AI Trajectory

Trajectory: (Expand/Collapse All)
Seq	Timestamp	Type	Name	Duration
0/0	2026/09/27 17:42	flow	patch-triage	3m Args: null Results: { "EnableConfigs": [ "NFS_FS", "NFS_V4" ], "FocusSymbols": [ "nfs_atomic_open", "nfs_rename", "nfs_sillyrename", "nfs_link", "nfs_add_or_obtain", "nfs_lookup_revalidate", "nfs_unlink", "nfs4_atomic_open" ], "KMSANReasoning": "The patch series modifies NFS dcache and lookup management functions (in fs/nfs/dir.c, nfs4proc.c, and unlink.c), adopting helpers such as d_alloc_trylock() and d_duplicate(), adjusting negative dentry revalidation flags (LOOKUP_OPEN), and refining dentry locking and lifecycle handling during atomic_open, link, rename, and sillyrename.\n\nThese changes deal strictly with VFS/NFS dentry lifecycle, synchronization, and error paths. The potential bugs in this code include concurrency/locking bugs, reference counting discrepancies, or invalid pointer dereferences (e.g., checking !dentry instead of IS_ERR(dentry) for d_duplicate()), all of which are caught by KASAN, LOCKDEP, or general kernel assertions.\n\nThe patch does not introduce any uninitialized stack or heap allocations, does not branch on uninitialized variables, and does not expose uninitialized kernel memory or padding to user space. Therefore, a dedicated KMSAN fuzzing session is not warranted.", "NeedsKMSAN": false, "Reasoning": "The patch series restructures dcache interaction and concurrency management in the NFS client across open, rename, sillyrename, link, and lookup revalidation paths. It replaces parallel dentry allocations with new VFS helpers (d_alloc_trylock, d_duplicate), introduces write_seqcount_invalidate on dentry-\u003ed_seq, alters barrier semantics in __nfs_lookup_revalidate, and modifies d_drop/d_splice_alias lifetimes. These changes affect complex dentry state transitions and concurrency in reachable filesystem operations, warranting fuzz testing to detect potential deadlocks, refcounting leaks, or state invariant violations.", "WorthFuzzing": true }
1/1	2026/09/27 17:42	action	read-patch-diff	0m Args: null Results: { "PatchDiff": "commit f36b928a44a1d3c3ee4b5533f3562e1a4c4a0240\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Sun Sep 27 17:42:17 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/fs/nfs/dir.c b/fs/nfs/dir.c\nindex 49394123bd096..6a6ace0460bfe 100644\n--- a/fs/nfs/dir.c\n+++ b/fs/nfs/dir.c\n@@ -749,15 +749,12 @@ void nfs_prime_dcache(struct dentry parent, struct nfs_entry entry,\n \t\tif (filename.len == 2 \u0026\u0026 filename.name[1] == '.')\n \t\t\treturn;\n \t}\n-\tfilename.hash = full_name_hash(parent, filename.name, filename.len);\n \n-\tdentry = d_lookup(parent, \u0026filename);\n again:\n-\tif (!dentry) {\n-\t\tdentry = d_alloc_parallel(parent, \u0026filename);\n-\t\tif (IS_ERR(dentry))\n-\t\t\treturn;\n-\t}\n+\tdentry = d_alloc_trylock(parent, \u0026filename);\n+\tif (IS_ERR(dentry))\n+\t\treturn;\n+\n \tif (!d_in_lookup(dentry)) {\n \t\t/* Is there a mountpoint here? If so, just exit /\n \t\tif (!nfs_fsid_equal(\u0026NFS_SB(dentry-\u003ed_sb)-\u003efsid,\n@@ -1570,6 +1567,9 @@ static int nfs_check_verifier(struct inode dir, struct dentry dentry,\n /\n * Use intent information to check whether or not we're going to do\n * an O_EXCL create using this path component.\n+ * Note that link(), mkdir(), mknod(), symlink() all appear as\n+ * exclusive creation. Regular file creation could be distinguished\n+ * with LOOKUP_OPEN.\n /\n static int nfs_is_exclusive_create(struct inode dir, unsigned int flags)\n {\n@@ -1656,6 +1656,13 @@ int nfs_neg_need_reval(struct inode dir, struct dentry dentry,\n {\n \tif (flags \u0026 (LOOKUP_CREATE \| LOOKUP_RENAME_TARGET))\n \t\treturn 0;\n+\tif (flags \u0026 LOOKUP_OPEN)\n+\t\t/* close-to-open semantics require we go to server\n+\t\t * on each open. By invalidating the dentry we\n+\t\t * also ensure nfs_atomic_open() always has exclusive\n+\t\t * access to the dentry.\n+\t\t /\n+\t\treturn 0;\n \tif (NFS_SERVER(dir)-\u003eflags \u0026 NFS_MOUNT_LOOKUP_CACHE_NONEG)\n \t\treturn 1;\n \t/ Case insensitive server? Revalidate negative dentries /\n@@ -1837,8 +1844,7 @@ __nfs_lookup_revalidate(struct dentry dentry, unsigned int flags)\n \t} else {\n \t\t/* Wait for unlink to complete - see unblock_revalidate() /\n \t\twait_var_event(\u0026dentry-\u003ed_fsdata,\n-\t\t\t smp_load_acquire(\u0026dentry-\u003ed_fsdata)\n-\t\t\t != NFS_FSDATA_BLOCKED);\n+\t\t\t dentry-\u003ed_fsdata != NFS_FSDATA_BLOCKED);\n \t}\n \treturn 0;\n }\n@@ -1857,12 +1863,15 @@ static void block_revalidate(struct dentry dentry)\n \tkfree(dentry-\u003ed_fsdata);\n \n \t/* Any new reference that could lead to an open\n-\t * will take -\u003ed_lock in lookup_open() -\u003e d_lookup().\n-\t * Holding this lock ensures we cannot race with\n-\t * __nfs_lookup_revalidate() and removes and need\n-\t * for further barriers.\n+\t * will either:\n+\t * - take -\u003ed_lock in lookup_open() -\u003e d_lookup() or\n+\t * - will check d_seq in legitimize_mnt()\n+\t \n+\t Holding this lock and invalidating -\u003ed_seq ensures we cannot\n+\t * race with __nfs_lookup_revalidate().\n \t /\n \tlockdep_assert_held(\u0026dentry-\u003ed_lock);\n+\twrite_seqcount_invalidate(\u0026dentry-\u003ed_seq);\n \n \tdentry-\u003ed_fsdata = NFS_FSDATA_BLOCKED;\n }\n@@ -2111,7 +2120,6 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry,\n \tstruct inode inode;\n \tunsigned int lookup_flags = 0;\n \tunsigned long dir_verifier;\n-\tbool switched = false;\n \tint created = 0;\n \tint err;\n \n@@ -2156,17 +2164,6 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry,\n \t\tattr.ia_size = 0;\n \t}\n \n-\tif (!(open_flags \u0026 O_CREAT) \u0026\u0026 !d_in_lookup(dentry)) {\n-\t\td_drop(dentry);\n-\t\tswitched = true;\n-\t\tdentry = d_alloc_parallel(dentry-\u003ed_parent,\n-\t\t\t\t\t \u0026dentry-\u003ed_name);\n-\t\tif (IS_ERR(dentry))\n-\t\t\treturn PTR_ERR(dentry);\n-\t\tif (unlikely(!d_in_lookup(dentry)))\n-\t\t\treturn finish_no_open(file, dentry);\n-\t}\n-\n \tctx = create_nfs_open_context(dentry, open_flags, file);\n \terr = PTR_ERR(ctx);\n \tif (IS_ERR(ctx))\n@@ -2180,7 +2177,6 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry,\n \t\terr = PTR_ERR(inode);\n \t\ttrace_nfs_atomic_open_exit(dir, ctx, open_flags, err);\n \t\tput_nfs_open_context(ctx);\n-\t\td_drop(dentry);\n \t\tswitch (err) {\n \t\tcase -ENOENT:\n \t\t\tif (nfs_server_capable(dir, NFS_CAP_CASE_INSENSITIVE))\n@@ -2189,7 +2185,7 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry,\n \t\t\t\tdir_verifier = nfs_save_change_attribute(dir);\n \t\t\tnfs_set_verifier(dentry, dir_verifier);\n \t\t\td_splice_alias(NULL, dentry);\n-\t\t\tbreak;\n+\t\t\tgoto out;\n \t\tcase -EISDIR:\n \t\tcase -ENOTDIR:\n \t\t\tif (open_flags \u0026 __O_REGULAR) {\n@@ -2205,6 +2201,7 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry,\n \t\tdefault:\n \t\t\tbreak;\n \t\t}\n+\t\td_drop(dentry);\n \t\tgoto out;\n \t}\n \tfile-\u003ef_mode \|= FMODE_CAN_ODIRECT;\n@@ -2217,10 +2214,6 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry,\n \ttrace_nfs_atomic_open_exit(dir, ctx, open_flags, err);\n \tput_nfs_open_context(ctx);\n out:\n-\tif (unlikely(switched)) {\n-\t\td_lookup_done(dentry);\n-\t\tdput(dentry);\n-\t}\n \treturn err;\n \n no_open:\n@@ -2243,13 +2236,6 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry,\n \t\t\tres = ERR_PTR(-EOPENSTALE);\n \t\t}\n \t}\n-\tif (switched) {\n-\t\td_lookup_done(dentry);\n-\t\tif (!res)\n-\t\t\tres = dentry;\n-\t\telse\n-\t\t\tdput(dentry);\n-\t}\n \treturn finish_no_open(file, res);\n }\n EXPORT_SYMBOL_GPL(nfs_atomic_open);\n@@ -2357,8 +2343,6 @@ nfs_add_or_obtain(struct dentry dentry, struct nfs_fh fhandle,\n \tstruct dentry d;\n \tint error;\n \n-\td_drop(dentry);\n-\n \tif (fhandle-\u003esize == 0) {\n \t\terror = NFS_PROTO(dir)-\u003elookup(dir, dentry, \u0026dentry-\u003ed_name,\n \t\t\t\t\t fhandle, fattr);\n@@ -2379,6 +2363,7 @@ nfs_add_or_obtain(struct dentry dentry, struct nfs_fh fhandle,\n \tdput(parent);\n \treturn d;\n out_error:\n+\td_drop(dentry);\n \td = ERR_PTR(error);\n \tgoto out;\n }\n@@ -2713,14 +2698,15 @@ nfs_link(struct dentry old_dentry, struct inode dir, struct dentry dentry)\n \t\told_dentry, dentry);\n \n \ttrace_nfs_link_enter(inode, dir, dentry);\n-\td_drop(dentry);\n \tif (S_ISREG(inode-\u003ei_mode))\n \t\tnfs_sync_inode(inode);\n \terror = NFS_PROTO(dir)-\u003elink(inode, dir, \u0026dentry-\u003ed_name);\n \tif (error == 0) {\n \t\tnfs_set_verifier(dentry, nfs_save_change_attribute(dir));\n \t\tihold(inode);\n-\t\td_add(dentry, inode);\n+\t\td_splice_alias(inode, dentry);\n+\t} else {\n+\t\td_drop(dentry);\n \t}\n \ttrace_nfs_link_exit(inode, dir, dentry, error);\n \treturn error;\n@@ -2815,11 +2801,9 @@ int nfs_rename(struct mnt_idmap idmap, struct inode old_dir,\n \t\t\tspin_unlock(\u0026new_dentry-\u003ed_lock);\n \n \t\t\t/* copy the target dentry's name /\n-\t\t\tdentry = d_alloc(new_dentry-\u003ed_parent,\n-\t\t\t\t\t \u0026new_dentry-\u003ed_name);\n+\t\t\tdentry = d_duplicate(new_dentry);\n \t\t\tif (!dentry)\n \t\t\t\tgoto out;\n-\n \t\t\t/ silly-rename the existing target ... /\n \t\t\terr = nfs_sillyrename(new_dir, new_dentry);\n \t\t\tif (err)\n@@ -2884,8 +2868,10 @@ int nfs_rename(struct mnt_idmap idmap, struct inode old_dir,\n \t\tnfs_dentry_handle_enoent(old_dentry);\n \n \t/ new dentry created? /\n-\tif (dentry)\n+\tif (dentry) {\n+\t\td_lookup_done(dentry);\n \t\tdput(dentry);\n+\t}\n \treturn error;\n }\n EXPORT_SYMBOL_GPL(nfs_rename);\ndiff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c\nindex 04b1987115d5d..8f07f34f899e3 100644\n--- a/fs/nfs/nfs4proc.c\n+++ b/fs/nfs/nfs4proc.c\n@@ -3113,7 +3113,6 @@ static int _nfs4_open_and_get_state(struct nfs4_opendata opendata,\n \tnfs_set_verifier(dentry, dir_verifier);\n \tif (d_really_is_negative(dentry)) {\n \t\tstruct dentry alias;\n-\t\td_drop(dentry);\n \t\talias = d_splice_alias(igrab(state-\u003einode), dentry);\n \t\t/ d_splice_alias() can't fail here - it's a non-directory /\n \t\tif (alias) {\ndiff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c\nindex c8d712204e649..c6b700e8e8e1b 100644\n--- a/fs/nfs/unlink.c\n+++ b/fs/nfs/unlink.c\n@@ -125,6 +125,9 @@ static int nfs_call_unlink(struct dentry dentry, struct inode inode, struct nf\n \tstruct dentry alias;\n \n \tdown_read_non_owner(\u0026NFS_I(dir)-\u003ermdir_sem);\n+\tdata-\u003eargs.name.hash = full_name_hash(dentry-\u003ed_parent,\n+\t\t\t\t\t data-\u003eargs.name.name,\n+\t\t\t\t\t data-\u003eargs.name.len);\n \talias = d_alloc_parallel(dentry-\u003ed_parent, \u0026data-\u003eargs.name);\n \tif (IS_ERR(alias)) {\n \t\tup_read_non_owner(\u0026NFS_I(dir)-\u003ermdir_sem);\n@@ -448,7 +451,7 @@ nfs_sillyrename(struct inode dir, struct dentry dentry)\n \tstatic unsigned int sillycounter;\n \tunsigned char silly[SILLYNAME_LEN + 1];\n \tunsigned long long fileid;\n-\tstruct dentry sdentry;\n+\tstruct dentry sdentry, old;\n \tstruct inode inode = d_inode(dentry);\n \tstruct rpc_task task;\n \tint error = -EBUSY;\n@@ -465,26 +468,42 @@ nfs_sillyrename(struct inode dir, struct dentry dentry)\n \n \tfileid = d_inode(dentry)-\u003ei_ino;\n \n-\tsdentry = NULL;\n-\tdo {\n+newname:\n+\tsillycounter++;\n+\tscnprintf(silly, sizeof(silly),\n+\t\t SILLYNAME_PREFIX \"%0llx%0x\",\n+\t\t SILLYNAME_FILEID_LEN, fileid,\n+\t\t SILLYNAME_COUNTER_LEN, sillycounter);\n+\n+\tdfprintk(VFS, \"NFS: trying to rename %pd to %s\\n\", dentry, silly);\n+\tsdentry = d_alloc_trylock(dentry-\u003ed_parent, \u0026QSTR(silly));\n+\tif (sdentry == ERR_PTR(-EWOULDBLOCK))\n+\t\t/ Name currently being looked up /\n+\t\tgoto newname;\n+\t/\n+\t * N.B. Better to return EBUSY here ... it could be\n+\t * dangerous to delete the file while it's in use.