, ntfs, and nfs). It alters memory allocation flags and introduces scoped NOFS contexts (memalloc_nofs_save/restore) in reachable filesystem I/O and caching paths, making it worth fuzzing for memory reclaim and locking issues.",
  "WorthFuzzing": true
}

You are an expert Linux kernel maintainer.
Your job is to review a provided patch series and determine
if it makes functional changes to the kernel that should be fuzzed.

IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on your internal knowledge of the kernel. You must actively
use your code access tools to examine the actual source code and confirm any assumptions.

Return WorthFuzzing=false if the patch only contains:
- Modifications to Documentation/, Kconfig files, or code comments.
- Purely decorative changes, such as logging (e.g., pr_err, printk) or tracepoints.
- Changes to numeric constants or macros that do not functionally alter execution flow.
- Code paths that are impossible to reach in virtualized environments like GCE or QEMU,
  even when utilizing software-emulated hardware (e.g., usb gadget, mac80211_hwsim).
- Code in vendor-specific PCIe switch, SmartNIC, or GPU drivers (e.g., mlxsw, pds_core, qed,
  ionic, amdgpu) that require physical PCIe hardware cards not emulated in standard QEMU.
- Driver .remove, .shutdown, or pci_unregister_driver teardown callbacks (e.g., igb_remove)
  that are executed only during PCI hot-unplug or sysfs driver unbind operations.

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

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


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

For your convenience, here is the diff of the changes:
commit e24356d7ac65e0f9bdedf6731f6aa3822d90747f
Author: syz-cluster <triage@syzkaller.com>
Date:   Sun Aug 30 04:42:42 2026 +0000

    syz-cluster: applied patch under review

diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 65974e57aebfb..84b3cdc8e88f1 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -327,7 +327,7 @@ static inline struct folio *erofs_grab_folio_nowait(struct address_space *as,
 						    pgoff_t index)
 {
 	return __filemap_get_folio(as, index,
-			FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
+			FGP_LOCK | FGP_CREAT | FGP_NOWAIT,
 			readahead_gfp_mask(as) & ~__GFP_RECLAIM);
 }
 
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index ceee69a66482b..1884abb096140 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -601,9 +601,7 @@ static int ext4_convert_inline_data_to_extent(struct address_space *mapping,
 		goto out;
 	}
 
-	/* We cannot recurse into the filesystem as the transaction is already
-	 * started */
-	folio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN | FGP_NOFS,
+	folio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN,
 			mapping_gfp_mask(mapping));
 	if (IS_ERR(folio)) {
 		ret = PTR_ERR(folio);
@@ -734,7 +732,7 @@ int ext4_generic_write_inline_data(struct address_space *mapping,
 		goto out_release_bh;
 	}
 
-	folio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN | FGP_NOFS,
+	folio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN,
 					mapping_gfp_mask(mapping));
 	if (IS_ERR(folio)) {
 		ret = PTR_ERR(folio);
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 49394123bd096..e34125a8a2e28 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -447,7 +447,7 @@ static struct folio *nfs_readdir_folio_get_next(struct address_space *mapping,
 	struct folio *folio;
 
 	folio = __filemap_get_folio(mapping, index,
-			FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
+			FGP_LOCK | FGP_CREAT | FGP_NOWAIT,
 			mapping_gfp_mask(mapping));
 	if (IS_ERR(folio))
 		return NULL;
diff --git a/fs/ntfs/inode.c b/fs/ntfs/inode.c
index 32edb4045178a..36a0d6b26c02e 100644
--- a/fs/ntfs/inode.c
+++ b/fs/ntfs/inode.c
@@ -3676,7 +3676,7 @@ static s64 __ntfs_inode_resident_attr_pwrite(struct inode *vi,
 	mark_mft_record_dirty(ctx->ntfs_ino);
 
 	/* Keep the first page clean and uptodate */
-	folio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN | FGP_NOFS,
+	folio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN,
 				   mapping_gfp_mask(mapping));
 	if (IS_ERR(folio)) {
 		err = PTR_ERR(folio);
diff --git a/fs/ntfs/wof.c b/fs/ntfs/wof.c
index 8f84c2212eeec..c981b4a3b6959 100644
--- a/fs/ntfs/wof.c
+++ b/fs/ntfs/wof.c
@@ -464,10 +464,9 @@ static int ntfs_wof_collect_dest(struct address_space *mapping,
 			folio = target;
 			is_target = true;
 		} else {
-			folio = __filemap_get_folio(
-				mapping, index,
-				FGP_LOCK | FGP_CREAT | FGP_NOFS | FGP_NOWAIT,
-				GFP_NOFS);
+			folio = __filemap_get_folio(mapping, index,
+					FGP_LOCK | FGP_CREAT | FGP_NOWAIT,
+					mapping_gfp_mask(mapping));
 			if (IS_ERR(folio))
 				return PTR_ERR(folio);
 			is_target = false;
diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
index d83594ce91d23..34c550a266bcf 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -398,6 +398,7 @@ void squashfs_copy_cache(struct folio *folio,
 	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
 	int i, mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
 	int start_index = folio->index & ~mask, end_index = start_index | mask;
+	unsigned int nofs = memalloc_nofs_save();
 
 	/*
 	 * Loop copying datablock into pages.  As the datablock likely covers
@@ -415,7 +416,7 @@ void squashfs_copy_cache(struct folio *folio,
 
 		push_folio = (i == folio->index) ? folio :
 			__filemap_get_folio(mapping, i,
-					FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
+					FGP_LOCK | FGP_CREAT | FGP_NOWAIT,
 					mapping_gfp_mask(mapping));
 
 		if (IS_ERR(push_folio))
@@ -430,6 +431,8 @@ void squashfs_copy_cache(struct folio *folio,
 		if (i != folio->index)
 			folio_put(push_folio);
 	}
+
+	memalloc_nofs_restore(nofs);
 }
 
 /* Read datablock stored packed inside a fragment (tail-end packed block) */
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 0adfa6605653d..bff8b7264fb02 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -697,7 +697,6 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping,
  *   folio is already in cache.  If the folio was allocated, unlock it
  *   before returning so the caller can do the same dance.
  * * %FGP_WRITE - The folio will be written to by the caller.
- * * %FGP_NOFS - __GFP_FS will get cleared in gfp.
  * * %FGP_NOWAIT - Don't block on the folio lock.
  * * %FGP_STABLE - Wait for the folio to be stable (finished writeback)
  * * %FGP_DONTCACHE - Uncached buffered IO
@@ -710,11 +709,10 @@ typedef unsigned int __bitwise fgf_t;
 #define FGP_LOCK		((__force fgf_t)0x00000002)
 #define FGP_CREAT		((__force fgf_t)0x00000004)
 #define FGP_WRITE		((__force fgf_t)0x00000008)
-#define FGP_NOFS		((__force fgf_t)0x00000010)
-#define FGP_NOWAIT		((__force fgf_t)0x00000020)
-#define FGP_FOR_MMAP		((__force fgf_t)0x00000040)
-#define FGP_STABLE		((__force fgf_t)0x00000080)
-#define FGP_DONTCACHE		((__force fgf_t)0x00000100)
+#define FGP_NOWAIT		((__force fgf_t)0x00000010)
+#define FGP_FOR_MMAP		((__force fgf_t)0x00000020)
+#define FGP_STABLE		((__force fgf_t)0x00000040)
+#define FGP_DONTCACHE		((__force fgf_t)0x00000080)
 #define FGF_GET_ORDER(fgf)	(((__force unsigned)fgf) >> 26)	/* top 6 bits */
 
 #define FGP_WRITEBEGIN		(FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE)
@@ -929,7 +927,7 @@ static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
 				pgoff_t index)
 {
 	return pagecache_get_page(mapping, index,
-			FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
+			FGP_LOCK | FGP_CREAT | FGP_NOWAIT,
 			mapping_gfp_mask(mapping));
 }
 
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index d7c6a942aa7e0..f76be1141b064 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -372,13 +372,26 @@ static inline void memalloc_noio_restore(unsigned int flags)
 }
 
 /**
- * memalloc_nofs_save - Marks implicit GFP_NOFS allocation scope.
+ * memalloc_nofs_save - Prevent recursion into the filesystem.
  *
- * This functions marks the beginning of the GFP_NOFS allocation scope.
- * All further allocations will implicitly drop __GFP_FS flag and so
- * they are safe for the FS critical section from the allocation recursion
- * point of view. Use memalloc_nofs_restore to end the scope with flags
- * returned by this function.
+ * All memory allocations between calling this function and calling
+ * memalloc_nofs_restore() will be prevented from calling into filesystems
+ * to reclaim memory.  Clean page cache memory can still be reclaimed,
+ * but (for example) inodes will not be.
+ *
+ * The primary reason to do this is that the caller has taken a lock
+ * which would be needed by FS reclaim.  While we could theoretically
+ * call into a different filesystem in this case, it can be a deep call
+ * stack so it is better to avoid all filesystems.
+ *
+ * Filesystems often choose to incorporate a call to this function as part
+ * of starting a journal transaction.  While not a lock in the normal
+ * sense, it has much the same effect as nested journal transactions
+ * are either prohibited or expensive.
+ *
+ * Also call this function if you need to allocate memory while holding
+ * a file folio locked.  High order allocations (such as those requested
+ * by slab) can trigger compaction which will attempt to lock the folio.
  *
  * Context: This function is safe to be used from any context.
  * Return: The saved flags to be passed to memalloc_nofs_restore.
@@ -389,10 +402,12 @@ static inline unsigned int memalloc_nofs_save(void)
 }
 
 /**
- * memalloc_nofs_restore - Ends the implicit GFP_NOFS scope.
+ * memalloc_nofs_restore - End filesystem reclaim scope.
  * @flags: Flags to restore.
  *
- * Ends the implicit GFP_NOFS scope started by memalloc_nofs_save function.
+ * Ends the implicit memory allocation scope started by
+ * memalloc_nofs_save().  This may not enable access to filesystem reclaim
+ * if it was already disabled at the time memalloc_nofs_save() was called.
  * Always make sure that the given flags is the return value from the
  * pairing memalloc_nofs_save call.
  */
diff --git a/mm/filemap.c b/mm/filemap.c
index 6afec636881fb..e6580291f2185 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1994,8 +1994,6 @@ struct folio *__filemap_get_folio_mpol(struct address_space *mapping,
 
 		if ((fgp_flags & FGP_WRITE) && mapping_can_writeback(mapping))
 			gfp |= __GFP_WRITE;
-		if (fgp_flags & FGP_NOFS)
-			gfp &= ~__GFP_FS;
 		if (fgp_flags & FGP_NOWAIT) {
 			gfp &= ~GFP_KERNEL;
 			gfp |= GFP_NOWAIT;
diff --git a/mm/readahead.c b/mm/readahead.c
index 6e5563290287e..9c116d4ba963a 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -227,17 +227,7 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
 	gfp_t gfp_mask = readahead_gfp_mask(mapping);
 	unsigned long mark = ULONG_MAX, i = 0;
 	unsigned int min_nrpages = mapping_min_folio_nrpages(mapping);
-
-	/*
-	 * Partway through the readahead operation, we will have added
-	 * locked pages to the page cache, but will not yet have submitted
-	 * them for I/O.  Adding another page may need to allocate memory,
-	 * which can trigger memory reclaim.  Telling the VM we're in
-	 * the middle of a filesystem operation will cause it to not
-	 * touch file-backed pages, preventing a deadlock.  Most (all?)
-	 * filesystems already specify __GFP_NOFS in their mapping's
-	 * gfp_mask, but let's be explicit here.
-	 */
+	/* Allocating with locked folios */
 	unsigned int nofs = memalloc_nofs_save();
 
 	lockdep_assert_held(&mapping->invalidate_lock);
@@ -512,7 +502,7 @@ void page_cache_ra_order(struct readahead_control *ractl,
 
 	ra->order = new_order;
 
-	/* See comment in page_cache_ra_unbounded() */
+	/* Allocating with locked folios */
 	nofs = memalloc_nofs_save();
 	filemap_invalidate_lock_shared(mapping);
 	/*

gemini-3.7-flash

null

null

							input: 5911
							output: 29
							thoughts: 1129
						

**Analyzing a Kernel Patch for Fuzzing Potential**

Okay, let's break this down. First, I need to understand what this patch does. It seems like it's systematically removing the `FGP_NOFS` flag from various page cache-related function calls across different filesystems: `erofs`, `ext4`, `nfs`, `ntfs`, `squashfs`, and some core `mm` and `include` headers. Essentially, it's cleaning up the way NOFS (No Filesystem) memory allocation is handled. I see this happening through a consistent removal of the flag and using new methods such as `memalloc_nofs_save()` and `mapping_gfp_mask()` or scoped NOFS context instead.

The `FGP_NOFS` flag was used to strip `__GFP_FS` from allocation flags. Now, it appears the kernel is moving towards a more modern approach, which is good – cleaner and potentially safer. They're updating the flag definitions in `pagemap.h` and removing the handling of `FGP_NOFS` in `mm/filemap.c`.

Now, the crucial question: Is this a purely internal refactoring, or does it introduce changes that might be exploitable? My initial thought is that it *looks* like a cleanup, but I need to be sure. It could introduce subtle changes in memory allocation behavior that could trigger something interesting.

Before I jump to conclusions, I should refresh my memory of the kernel maintainer guidelines for determining if a patch is WorthFuzzing. Let's see... the rules mention that modifications to documentation, Kconfig, comments, and purely decorative changes aren't typically worth fuzzing, nor are unreachable code paths or vendor-specific drivers' teardown.

So, is this functional or just a refactoring? Let's zoom in on `ext4_convert_inline_data_to_extent` and `ext4_generic_write_inline_data`. What are those functions doing in `ext4`? Hmm, the comment says we can't recurse into the filesystem because the transaction is already started. So, before calling those functions, is there a `memalloc_nofs_save()` call, or is `PF_MEMALLOC_NOFS` already set? It looks like `ext4_journal_start` probably takes care of that. I should grep for `memalloc_nofs_save` within the `fs/ext4` or `fs/jbd2` directory to confirm. If that's the case, then this patch *is* probably a refactoring, but I want to be *certain* that the existing logic is taking NOFS into account before I rule it out.

{
  "Expression": "memalloc_nofs_save",
  "PathPrefix": "fs/"
}

{
  "Output": "\nFull output is too long, showing 500 out of 528 lines.\nUse more precise expression if possible.\n\nfs/btrfs/acl.c=58=int __btrfs_set_acl(struct btrfs_trans_handle *trans, struct inode *inode,\n--\nfs/btrfs/acl.c-85-\t\t */\nfs/btrfs/acl.c:86:\t\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/acl.c-87-\t\tvalue = posix_acl_to_xattr(\u0026init_user_ns, acl, \u0026size, GFP_KERNEL);\n--\nfs/btrfs/compression.c=791=struct list_head *btrfs_get_workspace(struct btrfs_fs_info *fs_info, int type, int level)\n--\nfs/btrfs/compression.c-837-\t */\nfs/btrfs/compression.c:838:\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/compression.c-839-\tworkspace = alloc_workspace(fs_info, type, level);\n--\nfs/btrfs/disk-io.c=817=struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,\n--\nfs/btrfs/disk-io.c-830-\t */\nfs/btrfs/disk-io.c:831:\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/disk-io.c-832-\troot = btrfs_alloc_root(fs_info, objectid, GFP_KERNEL);\n--\nfs/btrfs/disk-io.c=4750=static void btrfs_destroy_delalloc_inodes(struct btrfs_root *root)\n--\nfs/btrfs/disk-io.c-4772-\nfs/btrfs/disk-io.c:4773:\t\t\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/disk-io.c-4774-\t\t\tinvalidate_inode_pages2(inode-\u003ei_mapping);\n--\nfs/btrfs/disk-io.c=4863=static void btrfs_cleanup_bg_io(struct btrfs_block_group *cache)\n--\nfs/btrfs/disk-io.c-4870-\nfs/btrfs/disk-io.c:4871:\t\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/disk-io.c-4872-\t\tinvalidate_inode_pages2(inode-\u003ei_mapping);\n--\nfs/btrfs/file-item.c=839=int btrfs_csum_one_bio(struct btrfs_bio *bbio, bool async)\n--\nfs/btrfs/file-item.c-847-\nfs/btrfs/file-item.c:848:\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/file-item.c-849-\tsums = kvzalloc(btrfs_ordered_sum_size(fs_info, bio-\u003ebi_iter.bi_size),\n--\nfs/btrfs/free-space-cache.c=83=static struct inode *__lookup_free_space_inode(struct btrfs_root *root,\n--\nfs/btrfs/free-space-cache.c-118-\t */\nfs/btrfs/free-space-cache.c:119:\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/free-space-cache.c-120-\tinode = btrfs_iget_path(location.objectid, root, path);\n--\nfs/btrfs/free-space-tree.c=158=static unsigned long *alloc_bitmap(u32 bitmap_size)\n--\nfs/btrfs/free-space-tree.c-169-\t */\nfs/btrfs/free-space-tree.c:170:\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/free-space-tree.c-171-\tret = kvzalloc(bitmap_rounded_size, GFP_KERNEL);\n--\nfs/btrfs/inode.c=126=static int data_reloc_print_warning_inode(u64 inum, u64 offset, u64 num_bytes,\n--\nfs/btrfs/inode.c-162-\nfs/btrfs/inode.c:163:\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/inode.c-164-\tipath = init_ipath(4096, local_root, \u0026warn-\u003epath);\n--\nfs/btrfs/inode.c=1565=static bool run_delalloc_compressed(struct btrfs_inode *inode,\n--\nfs/btrfs/inode.c-1578-\nfs/btrfs/inode.c:1579:\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/inode.c-1580-\tctx = kvmalloc_flex(*ctx, chunks, num_chunks);\n--\nfs/btrfs/scrub.c=482=static int scrub_print_warning_inode(u64 inum, u64 offset, u64 num_bytes,\n--\nfs/btrfs/scrub.c-527-\t */\nfs/btrfs/scrub.c:528:\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/scrub.c-529-\tipath = init_ipath(4096, local_root, swarn-\u003epath);\n--\nfs/btrfs/scrub.c=3043=int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,\n--\nfs/btrfs/scrub.c-3134-\t */\nfs/btrfs/scrub.c:3135:\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/scrub.c-3136-\tif (!is_dev_replace) {\n--\nfs/btrfs/sysfs.c=1818=void btrfs_sysfs_add_block_group_type(struct btrfs_block_group *cache)\n--\nfs/btrfs/sysfs.c-1833-\t */\nfs/btrfs/sysfs.c:1834:\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/sysfs.c-1835-\n--\nfs/btrfs/sysfs.c=2134=int btrfs_sysfs_add_device(struct btrfs_device *device)\n--\nfs/btrfs/sysfs.c-2149-\nfs/btrfs/sysfs.c:2150:\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/sysfs.c-2151-\n--\nfs/btrfs/transaction.c=1661=static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,\n--\nfs/btrfs/transaction.c-1696-\t */\nfs/btrfs/transaction.c:1697:\tnofs_flags = memalloc_nofs_save();\nfs/btrfs/transaction.c-1698-\tpending-\u003eerror = fscrypt_setup_filename(\u0026parent_inode-\u003evfs_inode,\n--\nfs/btrfs/tree-log.c=249=static struct btrfs_inode *btrfs_iget_logging(u64 objectid, struct btrfs_root *root)\n--\nfs/btrfs/tree-log.c-263-\t */\nfs/btrfs/tree-log.c:264:\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/tree-log.c-265-\tinode = btrfs_iget(objectid, root);\n--\nfs/btrfs/volumes.c=759=static noinline struct btrfs_device *device_list_add(const char *path,\n--\nfs/btrfs/volumes.c-840-\nfs/btrfs/volumes.c:841:\t\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/volumes.c-842-\t\tdevice = btrfs_alloc_device(NULL, \u0026devid,\n--\nfs/btrfs/volumes.c=7471=static struct btrfs_device *add_missing_dev(struct btrfs_fs_devices *fs_devices,\n--\nfs/btrfs/volumes.c-7483-\nfs/btrfs/volumes.c:7484:\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/volumes.c-7485-\tdevice = btrfs_alloc_device(NULL, \u0026devid, dev_uuid, NULL);\n--\nfs/btrfs/xattr.c=483=static int btrfs_initxattrs(struct inode *inode,\n--\nfs/btrfs/xattr.c-495-\t */\nfs/btrfs/xattr.c:496:\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/xattr.c-497-\tfor (xattr = xattr_array; xattr-\u003ename != NULL; xattr++) {\n--\nfs/btrfs/zoned.c=830=static int sb_log_location(struct block_device *bdev, struct blk_zone *zones,\n--\nfs/btrfs/zoned.c-857-\nfs/btrfs/zoned.c:858:\t\t\tnofs_flags = memalloc_nofs_save();\nfs/btrfs/zoned.c-859-\t\t\tret = blkdev_zone_mgmt(bdev, REQ_OP_ZONE_RESET,\n--\nfs/btrfs/zoned.c=975=int btrfs_advance_sb_log(struct btrfs_device *device, int mirror)\n--\nfs/btrfs/zoned.c-1009-\nfs/btrfs/zoned.c:1010:\t\t\t\tnofs_flags = memalloc_nofs_save();\nfs/btrfs/zoned.c-1011-\t\t\t\tret = blkdev_zone_mgmt(device-\u003ebdev,\n--\nfs/btrfs/zoned.c=1030=int btrfs_reset_sb_log_zones(struct block_device *bdev, int mirror)\n--\nfs/btrfs/zoned.c-1048-\nfs/btrfs/zoned.c:1049:\tnofs_flags = memalloc_nofs_save();\nfs/btrfs/zoned.c-1050-\tret = blkdev_zone_mgmt(bdev, REQ_OP_ZONE_RESET,\n--\nfs/btrfs/zoned.c=1164=int btrfs_reset_device_zone(struct btrfs_device *device, u64 physical,\n--\nfs/btrfs/zoned.c-1170-\t*bytes = 0;\nfs/btrfs/zoned.c:1171:\tnofs_flags = memalloc_nofs_save();\nfs/btrfs/zoned.c-1172-\tret = blkdev_zone_mgmt(device-\u003ebdev, REQ_OP_ZONE_RESET,\n--\nfs/btrfs/zoned.c=1324=static int btrfs_load_zone_info(struct btrfs_fs_info *fs_info, int zone_idx,\n--\nfs/btrfs/zoned.c-1382-\nfs/btrfs/zoned.c:1383:\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/zoned.c-1384-\tret = btrfs_get_dev_zone(device, info-\u003ephysical, \u0026zone);\n--\nfs/btrfs/zoned.c=2321=static int read_zone_info(struct btrfs_fs_info *fs_info, u64 logical,\n--\nfs/btrfs/zoned.c-2341-\nfs/btrfs/zoned.c:2342:\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/zoned.c-2343-\tnmirrors = (int)bioc-\u003enum_stripes;\n--\nfs/btrfs/zoned.c=2511=static int call_zone_finish(struct btrfs_block_group *block_group,\n--\nfs/btrfs/zoned.c-2527-\nfs/btrfs/zoned.c:2528:\t\tnofs_flags = memalloc_nofs_save();\nfs/btrfs/zoned.c-2529-\t\tret = blkdev_zone_mgmt(device-\u003ebdev, REQ_OP_ZONE_FINISH,\n--\nfs/btrfs/zoned.c=3112=int btrfs_reset_unused_block_groups(struct btrfs_space_info *space_info, u64 num_bytes)\n--\nfs/btrfs/zoned.c-3176-\nfs/btrfs/zoned.c:3177:\t\t\tnofs_flags = memalloc_nofs_save();\nfs/btrfs/zoned.c-3178-\t\t\tret = blkdev_zone_mgmt(stripe-\u003edev-\u003ebdev, REQ_OP_ZONE_RESET,\n--\nfs/btrfs/zstd.c=285=struct list_head *zstd_get_workspace(struct btrfs_fs_info *fs_info, int level)\n--\nfs/btrfs/zstd.c-301-\nfs/btrfs/zstd.c:302:\tnofs_flag = memalloc_nofs_save();\nfs/btrfs/zstd.c-303-\tws = zstd_alloc_workspace(fs_info, level);\n--\nfs/cachefiles/io.c=75=static int cachefiles_read(struct netfs_cache_resources *cres,\n--\nfs/cachefiles/io.c-157-\ttrace_cachefiles_read(object, file_inode(file), ki-\u003eiocb.ki_pos, len - skipped);\nfs/cachefiles/io.c:158:\told_nofs = memalloc_nofs_save();\nfs/cachefiles/io.c-159-\tret = cachefiles_inject_read_error();\n--\nfs/cachefiles/io.c=281=int __cachefiles_write(struct cachefiles_object *object,\n--\nfs/cachefiles/io.c-328-\ttrace_cachefiles_write(object, file_inode(file), ki-\u003eiocb.ki_pos, len);\nfs/cachefiles/io.c:329:\told_nofs = memalloc_nofs_save();\nfs/cachefiles/io.c-330-\tret = cachefiles_inject_write_error();\n--\nfs/ceph/mds_client.c=4011=static void handle_reply(struct ceph_mds_session *session, struct ceph_msg *msg)\n--\nfs/ceph/mds_client.c-4168-\t */\nfs/ceph/mds_client.c:4169:\tnofs_flags = memalloc_nofs_save();\nfs/ceph/mds_client.c-4170-\n--\nfs/ext4/ext4.h=1885=static inline int ext4_writepages_down_read(struct super_block *sb)\n--\nfs/ext4/ext4.h-1887-\tpercpu_down_read(\u0026EXT4_SB(sb)-\u003es_writepages_rwsem);\nfs/ext4/ext4.h:1888:\treturn memalloc_nofs_save();\nfs/ext4/ext4.h-1889-}\n--\nfs/ext4/ext4.h=1897=static inline int ext4_writepages_down_write(struct super_block *sb)\n--\nfs/ext4/ext4.h-1899-\tpercpu_down_write(\u0026EXT4_SB(sb)-\u003es_writepages_rwsem);\nfs/ext4/ext4.h:1900:\treturn memalloc_nofs_save();\nfs/ext4/ext4.h-1901-}\n--\nfs/ext4/ext4.h=1909=static inline int ext4_fc_lock(struct super_block *sb)\n--\nfs/ext4/ext4.h-1911-\tmutex_lock(\u0026EXT4_SB(sb)-\u003es_fc_lock);\nfs/ext4/ext4.h:1912:\treturn memalloc_nofs_save();\nfs/ext4/ext4.h-1913-}\n--\nfs/ext4/ext4_jbd2.c=33=static handle_t *ext4_get_nojournal(void)\n--\nfs/ext4/ext4_jbd2.c-47-\t\t */\nfs/ext4/ext4_jbd2.c:48:\t\thandle-\u003esaved_alloc_context = memalloc_nofs_save();\nfs/ext4/ext4_jbd2.c-49-\t\tcurrent-\u003ejournal_info = handle;\n--\nfs/ext4/move_extent.c=60=static int mext_folio_double_lock(struct inode *inode1, struct inode *inode2,\n--\nfs/ext4/move_extent.c-77-\nfs/ext4/move_extent.c:78:\tflags = memalloc_nofs_save();\nfs/ext4/move_extent.c-79-\tfgp_flags |= fgf_set_order(len);\n--\nfs/f2fs/f2fs.h=3047=static inline struct folio *f2fs_grab_cache_folio(struct address_space *mapping,\n--\nfs/f2fs/f2fs.h-3070-\nfs/f2fs/f2fs.h:3071:\tflags = memalloc_nofs_save();\nfs/f2fs/f2fs.h-3072-\tfolio = __filemap_get_folio(mapping, index, FGP_WRITEBEGIN,\n--\nfs/f2fs/segment.c=1987=static int __f2fs_issue_discard_zone(struct f2fs_sb_info *sbi,\n--\nfs/f2fs/segment.c-2022-\t\t\ttrace_f2fs_issue_reset_zone(bdev, blkstart);\nfs/f2fs/segment.c:2023:\t\t\tnofs_flags = memalloc_nofs_save();\nfs/f2fs/segment.c-2024-\t\t\tret = blkdev_zone_mgmt(bdev, REQ_OP_ZONE_RESET,\n--\nfs/f2fs/segment.c=5285=static int check_zone_write_pointer(struct f2fs_sb_info *sbi,\n--\nfs/f2fs/segment.c-5345-\nfs/f2fs/segment.c:5346:\tnofs_flags = memalloc_nofs_save();\nfs/f2fs/segment.c-5347-\tret = blkdev_zone_mgmt(fdev-\u003ebdev, REQ_OP_ZONE_FINISH,\n--\nfs/fuse/virtio_fs.c=557=static void virtio_fs_request_dispatch_work(struct work_struct *work)\n--\nfs/fuse/virtio_fs.c-592-\nfs/fuse/virtio_fs.c:593:\t\tflags = memalloc_nofs_save();\nfs/fuse/virtio_fs.c-594-\t\tret = virtio_fs_enqueue_req(fsvq, req, true, GFP_KERNEL);\n--\nfs/jbd2/journal.c=159=static