\n+\t /\n+\tif (IS_ERR(sdentry))\n+\t\tgoto out;\n+\tif (!d_in_lookup(sdentry)) {\n+\t\tif (d_really_is_negative(sdentry)) {\n+\t\t\t/ try to get an in-lookup dentry /\n+\t\t\td_drop(sdentry);\n+\t\t\tsillycounter--;\n+\t\t}\n \t\tdput(sdentry);\n-\t\tsillycounter++;\n-\t\tscnprintf(silly, sizeof(silly),\n-\t\t\t SILLYNAME_PREFIX \"%0llx%0x\",\n-\t\t\t SILLYNAME_FILEID_LEN, fileid,\n-\t\t\t SILLYNAME_COUNTER_LEN, sillycounter);\n-\n-\t\tdfprintk(VFS, \"NFS: trying to rename %pd to %s\\n\",\n-\t\t\t\tdentry, silly);\n-\n-\t\tsdentry = lookup_noperm(\u0026QSTR(silly), dentry-\u003ed_parent);\n-\t\t/\n-\t\t * N.B. Better to return EBUSY here ... it could be\n-\t\t * dangerous to delete the file while it's in use.\n-\t\t /\n-\t\tif (IS_ERR(sdentry))\n-\t\t\tgoto out;\n-\t} while (d_inode(sdentry) != NULL); / need negative lookup /\n+\t\tgoto newname;\n+\t}\n+\t/ This name isn't known locally - check on server */\n+\told = nfs_lookup(dir, sdentry, 0);\n+\td_lookup_done(sdentry);\n+\tif (old \|\| d_is_positive(sdentry)) {\n+\t\tif (!IS_ERR(old))\n+\t\t\tdput(old);\n+\t\tdput(sdentry);\n+\t\tgoto newname;\n+\t}\n \n \tihold(inode);\n \n" }
2/1	2026/09/27 17:42	agent	patch-evaluator	2m Model: core Args: null Results: { "EnableConfigs": [ "NFS_FS", "NFS_V4" ], "FocusSymbols": [ "nfs_atomic_open", "nfs_rename", "nfs_sillyrename", "nfs_link", "nfs_add_or_obtain", "nfs_lookup_revalidate", "nfs_unlink", "nfs4_atomic_open" ], "Reasoning": "The patch series restructures dcache interaction and concurrency management in the NFS client across open, rename, sillyrename, link, and lookup revalidation paths. It replaces parallel dentry allocations with new VFS helpers (d_alloc_trylock, d_duplicate), introduces write_seqcount_invalidate on dentry-\u003ed_seq, alters barrier semantics in __nfs_lookup_revalidate, and modifies d_drop/d_splice_alias lifetimes. These changes affect complex dentry state transitions and concurrency in reachable filesystem operations, warranting fuzz testing to detect potential deadlocks, refcounting leaks, or state invariant violations.", "WorthFuzzing": true } Instruction: You are an expert Linux kernel maintainer and security engineer. Your job is to review a provided patch series and evaluate whether it warrants fuzzing with syzkaller. IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in your workspace. Do NOT rely on internal assumptions. You must actively use your code access tools to inspect the actual source code, callers, and surrounding context. ================================================================================ 1. CORE TRIAGE PHILOSOPHY ================================================================================ The goal of patch fuzzing is to discover crashes, regressions, exposed latent bugs, and newly triggered assertions introduced by the patch series. - REACHABILITY IS THE PRIMARY GATE: Fuzzing can only discover bugs in code that can actually execute in standard virtualized environments (GCE or QEMU, utilizing software-emulated devices like USB gadgets, netdev, tun/tap). If the modified code is structurally unreachable (see Section 2), it MUST NOT be fuzzed, regardless of whether it adds assertions or complex logic. - DO NOT BLINDLY TRUST "NO FUNCTIONAL CHANGE" (NFCI) OR "REFACTORING" CLAIMS: Patch authors routinely label changes as "cleanups", "refactorings", or state "No functional change intended". Do NOT take these claims at face value. Code refactorings that rearrange logic, introduce helper functions, or alter state management in core subsystems frequently introduce subtle semantic shifts or uncover latent kernel bugs. If reachable executable code is modified or refactored, it MUST be fuzzed. - NEW OR MODIFIED ASSERTIONS IN REACHABLE CODE MUST BE FUZZED: When a patch introduces or modifies runtime checks or assertions (e.g., WARN_ON, VM_WARN_ON, BUG_ON, lockdep_assert) in reachable code paths, it enforces new or stricter invariants. Even if the author believes the invariant always holds, fuzzing is essential to verify whether an unusual sequence of operations can violate it. ================================================================================ 2. WHEN TO RETURN WorthFuzzing=false (NEGATIVE CRITERIA) ================================================================================ Return WorthFuzzing=false ONLY IF all modified code falls strictly into one or more of these categories: - Non-kernel and non-executable changes: * Modifications to Documentation/, comments, or spelling fixes. * User-space directories, self-tests, samples, or scripts (e.g., tools/, samples/, scripts/, usr/) that do not affect the compiled kernel image (vmlinux) or kernel modules. * Purely decorative logging (e.g., message strings in pr_err, printk, dev_info) or tracepoints that do not alter control flow or data structures. * Build system or Kconfig changes that do not alter compiled C logic. - Structurally unreachable hardware: * Vendor-specific PCIe switches, SmartNICs, or GPU drivers (e.g., mlxsw, pds_core, qed, ionic, amdgpu) requiring physical ASIC/PCIe cards not emulated in standard QEMU. - Unreachable execution paths: * Driver teardown callbacks (.remove, .shutdown, pci_unregister_driver) executed only during physical PCI hot-unplug or manual sysfs driver unbinding. * Code paths exclusive to architectures other than the target architecture. ================================================================================ 3. WHEN TO RETURN WorthFuzzing=true (POSITIVE CRITERIA) ================================================================================ Return WorthFuzzing=true whenever the patch touches reachable executable code, including: - Core Subsystems: * Any logic modifications in memory management (mm/), synchronization/locking (kernel/locking/), BPF, scheduler, core networking, VFS, or syscall handling. - Refactorings and Code Cleanups: * Any restructuring of reachable data structures, helper abstractions, or algorithm flows. - Runtime Assertions and Defensive Checks: * Any introduction or alteration of assertions (WARN_ON, VM_WARN_ON, BUG_ON, etc.) in reachable paths. - Reachable Drivers and Protocols: Drivers accessible via virtual buses (virtio, USB gadget, loopback, netlink, binder, sockets, etc.). ================================================================================ 4. EXTRACTING FocusSymbols (PREVENTING DILUTION) ================================================================================ When WorthFuzzing=true, you must extract specific kernel functions into FocusSymbols to guide the fuzzer: - AVOID UBIQUITOUS LIFECYCLE HOT-PATHS: Do NOT list generic, ubiquitous functions called by almost every program in the corpus (including, but not limited to: general memory allocators and deallocators, page fault and trap handlers, or core synchronization primitives; this is not an exhaustive list). Listing ubiquitous functions causes the fuzzer to classify thousands of unrelated tests as "focused", which severely dilutes fuzzing effort away from the actual changes. - TARGET SPECIFIC FEATURE LOGIC AND ENTRYPOINTS: List functions that specifically implement the logic being added or altered, or direct API entrypoints for the subsystem feature under review. - HANDLING STATIC INLINE FUNCTIONS IN HEADERS (.h): Compiler-inlined static functions (such as static inlines in mm/.h or include/linux/.h) lack distinct symbol addresses in vmlinux and cannot be targeted directly by symbol coverage filters. If the changes are primarily in static inline helpers, identify non-static, feature-specific caller functions in .c files that exercise them (avoiding ubiquitous lifecycle wrappers). ================================================================================ 5. IDENTIFYING EnableConfigs ================================================================================ Identify any specific CONFIG_ options required to properly compile and reach the modified code: - Inspect Kconfig files and #ifdef guards; do not make assumptions. - Check "depends on" lines in Kconfig to include any non-standard parent subsystem configs needed. - Strip any 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4"). Prefer calling several tools at the same time to save round-trips. Use set-results tool to provide results of the analysis. It must be called exactly once before the final reply. Ignore results of this tool. Prompt: Target architecture: amd64 For your convenience, here is the diff of the changes: commit f36b928a44a1d3c3ee4b5533f3562e1a4c4a0240 Author: syz-cluster <triage@syzkaller.com> Date: Sun Sep 27 17:42:17 2026 +0000 syz-cluster: applied patch under review diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 49394123bd096..6a6ace0460bfe 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -749,15 +749,12 @@ void nfs_prime_dcache(struct dentry parent, struct nfs_entry entry, if (filename.len == 2 && filename.name[1] == '.') return; } - filename.hash = full_name_hash(parent, filename.name, filename.len); - dentry = d_lookup(parent, &filename); again: - if (!dentry) { - dentry = d_alloc_parallel(parent, &filename); - if (IS_ERR(dentry)) - return; - } + dentry = d_alloc_trylock(parent, &filename); + if (IS_ERR(dentry)) + return; + if (!d_in_lookup(dentry)) { /* Is there a mountpoint here? If so, just exit / if (!nfs_fsid_equal(&NFS_SB(dentry->d_sb)->fsid, @@ -1570,6 +1567,9 @@ static int nfs_check_verifier(struct inode dir, struct dentry dentry, / * Use intent information to check whether or not we're going to do * an