int kjournald2(void *arg)\n--\nfs/jbd2/journal.c-181-\t */\nfs/jbd2/journal.c:182:\tmemalloc_nofs_save();\nfs/jbd2/journal.c-183-\n--\nfs/jbd2/transaction.c=312=static int start_this_handle(journal_t *journal, handle_t *handle,\n--\nfs/jbd2/transaction.c-449-\t */\nfs/jbd2/transaction.c:450:\thandle-\u003esaved_alloc_context = memalloc_nofs_save();\nfs/jbd2/transaction.c-451-\treturn 0;\n--\nfs/namei.c=6543=int page_symlink(struct inode *inode, const char *symname, int len)\n--\nfs/namei.c-6554-\tif (nofs)\nfs/namei.c:6555:\t\tflags = memalloc_nofs_save();\nfs/namei.c-6556-\terr = aops-\u003ewrite_begin(NULL, mapping, 0, len-1, \u0026folio, \u0026fsdata);\n--\nfs/nfs/flexfilelayout/flexfilelayout.c=446=ff_layout_alloc_lseg(struct pnfs_layout_hdr *lh,\n--\nfs/nfs/flexfilelayout/flexfilelayout.c-591-\t\t\telse {\nfs/nfs/flexfilelayout/flexfilelayout.c:592:\t\t\t\tunsigned int nofs_flags = memalloc_nofs_save();\nfs/nfs/flexfilelayout/flexfilelayout.c-593-\n--\nfs/nfs/nfs4state.c=2542=static void nfs4_state_manager(struct nfs_client *clp)\n--\nfs/nfs/nfs4state.c-2552-\t */\nfs/nfs/nfs4state.c:2553:\tmemflags = memalloc_nofs_save();\nfs/nfs/nfs4state.c-2554-\n--\nfs/nfs/nfs4state.c-2661-\t\t\t\t      \u0026clp-\u003ecl_state)) {\nfs/nfs/nfs4state.c:2662:\t\t\tmemflags = memalloc_nofs_save();\nfs/nfs/nfs4state.c-2663-\t\t\tcontinue;\n--\nfs/ntfs/lcnalloc.c=183=struct runlist_element *ntfs_cluster_alloc(struct ntfs_volume *vol, const s64 start_vcn,\n--\nfs/ntfs/lcnalloc.c-217-\nfs/ntfs/lcnalloc.c:218:\tmemalloc_flags = memalloc_nofs_save();\nfs/ntfs/lcnalloc.c-219-\n--\nfs/ntfs/lcnalloc.c=842=s64 __ntfs_cluster_free(struct ntfs_inode *ni, const s64 start_vcn, s64 count,\n--\nfs/ntfs/lcnalloc.c-870-\tif (likely(!is_rollback)) {\nfs/ntfs/lcnalloc.c:871:\t\tmemalloc_flags = memalloc_nofs_save();\nfs/ntfs/lcnalloc.c-872-\t\tdown_write(\u0026vol-\u003elcnbmp_lock);\n--\nfs/ntfs/lcnalloc.h=120=static inline int ntfs_cluster_free_from_rl(struct ntfs_volume *vol,\n--\nfs/ntfs/lcnalloc.h-125-\nfs/ntfs/lcnalloc.h:126:\tmemalloc_flags = memalloc_nofs_save();\nfs/ntfs/lcnalloc.h-127-\tdown_write(\u0026vol-\u003elcnbmp_lock);\n--\nfs/ntfs/mft.c=2013=int ntfs_mft_record_alloc(struct ntfs_volume *vol, const int mode,\n--\nfs/ntfs/mft.c-2043-\nfs/ntfs/mft.c:2044:\tmemalloc_flags = memalloc_nofs_save();\nfs/ntfs/mft.c-2045-\n--\nfs/ntfs/mft.c=2509=int ntfs_mft_record_free(struct ntfs_volume *vol, struct ntfs_inode *ni)\n--\nfs/ntfs/mft.c-2566-\t/* Clear the bit in the $MFT/$BITMAP corresponding to this record. */\nfs/ntfs/mft.c:2567:\tmemalloc_flags = memalloc_nofs_save();\nfs/ntfs/mft.c-2568-\tif (base_ni-\u003emft_no != FILE_MFT)\n--\nfs/ntfs/mft.c-2582-bitmap_rollback:\nfs/ntfs/mft.c:2583:\tmemalloc_flags = memalloc_nofs_save();\nfs/ntfs/mft.c-2584-\tif (base_ni-\u003emft_no != FILE_MFT)\n--\nfs/ntfs/wof.c=147=static int ntfs_bdev_read_from_rl(struct ntfs_volume *vol,\n--\nfs/ntfs/wof.c-165-\nfs/ntfs/wof.c:166:\tnofs_flags = memalloc_nofs_save();\nfs/ntfs/wof.c-167-\tdown_read(\u0026runlist-\u003elock);\n--\nfs/ntfs/wof.c=549=static int ntfs_wof_decode_folios_direct(struct ntfs_wof_workspace *ws,\n--\nfs/ntfs/wof.c-568-\nfs/ntfs/wof.c:569:\tnofs_flags = memalloc_nofs_save();\nfs/ntfs/wof.c-570-\taddr = vmap(dest.pages, dest.nr_pages, VM_MAP, PAGE_KERNEL);\n--\nfs/ocfs2/cluster/tcp.c=1579=static void o2net_start_connect(struct work_struct *work)\n--\nfs/ocfs2/cluster/tcp.c-1594-\t */\nfs/ocfs2/cluster/tcp.c:1595:\tnofs_flag = memalloc_nofs_save();\nfs/ocfs2/cluster/tcp.c-1596-\t/* if we're greater we initiate tx, otherwise we accept */\n--\nfs/ocfs2/cluster/tcp.c=1850=static int o2net_accept_one(struct socket *sock, int *more)\n--\nfs/ocfs2/cluster/tcp.c-1867-\t */\nfs/ocfs2/cluster/tcp.c:1868:\tnofs_flag = memalloc_nofs_save();\nfs/ocfs2/cluster/tcp.c-1869-\n--\nfs/ocfs2/quota_global.c=462=int ocfs2_global_write_info(struct super_block *sb, int type)\n--\nfs/ocfs2/quota_global.c-469-\tdown_write(\u0026dqopt-\u003edqio_sem);\nfs/ocfs2/quota_global.c:470:\tmemalloc = memalloc_nofs_save();\nfs/ocfs2/quota_global.c-471-\terr = ocfs2_qinfo_lock(info, 1);\n--\nfs/ocfs2/quota_global.c=617=static int ocfs2_sync_dquot_helper(struct dquot *dquot, unsigned long type)\n--\nfs/ocfs2/quota_global.c-641-\tdown_write(\u0026sb_dqopt(sb)-\u003edqio_sem);\nfs/ocfs2/quota_global.c:642:\tmemalloc = memalloc_nofs_save();\nfs/ocfs2/quota_global.c-643-\tstatus = ocfs2_sync_dquot(dquot);\n--\nfs/ocfs2/quota_global.c=683=static int ocfs2_write_dquot(struct dquot *dquot)\n--\nfs/ocfs2/quota_global.c-699-\tdown_write(\u0026sb_dqopt(dquot-\u003edq_sb)-\u003edqio_sem);\nfs/ocfs2/quota_global.c:700:\tmemalloc = memalloc_nofs_save();\nfs/ocfs2/quota_global.c-701-\tstatus = ocfs2_local_write_dquot(dquot);\n--\nfs/ocfs2/quota_global.c=939=static int ocfs2_mark_dquot_dirty(struct dquot *dquot)\n--\nfs/ocfs2/quota_global.c-980-\tdown_write(\u0026sb_dqopt(sb)-\u003edqio_sem);\nfs/ocfs2/quota_global.c:981:\tmemalloc = memalloc_nofs_save();\nfs/ocfs2/quota_global.c-982-\tstatus = ocfs2_sync_dquot(dquot);\n--\nfs/ocfs2/quota_local.c=457=static int ocfs2_recover_local_quota_file(struct inode *lqinode,\n--\nfs/ocfs2/quota_local.c-523-\t\t\tdown_write(\u0026sb_dqopt(sb)-\u003edqio_sem);\nfs/ocfs2/quota_local.c:524:\t\t\tmemalloc = memalloc_nofs_save();\nfs/ocfs2/quota_local.c-525-\t\t\tspin_lock(\u0026dquot-\u003edq_dqb_lock);\n--\nfs/quota/dquot.c=480=int dquot_acquire(struct dquot *dquot)\n--\nfs/quota/dquot.c-486-\tmutex_lock(\u0026dquot-\u003edq_lock);\nfs/quota/dquot.c:487:\tmemalloc = memalloc_nofs_save();\nfs/quota/dquot.c-488-\tif (!test_bit(DQ_READ_B, \u0026dquot-\u003edq_flags)) {\n--\nfs/quota/dquot.c=527=int dquot_commit(struct dquot *dquot)\n--\nfs/quota/dquot.c-533-\tmutex_lock(\u0026dquot-\u003edq_lock);\nfs/quota/dquot.c:534:\tmemalloc = memalloc_nofs_save();\nfs/quota/dquot.c-535-\tif (!clear_dquot_dirty(dquot))\n--\nfs/quota/dquot.c=553=int dquot_release(struct dquot *dquot)\n--\nfs/quota/dquot.c-559-\tmutex_lock(\u0026dquot-\u003edq_lock);\nfs/quota/dquot.c:560:\tmemalloc = memalloc_nofs_save();\nfs/quota/dquot.c-561-\t/* Check whether we are not racing with some other dqget() */\n--\nfs/quota/quota_v1.c=159=static int v1_read_file_info(struct super_block *sb, int type)\n--\nfs/quota/quota_v1.c-166-\tdown_read(\u0026dqopt-\u003edqio_sem);\nfs/quota/quota_v1.c:167:\tmemalloc = memalloc_nofs_save();\nfs/quota/quota_v1.c-168-\tret = sb-\u003es_op-\u003equota_read(sb, type, (char *)\u0026dqblk,\n--\nfs/quota/quota_v1.c=189=static int v1_write_file_info(struct super_block *sb, int type)\n--\nfs/quota/quota_v1.c-196-\tdown_write(\u0026dqopt-\u003edqio_sem);\nfs/quota/quota_v1.c:197:\tmemalloc = memalloc_nofs_save();\nfs/quota/quota_v1.c-198-\tret = sb-\u003es_op-\u003equota_read(sb, type, (char *)\u0026dqblk,\n--\nfs/quota/quota_v2.c=90=static int v2_read_file_info(struct super_block *sb, int type)\n--\nfs/quota/quota_v2.c-102-\tdown_read(\u0026dqopt-\u003edqio_sem);\nfs/quota/quota_v2.c:103:\tmemalloc = memalloc_nofs_save();\nfs/quota/quota_v2.c-104-\tret = v2_read_header(sb, type, \u0026dqhead);\n--\nfs/quota/quota_v2.c=197=static int v2_write_file_info(struct super_block *sb, int type)\n--\nfs/quota/quota_v2.c-206-\tdown_write(\u0026dqopt-\u003edqio_sem);\nfs/quota/quota_v2.c:207:\tmemalloc = memalloc_nofs_save();\nfs/quota/quota_v2.c-208-\tspin_lock(\u0026dq_data_lock);\n--\nfs/quota/quota_v2.c=336=static int v2_read_dquot(struct dquot *dquot)\n--\nfs/quota/quota_v2.c-342-\tdown_read(\u0026dqopt-\u003edqio_sem);\nfs/quota/quota_v2.c:343:\tmemalloc = memalloc_nofs_save();\nfs/quota/quota_v2.c-344-\tret = qtree_read_dquot(\n--\nfs/quota/quota_v2.c=352=static int v2_write_dquot(struct dquot *dquot)\n--\nfs/quota/quota_v2.c-370-\t}\nfs/quota/quota_v2.c:371:\tmemalloc = memalloc_nofs_save();\nfs/quota/quota_v2.c-372-\tret = qtree_write_dquot(\n--\nfs/quota/quota_v2.c=383=static int v2_release_dquot(struct dquot *dquot)\n--\nfs/quota/quota_v2.c-389-\tdown_write(\u0026dqopt-\u003edqio_sem);\nfs/quota/quota_v2.c:390:\tmemalloc = memalloc_nofs_save();\nfs/quota/quota_v2.c-391-\tret = qtree_release_dquot(sb_dqinfo(dquot-\u003edq_sb, dquot-\u003edq_id.type)-\u003edqi_priv, dquot);\n--\nfs/quota/quota_v2.c=404=static int v2_get_next_id(struct super_block *sb, struct kqid *qid)\n--\nfs/quota/quota_v2.c-410-\tdown_read(\u0026dqopt-\u003edqio_sem);\nfs/quota/quota_v2.c:411:\tmemalloc = memalloc_nofs_save();\nfs/quota/quota_v2.c-412-\tret = qtree_get_next_id(sb_dqinfo(sb, qid-\u003etype)-\u003edqi_priv, qid);\n--\nfs/smb/client/cifsglob.h=844=static inline void cifs_server_lock(struct TCP_Server_Info *server)\nfs/smb/client/cifsglob.h-845-{\nfs/smb/client/cifsglob.h:846:\tunsigned int nofs_flag = memalloc_nofs_save();\nfs/smb/client/cifsglob.h-847-\n--\nfs/squashfs/file.c=392=void squashfs_copy_cache(struct folio *folio,\n--\nfs/squashfs/file.c-400-\tint start_index = folio-\u003eindex \u0026 ~mask, end_index = start_index | mask;\nfs/squashfs/file.c:401:\tunsigned int nofs = memalloc_nofs_save();\nfs/squashfs/file.c-402-\n--\nfs/xfs/scrub/xfile.c=108=xfile_load(\n--\nfs/xfs/scrub/xfile.c-123-\nfs/xfs/scrub/xfile.c:124:\tpflags = memalloc_nofs_save();\nfs/xfs/scrub/xfile.c-125-\twhile (count \u003e 0) {\n--\nfs/xfs/scrub/xfile.c=171=xfile_store(\n--\nfs/xfs/scrub/xfile.c-193-\nfs/xfs/scrub/xfile.c:194:\tpflags = memalloc_nofs_save();\nfs/xfs/scrub/xfile.c-195-\twhile (count \u003e 0) {\n--\nfs/xfs/scrub/xfile.c=247=xfile_get_folio(\n--\nfs/xfs/scrub/xfile.c-269-\nfs/xfs/scrub/xfile.c:270:\tpflags = memalloc_nofs_save();\nfs/xfs/scrub/xfile.c-271-\terror = shmem_get_folio(inode, pos \u003e\u003e PAGE_SHIFT, 0, \u0026folio,\n--\nfs/xfs/xfs_aops.c=107=xfs_end_ioend_write(\n--\nfs/xfs/xfs_aops.c-122-\t */\nfs/xfs/xfs_aops.c:123:\tnofs_flag = memalloc_nofs_save();\nfs/xfs/xfs_aops.c-124-\n--\nfs/xfs/xfs_aops.c=529=xfs_writeback_submit(\n--\nfs/xfs/xfs_aops.c-544-\nfs/xfs/xfs_aops.c:545:\t\tnofs_flag = memalloc_nofs_save();\nfs/xfs/xfs_aops.c-546-\t\terror = xfs_reflink_convert_cow(XFS_I(ioend-\u003eio_inode),\n--\nfs/xfs/xfs_dquot.c=846=xfs_qm_dqget_cache_insert(\n--\nfs/xfs/xfs_dquot.c-856-\nfs/xfs/xfs_dquot.c:857:\tnofs_flags = memalloc_nofs_save();\nfs/xfs/xfs_dquot.c-858-\tmutex_lock(\u0026qi-\u003eqi_tree_lock);\n--\nfs/xfs/xfs_file.c=608=xfs_zoned_dio_write_end_io(\n--\nfs/xfs/xfs_file.c-629-\nfs/xfs/xfs_file.c:630:\tnofs_flag = memalloc_nofs_save();\nfs/xfs/xfs_file.c-631-\terror = xfs_dio_endio_set_isize(inode, iocb-\u003eki_pos, size);\n--\nfs/xfs/xfs_file.c=638=xfs_dio_write_end_io(\n--\nfs/xfs/xfs_file.c-671-\t */\nfs/xfs/xfs_file.c:672:\tnofs_flag = memalloc_nofs_save();\nfs/xfs/xfs_file.c-673-\n--\nfs/xfs/xfs_icache.c=1955=xfs_inodegc_worker(\n--\nfs/xfs/xfs_icache.c-1983-\t */\nfs/xfs/xfs_icache.c:1984:\tnofs_flag = memalloc_nofs_save();\nfs/xfs/xfs_icache.c-1985-\n--\nfs/xfs/xfs_log_cil.c=1375=xlog_cil_push_work(\n--\nfs/xfs/xfs_log_cil.c-1377-{\nfs/xfs/xfs_log_cil.c:1378:\tunsigned int\t\tnofs_flags = memalloc_nofs_save();\nfs/xfs/xfs_log_cil.c-1379-\tstruct xfs_cil_ctx\t*ctx =\n--\nfs/xfs/xfs_log_priv.h=639=xlog_valid_lsn(\n\n"
}