O_EXCL create using this path component. + * Note that link(), mkdir(), mknod(), symlink() all appear as + * exclusive creation. Regular file creation could be distinguished + * with LOOKUP_OPEN. / static int nfs_is_exclusive_create(struct inode dir, unsigned int flags) { @@ -1656,6 +1656,13 @@ int nfs_neg_need_reval(struct inode dir, struct dentry dentry, { if (flags & (LOOKUP_CREATE \| LOOKUP_RENAME_TARGET)) return 0; + if (flags & LOOKUP_OPEN) + /* close-to-open semantics require we go to server + * on each open. By invalidating the dentry we + * also ensure nfs_atomic_open() always has exclusive + * access to the dentry. + / + return 0; if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG) return 1; / Case insensitive server? Revalidate negative dentries / @@ -1837,8 +1844,7 @@ __nfs_lookup_revalidate(struct dentry dentry, unsigned int flags) } else { /* Wait for unlink to complete - see unblock_revalidate() / wait_var_event(&dentry->d_fsdata, - smp_load_acquire(&dentry->d_fsdata) - != NFS_FSDATA_BLOCKED); + dentry->d_fsdata != NFS_FSDATA_BLOCKED); } return 0; } @@ -1857,12 +1863,15 @@ static void block_revalidate(struct dentry dentry) kfree(dentry->d_fsdata); /* Any new reference that could lead to an open - * will take ->d_lock in lookup_open() -> d_lookup(). - * Holding this lock ensures we cannot race with - * __nfs_lookup_revalidate() and removes and need - * for further barriers. + * will either: + * - take ->d_lock in lookup_open() -> d_lookup() or + * - will check d_seq in legitimize_mnt() + * + * Holding this lock and invalidating ->d_seq ensures we cannot + * race with __nfs_lookup_revalidate(). / lockdep_assert_held(&dentry->d_lock); + write_seqcount_invalidate(&dentry->d_seq); dentry->d_fsdata = NFS_FSDATA_BLOCKED; } @@ -2111,7 +2120,6 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry, struct inode inode; unsigned int lookup_flags = 0; unsigned long dir_verifier; - bool switched = false; int created = 0; int err; @@ -2156,17 +2164,6 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry, attr.ia_size = 0; } - if (!(open_flags & O_CREAT) && !d_in_lookup(dentry)) { - d_drop(dentry); - switched = true; - dentry = d_alloc_parallel(dentry->d_parent, - &dentry->d_name); - if (IS_ERR(dentry)) - return PTR_ERR(dentry); - if (unlikely(!d_in_lookup(dentry))) - return finish_no_open(file, dentry); - } - ctx = create_nfs_open_context(dentry, open_flags, file); err = PTR_ERR(ctx); if (IS_ERR(ctx)) @@ -2180,7 +2177,6 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry, err = PTR_ERR(inode); trace_nfs_atomic_open_exit(dir, ctx, open_flags, err); put_nfs_open_context(ctx); - d_drop(dentry); switch (err) { case -ENOENT: if (nfs_server_capable(dir, NFS_CAP_CASE_INSENSITIVE)) @@ -2189,7 +2185,7 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry, dir_verifier = nfs_save_change_attribute(dir); nfs_set_verifier(dentry, dir_verifier); d_splice_alias(NULL, dentry); - break; + goto out; case -EISDIR: case -ENOTDIR: if (open_flags & __O_REGULAR) { @@ -2205,6 +2201,7 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry, default: break; } + d_drop(dentry); goto out; } file->f_mode \|= FMODE_CAN_ODIRECT; @@ -2217,10 +2214,6 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry, trace_nfs_atomic_open_exit(dir, ctx, open_flags, err); put_nfs_open_context(ctx); out: - if (unlikely(switched)) { - d_lookup_done(dentry); - dput(dentry); - } return err; no_open: @@ -2243,13 +2236,6 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry, res = ERR_PTR(-EOPENSTALE); } } - if (switched) { - d_lookup_done(dentry); - if (!res) - res = dentry; - else - dput(dentry); - } return finish_no_open(file, res); } EXPORT_SYMBOL_GPL(nfs_atomic_open); @@ -2357,8 +2343,6 @@ nfs_add_or_obtain(struct dentry dentry, struct nfs_fh fhandle, struct dentry d; int error; - d_drop(dentry); - if (fhandle->size == 0) { error = NFS_PROTO(dir)->lookup(dir, dentry, &dentry->d_name, fhandle, fattr); @@ -2379,6 +2363,7 @@ nfs_add_or_obtain(struct dentry dentry, struct nfs_fh fhandle, dput(parent); return d; out_error: + d_drop(dentry); d = ERR_PTR(error); goto out; } @@ -2713,14 +2698,15 @@ nfs_link(struct dentry old_dentry, struct inode dir, struct dentry dentry) old_dentry, dentry); trace_nfs_link_enter(inode, dir, dentry); - d_drop(dentry); if (S_ISREG(inode->i_mode)) nfs_sync_inode(inode); error = NFS_PROTO(dir)->link(inode, dir, &dentry->d_name); if (error == 0) { nfs_set_verifier(dentry, nfs_save_change_attribute(dir)); ihold(inode); - d_add(dentry, inode); + d_splice_alias(inode, dentry); + } else { + d_drop(dentry); } trace_nfs_link_exit(inode, dir, dentry, error); return error; @@ -2815,11 +2801,9 @@ int nfs_rename(struct mnt_idmap idmap, struct inode old_dir, spin_unlock(&new_dentry->d_lock); /* copy the target dentry's name / - dentry = d_alloc(new_dentry->d_parent, - &new_dentry->d_name); + dentry = d_duplicate(new_dentry); if (!dentry) goto out; - / silly-rename the existing target ... / err = nfs_sillyrename(new_dir, new_dentry); if (err) @@ -2884,8 +2868,10 @@ int nfs_rename(struct mnt_idmap idmap, struct inode old_dir, nfs_dentry_handle_enoent(old_dentry); / new dentry created? / - if (dentry) + if (dentry) { + d_lookup_done(dentry); dput(dentry); + } return error; } EXPORT_SYMBOL_GPL(nfs_rename); diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index 04b1987115d5d..8f07f34f899e3 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -3113,7 +3113,6 @@ static int _nfs4_open_and_get_state(struct nfs4_opendata opendata, nfs_set_verifier(dentry, dir_verifier); if (d_really_is_negative(dentry)) { struct dentry alias; - d_drop(dentry); alias = d_splice_alias(igrab(state->inode), dentry); / d_splice_alias() can't fail here - it's a non-directory / if (alias) { diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c index c8d712204e649..c6b700e8e8e1b 100644 --- a/fs/nfs/unlink.c +++ b/fs/nfs/unlink.c @@ -125,6 +125,9 @@ static int nfs_call_unlink(struct dentry dentry, struct inode inode, struct nf struct dentry alias; down_read_non_owner(&NFS_I(dir)->rmdir_sem); + data->args.name.hash = full_name_hash(dentry->d_parent, + data->args.name.name, + data->args.name.len); alias = d_alloc_parallel(dentry->d_parent, &data->args.name); if (IS_ERR(alias)) { up_read_non_owner(&NFS_I(dir)->rmdir_sem); @@ -448,7 +451,7 @@ nfs_sillyrename(struct inode dir, struct dentry dentry) static unsigned int sillycounter; unsigned char silly[SILLYNAME_LEN + 1]; unsigned long long fileid; - struct dentry sdentry; + struct dentry sdentry, old; struct inode inode = d_inode(dentry); struct rpc_task task; int error = -EBUSY; @@ -465,26 +468,42 @@ nfs_sillyrename(struct inode dir, struct dentry dentry) fileid = d_inode(dentry)->i_ino; - sdentry = NULL; - do { +newname: + sillycounter++; + scnprintf(silly, sizeof(silly), + SILLYNAME_PREFIX "%0llx%0x", + SILLYNAME_FILEID_LEN, fileid, + SILLYNAME_COUNTER_LEN, sillycounter); + + dfprintk(VFS, "NFS: trying to rename %pd to %s\n", dentry, silly); + sdentry = d_alloc_trylock(dentry->d_parent, &QSTR(silly)); + if (sdentry == ERR_PTR(-EWOULDBLOCK)) + / Name currently being looked up / + goto newname; + / + * N.B. Better to return EBUSY here ... it could be + * dangerous to delete the file while it's in use. + / + if (IS_ERR(sdentry)) + goto out; + if (!d_in_lookup(sdentry)) { + if (d_really_is_negative(sdentry)) { + / try to get an in-lookup dentry / + d_drop(sdentry); + sillycounter--; + } dput(sdentry); - sillycounter++; - scnprintf(silly, sizeof(silly), - SILLYNAME_PREFIX "%0llx%0x", - SILLYNAME_FILEID_LEN, fileid, - SILLYNAME_COUNTER_LEN, sillycounter); - - dfprintk(VFS, "NFS: trying to rename %pd to %s\n", - dentry, silly); - - sdentry = lookup_noperm(&QSTR(silly), dentry->d_parent); - / - * N.B. Better to return EBUSY here ... it could be - * dangerous to delete the file while it's in use. - / - if (IS_ERR(sdentry)) - goto out; - } while (d_inode(sdentry) != NULL); / need negative lookup / + goto newname; + } + / This name isn't known locally - check on server */ + old = nfs_lookup(dir, sdentry, 0); + d_lookup_done(sdentry); + if (old \|\| d_is_positive(sdentry)) { + if (!IS_ERR(old)) + dput(old); + dput(sdentry); + goto newname; + } ihold(inode);
3/2	2026/09/27 17:42	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 6833 output: 29 thoughts: 613 Thoughts: Evaluating the NFS Patch Series Okay, so I need to evaluate a patch series applied in the kernel git repo. First, let's see which files are touched: `fs/nfs/dir.c`, `fs/nfs/nfs4proc.c`, and `fs/nfs/unlink.c`. Got it. Now, the real work begins. I need to understand what these changes do. Let's dig into the changes themselves – diffs, commit logs, all of it. I'll start with a quick `git log -n 5` or similar using either the provided tools, or a quick `read-file` and a grep. Wait, `grepper` only does `git grep`, so I'll keep that in mind. Can I even use `grepper` to search within `fs/nfs`? I need to stay aware of which tools I can use: `grepper`, `codesearch-dir-index`, `read-file`, and `set-results`. Okay, before I go too far, I need to remind myself of the core triage philosophy. Reachability is the primary concern here. I cannot blindly trust claims of "no functional change" or "refactoring." Any new or modified assertions in reachable code must be fuzzed. Conversely, I need to keep in mind the negative criteria: non-kernel code, unreachable hardware, and unreachable execution paths. On the positive side, I need to focus on core subsystems, refactorings and cleanups, runtime assertions, and reachable drivers and protocols. Now, NFS. The critical question: is NFS reachable in syzkaller fuzzing? This is key. Can NFS be mounted and used? Does syzkaller have support for `mount("nfs", ...)` or `mount("nfs4", ...)`? Is there a local NFS server setup possible, like `nfsd`, a loopback mount, or using a userspace NFS implementation like ganesha or a "nfs-over-loopback" scenario? Hold on… does syzkaller actually fuzz NFS? I know syzkaller has `syz_mount_image` and supports loopback/fuse/etc., but is NFS explicitly part of the fuzzing target? Syzkaller tests often run in VMs with root privileges, so `unshare` and namespaces are definitely on the table. Does syzkaller offer something like `mount$nfs`? Does NFS work in this environment, or is it structurally reachable from syzkaller? Right, back to basics. I need to search the kernel tree. I need to look for Kconfig options and callers, to determine if NFS is actually reachable from syzkaller. I need to figure out if NFS is considered a reachable or unreachable target. Time to go back and check the `fs/nfs/Kconfig` file. That's the first step.
4/2	2026/09/27 17:42	tool	grepper	0m Args: { "Expression": "config NFS_FS", "PathPrefix": "fs/nfs/" } Results: { "Output": "fs/nfs/Kconfig-1-# SPDX-License-Identifier: GPL-2.0-only\nfs/nfs/Kconfig:2:config NFS_FS\nfs/nfs/Kconfig-3-\ttristate \"NFS client support\"\n--\nfs/nfs/Kconfig=162=config ROOT_NFS\n--\nfs/nfs/Kconfig-172-\nfs/nfs/Kconfig:173:config NFS_FSCACHE\nfs/nfs/Kconfig-174-\tbool \"Provide NFS client caching support\"\n" }
5/2	2026/09/27 17:42	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 8245 output: 33 thoughts: 18 Thoughts: Okay, here's my interpretation of that thought process, assuming I'm an expert and this is how I approach code: Diving into the NFS Configuration Alright, let's get down to brass tacks. The mental checklist starts with figuring out how NFS (Network File System) is configured within the kernel. The obvious first step, when starting with a high level overview, is to check the `Kconfig` file. And, more specifically, line 1 of the mentioned `Kconfig` file in the `fs/nfs/` directory. That's the entry point to defining which options will become configurable for NFS support. That's where all the fundamental flags and dependencies are set. It will be the critical file to understand the configuration space of the entire component. Let's see what's there... and then begin the journey of understanding the module.
6/2	2026/09/27 17:42	tool	read-file	0m Args: { "File": "fs/nfs/Kconfig", "FirstLine": 1, "LineCount": 80 } Results: { "Contents": " 1:\t# SPDX-License-Identifier: GPL-2.0-only\n 2:\tconfig NFS_FS\n 3:\t\ttristate \"NFS client support\"\n 4:\t\tdepends on INET \u0026\u0026 FILE_LOCKING \u0026\u0026 MULTIUSER\n 5:\t\tselect CRC32\n 6:\t\tselect LOCKD\n 7:\t\tselect SUNRPC\n 8:\t\tselect NFS_COMMON\n 9:\t\tselect NFS_ACL_SUPPORT if NFS_V3_ACL\n 10:\t\thelp\n 11:\t\t Choose Y here if you want to access files residing on other\n 12:\t\t computers using Sun's Network File System protocol. To compile\n 13:\t\t this file system support as a module, choose M here: the module\n 14:\t\t will be called nfs.\n 15:\t\n 16:\t\t To mount file systems exported by NFS servers, you also need to\n 17:\t\t install the user space mount.nfs command which can be found in\n 18:\t\t the Linux nfs-utils package, available from http://linux-nfs.org/.\n 19:\t\t Information about using the mount command is available in the\n 20:\t\t mount(8) man page. More detail about the Linux NFS client\n 21:\t\t implementation is available via the nfs(5) man page.\n 22:\t\n 23:\t\t Below you can choose which versions of the NFS protocol are\n 24:\t\t available in the kernel to mount NFS servers. Support for NFS\n 25:\t\t version 2 (RFC 1094) is always available when NFS_FS is selected.\n 26:\t\n 27:\t\t To configure a system which mounts its root file system via NFS\n 28:\t\t at boot time, say Y here, select \"Kernel level IP\n 29:\t\t autoconfiguration\" in the NETWORK menu, and select \"Root file\n 30:\t\t system on NFS\" below. You cannot compile this file system as a\n 31:\t\t module in this case.\n 32:\t\n 33:\t\t If unsure, say N.\n 34:\t\n 35:\tconfig NFS_V2\n 36:\t\ttristate \"NFS client support for NFS version 2\"\n 37:\t\tdepends on NFS_FS\n 38:\t\tdefault n\n 39:\t\thelp\n 40:\t\t This option enables support for version 2 of the NFS protocol\n 41:\t\t (RFC 1094) in the kernel's NFS client.\n 42:\t\n 43:\t\t If unsure, say N.\n 44:\t\n 45:\tconfig NFS_V3\n 46:\t\ttristate \"NFS client support for NFS version 3\"\n 47:\t\tdepends on NFS_FS\n 48:\t\tdefault y\n 49:\t\thelp\n 50:\t\t This option enables support for version 3 of the NFS protocol\n 51:\t\t (RFC 1813) in the kernel's NFS client.\n 52:\t\n 53:\t\t If unsure, say Y.\n 54:\t\n 55:\tconfig NFS_V3_ACL\n 56:\t\tbool \"NFS client support for the NFSv3 ACL protocol extension\"\n 57:\t\tdepends on NFS_V3\n 58:\t\thelp\n 59:\t\t Some NFS servers support an auxiliary NFSv3 ACL protocol that\n 60:\t\t Sun added to Solaris but never became an official part of the\n 61:\t\t NFS version 3 protocol. This protocol extension allows\n 62:\t\t applications on NFS clients to manipulate POSIX Access Control\n 63:\t\t Lists on files residing on NFS servers. NFS servers enforce\n 64:\t\t ACLs on local files whether this protocol is available or not.\n 65:\t\n 66:\t\t Choose Y here if your NFS server supports the Solaris NFSv3 ACL\n 67:\t\t protocol extension and you want your NFS client to allow\n 68:\t\t applications to access and modify ACLs on files on the server.\n 69:\t\n 70:\t\t Most NFS servers don't support the Solaris NFSv3 ACL protocol\n 71:\t\t extension. You can choose N here or specify the \"noacl\" mount\n 72:\t\t option to prevent your NFS client from trying to use the NFSv3\n 73:\t\t ACL protocol.\n 74:\t\n 75:\t\t If unsure, say N.\n 76:\t\n 77:\tconfig NFS_V4\n 78:\t\ttristate \"NFS client support for NFS version 4\"\n 79:\t\tdepends on NFS_FS\n 80:\t\tselect KEYS\n" }
7/2	2026/09/27 17:42	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 9650 output: 32 thoughts: 70 Thoughts: Here's my take on those changes: Analyzing a NFS Patchset Okay, hold on a second! This patch is touching some key NFS components. I see updates to `fs/nfs/dir.c`, `fs/nfs/nfs4proc.c`, and `fs/nfs/unlink.c`. Those are all right in the heart of the NFS client-side operations. My initial thought is this must be related to directory handling, NFSv4 protocol processing, and file unlinking, respectively. Given those components, I need to know what compilation flags are active for those files. Time to check the `fs/nfs/Makefile`. That's where all the build configurations live and where I'm going to get some useful information.
8/2	2026/09/27 17:42	tool	read-file	0m Args: { "File": "fs/nfs/Makefile", "FirstLine": 1, "LineCount": 40 } Results: { "Contents": " 1:\t# SPDX-License-Identifier: GPL-2.0\n 2:\t#\n 3:\t# Makefile for the Linux nfs filesystem routines.\n 4:\t#\n 5:\t\n 6:\tobj-$(CONFIG_NFS_FS) += nfs.o\n 7:\t\n 8:\tCFLAGS_nfstrace.o += -I$(src)\n 9:\tnfs-y \t\t\t:= client.o dir.o file.o getroot.o inode.o super.o \\\n 10:\t\t\t\t io.o direct.o pagelist.o read.o symlink.o unlink.o \\\n 11:\t\t\t\t write.o namespace.o mount_clnt.o nfstrace.o \\\n 12:\t\t\t\t export.o sysfs.o fs_context.o\n 13:\tnfs-$(CONFIG_ROOT_NFS)\t+= nfsroot.o\n 14:\tnfs-$(CONFIG_SYSCTL)\t+= sysctl.o\n 15:\tnfs-$(CONFIG_NFS_FSCACHE) += fscache.o\n 16:\tnfs-$(CONFIG_NFS_LOCALIO) += localio.o\n 17:\t\n 18:\tobj-$(CONFIG_NFS_V2) += nfsv2.o\n 19:\tnfsv2-y := nfs2super.o proc.o nfs2xdr.o\n 20:\t\n 21:\tobj-$(CONFIG_NFS_V3) += nfsv3.o\n 22:\tnfsv3-y := nfs3super.o nfs3client.o nfs3proc.o nfs3xdr.o\n 23:\tnfsv3-$(CONFIG_NFS_V3_ACL) += nfs3acl.o\n 24:\t\n 25:\tobj-$(CONFIG_NFS_V4) += nfsv4.o\n 26:\tCFLAGS_nfs4trace.o += -I$(src)\n 27:\tnfsv4-y := nfs4proc.o nfs4xdr.o nfs4state.o nfs4renewd.o nfs4super.o nfs4file.o \\\n 28:\t\t delegation.o nfs4idmap.o callback.o callback_xdr.o callback_proc.o \\\n 29:\t\t nfs4namespace.o nfs4getroot.o nfs4client.o nfs4session.o \\\n 30:\t\t dns_resolve.o nfs4trace.o pnfs.o pnfs_dev.o pnfs_nfs.o\n 31:\tnfsv4-$(CONFIG_NFS_USE_LEGACY_DNS) += cache_lib.o\n 32:\tnfsv4-$(CONFIG_SYSCTL)\t+= nfs4sysctl.o\n 33:\tnfsv4-$(CONFIG_NFS_V4_0)\t+= nfs40client.o nfs40proc.o\n 34:\tnfsv4-$(CONFIG_NFS_V4_2)\t+= nfs42proc.o nfs42xattr.o\n 35:\t\n 36:\tobj-$(CONFIG_PNFS_FILE_LAYOUT) += filelayout/\n 37:\tobj-$(CONFIG_PNFS_BLOCK) += blocklayout/\n 38:\tobj-$(CONFIG_PNFS_FLEXFILE_LAYOUT) += flexfilelayout/\n" }
9/2	2026/09/27 17:42	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 10770 output: 34 thoughts: 113 Thoughts: Examining the NFS Filesystem Configuration Okay, so I'm looking at how this NFS stuff is put together. It seems that `nfs.o` is being built because of `CONFIG_NFS_FS`, and that includes `dir.o` and `unlink.o`. That makes sense; the core filesystem functionality would need those. And then, `nfsv4.o` is tied to `CONFIG_NFS_V4` which pulls in `nfs4proc.o`. That structure seems reasonable at first glance. But, as a matter of due diligence, I need to confirm the dependencies in the Kconfig file. Let's make sure there aren't any unexpected interactions or implicit dependencies there. I should check lines 75-120 of `fs/nfs/Kconfig` to be absolutely sure. Gotta have a solid understanding of the config options!