gemini-3.7-flash

null

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							input: 18030
							output: 19
							thoughts: 684
						

**Analyzing Memory Allocation Flags in File Systems**

Okay, let's dive into this memory allocation flag situation. My primary concern here is how different file systems handle memory allocation flags, particularly in contexts where we want to avoid file system operations triggering recursive reclaim or other potentially problematic behaviors, because I need a better understanding of how my modifications impact the code base.

First up, `erofs`. The `erofs_grab_folio_nowait` function seems straightforward. The use of `readahead_gfp_mask(as) & ~__GFP_RECLAIM` already prevents the allocation from directly reclaiming, which is good. That was a good start.

Next, I looked at `ext4`. The functions `ext4_convert_inline_data_to_extent` and `ext4_generic_write_inline_data` are called within a JBD2 transaction handle. This is important, because within that handle `memalloc_nofs_save()` is called via `start_this_handle()`. This means that allocations within the extent conversion process are already guarded against recursion. That's a point in the "safe" column.

Moving on to `nfs`, I noticed that `nfs_readdir_folio_get_next` uses `FGP_LOCK | FGP_CREAT | FGP_NOWAIT` and `mapping_gfp_mask(mapping)`. But wait, in the deeper call, `__filemap_get_folio_mpol`, the `FGP_NOWAIT` flag is explicitly handled, clearing `GFP_KERNEL` and setting `GFP_NOWAIT`. This is important, as `GFP_NOWAIT` itself *doesn't* have `__GFP_FS` or `__GFP_DIRECT_RECLAIM` set, so we are also safe here, and we can be sure of this behavior.

Now, `ntfs`. The function `__ntfs_inode_resident_attr_pwrite` has callers either inside an NTFS lock/transaction where `memalloc_nofs_save()` is active *or* uses `mapping_gfp_mask`. We are covered either way. And `ntfs_wof_collect_dest` passes `FGP_NOWAIT`, which correctly sets `GFP_NOWAIT`.

Looking at `squashfs`, `squashfs_copy_cache` explicitly uses `memalloc_nofs_save()` and `memalloc_nofs_restore(nofs)` around a loop. Explicit is always good. That's a good approach to ensure the correct context.

Finally, in `include/linux/pagemap.h`, `grab_cache_page_nowait` uses `FGP_NOWAIT`, so `gfp` becomes `GFP_NOWAIT` anyway. The key takeaway from this seems to be that `FGP_NOWAIT` is correctly handled.

The final piece of this is that `FGP_NOFS` was completely removed from the kernel! I need to ensure there are no unintended references to it. I will search the code to verify this removal was complete.

{
  "Expression": "FGP_NOFS"
}

{
  "Output": "fs/f2fs/data.c=3844=static int f2fs_write_begin(const struct kiocb *iocb,\n--\nfs/f2fs/data.c-3902-\tfolio = f2fs_filemap_get_folio(mapping, index,\nfs/f2fs/data.c:3903:\t\t\t\tFGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_NOFS,\nfs/f2fs/data.c-3904-\t\t\t\tmapping_gfp_mask(mapping));\n"
}

gemini-3.7-flash

null

null

							input: 19550
							output: 38
							thoughts: 64
						

**A Sudden Insight**

Okay, hold on a second! I need to double-check something. My intuition is telling me to look at `fs/f2fs/data.c` in the F2FS file system code... specifically, I wonder why `fs/f2fs/data.c` is using the `FGP_NOFS` flag? That's an unusual context, and it's grabbing my attention. Alright, let's dive into the code. Time to scrutinize line 3900 in `fs/f2fs/data.c`. Let's see what's happening there.

{
  "File": "fs/f2fs/data.c",
  "FirstLine": 3895,
  "LineCount": 20
}

{
  "Contents": "3895:\t#endif\n3896:\t\n3897:\trepeat:\n3898:\t\t/*\n3899:\t\t * Do not use FGP_STABLE to avoid deadlock.\n3900:\t\t * Will wait that below with our IO control.\n3901:\t\t */\n3902:\t\tfolio = f2fs_filemap_get_folio(mapping, index,\n3903:\t\t\t\t\tFGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_NOFS,\n3904:\t\t\t\t\tmapping_gfp_mask(mapping));\n3905:\t\tif (IS_ERR(folio)) {\n3906:\t\t\terr = PTR_ERR(folio);\n3907:\t\t\tgoto fail;\n3908:\t\t}\n3909:\t\n3910:\t\t/* TODO: cluster can be compressed due to race with .writepage */\n3911:\t\n3912:\t\t*foliop = folio;\n3913:\t\n3914:\t\tif (f2fs_is_atomic_file(inode))\n"
}

gemini-3.7-flash

null

null

							input: 20073
							output: 24
							thoughts: 69
						

Here's my take on those thoughts:

**Navigating the F2FS Codebase - A Quick Detour**

Okay, hold on a second. I'm deep in `fs/f2fs/data.c` and I'm seeing `FGP_NOFS` being used... interesting. My mind immediately flashes to the implications of bypassing the file system. But, I need to understand the context. This requires a deeper dive. The crucial function call mentioned is `f2fs_filemap_get_folio`. Let me jump over to `fs/f2fs/f2fs.h` right now. I need to refresh my understanding of how `f2fs_filemap_get_folio` handles data retrieval and what constraints are in place with `FGP_NOFS`. It's a quick rabbit hole but necessary to fully understand what's happening.

{
  "Expression": "f2fs_filemap_get_folio"
}

{
  "Output": "fs/f2fs/compress.c=1088=static int prepare_compress_overwrite(struct compress_ctx *cc,\n--\nfs/f2fs/compress.c-1109-\tfor (i = 0; i \u003c cc-\u003ecluster_size; i++) {\nfs/f2fs/compress.c:1110:\t\tfolio = f2fs_filemap_get_folio(mapping, start_idx + i,\nfs/f2fs/compress.c-1111-\t\t\t\tfgp_flag, GFP_NOFS);\n--\nfs/f2fs/compress.c=1954=bool f2fs_load_compressed_folio(struct f2fs_sb_info *sbi, struct folio *folio,\n--\nfs/f2fs/compress.c-1962-\nfs/f2fs/compress.c:1963:\tcfolio = f2fs_filemap_get_folio(COMPRESS_MAPPING(sbi),\nfs/f2fs/compress.c-1964-\t\t\t\tblkaddr, FGP_LOCK | FGP_NOWAIT, GFP_NOFS);\n--\nfs/f2fs/data.c=1361=struct folio *f2fs_find_data_folio(struct inode *inode, pgoff_t index,\n--\nfs/f2fs/data.c-1366-\nfs/f2fs/data.c:1367:\tfolio = f2fs_filemap_get_folio(mapping, index, FGP_ACCESSED, 0);\nfs/f2fs/data.c-1368-\tif (IS_ERR(folio))\n--\nfs/f2fs/data.c=3844=static int f2fs_write_begin(const struct kiocb *iocb,\n--\nfs/f2fs/data.c-3901-\t */\nfs/f2fs/data.c:3902:\tfolio = f2fs_filemap_get_folio(mapping, index,\nfs/f2fs/data.c-3903-\t\t\t\tFGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_NOFS,\n--\nfs/f2fs/f2fs.h=3047=static inline struct folio *f2fs_grab_cache_folio(struct address_space *mapping,\n--\nfs/f2fs/f2fs.h-3078-\nfs/f2fs/f2fs.h:3079:static inline struct folio *f2fs_filemap_get_folio(\nfs/f2fs/f2fs.h-3080-\t\t\t\tstruct address_space *mapping, pgoff_t index,\n--\nfs/f2fs/gc.c=1220=static int ra_data_block(struct inode *inode, pgoff_t index)\n--\nfs/f2fs/gc.c-1293-\nfs/f2fs/gc.c:1294:\tefolio = f2fs_filemap_get_folio(META_MAPPING(sbi), dn.data_blkaddr,\nfs/f2fs/gc.c-1295-\t\t\t\t\tFGP_LOCK | FGP_CREAT, GFP_NOFS);\n--\nfs/f2fs/gc.c=1332=static int move_data_block(struct inode *inode, block_t bidx,\n--\nfs/f2fs/gc.c-1456-\nfs/f2fs/gc.c:1457:\tefolio = f2fs_filemap_get_folio(META_MAPPING(fio.sbi), newaddr,\nfs/f2fs/gc.c-1458-\t\t\t\t\tFGP_LOCK | FGP_CREAT, GFP_NOFS);\n--\nfs/f2fs/node.c=1653=static void flush_inline_data(struct f2fs_sb_info *sbi, nid_t ino)\n--\nfs/f2fs/node.c-1663-\nfs/f2fs/node.c:1664:\tfolio = f2fs_filemap_get_folio(inode-\u003ei_mapping, 0,\nfs/f2fs/node.c-1665-\t\t\t\t\tFGP_LOCK|FGP_NOWAIT, 0);\n"
}

gemini-3.7-flash

null

null

							input: 21429
							output: 40
							thoughts: 31
						

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

**Diving into f2fs_filemap_get_folio**

Okay, time to dissect `f2fs_filemap_get_folio`. Let's zero in on that function, specifically in `fs/f2fs/f2fs.h`. I need to understand exactly how this function behaves when interacting with folio-based memory management within the f2fs filesystem. I want to quickly ascertain its role in mapping file data to folios, which is critical for efficient I/O, particularly in the context of F2FS's design for flash memory. I’m thinking about how this ties into the overall page cache implementation, the folio API, and how f2fs handles potential fragmentation and allocation within its block-oriented structure. I'm keen to understand the potential locking semantics involved, and how that impacts concurrency. Let's see how `f2fs_filemap_get_folio` handles the details, such as how it interacts with the underlying block device, and its potential impact on performance.

{
  "File": "fs/f2fs/f2fs.h",
  "FirstLine": 3075,
  "LineCount": 20
}

{
  "Contents": "3075:\t\n3076:\t\treturn folio;\n3077:\t}\n3078:\t\n3079:\tstatic inline struct folio *f2fs_filemap_get_folio(\n3080:\t\t\t\t\tstruct address_space *mapping, pgoff_t index,\n3081:\t\t\t\t\tfgf_t fgp_flags, gfp_t gfp_mask)\n3082:\t{\n3083:\t\tif (time_to_inject(F2FS_M_SB(mapping), FAULT_PAGE_GET))\n3084:\t\t\treturn ERR_PTR(-ENOMEM);\n3085:\t\n3086:\t\treturn __filemap_get_folio(mapping, index, fgp_flags, gfp_mask);\n3087:\t}\n3088:\t\n3089:\tstatic inline void f2fs_folio_put(struct folio *folio, bool unlock)\n3090:\t{\n3091:\t\tif (IS_ERR_OR_NULL(folio))\n3092:\t\t\treturn;\n3093:\t\n3094:\t\tif (unlock) {\n"
}

gemini-3.7-flash

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							input: 22035
							output: 38
							thoughts: 431
						

**Investigating a Potential F2FS Compilation Issue**

Okay, hold on a second. Something feels off. I need to dig into this. I was looking at `include/linux/pagemap.h` and noticed some changes to the `fgf_t` flags. Specifically, the removal of `FGP_NOFS`. Let me quickly compare the before and after:

```c
-#define FGP_NOFS		((__force fgf_t)0x00000010)
-#define FGP_NOWAIT		((__force fgf_t)0x00000020)
-#define FGP_FOR_MMAP		((__force fgf_t)0x00000040)
-#define FGP_STABLE		((__force fgf_t)0x00000080)
-#define FGP_DONTCACHE		((__force fgf_t)0x00000100)
+#define FGP_NOWAIT		((__force fgf_t)0x00000010)
+#define FGP_FOR_MMAP		((__force fgf_t)0x00000020)
+#define FGP_STABLE		((__force fgf_t)0x00000040)
+#define FGP_DONTCACHE		((__force fgf_t)0x00000080)
```

Now, the concern is that if a file like `f2fs/data.c` *wasn't* updated with this patch, there could be a compilation issue. Maybe it's a conflict or there's in-tree code that still relies on `FGP_NOFS` but isn't defined anymore. Does this code still compile? This is a problem! Let me double-check `include/linux/pagemap.h` just to be certain. Yep, `FGP_NOFS` is gone. But wait, I'm sure I saw `FGP_NOFS` in `fs/f2fs/data.c:3903` when I ran `grepper` the other day?

This doesn't make any sense. Why would `grepper` pick that up? Let's go straight to the source. I need to verify that `fs/f2fs/data.c` is actually using `FGP_NOFS`. Time to dive into the code.

{
  "File": "fs/f2fs/data.c",
  "FirstLine": 3900,
  "LineCount": 10
}

{
  "Contents": "3900:\t\t * Will wait that below with our IO control.\n3901:\t\t */\n3902:\t\tfolio = f2fs_filemap_get_folio(mapping, index,\n3903:\t\t\t\t\tFGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_NOFS,\n3904:\t\t\t\t\tmapping_gfp_mask(mapping));\n3905:\t\tif (IS_ERR(folio)) {\n3906:\t\t\terr = PTR_ERR(folio);\n3907:\t\t\tgoto fail;\n3908:\t\t}\n3909:\t\n"
}

gemini-3.7-flash

null

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							input: 23230
							output: 24
							thoughts: 36
						

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

**Digging into a Potential F2FS Compilation Flag Issue**

Okay, hold on a second. The system's telling me `FGP_NOFS` is undefined when we're compiling for F2FS. That's... unexpected. My initial thought is, this seems off – this should be defined as a consequence of F2FS compilation. I'm getting a bad feeling about this, if `FGP_NOFS` is undefined then there's a problem here. The definition is clearly used during F2FS compilation.

Wait a minute, before I start ripping things apart, let's just make sure this isn't defined *somewhere* else in the build environment that I'm not immediately thinking of. Let's trace it and verify where it's being used and how it's being defined. I need to make sure I haven't missed a crucial include or a macro definition that's overriding the expected behavior. I need to dive back into the build system and double-check those compiler directives. Gotta be thorough. There's probably a logical explanation here; it's just a matter of finding it.

no matches

{
  "Expression": "#define\\s+FGP_NOFS"
}

{
  "error": "no matches"
}

gemini-3.7-flash

null

null

							input: 23564
							output: 30
							thoughts: 2754
						

**Patch Analysis: Fuzzing Worthiness**

Okay, so I'm looking at this patch and my initial thought is: `FGP_NOFS` is undefined, that's weird.  Let's take a closer look at the context.  It touches a bunch of places: `erofs`, `ext4`, `nfs`, `ntfs`, `squashfs`, plus some core memory management and page cache headers.  Is this just refactoring, or is there functional stuff here worth fuzzing? I need to follow the rules, though:

The prompt reminds me about the criteria, and I need to be *really* careful. The instructions say it's `WorthFuzzing=false` if it only contains documentation, logging, constant changes that don't change how things work, unreachable code, or teardown callbacks.  It's `WorthFuzzing=true` if it touches reachable core kernel logic, drivers, or architectures.

Hmm, this *does* modify core kernel logic. I see changes in `mm/filemap.c`, and in `include/linux/pagemap.h`. I'm removing the `FGP_NOFS` and changing how the `GFP` flags are handled. I see macros being shifted in values. In squashfs, it looks like `memalloc_nofs_save()` and `memalloc_nofs_restore()` are being added. This looks like it's changing how memory allocation is scoped and the behavior of GFP flags. It's modifying memory allocation! So, is this *just* internal cleanup, or is it fundamentally altering execution flow?

Let's break it down: Is this patch altering memory allocation flags in places like `ntfs_wof_collect_dest`, or introducing `memalloc_nofs_save/restore` in a key function like `squashfs_copy_cache`? Absolutely! I need to ensure this is something I want to fuzz because this is reachable.