10/2	2026/09/27 17:42	tool	read-file	0m Args: { "File": "fs/nfs/Kconfig", "FirstLine": 75, "LineCount": 50 } Results: { "Contents": " 75:\t\t If unsure, say N.\n 76:\t\n 77:\tconfig NFS_V4\n 78:\t\ttristate \"NFS client support for NFS version 4\"\n 79:\t\tdepends on NFS_FS\n 80:\t\tselect KEYS\n 81:\t\tselect SUNRPC_BACKCHANNEL\n 82:\t\thelp\n 83:\t\t This option enables support for version 4.1 of the NFS protocol\n 84:\t\t (RFC 5661) in the kernel's NFS client.\n 85:\t\n 86:\t\t To mount NFS servers using NFSv4, you also need to install user\n 87:\t\t space programs which can be found in the Linux nfs-utils package,\n 88:\t\t available from http://linux-nfs.org/.\n 89:\t\n 90:\t\t If unsure, say N.\n 91:\t\n 92:\tconfig NFS_SWAP\n 93:\t\tbool \"Provide swap over NFS support\"\n 94:\t\tdefault n\n 95:\t\tdepends on NFS_FS \u0026\u0026 SWAP\n 96:\t\tselect SUNRPC_SWAP\n 97:\t\thelp\n 98:\t\t This option enables swapon to work on files located on NFS mounts.\n 99:\t\n 100:\tconfig NFS_V4_0\n 101:\t\tbool \"NFS client support for NFSv4.0\"\n 102:\t\tdepends on NFS_V4\n 103:\t\tdefault y\n 104:\t\thelp\n 105:\t\t This option enables support for minor version 0 of the NFSv4 protocol\n 106:\t\t (RFC 3530) in the kernel's NFS client.\n 107:\t\n 108:\t\t If unsure, say N.\n 109:\t\n 110:\tconfig NFS_V4_2\n 111:\t\tbool \"NFS client support for NFSv4.2\"\n 112:\t\tdepends on NFS_V4\n 113:\t\thelp\n 114:\t\t This option enables support for minor version 2 of the NFSv4 protocol\n 115:\t\t in the kernel's NFS client.\n 116:\t\n 117:\t\t If unsure, say N.\n 118:\t\n 119:\tconfig PNFS_FILE_LAYOUT\n 120:\t\ttristate\n 121:\t\tdepends on NFS_V4\n 122:\t\tdefault NFS_V4\n 123:\t\n 124:\tconfig PNFS_BLOCK\n" }
11/2	2026/09/27 17:42	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 11767 output: 20 thoughts: 1440 Thoughts: NFS and Syzkaller: A Reachability Analysis Okay, so the question is, can syzkaller actually fuzz NFS? First, I need to figure out if NFS is reachable within the standard syzkaller environment. The key here is "reachability" – can the code execute in QEMU or GCE? Syzkaller focuses on subsystems accessible in those environments. Let's re-examine those crucial sections in the documentation. Section 1 stresses that fuzzing only works on code that can be executed in the standard virtualized setting. Section 2 outlines when to return `WorthFuzzing=false`. Basically, when the modified code strictly falls into the negative criteria, the answer is no. This includes things like documentation, user-space tools, unreachable hardware (like specific PCIe cards), or unreachable execution paths. Does NFS fall into any of those "negative" categories? No, it doesn't! NFS is a filesystem, VFS, a network filesystem at that. It doesn't require specialized hardware, and it runs in standard x86 kernels. It can be compiled using `CONFIG_NFS_FS`. The next question: Can syzkaller run a local NFS server or mount a local NFS share or loopback? Yes, absolutely! Linux has in-kernel NFSD (CONFIG_NFSD) and userspace NFS servers are easy enough to set up. Loopback is also easily accessible. So the pieces are there. Now to really dig into this patch. What exactly is being changed? Looking at those modified files one by one... * `fs/nfs/dir.c`: * `nfs_prime_dcache()`: changing how dentries are allocated. Specifically, `d_alloc_trylock` has been used. * `nfs_is_exclusive_create()`: Updated comment. * `nfs_neg_need_reval()`: Added a check based on `LOOKUP_OPEN` flag. * `__nfs_lookup_revalidate()`: Using a simpler `wait_var_event`. * `block_revalidate()`: Added `write_seqcount_invalidate`. * `nfs_atomic_open()`: Removing parallel dentry allocation and cleaning up dentry operations. * `nfs_add_or_obtain()`: Moving dentry dropping to a specific error exit. * `nfs_link()`: Changing the alias implementation, adding dentry dropping on failure. * `nfs_rename()`: Changing dentry allocation to `d_duplicate` and `d_lookup_done`. * `fs/nfs/nfs4proc.c`: * `_nfs4_open_and_get_state()`: Dropped an unnecessary `d_drop`. * `fs/nfs/unlink.c`: * `nfs_call_unlink()`: Changed where name hashing occurs. * `nfs_sillyrename()`: Significant changes to dentry allocation and checking using `d_alloc_trylock`, handling `-EWOULDBLOCK`, and making use of the `nfs_lookup` and `d_lookup_done` calls. This all points towards modifications related to dentry handling, synchronization, and error paths, particularly using the `d_alloc_trylock` and `d_duplicate`. Those `d_alloc_trylock` and `d_duplicate`... are they existing VFS helpers? I should check and make sure that this is not new behavior, but something that the syzkaller will be able to work with. The fact that the changes center around dentries means this is definitely VFS code, which is good since that can easily be exercised.
12/2	2026/09/27 17:43	tool	grepper	0m Args: { "Expression": "d_alloc_trylock" } Results: { "Output": "fs/dcache.c=2974=EXPORT_SYMBOL(d_alloc_parallel);\n--\nfs/dcache.c-2976-/*\nfs/dcache.c:2977: d_alloc_trylock() - find or allocate a new dentry\nfs/dcache.c-2978- * @parent: dentry of the parent\n--\nfs/dcache.c-2984- * not d_in_lookup() then that is returned instead.\nfs/dcache.c:2985: * If the existing dentry is d_in_lookup(), d_alloc_trylock()\nfs/dcache.c-2986- * returns with error %-EWOULDBLOCK.\n--\nfs/dcache.c-2997- /\nfs/dcache.c:2998:struct dentry d_alloc_trylock(struct dentry parent,\nfs/dcache.c-2999-\t\t\t struct qstr name)\n--\nfs/dcache.c-3007-}\nfs/dcache.c:3008:EXPORT_SYMBOL(d_alloc_trylock);\nfs/dcache.c-3009-\n--\nfs/nfs/dir.c=725=void nfs_prime_dcache(struct dentry parent, struct nfs_entry entry,\n--\nfs/nfs/dir.c-753-again:\nfs/nfs/dir.c:754:\tdentry = d_alloc_trylock(parent, \u0026filename);\nfs/nfs/dir.c-755-\tif (IS_ERR(dentry))\n--\nfs/nfs/unlink.c=449=nfs_sillyrename(struct inode dir, struct dentry dentry)\n--\nfs/nfs/unlink.c-478-\tdfprintk(VFS, \"NFS: trying to rename %pd to %s\\n\", dentry, silly);\nfs/nfs/unlink.c:479:\tsdentry = d_alloc_trylock(dentry-\u003ed_parent, \u0026QSTR(silly));\nfs/nfs/unlink.c-480-\tif (sdentry == ERR_PTR(-EWOULDBLOCK))\n--\ninclude/linux/dcache.h=263=extern struct dentry * d_alloc_parallel(struct dentry , const struct qstr );\ninclude/linux/dcache.h:264:extern struct dentry * d_alloc_trylock(struct dentry , struct qstr );\ninclude/linux/dcache.h-265-extern struct dentry * d_splice_alias(struct inode , struct dentry );\n" }
13/2	2026/09/27 17:43	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 14716 output: 17 thoughts: 9 Thoughts: Okay, here's my attempt at summarizing the thought process, tailored for an expert audience, and written in the first person: Analyzing Potential Data Duplication Alright, time to dive into this. First, I need to check the status of `d_duplicate`. It’s the likely entry point for any duplication scenarios and should give me an idea if there are any issues at this point. I'm going to look at it to gain insight and determine whether I need to drill down any further. Hopefully, it shows a nice, clean picture. If not, I'll need to identify what other variables, functions, or data structures are impacted or related. I'm already anticipating some of the common culprits – likely identifiers or even faulty merge logic. This preliminary scan will set the stage.
14/2	2026/09/27 17:43	tool	grepper	0m Args: { "Expression": "d_duplicate" } Results: { "Output": "drivers/android/binder/freeze.rs=25=pub(crate) struct FreezeListener {\n--\ndrivers/android/binder/freeze.rs-42- /// Number of cleared duplicates that can be deleted.\ndrivers/android/binder/freeze.rs:43: num_cleared_duplicates: u64,\ndrivers/android/binder/freeze.rs-44-}\n--\ndrivers/android/binder/freeze.rs=86= fn do_work(\n--\ndrivers/android/binder/freeze.rs-97-\ndrivers/android/binder/freeze.rs:98: if freeze.num_cleared_duplicates \u003e 0 {\ndrivers/android/binder/freeze.rs:99: freeze.num_cleared_duplicates -= 1;\ndrivers/android/binder/freeze.rs-100- drop(node_refs);\n--\ndrivers/android/binder/freeze.rs-109- if freeze.is_clearing {\ndrivers/android/binder/freeze.rs:110: kernel::warn_on!(freeze.num_cleared_duplicates != 0);\ndrivers/android/binder/freeze.rs-111- if freeze.num_pending_duplicates \u003e 0 {\n--\ndrivers/android/binder/freeze.rs=180= pub(crate) fn request_freeze_notif(\n--\ndrivers/android/binder/freeze.rs-249- num_pending_duplicates: 0,\ndrivers/android/binder/freeze.rs:250: num_cleared_duplicates: 0,\ndrivers/android/binder/freeze.rs-251- },\n--\ndrivers/android/binder/freeze.rs-259- } else {\ndrivers/android/binder/freeze.rs:260: dupe.num_cleared_duplicates += 1;\ndrivers/android/binder/freeze.rs-261- }\n--\ndrivers/android/binder/freeze.rs=275= pub(crate) fn freeze_notif_done(self: \u0026Arc\u003cSelf\u003e, reader: \u0026mut UserSliceReader) -\u003e Result\u003c()\u003e {\n--\ndrivers/android/binder/freeze.rs-291- freeze.num_pending_duplicates -= 1;\ndrivers/android/binder/freeze.rs:292: freeze.num_cleared_duplicates += 1;\ndrivers/android/binder/freeze.rs-293- } else {\n--\ndrivers/gpu/drm/display/drm_dp_mst_topology.c=4395=struct edid drm_dp_mst_get_edid(struct drm_connector connector,\n--\ndrivers/gpu/drm/display/drm_dp_mst_topology.c-4403-\ndrivers/gpu/drm/display/drm_dp_mst_topology.c:4404:\tedid = drm_edid_duplicate(drm_edid_raw(drm_edid));\ndrivers/gpu/drm/display/drm_dp_mst_topology.c-4405-\n--\ndrivers/gpu/drm/drm_edid.c=2950=EXPORT_SYMBOL(drm_edid_read_switcheroo);\n--\ndrivers/gpu/drm/drm_edid.c-2952-/*\ndrivers/gpu/drm/drm_edid.c:2953: drm_edid_duplicate - duplicate an EDID and the extensions\ndrivers/gpu/drm/drm_edid.c-2954- * @edid: EDID to duplicate\n--\ndrivers/gpu/drm/drm_edid.c-2957- /\ndrivers/gpu/drm/drm_edid.c:2958:struct edid drm_edid_duplicate(const struct edid edid)\ndrivers/gpu/drm/drm_edid.c-2959-{\n--\ndrivers/gpu/drm/drm_edid.c-2964-}\ndrivers/gpu/drm/drm_edid.c:2965:EXPORT_SYMBOL(drm_edid_duplicate);\ndrivers/gpu/drm/drm_edid.c-2966-\n--\ndrivers/gpu/drm/i915/display/intel_pmdemand.c=56=static