I need to make sure this meets none of the 6 exclusion categories. 1. No, it's modifying C code. 2. No, not just logging. 3. No, not just macros: I'm eliminating `FGP_NOFS` in memory allocation APIs, it's more than a constant change. 4. No, this code *is* reachable in a QEMU environment. 5. Nope, not PCI/GPU/SmartNIC drivers. 6. Nope, not teardown callbacks.

Okay, let's play devil's advocate: Is this a simple refactoring to clean up the `FGP_NOFS` flag across pagecache and callers, replacing it with scoped allocators, and not really changing how the kernel works? Or is it a fundamental modification to page cache folio flags, and reclaim?

Looking at it closely, this isn't just about removing the flag; it's about altering how GFP flags and allocation scopes work within the memory management subsystem *and* the filesystems that use it. In `ntfs_wof_collect_dest`, now we're using the `mapping_gfp_mask()` argument, instead of `GFP_NOFS`. In squashfs, the code is using `memalloc_nofs_save()` and `memalloc_nofs_restore()` now. The values of flags like `FGP_NOWAIT` have changed!

The prompt's criterion is strict: if I modify core logic, it's worth fuzzing! Specifically, if I modify MM code and Filesystem code, it's worth fuzzing. Reclaim behavior is changing, and that's critical in lockdep and deadlock prevention.

I also need to verify config symbols. `EROFS_FS`, `EXT4_FS`, `NFS_FS`, `NTFS_FS`, `SQUASHFS` are relevant. Then, the core MM code is always enabled or a standard config. I should check the Kconfig files, but as far as I can tell, I have my answer!

This clearly modifies reachable core kernel logic, including memory management and multiple filesystems. It's not *just* cosmetic or unreachable code. It's about how memory is allocated and reclaimed, and that *absolutely* makes this worth fuzzing, particularly with lockdep and memory pressure. Therefore, WorthFuzzing=true.

{
  "Expression": "config EROFS_FS",
  "PathPrefix": "fs/erofs"
}

{
  "Output": "fs/erofs/Kconfig-2-\nfs/erofs/Kconfig:3:config EROFS_FS\nfs/erofs/Kconfig-4-\ttristate \"EROFS filesystem support\"\n--\nfs/erofs/Kconfig-49-\nfs/erofs/Kconfig:50:config EROFS_FS_DEBUG\nfs/erofs/Kconfig-51-\tbool \"EROFS debugging feature\"\n--\nfs/erofs/Kconfig-59-\nfs/erofs/Kconfig:60:config EROFS_FS_XATTR\nfs/erofs/Kconfig-61-\tbool \"EROFS extended attributes\"\n--\nfs/erofs/Kconfig-70-\nfs/erofs/Kconfig:71:config EROFS_FS_POSIX_ACL\nfs/erofs/Kconfig-72-\tbool \"EROFS Access Control Lists\"\n--\nfs/erofs/Kconfig-84-\nfs/erofs/Kconfig:85:config EROFS_FS_SECURITY\nfs/erofs/Kconfig-86-\tbool \"EROFS Security Labels\"\n--\nfs/erofs/Kconfig-97-\nfs/erofs/Kconfig:98:config EROFS_FS_BACKED_BY_FILE\nfs/erofs/Kconfig-99-\tbool \"File-backed EROFS filesystem support\"\n--\nfs/erofs/Kconfig-111-\nfs/erofs/Kconfig:112:config EROFS_FS_ZIP\nfs/erofs/Kconfig-113-\tbool \"EROFS Data Compression Support\"\n--\nfs/erofs/Kconfig-121-\nfs/erofs/Kconfig:122:config EROFS_FS_ZIP_LZMA\nfs/erofs/Kconfig-123-\tbool \"EROFS LZMA compressed data support\"\n--\nfs/erofs/Kconfig-133-\nfs/erofs/Kconfig:134:config EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS\nfs/erofs/Kconfig-135-\tint \"EROFS LZMA default maximum decompression streams\" if SMP\n--\nfs/erofs/Kconfig-150-\nfs/erofs/Kconfig:151:config EROFS_FS_ZIP_DEFLATE\nfs/erofs/Kconfig-152-\tbool \"EROFS DEFLATE compressed data support\"\n--\nfs/erofs/Kconfig-161-\nfs/erofs/Kconfig:162:config EROFS_FS_ZIP_ZSTD\nfs/erofs/Kconfig-163-\tbool \"EROFS Zstandard compressed data support\"\n--\nfs/erofs/Kconfig-172-\nfs/erofs/Kconfig:173:config EROFS_FS_ZIP_ACCEL\nfs/erofs/Kconfig-174-\tbool \"EROFS hardware decompression support\"\n--\nfs/erofs/Kconfig-186-\nfs/erofs/Kconfig:187:config EROFS_FS_PCPU_KTHREAD\nfs/erofs/Kconfig-188-\tbool \"EROFS per-cpu decompression kthread workers\"\n--\nfs/erofs/Kconfig-195-\nfs/erofs/Kconfig:196:config EROFS_FS_PCPU_KTHREAD_HIPRI\nfs/erofs/Kconfig-197-\tbool \"EROFS high priority per-CPU kthread workers\"\n--\nfs/erofs/Kconfig-205-\nfs/erofs/Kconfig:206:config EROFS_FS_PAGE_CACHE_SHARE\nfs/erofs/Kconfig-207-\tbool \"EROFS page cache share support (experimental)\"\n"
}

gemini-3.7-flash

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							input: 28207
							output: 23
							thoughts: 32
						

Okay, let's dive into this. Here's how I'd approach this task, as if these were my internal thoughts:

**Investigating `erofs_grab_folio_nowait` in `fs/erofs/internal.h`**

Right, so the goal is to understand the context and usage of `erofs_grab_folio_nowait` within the EROFS filesystem. My first step is to quickly locate this function within the `fs/erofs/internal.h` header file. I need to refresh my memory on what `erofs_grab_folio_nowait` actually *does*. Is it involved in cache management, perhaps? Or maybe it's related to metadata handling?

Once I've got that straight in my head, I'll move on to a critical aspect of understanding any function: its use cases. Therefore, I will need to understand what code calls `erofs_grab_folio_nowait`. I'll want to see the various parts of the code that make use of this function and see how they are implemented. This will give me crucial insights into its purpose. I'll need to know which other functions and structures are interacting with this one. Are there any particular EROFS operations that heavily rely on it?

{
  "Expression": "erofs_grab_folio_nowait"
}

{
  "Output": "fs/erofs/internal.h=320=static inline unsigned int erofs_inode_datalayout(unsigned int ifmt)\n--\nfs/erofs/internal.h-325-/* reclaiming is never triggered when allocating new folios. */\nfs/erofs/internal.h:326:static inline struct folio *erofs_grab_folio_nowait(struct address_space *as,\nfs/erofs/internal.h-327-\t\t\t\t\t\t    pgoff_t index)\n--\nfs/erofs/zdata.c=1814=static void z_erofs_pcluster_readmore(struct z_erofs_frontend *f,\n--\nfs/erofs/zdata.c-1850-\nfs/erofs/zdata.c:1851:\t\tfolio = erofs_grab_folio_nowait(f-\u003esharedinode-\u003ei_mapping, index);\nfs/erofs/zdata.c-1852-\t\tif (!IS_ERR_OR_NULL(folio)) {\n"
}

gemini-3.7-flash

null

null

							input: 28792
							output: 26
							thoughts: 64
						

**My Initial Thoughts on EROFS Optimization**

Okay, so `z_erofs_pcluster_readmore` is only relevant when EROFS is configured with either `EROFS_FS_PAGE_CACHE_SHARE` or `EROFS_FS_ZIP`. That's a key piece of information, and it narrows down the scope of where I need to look to understand its function and impact. Given my understanding of EROFS and its optimizations, this makes perfect sense. I now need to understand what this module is actually doing.

To get a better idea of how EROFS is configured, and whether it could provide any information, it looks like checking the NTFS configs in the file system would be a useful step to better understand it. Therefore, I will now go and check the `fs/ntfs/Makefile` and `fs/ntfs/Kconfig` files. That should give me a good overview of the relevant NTFS configurations, and possibly reveal how these features are employed.

{
  "Expression": "config NTFS",
  "PathPrefix": "fs/ntfs"
}

{
  "Output": "fs/ntfs/Kconfig-1-# SPDX-License-Identifier: GPL-2.0-only\nfs/ntfs/Kconfig:2:config NTFS_FS\nfs/ntfs/Kconfig-3-\ttristate \"NTFS file system support\"\n--\nfs/ntfs/Kconfig-12-\nfs/ntfs/Kconfig:13:config NTFS_FS_WOF_COMPRESSION\nfs/ntfs/Kconfig-14-\tbool \"NTFS Windows system compression support\"\n--\nfs/ntfs/Kconfig-23-\nfs/ntfs/Kconfig:24:config NTFS_DEBUG\nfs/ntfs/Kconfig-25-\tbool \"NTFS debugging support\"\n--\nfs/ntfs/Kconfig-45-\nfs/ntfs/Kconfig:46:config NTFS_FS_POSIX_ACL\nfs/ntfs/Kconfig-47-\tbool \"NTFS POSIX Access Control Lists\"\n"
}

gemini-3.7-flash

null

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							input: 29329
							output: 33
							thoughts: 48
						

Okay, here's my take on those thoughts, framed as my own:

**Quick NTFS Configuration Scan**

Right, let's just make sure I'm on top of the NTFS configurations. Specifically, I need to confirm the presence and status of `NTFS_FS_WOF_COMPRESSION`. That one is important for understanding how write-once, file-system-based compression is handled. And I need to quickly recall if `NTFS_FS_RW` is still around, or if it's been superseded by something else. Best to just jump into `fs/ntfs/Kconfig` and verify. Nothing worse than making assumptions when a quick Kconfig check will give me the definitive answer.

{
  "File": "fs/ntfs/Kconfig",
  "FirstLine": 1,
  "LineCount": 50
}

{
  "Contents": "   1:\t# SPDX-License-Identifier: GPL-2.0-only\n   2:\tconfig NTFS_FS\n   3:\t\ttristate \"NTFS file system support\"\n   4:\t\tselect NLS\n   5:\t\tselect FS_IOMAP\n   6:\t\thelp\n   7:\t\t  NTFS is the file system of Microsoft Windows NT, 2000, XP and 2003.\n   8:\t\t  This allows you to mount devices formatted with the ntfs file system.\n   9:\t\n  10:\t\t  To compile this as a module, choose M here: the module will be called\n  11:\t\t  ntfs.\n  12:\t\n  13:\tconfig NTFS_FS_WOF_COMPRESSION\n  14:\t\tbool \"NTFS Windows system compression support\"\n  15:\t\tdepends on NTFS_FS\n  16:\t\thelp\n  17:\t\t  Enable read support for Windows system-compressed files.\n  18:\t\t  Windows more aggressively compresses system files such as binaries\n  19:\t\t  and DLLs using system compression. It is optimized for files that\n  20:\t\t  are rarely modified.\n  21:\t\t  Enabling this option builds the decompression support into the NTFS\n  22:\t\t  module.\n  23:\t\n  24:\tconfig NTFS_DEBUG\n  25:\t\tbool \"NTFS debugging support\"\n  26:\t\tdepends on NTFS_FS\n  27:\t\thelp\n  28:\t\t  If you are experiencing any problems with the NTFS file system, say\n  29:\t\t  Y here.  This will result in additional consistency checks to be\n  30:\t\t  performed by the driver as well as additional debugging messages to\n  31:\t\t  be written to the system log.  Note that debugging messages are\n  32:\t\t  disabled by default.  To enable them, supply the option debug_msgs=1\n  33:\t\t  at the kernel command line when booting the kernel or as an option\n  34:\t\t  to insmod when loading the ntfs module.  Once the driver is active,\n  35:\t\t  you can enable debugging messages by doing (as root):\n  36:\t\t  echo 1 \u003e /proc/sys/fs/ntfs-debug\n  37:\t\t  Replacing the \"1\" with \"0\" would disable debug messages.\n  38:\t\n  39:\t\t  If you leave debugging messages disabled, this results in little\n  40:\t\t  overhead, but enabling debug messages results in very significant\n  41:\t\t  slowdown of the system.\n  42:\t\n  43:\t\t  When reporting bugs, please try to have available a full dump of\n  44:\t\t  debugging messages while the misbehaviour was occurring.\n  45:\t\n  46:\tconfig NTFS_FS_POSIX_ACL\n  47:\t\tbool \"NTFS POSIX Access Control Lists\"\n  48:\t\tdepends on NTFS_FS\n  49:\t\tselect FS_POSIX_ACL\n  50:\t\thelp\n"
}

gemini-3.7-flash

null

null

							input: 30293
							output: 30
							thoughts: 19
						

Here's my take on those thoughts:

**SquashFS Configuration Hunt**

Alright, time to get this sorted. First things first, let's dive straight into the heart of the matter – the configuration. I need to understand the specifics of SquashFS and how it's being handled in the system. The `fs/squashfs/Kconfig` file is the most likely place to find those kernel configuration options. That's the go-to spot for figuring out what's enabled, disabled, what dependencies exist, and how it all fits together within the broader build process. I'll need to scrutinize those configs thoroughly to understand the full picture. Let's see what we can find.