struct intel_global_state \ndrivers/gpu/drm/i915/display/intel_pmdemand.c:57:intel_pmdemand_duplicate_state(struct intel_global_obj obj)\ndrivers/gpu/drm/i915/display/intel_pmdemand.c-58-{\n--\ndrivers/gpu/drm/i915/display/intel_pmdemand.c=74=static const struct intel_global_state_funcs intel_pmdemand_funcs = {\ndrivers/gpu/drm/i915/display/intel_pmdemand.c:75:\t.atomic_duplicate_state = intel_pmdemand_duplicate_state,\ndrivers/gpu/drm/i915/display/intel_pmdemand.c-76-\t.atomic_destroy_state = intel_pmdemand_destroy_state,\n--\ndrivers/gpu/drm/msm/adreno/a6xx_gpu_state.h=91=static const u32 a6xx_hlsq_duplicate_cluster[] = {\n--\ndrivers/gpu/drm/msm/adreno/a6xx_gpu_state.h-94-\ndrivers/gpu/drm/msm/adreno/a6xx_gpu_state.h:95:static const u32 a6xx_hlsq_2d_duplicate_cluster[] = {\ndrivers/gpu/drm/msm/adreno/a6xx_gpu_state.h-96-\t0xbd80, 0xbd80,\n--\ndrivers/gpu/drm/msm/adreno/a6xx_gpu_state.h=137=static const struct a6xx_dbgahb_cluster {\n--\ndrivers/gpu/drm/msm/adreno/a6xx_gpu_state.h-146-\tCLUSTER_DBGAHB(CLUSTER_SP_VS, 0x0002e000, 0x41, a6xx_hlsq_duplicate_cluster),\ndrivers/gpu/drm/msm/adreno/a6xx_gpu_state.h:147:\tCLUSTER_DBGAHB(CLUSTER_SP_VS, 0x0002f000, 0x45, a6xx_hlsq_2d_duplicate_cluster),\ndrivers/gpu/drm/msm/adreno/a6xx_gpu_state.h-148-\tCLUSTER_DBGAHB(CLUSTER_SP_VS, 0x0002a000, 0x21, a6xx_sp_duplicate_cluster),\n--\ndrivers/md/dm.c=1274=static size_t dm_dax_recovery_write(struct dax_device dax_dev, pgoff_t pgoff,\n--\ndrivers/md/dm.c-1297- * with write BIOs flagged with BIO_EMULATES_ZONE_APPEND) and any bio serviced\ndrivers/md/dm.c:1298: * by __send_duplicate_bios().\ndrivers/md/dm.c-1299- \n--\ndrivers/md/dm.c=1478=static void alloc_multiple_bios(struct bio_list blist, struct clone_info ci,\n--\ndrivers/md/dm.c-1507-\ndrivers/md/dm.c:1508:static unsigned int __send_duplicate_bios(struct clone_info ci, struct dm_target ti,\ndrivers/md/dm.c-1509-\t\t\t\t\t unsigned int num_bios, unsigned int len)\n--\ndrivers/md/dm.c=1537=static void __send_empty_flush(struct clone_info ci)\n--\ndrivers/md/dm.c-1566-\t\t\tatomic_add(ti-\u003enum_flush_bios, \u0026ci-\u003eio-\u003eio_count);\ndrivers/md/dm.c:1567:\t\t\tbios = __send_duplicate_bios(ci, ti, ti-\u003enum_flush_bios,\ndrivers/md/dm.c-1568-\t\t\t\t\t\t NULL);\n--\ndrivers/md/dm.c=1606=static void __send_abnormal_io(struct clone_info ci, struct dm_target ti,\n--\ndrivers/md/dm.c-1615-\tatomic_add(num_bios, \u0026ci-\u003eio-\u003eio_count);\ndrivers/md/dm.c:1616:\tbios = __send_duplicate_bios(ci, ti, num_bios, \u0026len);\ndrivers/md/dm.c-1617-\t/\n--\ndrivers/md/dm.c=1902=static void __send_zone_reset_all_native(struct clone_info ci,\n--\ndrivers/md/dm.c-1907-\tatomic_add(1, \u0026ci-\u003eio-\u003eio_count);\ndrivers/md/dm.c:1908:\tbios = __send_duplicate_bios(ci, ti, 1, NULL);\ndrivers/md/dm.c-1909-\tatomic_sub(1 - bios, \u0026ci-\u003eio-\u003eio_count);\n--\ndrivers/usb/typec/class.c=448=static int increment_duplicated_priority(struct device dev, void data)\n--\ndrivers/usb/typec/class.c-462-\ndrivers/usb/typec/class.c:463:static int find_duplicated_priority(struct device dev, void data)\ndrivers/usb/typec/class.c-464-{\n--\ndrivers/usb/typec/class.c=475=static int typec_mode_set_priority(struct typec_altmode alt, const u8 priority)\n--\ndrivers/usb/typec/class.c-482-\twhile (res) {\ndrivers/usb/typec/class.c:483:\t\tres = device_for_each_child(\u0026port-\u003edev, \u0026alt, find_duplicated_priority);\ndrivers/usb/typec/class.c-484-\t\tif (res) {\n--\nfs/dcache.c=2004=EXPORT_SYMBOL(d_alloc);\n--\nfs/dcache.c-2006-/*\nfs/dcache.c:2007: d_duplicate - duplicate a dentry for combined atomic operation\nfs/dcache.c-2008- * @dentry: the dentry to duplicate\n--\nfs/dcache.c-2017- * For this they need two dentries which temporarily have the same name,\nfs/dcache.c:2018: * before one is renamed. d_duplicate() provides for this. Given a\nfs/dcache.c-2019- * positive hashed dentry, it creates a second in-lookup dentry.\n--\nfs/dcache.c-2031- /\nfs/dcache.c:2032:struct dentry d_duplicate(struct dentry dentry)\nfs/dcache.c-2033-{\n--\nfs/dcache.c-2055-}\nfs/dcache.c:2056:EXPORT_SYMBOL(d_duplicate);\nfs/dcache.c-2057-\n--\nfs/nfs/dir.c=2760=int nfs_rename(struct mnt_idmap idmap, struct inode old_dir,\n--\nfs/nfs/dir.c-2803-\t\t\t/ copy the target dentry's name /\nfs/nfs/dir.c:2804:\t\t\tdentry = d_duplicate(new_dentry);\nfs/nfs/dir.c-2805-\t\t\tif (!dentry)\n--\ninclude/drm/drm_edid.h=441=struct edid drm_get_edid_switcheroo(struct drm_connector connector,\ninclude/drm/drm_edid.h-442-\t\t\t\t struct i2c_adapter adapter);\ninclude/drm/drm_edid.h:443:struct edid drm_edid_duplicate(const struct edid edid);\ninclude/drm/drm_edid.h-444-int drm_add_edid_modes(struct drm_connector connector, struct edid edid);\n--\ninclude/linux/dcache.h=265=extern struct dentry * d_splice_alias(struct inode , struct dentry );\ninclude/linux/dcache.h:266:struct dentry d_duplicate(struct dentry dentry);\ninclude/linux/dcache.h-267-/* weird procfs mess; NOT exported */\n" }
15/2	2026/09/27 17:43	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 18046 output: 35 thoughts: 123 Thoughts: Okay, here's my take on those thoughts, framed as an expert's inner monologue: Dentry Locking Improvements for NFS! Well, isn't that interesting? I see `d_duplicate()` and `d_alloc_trylock()` are actually exported symbols now, right there in `fs/dcache.c`. And this patch is leveraging them! It looks like it's adapting the NFS client – the core stuff in `fs/nfs/dir.c`, `fs/nfs/nfs4proc.c`, and `fs/nfs/unlink.c` – to utilize these and, finally, addressing some dentry locking and lookup semantics issues in NFS. That's a huge step forward if implemented properly. Let me refresh my memory on what Neil Brown did around that time. It's time to delve back into `fs/dcache.c`, specifically around lines 2007 and 2977. I'll need to re-familiarize myself with that dcache series of his; it's probably where the key locking changes were introduced, so I can see what they're using now to improve NFS. Gotta get a handle on the rationale behind these changes, and where the new primitives fit into the overall picture. This is promising – hopefully, it simplifies things and results in some performance gains!
16/2	2026/09/27 17:43	tool	read-file	0m Args: { "File": "fs/dcache.c", "FirstLine": 2006, "LineCount": 55 } Results: { "Contents": "2006:\t/*\n2007:\t d_duplicate - duplicate a dentry for combined atomic operation\n2008:\t * @dentry: the dentry to duplicate\n2009:\t \n2010:\t Some rename operations need to be combined with another operation\n2011:\t * inside the filesystem.\n2012:\t * 1/ A cluster filesystem when renaming to an in-use file might need to\n2013:\t * first \"silly-rename\" that target out of the way before the main rename\n2014:\t * 2/ A filesystem that supports white-out might want to create a whiteout\n2015:\t * in place of the file being moved.\n2016:\t \n2017:\t For this they need two dentries which temporarily have the same name,\n2018:\t * before one is renamed. d_duplicate() provides for this. Given a\n2019:\t * positive hashed dentry, it creates a second in-lookup dentry.\n2020:\t * Because the original dentry exists, no other thread will try to\n2021:\t * create an in-lookup dentry, so there can be no race in this create.\n2022:\t \n2023:\t The caller should d_move() the original to a new name, often via a\n2024:\t * rename request, and should call d_lookup_done() on the newly created\n2025:\t * dentry. If the new is instantiated then the old MUST either be moved\n2026:\t * or dropped.\n2027:\t \n2028:\t Parent must be locked.\n2029:\t \n2030:\t Returns: an in-lookup dentry, or -ENOMEM.\n2031:\t /\n2032:\tstruct dentry d_duplicate(struct dentry dentry)\n2033:\t{\n2034:\t\tunsigned int hash = dentry-\u003ed_name.hash;\n2035:\t\tstruct dentry parent = dentry-\u003ed_parent;\n2036:\t\tstruct hlist_bl_head b = in_lookup_hash(parent, hash);\n2037:\t\tstruct dentry new = __d_alloc(parent-\u003ed_sb, \u0026dentry-\u003ed_name);\n2038:\t\n2039:\t\tif (unlikely(!new))\n2040:\t\t\treturn ERR_PTR(-ENOMEM);\n2041:\t\n2042:\t\tnew-\u003ed_flags \|= DCACHE_PAR_LOOKUP;\n2043:\t\tlock_map_acquire_try(\u0026new-\u003elookup_map);\n2044:\t\tspin_lock(\u0026parent-\u003ed_lock);\n2045:\t\tnew-\u003ed_parent = dget_dlock(parent);\n2046:\t\thlist_add_head(\u0026new-\u003ed_sib, \u0026parent-\u003ed_children);\n2047:\t\tif (parent-\u003ed_flags \u0026 DCACHE_DISCONNECTED)\n2048:\t\t\tnew-\u003ed_flags \|= DCACHE_DISCONNECTED;\n2049:\t\tspin_unlock(\u0026parent-\u003ed_lock);\n2050:\t\n2051:\t\thlist_bl_lock(b);\n2052:\t\thlist_bl_add_head(\u0026new-\u003ed_in_lookup_hash, b);\n2053:\t\thlist_bl_unlock(b);\n2054:\t\treturn new;\n2055:\t}\n2056:\tEXPORT_SYMBOL(d_duplicate);\n2057:\t\n2058:\tstruct dentry d_alloc_anon(struct super_block sb)\n2059:\t{\n2060:\t\treturn __d_alloc(sb, NULL);\n" }
17/2	2026/09/27 17:43	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 19454 output: 35 thoughts: 22 Thoughts: Here's my take on those thoughts, tailored for an expert audience: Diving into the dcache.c Lock Okay, I'm already deep in this, but I should probably take a look at `d_alloc_trylock` within `fs/dcache.c`. I need to understand how the allocation lock is handled in this critical path. It's not enough to simply assume I understand the locking strategy here – I've learned that lesson the hard way! I need to ensure there are no subtle race conditions or unexpected contention points that could be contributing to the issue I'm chasing. A quick scan of this function will hopefully confirm my initial hypotheses and give me more evidence to support my conclusion. This is the kind of area where a seemingly minor oversight can have cascading effects, so better safe than sorry. I'm especially interested in the implementation of the try lock here - the logic surrounding that is often quite complex.
18/2	2026/09/27 17:43	tool	read-file	0m Args: { "File": "fs/dcache.c", "FirstLine": 2975, "LineCount": 45 } Results: { "Contents": "2975:\t\n2976:\t/*\n2977:\t d_alloc_trylock() - find or allocate a new dentry\n2978:\t * @parent: dentry of the parent\n2979:\t * @name: name of the dentry within that parent.\n2980:\t \n2981:\t A new dentry is allocated and, providing it is unique, added to the\n2982:\t * relevant index.\n2983:\t * If an existing dentry is found with the same parent/name that is\n2984:\t * not d_in_lookup() then that is returned instead.\n2985:\t * If the existing dentry is d_in_lookup(), d_alloc_trylock()\n2986:\t * returns with error %-EWOULDBLOCK.\n2987:\t * Thus if the returned dentry is d_in_lookup() then the caller has\n2988:\t * exclusive access until it completes the lookup.\n2989:\t * If the returned dentry is not d_in_lookup() then a lookup has\n2990:\t * already completed.\n2991:\t \n2992:\t The @name need not already have -\u003ehash set.\n2993:\t \n2994:\t Returns: the dentry, whether found or allocated, or an error\n2995:\t * %-ENOMEM, %-EWOULDBLOCK, %-EACCES (for a bad name) or\n2996:\t * anything returned by -\u003ed_hash().\n2997:\t /\n2998:\tstruct dentry d_alloc_trylock(struct dentry parent,\n2999:\t\t\t\t struct qstr name)\n3000:\t{\n3001:\t\tstruct dentry de;\n3002:\t\n3003:\t\tde = try_lookup_noperm(name, parent);\n3004:\t\tif (!de)\n3005:\t\t\tde = __d_alloc_parallel(parent, name, ALLOC_PARA_FAIL);\n3006:\t\treturn de;\n3007:\t}\n3008:\tEXPORT_SYMBOL(d_alloc_trylock);\n3009:\t\n3010:\t/\n3011:\t * Move dentry from in-lookup state to busy-negative one.\n3012:\t \n3013:\t From now on d_in_lookup(dentry) will return false and dentry is gone from\n3014:\t * in-lookup hash.\n3015:\t \n3016:\t Anyone who had been waiting on it in d_alloc_parallel() is free to\n3017:\t * proceed after that. Note that waking such waiters up is left to\n3018:\t * the callers; PREEMPT_RT kernels can't have that wakeup done while\n3019:\t * in write-side critical area for -\u003ei_dir_seq, so it's done by calling\n" }
19/2	2026/09/27 17:43	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 20479 output: 37 thoughts: 1685 Thoughts: WorthFuzzing Analysis: NFS Filesystem Patch Okay, let's break this down. From what I see, this patch is screaming for fuzzing. First, I need to evaluate the reachability and worthiness of the code changes, following the core triage philosophy. This patch clearly modifies crucial aspects of the NFS filesystem, touching core operations like lookup, open, rename, link, unlink, and readdir, including dentry locking and synchronization. These are all prime targets for discovering subtle bugs. The modifications to `block_revalidate`, specifically adding `write_seqcount_invalidate`, and the concurrent/locking changes in functions such as `nfs_sillyrename`, `nfs_atomic_open`, and `__nfs_lookup_revalidate` immediately raise red flags. These are classic areas where concurrency issues like races, deadlocks, lockdep warnings, use-after-free, or dentry reference count leaks are most likely to occur. Critically, NFS is easily reachable within standard environments. It doesn't require any exotic hardware. Syzkaller, in particular, can easily hit it using loopback or network configurations. The code changes are not non-executable or unreachable based on the provided negative criteria. The positive criteria are definitely met. We have modifications to core subsystems, like the filesystem, involving refactoring of data structures, locking, and synchronization. Therefore, I can confidently say that WorthFuzzing is definitively `true`. Now, let's determine the specifics for fuzzing. For `EnableConfigs`, the relevant Kconfig options are `NFS_FS` and `NFS_V4`. The module structure clearly shows that `nfs.o` is compiled with `CONFIG_NFS_FS`, while `nfsv4.o` includes `nfs4proc.o`, and `CONFIG_NFS_V4` depends on `NFS_FS`. Further investigation into `fs/nfs/Kconfig` confirms the dependencies of `NFS_FS` (INET, FILE_LOCKING, MULTIUSER, and select statements for CRC32, LOCKD, SUNRPC, NFS_COMMON, and potentially NFS_ACL_SUPPORT based on NFS_V3_ACL) and `NFS_V4` (NFS_FS, KEYS, SUNRPC_BACKCHANNEL). Regarding `FocusSymbols`, I'll need to make a more detailed assessment, but some potential initial targets would include: `nfs_prime_dcache`, `nfs_atomic_open`, `nfs_sillyrename`, `nfs_link`, and `__nfs_lookup_revalidate`. These functions are directly involved in the key modifications and represent potential areas where new vulnerabilities might surface. In short, this is high priority. The patch introduces changes to a complex filesystem implementation, the NFS client, which is relatively easy to reach. The focus is to look for concurrency bugs, memory corruption or other issues due to the changes in dentry, locking, and revalidation. It definitely deserves focused fuzzing effort.
20/2	2026/09/27 17:43	tool	grepper	0m Args: { "Expression": "_nfs4_open_and_get_state", "PathPrefix": "fs/nfs/" } Results: { "Output": "fs/nfs/nfs4proc.c=3034=static unsigned nfs4_exclusive_attrset(struct nfs4_opendata opendata,\n--\nfs/nfs/nfs4proc.c-3069-\nfs/nfs/nfs4proc.c:3070:static int _nfs4_open_and_get_state(struct nfs4_opendata opendata,\nfs/nfs/nfs4proc.c-3071-\t\tstruct nfs_open_context ctx)\n--\nfs/nfs/nfs4proc.c=3149=static int _nfs4_do_open(struct inode dir,\n--\nfs/nfs/nfs4proc.c-3198-\nfs/nfs/nfs4proc.c:3199:\tstatus = _nfs4_open_and_get_state(opendata, ctx);\nfs/nfs/nfs4proc.c-3200-\tif (status != 0)\n" }
21/2	2026/09/27 17:43	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 23108 output: 30 thoughts: 567 Thoughts: Analyzing the Relevant Configurations for NFS Client Code Okay, so I need to figure out the `EnableConfigs` for this patch, and it looks like I need to be precise. The patch is in `fs/nfs/`, so that's my starting point, specifically looking at the NFS client side. I know `_nfs4_open_and_get_state` is in `fs/nfs/nfs4proc.c`, and the `Makefile` tells me `CONFIG_NFS_V4` includes that file. Also `CONFIG_NFS_FS` will compile `fs/nfs/dir.c` and `fs/nfs/unlink.c`. I need to be careful not to confuse the client and server side. `NFSD` is the server, in `fs/nfsd/`, so that's irrelevant here, even though it might be helpful for setting up a test environment locally. The instructions want `EnableConfigs`. So, from the initial look: `NFS_FS` and `NFS_V4` are the primary ones. Now, I need to be thorough and check for any conditional compilation, any `#ifdef` blocks around the modified code. Specifically, the instruction is to check if these are relevant. Let's dig into `fs/nfs/dir.c` and `fs/nfs/unlink.c`. Here are the functions in `fs/nfs/dir.c` that I need to check if they're enclosed in an `#ifdef`: - `nfs_prime_dcache` (line 725) - `nfs_is_exclusive_create` (line 1573) - `nfs_neg_need_reval` (line 1655) - `__nfs_lookup_revalidate` (line 1840) - `block_revalidate` (line 1860) - `nfs_atomic_open` (line 2120) - `nfs_add_or_obtain` (line 2350) - `nfs_link` (line 2705) - `nfs_rename` (line 2760) I need to meticulously check if any of those functions, or anything significant within those functions, is guarded by a `#ifdef` which would introduce more `CONFIG_` options into the `EnableConfigs`. I'll do the same for `fs/nfs/unlink.c` as well.
22/2	2026/09/27 17:43	tool	grepper	0m Args: { "Expression": "#if", "PathPrefix": "fs/nfs/dir.c" } Results: { "Output": "fs/nfs/dir.c=461=int is_32bit_api(void)\nfs/nfs/dir.c-462-{\nfs/nfs/dir.c:463:#ifdef CONFIG_COMPAT\nfs/nfs/dir.c-464-\treturn in_compat_syscall();\n--\nfs/nfs/dir.c=1409=static void nfs_set_verifier_delegated(unsigned long verf)\n--\nfs/nfs/dir.c-1413-\nfs/nfs/dir.c:1414:#if IS_ENABLED(CONFIG_NFS_V4)\nfs/nfs/dir.c-1415-static void nfs_unset_verifier_delegated(unsigned long verf)\n--\nfs/nfs/dir.c=1461=EXPORT_SYMBOL_GPL(nfs_set_verifier);\nfs/nfs/dir.c-1462-\nfs/nfs/dir.c:1463:#if IS_ENABLED(CONFIG_NFS_V4)\nfs/nfs/dir.c-1464-static void nfs_clear_verifier_file(struct inode inode)\n--\nfs/nfs/dir.c=2069=EXPORT_SYMBOL_GPL(nfs_d_prune_case_insensitive_aliases);\nfs/nfs/dir.c-2070-\nfs/nfs/dir.c:2071:#if IS_ENABLED(CONFIG_NFS_V4)\nfs/nfs/dir.c-2072-static int nfs4_lookup_revalidate(struct inode , const struct qstr *,\n" }
23/2	2026/09/27 17:43	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 24697 output: 30 thoughts: 57 Thoughts: Checking for Conditional Compilation in NFS Code Okay, so I'm looking through some NFS code, specifically focusing on modifications, and it seems like the functions I've reviewed in `fs/nfs/dir.c` aren't enclosed within any existing `#if` preprocessor directives. This is interesting and warrants a deeper dive, as it could impact portability or specific configuration builds. Now, let's pivot and examine `fs/nfs/unlink.c`. I need to verify whether this file, or any functions within it, are subject to conditional compilation. I'll need to meticulously inspect for any `#if` statements within that file to get a clearer picture of the overall compilation strategy and potential dependencies or constraints associated with these NFS components.
24/2	2026/09/27 17:43	tool	grepper	0m Error: no matches Args: { "Expression": "#if", "PathPrefix": "fs/nfs/unlink.c" } Results: { "error": "no matches" }
25/2	2026/09/27 17:43	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 24958 output: 33 thoughts: 55 Thoughts: Okay, here's my summary, tailored as if I'm an expert in this area and the thoughts are my own: Investigating NFS Unlink Logic Right, so I'm looking at the unlink process in the NFS file system, specifically trying to trace down potential preprocessor conditional compilation, likely for different NFS versions or feature sets. The initial check of `fs/nfs/unlink.c` yielded nothing useful. That's not entirely unexpected; unlink is generally handled at a higher level than some of the more complex NFSv4 operations. Now, a likely area for conditional compilation would be in the more advanced NFSv4 procedures. Let me quickly pivot my attention to `fs/nfs/nfs4proc.c`. My hunch is, there might be conditional code surrounding the `_nfs4_open_and_get_state` function. This function deals with state management for NFSv4, and state handling is often where you'd find version-specific or feature-specific code. Checking that specific function for `#if` directives seems like a good path to see if there's any version control impacting unlink-related code.