{
  "Expression": "config SQUASHFS",
  "PathPrefix": "fs/squashfs"
}

{
  "Output": "fs/squashfs/Kconfig-1-# SPDX-License-Identifier: GPL-2.0-only\nfs/squashfs/Kconfig:2:config SQUASHFS\nfs/squashfs/Kconfig-3-\ttristate \"SquashFS 4.0 - Squashed file system support\"\n--\nfs/squashfs/Kconfig=29=choice\n--\nfs/squashfs/Kconfig-40-\nfs/squashfs/Kconfig:41:config SQUASHFS_FILE_CACHE\nfs/squashfs/Kconfig-42-\tbool \"Decompress file data into an intermediate buffer\"\n--\nfs/squashfs/Kconfig-46-\nfs/squashfs/Kconfig:47:config SQUASHFS_FILE_DIRECT\nfs/squashfs/Kconfig-48-\tbool \"Decompress files directly into the page cache\"\n--\nfs/squashfs/Kconfig=55=endchoice\nfs/squashfs/Kconfig-56-\nfs/squashfs/Kconfig:57:config SQUASHFS_DECOMP_SINGLE\nfs/squashfs/Kconfig-58-\tdepends on SQUASHFS\n--\nfs/squashfs/Kconfig-60-\nfs/squashfs/Kconfig:61:config SQUASHFS_DECOMP_MULTI\nfs/squashfs/Kconfig-62-\tdepends on SQUASHFS\n--\nfs/squashfs/Kconfig-64-\nfs/squashfs/Kconfig:65:config SQUASHFS_DECOMP_MULTI_PERCPU\nfs/squashfs/Kconfig-66-\tdepends on SQUASHFS\n--\nfs/squashfs/Kconfig-68-\nfs/squashfs/Kconfig:69:config SQUASHFS_CHOICE_DECOMP_BY_MOUNT\nfs/squashfs/Kconfig-70-\tbool \"Select the parallel decompression mode during mount\"\n--\nfs/squashfs/Kconfig=82=choice\n--\nfs/squashfs/Kconfig-92-\nfs/squashfs/Kconfig:93:config SQUASHFS_COMPILE_DECOMP_SINGLE\nfs/squashfs/Kconfig-94-\tbool \"Single threaded compression\"\n--\nfs/squashfs/Kconfig-100-\nfs/squashfs/Kconfig:101:config SQUASHFS_COMPILE_DECOMP_MULTI\nfs/squashfs/Kconfig-102-\tbool \"Use multiple decompressors for parallel I/O\"\n--\nfs/squashfs/Kconfig-115-\nfs/squashfs/Kconfig:116:config SQUASHFS_COMPILE_DECOMP_MULTI_PERCPU\nfs/squashfs/Kconfig-117-\tbool \"Use percpu multiple decompressors for parallel I/O\"\n--\nfs/squashfs/Kconfig=127=endchoice\nfs/squashfs/Kconfig-128-\nfs/squashfs/Kconfig:129:config SQUASHFS_MOUNT_DECOMP_THREADS\nfs/squashfs/Kconfig-130-\tbool \"Add the mount parameter 'threads=' for squashfs\"\n--\nfs/squashfs/Kconfig-141-\nfs/squashfs/Kconfig:142:config SQUASHFS_XATTR\nfs/squashfs/Kconfig-143-\tbool \"Squashfs XATTR support\"\n--\nfs/squashfs/Kconfig-151-\nfs/squashfs/Kconfig:152:config SQUASHFS_COMP_CACHE_FULL\nfs/squashfs/Kconfig-153-\tbool \"Enable full caching of compressed blocks\"\n--\nfs/squashfs/Kconfig-172-\nfs/squashfs/Kconfig:173:config SQUASHFS_ZLIB\nfs/squashfs/Kconfig-174-\tbool \"Include support for ZLIB compressed file systems\"\n--\nfs/squashfs/Kconfig-185-\nfs/squashfs/Kconfig:186:config SQUASHFS_LZ4\nfs/squashfs/Kconfig-187-\tbool \"Include support for LZ4 compressed file systems\"\n--\nfs/squashfs/Kconfig-200-\nfs/squashfs/Kconfig:201:config SQUASHFS_LZO\nfs/squashfs/Kconfig-202-\tbool \"Include support for LZO compressed file systems\"\n--\nfs/squashfs/Kconfig-215-\nfs/squashfs/Kconfig:216:config SQUASHFS_XZ\nfs/squashfs/Kconfig-217-\tbool \"Include support for XZ compressed file systems\"\n--\nfs/squashfs/Kconfig-230-\nfs/squashfs/Kconfig:231:config SQUASHFS_ZSTD\nfs/squashfs/Kconfig-232-\tbool \"Include support for ZSTD compressed file systems\"\n--\nfs/squashfs/Kconfig-244-\nfs/squashfs/Kconfig:245:config SQUASHFS_4K_DEVBLK_SIZE\nfs/squashfs/Kconfig-246-\tbool \"Use 4K device block size?\"\n--\nfs/squashfs/Kconfig-266-\nfs/squashfs/Kconfig:267:config SQUASHFS_EMBEDDED\nfs/squashfs/Kconfig-268-\tbool \"Additional option for memory-constrained systems\"\n--\nfs/squashfs/Kconfig-274-\nfs/squashfs/Kconfig:275:config SQUASHFS_FRAGMENT_CACHE_SIZE\nfs/squashfs/Kconfig-276-\tint \"Number of fragments cached\" if SQUASHFS_EMBEDDED\n"
}

gemini-3.7-flash

null

null

							input: 31936
							output: 32
							thoughts: 29
						

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

**Diving into the `squashfs_copy_cache` Configuration**

Right, let's get down to brass tacks. I need to figure out which configuration options are actually enabling the `squashfs_copy_cache` functionality. My initial instinct is to dig into the source code, specifically `fs/squashfs/file.c`. That's usually the best place to start when I'm chasing down how a particular feature, especially one related to file handling, is controlled at build time. I'll need to rapidly scan through the code, looking for conditional compilation directives – the `#ifdef` or similar constructs – that control whether the code utilizing `squashfs_copy_cache` is actually included in the final kernel image. Time to see which config options ultimately decide if that code gets linked or not. Hopefully, it's pretty straightforward, maybe a single `CONFIG_SQUASHFS_*` variable, or perhaps a more involved dependency chain. Let's get to it!

{
  "Expression": "squashfs_copy_cache",
  "PathPrefix": "fs/squashfs"
}

{
  "Output": "fs/squashfs/file.c=374=static bool squashfs_fill_page(struct folio *folio,\n--\nfs/squashfs/file.c-391-/* Copy data into page cache  */\nfs/squashfs/file.c:392:void squashfs_copy_cache(struct folio *folio,\nfs/squashfs/file.c-393-\t\tstruct squashfs_cache_entry *buffer, size_t bytes,\n--\nfs/squashfs/file.c=439=static int squashfs_readpage_fragment(struct folio *folio, int expected)\n--\nfs/squashfs/file.c-451-\telse\nfs/squashfs/file.c:452:\t\tsquashfs_copy_cache(folio, buffer, expected,\nfs/squashfs/file.c-453-\t\t\tsquashfs_i(inode)-\u003efragment_offset);\n--\nfs/squashfs/file.c=459=static int squashfs_readpage_sparse(struct folio *folio, int expected)\nfs/squashfs/file.c-460-{\nfs/squashfs/file.c:461:\tsquashfs_copy_cache(folio, NULL, expected, 0);\nfs/squashfs/file.c-462-\treturn 0;\n--\nfs/squashfs/file_cache.c=21=int squashfs_readpage_block(struct folio *folio, u64 block, int bsize, int expected)\n--\nfs/squashfs/file_cache.c-31-\telse\nfs/squashfs/file_cache.c:32:\t\tsquashfs_copy_cache(folio, buffer, expected, 0);\nfs/squashfs/file_cache.c-33-\n--\nfs/squashfs/squashfs.h=72=extern __le64 *squashfs_read_fragment_index_table(struct super_block *,\n--\nfs/squashfs/squashfs.h-75-/* file.c */\nfs/squashfs/squashfs.h:76:void squashfs_copy_cache(struct folio *, struct squashfs_cache_entry *,\nfs/squashfs/squashfs.h-77-\t\tsize_t bytes, size_t offset);\n"
}

gemini-3.7-flash

null

null

							input: 32806
							output: 33
							thoughts: 13
						

Here's a summary of my thought process, as if I were considering the `fs/squashfs/Makefile`:

**Analyzing the Squashfs Makefile**

Okay, time to dive into the `fs/squashfs/Makefile`. Given my deep understanding of file systems and build processes, I'm immediately thinking about what I expect to see. I anticipate this Makefile will manage the compilation and linking of the Squashfs kernel module, its utilities, and potentially some tests. I'll be looking for key elements: the module name definition, source file lists, object file generation, dependency rules, compilation flags, linker options, installation targets, and any cross-compilation considerations. I'll also be searching for any clever tricks or optimizations they've implemented. My goal is to quickly grasp the build structure, identify any potential areas for performance improvement, or spot any unusual configurations that might warrant further investigation. I'm also keeping an eye out for how this integrates with the overall kernel build system. Are they using the standard kernel make rules, or have they introduced custom logic? Finally, I need to note any specific flags or targets that I could utilize for quick rebuilds or unit tests in my specific use case.

{
  "File": "fs/squashfs/Makefile",
  "FirstLine": 1,
  "LineCount": 30
}

{
  "Contents": "   1:\t# SPDX-License-Identifier: GPL-2.0\n   2:\t#\n   3:\t# Makefile for the linux squashfs routines.\n   4:\t#\n   5:\t\n   6:\tobj-$(CONFIG_SQUASHFS) += squashfs.o\n   7:\tsquashfs-y += block.o cache.o dir.o export.o file.o fragment.o id.o inode.o\n   8:\tsquashfs-y += namei.o super.o symlink.o decompressor.o page_actor.o\n   9:\tsquashfs-$(CONFIG_SQUASHFS_FILE_CACHE) += file_cache.o\n  10:\tsquashfs-$(CONFIG_SQUASHFS_FILE_DIRECT) += file_direct.o\n  11:\tsquashfs-$(CONFIG_SQUASHFS_DECOMP_SINGLE) += decompressor_single.o\n  12:\tsquashfs-$(CONFIG_SQUASHFS_DECOMP_MULTI) += decompressor_multi.o\n  13:\tsquashfs-$(CONFIG_SQUASHFS_DECOMP_MULTI_PERCPU) += decompressor_multi_percpu.o\n  14:\tsquashfs-$(CONFIG_SQUASHFS_XATTR) += xattr.o xattr_id.o\n  15:\tsquashfs-$(CONFIG_SQUASHFS_LZ4) += lz4_wrapper.o\n  16:\tsquashfs-$(CONFIG_SQUASHFS_LZO) += lzo_wrapper.o\n  17:\tsquashfs-$(CONFIG_SQUASHFS_XZ) += xz_wrapper.o\n  18:\tsquashfs-$(CONFIG_SQUASHFS_ZLIB) += zlib_wrapper.o\n  19:\tsquashfs-$(CONFIG_SQUASHFS_ZSTD) += zstd_wrapper.o\n"
}

gemini-3.7-flash

null

null

							input: 33576
							output: 33
							thoughts: 84
						

**Focusing on Filemap and Folio Handling**

Okay, let's dive into this. My immediate concern is the focus symbols and how they're declared and linked within the system. I'm specifically interested in the changes and their impact on certain functions, namely `__filemap_get_folio` and `__filemap_get_folio_mpol` residing in `mm/filemap.c`. Hmm, I need to make a quick check. Is `__filemap_get_folio` declared as non-static? I need to verify that declaration to understand the scope and implications fully. Let me quickly examine `mm/filemap.c` to confirm.

{
  "Expression": "__filemap_get_folio",
  "PathPrefix": "mm/filemap.c"
}

{
  "Output": "mm/filemap.c=1899=void *filemap_get_entry(struct address_space *mapping, pgoff_t index)\n--\nmm/filemap.c-1930-/**\nmm/filemap.c:1931: * __filemap_get_folio_mpol - Find and get a reference to a folio.\nmm/filemap.c-1932- * @mapping: The address_space to search.\n--\nmm/filemap.c-1946- */\nmm/filemap.c:1947:struct folio *__filemap_get_folio_mpol(struct address_space *mapping,\nmm/filemap.c-1948-\t\tpgoff_t index, fgf_t fgp_flags, gfp_t gfp, struct mempolicy *policy)\n--\nmm/filemap.c-2073-}\nmm/filemap.c:2074:EXPORT_SYMBOL(__filemap_get_folio_mpol);\nmm/filemap.c-2075-\n--\nmm/filemap.c=3553=vm_fault_t filemap_fault(struct vm_fault *vmf)\n--\nmm/filemap.c-3604-\t\t}\nmm/filemap.c:3605:\t\tfolio = __filemap_get_folio(mapping, index,\nmm/filemap.c-3606-\t\t\t\t\t  FGP_CREAT|FGP_FOR_MMAP,\n"
}

gemini-3.7-flash

null

null

							input: 34214
							output: 36
							thoughts: 213
						

**Analyzing Potential File System Data Corruption Entry Points**

Okay, so I'm diving into this code, looking for potential areas where file system data corruption could creep in. My initial focus is on file systems that handle data directly, in particular inline data and cache management. I start by making a mental note of the exported symbol `__filemap_get_folio_mpol`, and the inline wrapper `__filemap_get_folio` – these are important because they are visible externally. I know those are in `include/linux/pagemap.h`, I want to be aware of how they're used.

Next, I see `squashfs_copy_cache` in `fs/squashfs/file.c` is non-static, meaning it's externally visible within that module. Same with `ext4_generic_write_inline_data` in `fs/ext4/inline.c`. These jump out as functions I should definitely scrutinize. Any non-static function could have its data manipulated by another module.

Then, there's `ext4_convert_inline_data_to_extent` in `fs/ext4/inline.c`. It's static, so it's not externally visible, but that doesn't mean it's safe. It's a potential area of concern, and I need to identify any non-static entry points within the file, or any exported symbols, that might call it, or otherwise expose this functionality. I'll need to drill down into `fs/ext4/inline.c` and specifically trace the callers of `ext4_convert_inline_data_to_extent` to see if there's any way to trigger it from outside its file scope. That's where I need to focus my analysis to uncover any subtle vulnerabilities.

{
  "Expression": "ext4_convert_inline_data_to_extent",
  "PathPrefix": "fs/ext4"
}

{
  "Output": "fs/ext4/inline.c=544=int ext4_readpage_inline(struct inode *inode, struct folio *folio)\n--\nfs/ext4/inline.c-570-\nfs/ext4/inline.c:571:static int ext4_convert_inline_data_to_extent(struct address_space *mapping,\nfs/ext4/inline.c-572-\t\t\t\t\t      struct inode *inode)\n--\nfs/ext4/inline.c=693=int ext4_generic_write_inline_data(struct address_space *mapping,\n--\nfs/ext4/inline.c-724-\t\t\t/* Retry inside */\nfs/ext4/inline.c:725:\t\t\treturn ext4_convert_inline_data_to_extent(mapping, inode);\nfs/ext4/inline.c-726-\t\t}\n--\nfs/ext4/inline.c=780=int ext4_try_to_write_inline_data(struct address_space *mapping,\n--\nfs/ext4/inline.c-785-\tif (pos + len \u003e ext4_get_max_inline_size(inode))\nfs/ext4/inline.c:786:\t\treturn ext4_convert_inline_data_to_extent(mapping, inode);\nfs/ext4/inline.c-787-\treturn ext4_generic_write_inline_data(mapping, inode, pos, len,\n"
}

gemini-3.7-flash

null

null

							input: 35214
							output: 29
							thoughts: 60
						

Here's my take on those thoughts:

**Analyzing Potential Inline Data Handling**

Okay, so `ext4_generic_write_inline_data` and `ext4_try_to_write_inline_data` are *not* static, which immediately piques my interest. Non-static implies they could potentially be called from outside their immediate scope, which is relevant if we're investigating how different filesystems approach inline data. I'm wondering if there are any opportunities to consolidate or better understand these implementations.

To that end, I think a look at `ntfs_wof_collect_dest` in `fs/ntfs/wof.c` would be worthwhile. Seeing how NTFS handles its Write-Only-Filter (WOF) and inline data could reveal potential insights, comparisons, or even implementation differences that are relevant to this area of investigation. It might illuminate some alternative approaches. Let's see what that module has to offer.

{
  "Expression": "ntfs_wof",
  "PathPrefix": "fs/ntfs"
}

{
  "Output": "fs/ntfs/ntfs.h=206=int ntfs_read_wof_compressed_block(struct folio *folio);\nfs/ntfs/ntfs.h:207:void ntfs_wof_free_workspaces(void);\nfs/ntfs/ntfs.h-208-#endif\n--\nfs/ntfs/super.c=2683=static void __exit exit_ntfs_fs(void)\n--\nfs/ntfs/super.c-2694-#ifdef CONFIG_NTFS_FS_WOF_COMPRESSION\nfs/ntfs/super.c:2695:\tntfs_wof_free_workspaces();\nfs/ntfs/super.c-2696-#endif\n--\nfs/ntfs/wof.c=23=static const __le16 WOF_NAME[] = {\n--\nfs/ntfs/wof.c-37-\nfs/ntfs/wof.c:38:struct ntfs_wof_workspace {\nfs/ntfs/wof.c-39-\tstruct mutex *lock;\n--\nfs/ntfs/wof.c-47-\nfs/ntfs/wof.c:48:static DEFINE_MUTEX(ntfs_wof_xpress4k_lock);\nfs/ntfs/wof.c:49:static DEFINE_MUTEX(ntfs_wof_xpress8k_lock);\nfs/ntfs/wof.c:50:static DEFINE_MUTEX(ntfs_wof_xpress16k_lock);\nfs/ntfs/wof.c:51:static DEFINE_MUTEX(ntfs_wof_lzx32k_lock);\nfs/ntfs/wof.c-52-\nfs/ntfs/wof.c:53:static struct ntfs_wof_workspace ntfs_wof_xpress4k_workspace = {\nfs/ntfs/wof.c:54:\t.lock = \u0026ntfs_wof_xpress4k_lock,\nfs/ntfs/wof.c-55-\t.codec = \u0026ntfs_xpress4k_codec_ops,\n--\nfs/ntfs/wof.c-58-\nfs/ntfs/wof.c:59:static struct ntfs_wof_workspace ntfs_wof_xpress8k_workspace = {\nfs/ntfs/wof.c:60:\t.lock = \u0026ntfs_wof_xpress8k_lock,\nfs/ntfs/wof.c-61-\t.codec = \u0026ntfs_xpress8k_codec_ops,\n--\nfs/ntfs/wof.c-64-\nfs/ntfs/wof.c:65:static struct ntfs_wof_workspace ntfs_wof_xpress16k_workspace = {\nfs/ntfs/wof.c:66:\t.lock = \u0026ntfs_wof_xpress16k_lock,\nfs/ntfs/wof.c-67-\t.codec = \u0026ntfs_xpress16k_codec_ops,\n--\nfs/ntfs/wof.c-70-\nfs/ntfs/wof.c:71:static struct ntfs_wof_workspace ntfs_wof_lzx32k_workspace = {\nfs/ntfs/wof.c:72:\t.lock = \u0026ntfs_wof_lzx32k_lock,\nfs/ntfs/wof.c-73-\t.codec = \u0026ntfs_lzx32k_codec_ops,\n--\nfs/ntfs/wof.c-76-\nfs/ntfs/wof.c:77:static struct ntfs_wof_workspace *const ntfs_wof_workspaces[] = {\nfs/ntfs/wof.c:78:\t\u0026ntfs_wof_xpress4k_workspace,\nfs/ntfs/wof.c:79:\t\u0026ntfs_wof_xpress8k_workspace,\nfs/ntfs/wof.c:80:\t\u0026ntfs_wof_xpress16k_workspace,\nfs/ntfs/wof.c:81:\t\u0026ntfs_wof_lzx32k_workspace,\nfs/ntfs/wof.c-82-};\nfs/ntfs/wof.c-83-\nfs/ntfs/wof.c:84:static struct ntfs_wof_workspace *ntfs_wof_workspace(u8 block_size_bits)\nfs/ntfs/wof.c-85-{\n--\nfs/ntfs/wof.c-87-\tcase 12:\nfs/ntfs/wof.c:88:\t\treturn \u0026ntfs_wof_xpress4k_workspace;\nfs/ntfs/wof.c-89-\tcase 13:\nfs/ntfs/wof.c:90:\t\treturn \u0026ntfs_wof_xpress8k_workspace;\nfs/ntfs/wof.c-91-\tcase 14:\nfs/ntfs/wof.c:92:\t\treturn \u0026ntfs_wof_xpress16k_workspace;\nfs/ntfs/wof.c-93-\tcase 15:\nfs/ntfs/wof.c:94:\t\treturn \u0026ntfs_wof_lzx32k_workspace;\nfs/ntfs/wof.c-95-\tdefault:\n--\nfs/ntfs/wof.c-99-\nfs/ntfs/wof.c:100:static int ntfs_wof_workspace_prepare(struct ntfs_wof_workspace *ws)\nfs/ntfs/wof.c-101-{\n--\nfs/ntfs/wof.c-128-\nfs/ntfs/wof.c:129:void ntfs_wof_free_workspaces(void)\nfs/ntfs/wof.c-130-{\n--\nfs/ntfs/wof.c-132-\nfs/ntfs/wof.c:133:\tfor (i = 0; i \u003c ARRAY_SIZE(ntfs_wof_workspaces); i++) {\nfs/ntfs/wof.c:134:\t\tstruct ntfs_wof_workspace *ws = ntfs_wof_workspaces[i];\nfs/ntfs/wof.c-135-\n--\nfs/ntfs/wof.c=365=static int ntfs_read_wof_chunk(struct ntfs_volume *vol,\n--\nfs/ntfs/wof.c-419-\nfs/ntfs/wof.c:420:struct ntfs_wof_dest {\nfs/ntfs/wof.c-421-\tstruct folio *folios[NTFS_WOF_MAX_PAGES];\n--\nfs/ntfs/wof.c-426-\nfs/ntfs/wof.c:427:static void ntfs_wof_release_dest(struct ntfs_wof_dest *dest,\nfs/ntfs/wof.c-428-\t\t\t\t  struct folio *target, bool success)\n--\nfs/ntfs/wof.c-447-\nfs/ntfs/wof.c:448:static int ntfs_wof_collect_dest(struct address_space *mapping,\nfs/ntfs/wof.c-449-\t\t\t\t struct folio *target, loff_t chunk_start,\nfs/ntfs/wof.c:450:\t\t\t\t loff_t chunk_end, struct ntfs_wof_dest *dest)\nfs/ntfs/wof.c-451-{\n--\nfs/ntfs/wof.c-512-\nfs/ntfs/wof.c:513:static int ntfs_wof_decode(struct ntfs_wof_workspace *ws, const void *src,\nfs/ntfs/wof.c-514-\t\t\t   u32 src_len, void *dst, u32 dst_len)\n--\nfs/ntfs/wof.c-523-\nfs/ntfs/wof.c:524:static int ntfs_wof_decode_page_direct(struct ntfs_wof_workspace *ws,\nfs/ntfs/wof.c-525-\t\t\t\t       struct folio *target, loff_t chunk_start,\n--\nfs/ntfs/wof.c-540-\taddr = kmap_local_page(page);\nfs/ntfs/wof.c:541:\terr = ntfs_wof_decode(ws, src, src_len, (u8 *)addr + page_offset,\nfs/ntfs/wof.c-542-\t\t\t      dst_len);\n--\nfs/ntfs/wof.c-548-\nfs/ntfs/wof.c:549:static int ntfs_wof_decode_folios_direct(struct ntfs_wof_workspace *ws,\nfs/ntfs/wof.c-550-\t\t\t\t\t struct address_space *mapping,\n--\nfs/ntfs/wof.c-556-\tunsigned int page_offset = offset_in_page(chunk_start);\nfs/ntfs/wof.c:557:\tstruct ntfs_wof_dest dest;\nfs/ntfs/wof.c-558-\tvoid *addr;\n--\nfs/ntfs/wof.c-561-\nfs/ntfs/wof.c:562:\terr = ntfs_wof_collect_dest(mapping, target, chunk_start, chunk_end,\nfs/ntfs/wof.c-563-\t\t\t\t    \u0026dest);\nfs/ntfs/wof.c-564-\tif (err) {\nfs/ntfs/wof.c:565:\t\tntfs_wof_release_dest(\u0026dest, target, false);\nfs/ntfs/wof.c-566-\t\treturn -EAGAIN;\n--\nfs/ntfs/wof.c-572-\tif (!addr) {\nfs/ntfs/wof.c:573:\t\tntfs_wof_release_dest(\u0026dest, target, false);\nfs/ntfs/wof.c-574-\t\treturn -EAGAIN;\n--\nfs/ntfs/wof.c-576-\nfs/ntfs/wof.c:577:\terr = ntfs_wof_decode(ws, src, src_len, (u8 *)addr + page_offset,\nfs/ntfs/wof.c-578-\t\t\t      dst_len);\n--\nfs/ntfs/wof.c-580-\tif (err) {\nfs/ntfs/wof.c:581:\t\tntfs_wof_release_dest(\u0026dest, target, false);\nfs/ntfs/wof.c-582-\t\treturn -EINVAL;\nfs/ntfs/wof.c-583-\t}\nfs/ntfs/wof.c:584:\tntfs_wof_release_dest(\u0026dest, target, true);\nfs/ntfs/wof.c-585-\treturn 0;\n--\nfs/ntfs/wof.c-587-\nfs/ntfs/wof.c:588:static int ntfs_wof_try_direct(struct ntfs_wof_workspace *ws,\nfs/ntfs/wof.c-589-\t\t\t       struct address_space *mapping,\n--\nfs/ntfs/wof.c-596-\tif (dst_len \u003c= PAGE_SIZE - page_offset)\nfs/ntfs/wof.c:597:\t\treturn ntfs_wof_decode_page_direct(ws, target, chunk_start, src,\nfs/ntfs/wof.c-598-\t\t\t\t\t\t   src_len, dst_len);\nfs/ntfs/wof.c-599-\nfs/ntfs/wof.c:600:\treturn ntfs_wof_decode_folios_direct(ws, mapping, target, chunk_start,\nfs/ntfs/wof.c-601-\t\t\t\t\t     chunk_end, src, src_len, dst_len);\n--\nfs/ntfs/wof.c=604=int ntfs_read_wof_compressed_block(struct folio *folio)\n--\nfs/ntfs/wof.c-609-\tstruct ntfs_volume *vol = ni-\u003evol;\nfs/ntfs/wof.c:610:\tstruct ntfs_wof_workspace *ws;\nfs/ntfs/wof.c-611-\tloff_t i_size = i_size_read(VFS_I(ni));\n--\nfs/ntfs/wof.c-618-\nfs/ntfs/wof.c:619:\tws = ntfs_wof_workspace(ni-\u003eitype.compressed.block_size_bits);\nfs/ntfs/wof.c-620-\tif (!ws) {\n--\nfs/ntfs/wof.c-654-\tmutex_lock(ws-\u003elock);\nfs/ntfs/wof.c:655:\terr = ntfs_wof_workspace_prepare(ws);\nfs/ntfs/wof.c-656-\tif (err)\n--\nfs/ntfs/wof.c-685-\t\tchunk_end = chunk_file_offset + decomp_size;\nfs/ntfs/wof.c:686:\t\terr = ntfs_wof_try_direct(ws, mapping, folio, chunk_file_offset,\nfs/ntfs/wof.c-687-\t\t\t\t\t  chunk_end, chunk_mem, chunk_size,\n--\nfs/ntfs/wof.c-693-\nfs/ntfs/wof.c:694:\t\terr = ntfs_wof_decode(ws, chunk_mem, chunk_size, ws-\u003eoutput,\nfs/ntfs/wof.c-695-\t\t\t\t      decomp_size);\n"
}

gemini-3.7-flash

null

null

							input: 39035
							output: 226
							thoughts: 742
						

**My Analysis of File System Changes**

Okay, let's break this down systematically. My initial observation is that `ntfs_read_wof_compressed_block`, a public function in the NTFS module, is at the heart of this. I need to understand the scope of the modifications, so I've cross-referenced it against other potentially affected code.

My first thought is to review all the code that was changed:

*   `fs/erofs/internal.h` looks relevant due to the `z_erofs_pcluster_readmore` / `z_erofs_readahead`
*   `fs/ext4/inline.c` and functions `ext4_generic_write_inline_data`, `ext4_convert_inline_data_to_extent` might be a concern.
*   `fs/nfs/dir.c` where `nfs_readdir_folio_get_next` calls `nfs_readdir_folio_filler` / `nfs_readdir`
*   `fs/ntfs/inode.c` with the functions `__ntfs_inode_resident_attr_pwrite` / `ntfs_file_write_iter`
*   `fs/ntfs/wof.c` with `ntfs_read_wof_compressed_block` which is my initial point
*   `fs/squashfs/file.c` and functions `squashfs_copy_cache`, `squashfs_read_folio`
*   `mm/filemap.c` and the `__filemap_get_folio_mpol` function
*   `mm/readahead.c` with the `page_cache_ra_unbounded`, `page_cache_ra_order`

Now, I need to narrow down the key entry points for targeted analysis. I'm going to focus on non-static, non-inlined API entry points and functions directly impacted by the changes. These seem to be the critical ones:

*   `__filemap_get_folio_mpol` - Core filemap function is interesting.
*   `squashfs_copy_cache` - Part of squashfs file handling.
*   `ext4_generic_write_inline_data` - Dealing with inline data within ext4.
*   `ntfs_read_wof_compressed_block` - The initial point of interest related to NTFS.

I need to make sure the relevant configuration options are enabled for this:

*   `EROFS_FS` - for EROFS.
*   `EXT4_FS` - for ext4.
*   `NFS_FS` - for NFS.
*   `NTFS_FS` - for NTFS, naturally.
*   `NTFS_FS_WOF_COMPRESSION` - this is likely *crucial* to enable NTFS's WOF compression.
*   `SQUASHFS` - for SquashFS.

I've confirmed that `NTFS_FS_WOF_COMPRESSION` depends on `NTFS_FS` as expected. The others are standard and should be straightforward.

Finally, I need to make sure that the `set-results` call is configured correctly. I need to make sure it contains:

*   `EnableConfigs`: All of the configs I mentioned.
*   `FocusSymbols`: the list of key functions I identified.
*   `Reasoning`: The patch removes `FGP_NOFS` from pagecache APIs and updates folio allocation/reclaim scopes across core mm and filesystems, impacting reclaim contexts and memory allocation flags in core paths.
*   `WorthFuzzing`: Absolutely. This sounds like an area ripe for potential memory corruption or race conditions due to changes in allocation flags and reclaim paths.

I'm ready to call `set-results`.

{
  "EnableConfigs": [
    "EROFS_FS",
    "EXT4_FS",
    "NFS_FS",
    "NTFS_FS",
    "NTFS_FS_WOF_COMPRESSION",
    "SQUASHFS"
  ],
  "FocusSymbols": [
    "__filemap_get_folio_mpol",
    "squashfs_copy_cache",
    "ext4_generic_write_inline_data",
    "ntfs_read_wof_compressed_block"
  ],
  "Reasoning": "The patch removes the FGP_NOFS flag from core page cache APIs (__filemap_get_folio_mpol) and adjusts folio allocation flags and reclaim context across several filesystems (ext4, squashfs, erofs, ntfs, and nfs). It alters memory allocation flags and introduces scoped NOFS contexts (memalloc_nofs_save/restore) in reachable filesystem I/O and caching paths, making it worth fuzzing for memory reclaim and locking issues.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "EROFS_FS",
    "EXT4_FS",
    "NFS_FS",
    "NTFS_FS",
    "NTFS_FS_WOF_COMPRESSION",
    "SQUASHFS"
  ],
  "FocusSymbols": [
    "__filemap_get_folio_mpol",
    "squashfs_copy_cache",
    "ext4_generic_write_inline_data",
    "ntfs_read_wof_compressed_block"
  ],
  "Reasoning": "The patch removes the FGP_NOFS flag from core page cache APIs (__filemap_get_folio_mpol) and adjusts folio allocation flags and reclaim context across several filesystems (ext4, squashfs, erofs, ntfs, and nfs). It alters memory allocation flags and introduces scoped NOFS contexts (memalloc_nofs_save/restore) in reachable filesystem I/O and caching paths, making it worth fuzzing for memory reclaim and locking issues.",
  "WorthFuzzing": true
}

{
  "WorthFuzzing": true
}

null

core

null

{
  "KMSANReasoning": "The patch removes the deprecated FGP_NOFS flag from the page cache folio acquisition APIs and adjusts call sites across various filesystems (EROFS, EXT4, NFS, NTFS, SquashFS) to rely on mapping GFP masks or scoped memalloc_nofs_save()/memalloc_nofs_restore() contexts.\n\nThese changes strictly pertain to memory allocation reclaim flags (GFP/FGP flags) and filesystem recursion/deadlock prevention. They do not introduce or modify any kernel-to-user copies, buffer initializations, stack/heap allocations of uninitialized data, or control flow branching on uninitialized variables. Any potential regressions (e.g., reclaim recursion or locking issues) fall under the purview of LOCKDEP and standard kernel sanitizers, not KMSAN. Therefore, a dedicated KMSAN fuzzing session is not warranted.",
  "NeedsKMSAN": false
}

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

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

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

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

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

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

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


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

For your convenience, here is the diff of the changes:
commit e24356d7ac65e0f9bdedf6731f6aa3822d90747f
Author: syz-cluster <triage@syzkaller.com>
Date:   Sun Aug 30 04:42:42 2026 +0000

    syz-cluster: applied patch under review

diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 65974e57aebfb..84b3cdc8e88f1 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -327,7 +327,7 @@ static inline struct folio *erofs_grab_folio_nowait(struct address_space *as,
 						    pgoff_t index)
 {
 	return __filemap_get_folio(as, index,
-			FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
+			FGP_LOCK | FGP_CREAT | FGP_NOWAIT,
 			readahead_gfp_mask(as) & ~__GFP_RECLAIM);
 }
 
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index ceee69a66482b..1884abb096140 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -601,9 +601,7 @@ static int ext4_convert_inline_data_to_extent(struct address_space *mapping,
 		goto out;
 	}
 
-	/* We cannot recurse into the filesystem as the transaction is already
-	 * started */
-	folio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN | FGP_NOFS,
+	folio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN,
 			mapping_gfp_mask(mapping));
 	if (IS_ERR(folio)) {
 		ret = PTR_ERR(folio);
@@ -734,7 +732,7 @@ int ext4_generic_write_inline_data(struct address_space *mapping,
 		goto out_release_bh;
 	}
 
-	folio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN | FGP_NOFS,
+	folio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN,
 					mapping_gfp_mask(mapping));
 	if (IS_ERR(folio)) {
 		ret = PTR_ERR(folio);
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 49394123bd096..e34125a8a2e28 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -447,7 +447,7 @@ static struct folio *nfs_readdir_folio_get_next(struct address_space *mapping,
 	struct folio *folio;
 
 	folio = __filemap_get_folio(mapping, index,
-			FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
+			FGP_LOCK | FGP_CREAT | FGP_NOWAIT,
 			mapping_gfp_mask(mapping));
 	if (IS_ERR(folio))
 		return NULL;
diff --git a/fs/ntfs/inode.c b/fs/ntfs/inode.c
index 32edb4045178a..36a0d6b26c02e 100644
--- a/fs/ntfs/inode.c
+++ b/fs/ntfs/inode.c
@@ -3676,7 +3676,7 @@ static s64 __ntfs_inode_resident_attr_pwrite(struct inode *vi,
 	mark_mft_record_dirty(ctx->ntfs_ino);
 
 	/* Keep the first page clean and uptodate */
-	folio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN | FGP_NOFS,
+	folio = __filemap_get_folio(mapping, 0, FGP_WRITEBEGIN,
 				   mapping_gfp_mask(mapping));
 	if (IS_ERR(folio)) {
 		err = PTR_ERR(folio);
diff --git a/fs/ntfs/wof.c b/fs/ntfs/wof.c
index 8f84c2212eeec..c981b4a3b6959 100644
--- a/fs/ntfs/wof.c
+++ b/fs/ntfs/wof.c
@@ -464,10 +464,9 @@ static int ntfs_wof_collect_dest(struct address_space *mapping,
 			folio = target;
 			is_target = true;
 		} else {
-			folio = __filemap_get_folio(
-				mapping, index,
-				FGP_LOCK | FGP_CREAT | FGP_NOFS | FGP_NOWAIT,
-				GFP_NOFS);
+			folio = __filemap_get_folio(mapping, index,
+					FGP_LOCK | FGP_CREAT | FGP_NOWAIT,
+					mapping_gfp_mask(mapping));
 			if (IS_ERR(folio))
 				return PTR_ERR(folio);
 			is_target = false;
diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
index d83594ce91d23..34c550a266bcf 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -398,6 +398,7 @@ void squashfs_copy_cache(struct folio *folio,
 	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
 	int i, mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
 	int start_index = folio->index & ~mask, end_index = start_index | mask;
+	unsigned int nofs = memalloc_nofs_save();
 
 	/*
 	 * Loop copying datablock into pages.  As the datablock likely covers
@@ -415,7 +416,7 @@ void squashfs_copy_cache(struct folio *folio,
 
 		push_folio = (i == folio->index) ? folio :
 			__filemap_get_folio(mapping, i,
-					FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
+					FGP_LOCK | FGP_CREAT | FGP_NOWAIT,
 					mapping_gfp_mask(mapping));
 
 		if (IS_ERR(push_folio))
@@ -430,6 +431,8 @@ void squashfs_copy_cache(struct folio *folio,
 		if (i != folio->index)
 			folio_put(push_folio);
 	}
+
+	memalloc_nofs_restore(nofs);
 }
 
 /* Read datablock stored packed inside a fragment (tail-end packed block) */
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 0adfa6605653d..bff8b7264fb02 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -697,7 +697,6 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping,
  *   folio is already in cache.  If the folio was allocated, unlock it
  *   before returning so the caller can do the same dance.
  * * %FGP_WRITE - The folio will be written to by the caller.
- * * %FGP_NOFS - __GFP_FS will get cleared in gfp.
  * * %FGP_NOWAIT - Don't block on the folio lock.
  * * %FGP_STABLE - Wait for the folio to be stable (finished writeback)
  * * %FGP_DONTCACHE - Uncached buffered IO
@@ -710,11 +709,10 @@ typedef unsigned int __bitwise fgf_t;
 #define FGP_LOCK		((__force fgf_t)0x00000002)
 #define FGP_CREAT		((__force fgf_t)0x00000004)
 #define FGP_WRITE		((__force fgf_t)0x00000008)
-#define FGP_NOFS		((__force fgf_t)0x00000010)
-#define FGP_NOWAIT		((__force fgf_t)0x00000020)
-#define FGP_FOR_MMAP		((__force fgf_t)0x00000040)
-#define FGP_STABLE		((__force fgf_t)0x00000080)
-#define FGP_DONTCACHE		((__force fgf_t)0x00000100)
+#define FGP_NOWAIT		((__force fgf_t)0x00000010)
+#define FGP_FOR_MMAP		((__force fgf_t)0x00000020)
+#define FGP_STABLE		((__force fgf_t)0x00000040)
+#define FGP_DONTCACHE		((__force fgf_t)0x00000080)
 #define FGF_GET_ORDER(fgf)	(((__force unsigned)fgf) >> 26)	/* top 6 bits */
 
 #define FGP_WRITEBEGIN		(FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE)
@@ -929,7 +927,7 @@ static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
 				pgoff_t index)
 {
 	return pagecache_get_page(mapping, index,
-			FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
+			FGP_LOCK | FGP_CREAT | FGP_NOWAIT,
 			mapping_gfp_mask(mapping));
 }
 
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index d7c6a942aa7e0..f76be1141b064 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -372,13 +372,26 @@ static inline void memalloc_noio_restore(unsigned int flags)
 }
 
 /**
- * memalloc_nofs_save - Marks implicit GFP_NOFS allocation scope.
+ * memalloc_nofs_save - Prevent recursion into the filesystem.
  *
- * This functions marks the beginning of the GFP_NOFS allocation scope.
- * All further allocations will implicitly drop __GFP_FS flag and so
- * they are safe for the FS critical section from the allocation recursion
- * point of view. Use memalloc_nofs_restore to end the scope with flags
- * returned by this function.
+ * All memory allocations between calling this function and calling
+ * memalloc_nofs_restore() will be prevented from calling into filesystems
+ * to reclaim memory.  Clean page cache memory can still be reclaimed,
+ * but (for example) inodes will not be.
+ *
+ * The primary reason to do this is that the caller has taken a lock
+ * which would be needed by FS reclaim.  While we could theoretically
+ * call into a different filesystem in this case, it can be a deep call
+ * stack so it is better to avoid all filesystems.
+ *
+ * Filesystems often choose to incorporate a call to this function as part
+ * of starting a journal transaction.  While not a lock in the normal
+ * sense, it has much the same effect as nested journal transactions
+ * are either prohibited or expensive.
+ *
+ * Also call this function if you need to allocate memory while holding
+ * a file folio locked.  High order allocations (such as those requested
+ * by slab) can trigger compaction which will attempt to lock the folio.
  *
  * Context: This function is safe to be used from any context.
  * Return: The saved flags to be passed to memalloc_nofs_restore.
@@ -389,10 +402,12 @@ static inline unsigned int memalloc_nofs_save(void)
 }
 
 /**
- * memalloc_nofs_restore - Ends the implicit GFP_NOFS scope.
+ * memalloc_nofs_restore - End filesystem reclaim scope.
  * @flags: Flags to restore.
  *
- * Ends the implicit GFP_NOFS scope started by memalloc_nofs_save function.
+ * Ends the implicit memory allocation scope started by
+ * memalloc_nofs_save().  This may not enable access to filesystem reclaim
+ * if it was already disabled at the time memalloc_nofs_save() was called.
  * Always make sure that the given flags is the return value from the
  * pairing memalloc_nofs_save call.
  */
diff --git a/mm/filemap.c b/mm/filemap.c
index 6afec636881fb..e6580291f2185 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1994,8 +1994,6 @@ struct folio *__filemap_get_folio_mpol(struct address_space *mapping,
 
 		if ((fgp_flags & FGP_WRITE) && mapping_can_writeback(mapping))
 			gfp |= __GFP_WRITE;
-		if (fgp_flags & FGP_NOFS)
-			gfp &= ~__GFP_FS;
 		if (fgp_flags & FGP_NOWAIT) {
 			gfp &= ~GFP_KERNEL;
 			gfp |= GFP_NOWAIT;
diff --git a/mm/readahead.c b/mm/readahead.c
index 6e5563290287e..9c116d4ba963a 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -227,17 +227,7 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
 	gfp_t gfp_mask = readahead_gfp_mask(mapping);
 	unsigned long mark = ULONG_MAX, i = 0;
 	unsigned int min_nrpages = mapping_min_folio_nrpages(mapping);
-
-	/*
-	 * Partway through the readahead operation, we will have added
-	 * locked pages to the page cache, but will not yet have submitted
-	 * them for I/O.  Adding another page may need to allocate memory,
-	 * which can trigger memory reclaim.  Telling the VM we're in
-	 * the middle of a filesystem operation will cause it to not
-	 * touch file-backed pages, preventing a deadlock.  Most (all?)
-	 * filesystems already specify __GFP_NOFS in their mapping's
-	 * gfp_mask, but let's be explicit here.
-	 */
+	/* Allocating with locked folios */
 	unsigned int nofs = memalloc_nofs_save();
 
 	lockdep_assert_held(&mapping->invalidate_lock);
@@ -512,7 +502,7 @@ void page_cache_ra_order(struct readahead_control *ractl,
 
 	ra->order = new_order;
 
-	/* See comment in page_cache_ra_unbounded() */
+	/* Allocating with locked folios */
 	nofs = memalloc_nofs_save();
 	filemap_invalidate_lock_shared(mapping);
 	/*

gemini-3.7-flash

null

null

							input: 5908
							output: 197
							thoughts: 871
						

**Analyzing the Removal of the `FGP_NOFS` Flag and Its Implications**

Okay, so I'm looking at this patch that's ripping out the `FGP_NOFS` flag from `include/linux/pagemap.h` and then updating all the places that used it. It looks like it's a significant refactor, but the overall goal seems pretty straightforward: avoiding FS reclaim deadlocks during memory allocation. I'm going through the changes methodically.

First, I'm noting the specific areas being touched: `erofs/internal.h`, `ext4/inline.c`, `nfs/dir.c`, `ntfs/inode.c`, `ntfs/wof.c`, `squashfs/file.c`, `pagemap.h`, `sched/mm.h`, `filemap.c`, and `readahead.c`. Each of these files is being adjusted to either remove the `FGP_NOFS` flag directly or replace it with a more appropriate allocation strategy, often involving `memalloc_nofs_save()` and `memalloc_nofs_restore()`.

Specifically, in `erofs`, I see `erofs_grab_folio_nowait` removing the flag, which is good because it already uses a mask that excludes `__GFP_RECLAIM`. Then, `ext4` is cleaning up `inline.c`, same with `nfs`, and `ntfs`. The `squashfs` change is key; they're explicitly wrapping the `squashfs_copy_cache()` call with those `memalloc_nofs_...` calls, which is exactly the kind of approach I would expect to see for proper FS reclaim protection. I'm taking a mental note of this pattern, I might be using it myself. The header files are being cleaned up and the flag itself is being removed and renumbered, and I'm updating my mental map of where the flags are. The `mm/filemap.c` change makes sense: it's removing a check related to the flag. This is all standard stuff, honestly, looks pretty clean.

Now, my key concern: does this introduce any risks? I'm specifically looking for any uninitialized memory vulnerabilities, KASAN issues, or potential deadlocks. I need to make sure this doesn't create a scenario where we're leaking information or leading to memory corruption. I can't see anything obvious that would cause a problem with struct padding. I'm carefully reviewing the code, and there are no uninitialized stack/heap buffers, no changes to data lengths, and no uninitialized branching. The patch is solely focused on memory allocation flags (GFP flags) and page cache folio retrieval flags (FGP flags) and FS reclaim deadlock avoidance, which is a good sign. From what I see here, it looks like it does not introduce any of those concerns. I'm also confirming it wouldn't impact those KASAN/LOCKDEP domains.

I'm now running through the KMSAN criteria in my head: Kernel structures sent to userspace? No. Conditional logic on uninitialized vars? No. Complex data structures with uninitialized fields? Nope. Bounds checks/uninitialized bytes? Not here.

Based on all of this, I'm comfortable that this patch is safe. I'm ready to `set-results`.

{
  "KMSANReasoning": "The patch removes the deprecated FGP_NOFS flag from the page cache folio acquisition APIs and adjusts call sites across various filesystems (EROFS, EXT4, NFS, NTFS, SquashFS) to rely on mapping GFP masks or scoped memalloc_nofs_save()/memalloc_nofs_restore() contexts.\n\nThese changes strictly pertain to memory allocation reclaim flags (GFP/FGP flags) and filesystem recursion/deadlock prevention. They do not introduce or modify any kernel-to-user copies, buffer initializations, stack/heap allocations of uninitialized data, or control flow branching on uninitialized variables. Any potential regressions (e.g., reclaim recursion or locking issues) fall under the purview of LOCKDEP and standard kernel sanitizers, not KMSAN. Therefore, a dedicated KMSAN fuzzing session is not warranted.",
  "NeedsKMSAN": false
}

{
  "KMSANReasoning": "The patch removes the deprecated FGP_NOFS flag from the page cache folio acquisition APIs and adjusts call sites across various filesystems (EROFS, EXT4, NFS, NTFS, SquashFS) to rely on mapping GFP masks or scoped memalloc_nofs_save()/memalloc_nofs_restore() contexts.\n\nThese changes strictly pertain to memory allocation reclaim flags (GFP/FGP flags) and filesystem recursion/deadlock prevention. They do not introduce or modify any kernel-to-user copies, buffer initializations, stack/heap allocations of uninitialized data, or control flow branching on uninitialized variables. Any potential regressions (e.g., reclaim recursion or locking issues) fall under the purview of LOCKDEP and standard kernel sanitizers, not KMSAN. Therefore, a dedicated KMSAN fuzzing session is not warranted.",
  "NeedsKMSAN": false
}