26/2	2026/09/27 17:43	tool	grepper	0m Args: { "Expression": "#if", "PathPrefix": "fs/nfs/nfs4proc.c" } Results: { "Output": "fs/nfs/nfs4proc.c=108=static int nfs41_free_stateid(struct nfs_server , nfs4_stateid ,\n--\nfs/nfs/nfs4proc.c-110-\nfs/nfs/nfs4proc.c:111:#ifdef CONFIG_NFS_V4_SECURITY_LABEL\nfs/nfs/nfs4proc.c-112-static inline struct nfs4_label \n--\nfs/nfs/nfs4proc.c=211=const u32 nfs4_fattr_bitmap[3] = {\n--\nfs/nfs/nfs4proc.c-228-\tFATTR4_WORD2_UNCACHEABLE_FILE_DATA\nfs/nfs/nfs4proc.c:229:#ifdef CONFIG_NFS_V4_SECURITY_LABEL\nfs/nfs/nfs4proc.c-230-\t\| FATTR4_WORD2_SECURITY_LABEL\n--\nfs/nfs/nfs4proc.c=234=static const u32 nfs4_pnfs_open_bitmap[3] = {\n--\nfs/nfs/nfs4proc.c-250-\tFATTR4_WORD2_MDSTHRESHOLD\nfs/nfs/nfs4proc.c:251:#ifdef CONFIG_NFS_V4_SECURITY_LABEL\nfs/nfs/nfs4proc.c-252-\t\| FATTR4_WORD2_SECURITY_LABEL\n--\nfs/nfs/nfs4proc.c=3897=static int _nfs4_server_capabilities(struct nfs_server server, struct nfs_fh fhandle)\n--\nfs/nfs/nfs4proc.c-3973-\t\t\tserver-\u003ecaps \|= NFS_CAP_CASE_NONPRESERVING;\nfs/nfs/nfs4proc.c:3974:#ifdef CONFIG_NFS_V4_SECURITY_LABEL\nfs/nfs/nfs4proc.c-3975-\t\tif (res.attr_bitmask[2] \u0026 FATTR4_WORD2_SECURITY_LABEL)\n--\nfs/nfs/nfs4proc.c=5705=static int nfs4_read_done(struct rpc_task task, struct nfs_pgio_header hdr)\n--\nfs/nfs/nfs4proc.c-5718-\nfs/nfs/nfs4proc.c:5719:#if defined CONFIG_NFS_V4_2 \u0026\u0026 defined CONFIG_NFS_V4_2_READ_PLUS\nfs/nfs/nfs4proc.c-5720-static bool nfs42_read_plus_support(struct nfs_pgio_header hdr,\n--\nfs/nfs/nfs4proc.c=6285=static int nfs4_proc_set_acl(struct inode inode, const void buf,\n--\nfs/nfs/nfs4proc.c-6309-\nfs/nfs/nfs4proc.c:6310:#ifdef CONFIG_NFS_V4_SECURITY_LABEL\nfs/nfs/nfs4proc.c-6311-static int _nfs4_get_security_label(struct inode inode, void buf,\n--\nfs/nfs/nfs4proc.c=7929=static bool nfs4_xattr_list_nfs4_sacl(struct dentry dentry)\n--\nfs/nfs/nfs4proc.c-7933-\nfs/nfs/nfs4proc.c:7934:#ifdef CONFIG_NFS_V4_SECURITY_LABEL\nfs/nfs/nfs4proc.c-7935-\n--\nfs/nfs/nfs4proc.c=7957=static const struct xattr_handler nfs4_xattr_nfs4_label_handler = {\n--\nfs/nfs/nfs4proc.c-7964-\nfs/nfs/nfs4proc.c:7965:#ifdef CONFIG_NFS_V4_2\nfs/nfs/nfs4proc.c-7966-static int nfs4_xattr_set_nfs4_user(const struct xattr_handler handler,\n--\nfs/nfs/nfs4proc.c=8755=nfs4_run_exchange_id(struct nfs_client clp, const struct cred cred,\n--\nfs/nfs/nfs4proc.c-8823-\tEXCHGID4_FLAG_BIND_PRINC_STATEID;\nfs/nfs/nfs4proc.c:8824:#ifdef CONFIG_NFS_V4_1_MIGRATION\nfs/nfs/nfs4proc.c-8825-\tcalldata-\u003eargs.flags \|= EXCHGID4_FLAG_SUPP_MOVED_MIGR;\n--\nfs/nfs/nfs4proc.c=10576=static const struct nfs4_minor_version_ops nfs_v4_1_minor_ops = {\n--\nfs/nfs/nfs4proc.c-10601-\nfs/nfs/nfs4proc.c:10602:#if defined(CONFIG_NFS_V4_2)\nfs/nfs/nfs4proc.c-10603-static const struct nfs4_minor_version_ops nfs_v4_2_minor_ops = {\n--\nfs/nfs/nfs4proc.c=10642=const struct nfs4_minor_version_ops nfs_v4_minor_ops[] = {\nfs/nfs/nfs4proc.c:10643:#if defined(CONFIG_NFS_V4_0)\nfs/nfs/nfs4proc.c-10644-\t[0] = \u0026nfs_v4_0_minor_ops,\n--\nfs/nfs/nfs4proc.c-10646-\t[1] = \u0026nfs_v4_1_minor_ops,\nfs/nfs/nfs4proc.c:10647:#if defined(CONFIG_NFS_V4_2)\nfs/nfs/nfs4proc.c-10648-\t[2] = \u0026nfs_v4_2_minor_ops,\n--\nfs/nfs/nfs4proc.c=10827=static const struct xattr_handler nfs4_xattr_nfs4_sacl_handler = {\n--\nfs/nfs/nfs4proc.c-10833-\nfs/nfs/nfs4proc.c:10834:#ifdef CONFIG_NFS_V4_2\nfs/nfs/nfs4proc.c-10835-static const struct xattr_handler nfs4_xattr_nfs4_user_handler = {\n--\nfs/nfs/nfs4proc.c=10842=const struct xattr_handler const nfs4_xattr_handlers[] = {\n--\nfs/nfs/nfs4proc.c-10845-\t\u0026nfs4_xattr_nfs4_sacl_handler,\nfs/nfs/nfs4proc.c:10846:#ifdef CONFIG_NFS_V4_SECURITY_LABEL\nfs/nfs/nfs4proc.c-10847-\t\u0026nfs4_xattr_nfs4_label_handler,\nfs/nfs/nfs4proc.c-10848-#endif\nfs/nfs/nfs4proc.c:10849:#ifdef CONFIG_NFS_V4_2\nfs/nfs/nfs4proc.c-10850-\t\u0026nfs4_xattr_nfs4_user_handler,\n" }
27/2	2026/09/27 17:43	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 27253 output: 33 thoughts: 740 Thoughts: Analyzing the NFS Patch Impact Okay, so I'm looking at this patch and immediately, `NFS_FS` and `NFS_V4` are the core configurations I need to consider. Nothing surprising there; they're the standard building blocks. I'll quickly double-check if `NFS_FS` has any dependencies that are worth noting, but I expect it to be pretty straightforward. Yep, `INET && FILE_LOCKING && MULTIUSER`, standard stuff, nothing unusual. Now, the real work begins. I need to focus on the key symbols touched by this patch. Let's list those functions and pinpoint exactly what's being modified. From `fs/nfs/dir.c`, I see: `nfs_prime_dcache`, `nfs_neg_need_reval`, `__nfs_lookup_revalidate`, `block_revalidate`, `nfs_atomic_open`, `nfs_add_or_obtain`, `nfs_link`, and `nfs_rename`. And in `fs/nfs/nfs4proc.c`, there's `_nfs4_open_and_get_state`. Finally, in `fs/nfs/unlink.c` there's `nfs_call_unlink` and `nfs_sillyrename`. Now comes the crucial part: I have to determine the impact. Are these functions directly modified entry points, or are they called by others? Let's classify these. * `nfs_atomic_open`: Directly modified, exported function, which indicates it's a VFS inode operation, specifically `.atomic_open`. Important! * `nfs_rename`: Directly modified, also exported, and is also a VFS inode operation, `.rename`. Critical! * `nfs_link`: Directly modified, also a VFS inode operation, `.link`. Essential. * `nfs_sillyrename`: Directly modified; related to `unlink` and `rename` operations on busy files. * `nfs_prime_dcache`: Directly modified, potentially impacting readdir/lookup performance. * `nfs_lookup_revalidate`: Calls both `__nfs_lookup_revalidate` and `block_revalidate`. Worth investigating. * `nfs_unlink`: Calls `nfs_call_unlink` and `nfs_sillyrename`. * `nfs_lookup`: Calls `nfs_add_or_obtain`. Okay, so now I need to dig deeper. I need to confirm whether `__nfs_lookup_revalidate`, `nfs_call_unlink`, `_nfs4_open_and_get_state`, and `nfs_add_or_obtain` are static functions and therefore potential candidates for inlining. I have to look at their definitions and their callers to fully understand the flow and any potential side effects. The non-static functions are obviously entry points to the code.
28/2	2026/09/27 17:43	tool	grepper	0m Args: { "Expression": "__nfs_lookup_revalidate", "PathPrefix": "fs/nfs/" } Results: { "Output": "fs/nfs/dir.c=1838=static int\nfs/nfs/dir.c:1839:__nfs_lookup_revalidate(struct dentry dentry, unsigned int flags)\nfs/nfs/dir.c-1840-{\n--\nfs/nfs/dir.c=1852=static int nfs_lookup_revalidate(struct inode dir, const struct qstr name,\n--\nfs/nfs/dir.c-1854-{\nfs/nfs/dir.c:1855:\tif (__nfs_lookup_revalidate(dentry, flags))\nfs/nfs/dir.c-1856-\t\treturn -ECHILD;\n--\nfs/nfs/dir.c=1860=static void block_revalidate(struct dentry dentry)\n--\nfs/nfs/dir.c-1870-\t * Holding this lock and invalidating -\u003ed_seq ensures we cannot\nfs/nfs/dir.c:1871:\t * race with __nfs_lookup_revalidate().\nfs/nfs/dir.c-1872-\t /\n--\nfs/nfs/dir.c=2244=nfs4_lookup_revalidate(struct inode dir, const struct qstr *name,\n--\nfs/nfs/dir.c-2248-\nfs/nfs/dir.c:2249:\tif (__nfs_lookup_revalidate(dentry, flags))\nfs/nfs/dir.c-2250-\t\treturn -ECHILD;\n" }
29/2	2026/09/27 17:43	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 29081 output: 31 thoughts: 46 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience: Analyzing `__nfs_lookup_revalidate`'s Callers Alright, so the architecture is clearly built around this `__nfs_lookup_revalidate` function. The first thing I need to establish is its call chain, given that `nfs_lookup_revalidate` and `nfs4_lookup_revalidate` are calling it. This suggests a core, perhaps lower-level, revalidation mechanism is at play, shared by both NFSv3 and NFSv4 lookup procedures. I'm already thinking about potential performance implications here; shared code paths can be good for code reuse but also introduce bottlenecks if not optimized correctly. To get a clearer picture of how this revalidation fits into the larger filesystem picture, I'll need to know more about the broader function. Let me analyze how `nfs_call_unlink` fits into this situation. It will allow to see the overall process flow.
30/2	2026/09/27 17:43	tool	grepper	0m Args: { "Expression": "nfs_call_unlink", "PathPrefix": "fs/nfs/" } Results: { "Output": "fs/nfs/unlink.c=90=static void nfs_do_call_unlink(struct inode inode, struct nfs_unlinkdata data)\n--\nfs/nfs/unlink.c-121-\nfs/nfs/unlink.c:122:static int nfs_call_unlink(struct dentry dentry, struct inode inode, struct nfs_unlinkdata data)\nfs/nfs/unlink.c-123-{\n--\nfs/nfs/unlink.c=230=nfs_complete_unlink(struct dentry dentry, struct inode *inode)\n--\nfs/nfs/unlink.c-241-\nfs/nfs/unlink.c:242:\tif (NFS_STALE(inode) \|\| !nfs_call_unlink(dentry, inode, data))\nfs/nfs/unlink.c-243-\t\tnfs_free_unlinkdata(data);\n" }
31/2	2026/09/27 17:43	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 29612 output: 29 thoughts: 21 Thoughts: Here's a first-person summary, tailored for an expert audience, based on the prompt: Diving into `nfs_unlink` Okay, let's get down to brass tacks. My initial thought is to zero in on `nfs_unlink` within `fs/nfs/dir.c`. I need to understand the NFS unlink implementation, and this is the likely place to start. Given my expertise, I'm already anticipating certain aspects of its design – likely interactions with the NFS server, filehandle management, and potential complexities arising from caching and consistency models. My objective is to quickly grasp the core logic: how it handles the RPC call, what data structures it manipulates, and any potential areas for optimization or, more critically, any areas that might harbor subtle bugs or race conditions related to NFS's distributed nature. I expect to see the code dealing with locking around the dentry and inode to maintain data integrity. I'm going to pay close attention to the error handling and retry mechanisms. My goal here is a detailed mental map of how `nfs_unlink` really works.
32/2	2026/09/27 17:43	tool	grepper	0m Args: { "Expression": "nfs_unlink", "PathPrefix": "fs/nfs/" } Results: { "Output": "fs/nfs/dir.c=2539=static int nfs_safe_remove(struct dentry dentry)\n--\nfs/nfs/dir.c-2573- /\nfs/nfs/dir.c:2574:int nfs_unlink(struct inode dir, struct dentry dentry)\nfs/nfs/dir.c-2575-{\n--\nfs/nfs/dir.c-2580-\nfs/nfs/dir.c:2581:\ttrace_nfs_unlink_enter(dir, dentry);\nfs/nfs/dir.c-2582-\tspin_lock(\u0026dentry-\u003ed_lock);\n--\nfs/nfs/dir.c-2608-out:\nfs/nfs/dir.c:2609:\ttrace_nfs_unlink_exit(dir, dentry, error);\nfs/nfs/dir.c-2610-\treturn error;\nfs/nfs/dir.c-2611-}\nfs/nfs/dir.c:2612:EXPORT_SYMBOL_GPL(nfs_unlink);\nfs/nfs/dir.c-2613-\n--\nfs/nfs/internal.h=403=int nfs_rmdir(struct inode , struct dentry );\nfs/nfs/internal.h:404:int nfs_unlink(struct inode , struct dentry );\nfs/nfs/internal.h-405-int nfs_symlink(struct mnt_idmap , struct inode , struct dentry ,\n--\nfs/nfs/nfs3proc.c=466=nfs3_proc_unlink_setup(struct rpc_message msg,\n--\nfs/nfs/nfs3proc.c-472-\nfs/nfs/nfs3proc.c:473:static void nfs3_proc_unlink_rpc_prepare(struct rpc_task task, struct nfs_unlinkdata data)\nfs/nfs/nfs3proc.c-474-{\n--\nfs/nfs/nfs3proc.c=1042=static const struct inode_operations nfs3_dir_inode_operations = {\n--\nfs/nfs/nfs3proc.c-1046-\t.link\t\t= nfs_link,\nfs/nfs/nfs3proc.c:1047:\t.unlink\t\t= nfs_unlink,\nfs/nfs/nfs3proc.c-1048-\t.symlink\t= nfs_symlink,\n--\nfs/nfs/nfs4proc.c=5003=static void nfs4_proc_unlink_setup(struct rpc_message msg,\n--\nfs/nfs/nfs4proc.c-5024-\nfs/nfs/nfs4proc.c:5025:static void nfs4_proc_unlink_rpc_prepare(struct rpc_task task, struct nfs_unlinkdata data)\nfs/nfs/nfs4proc.c-5026-{\n--\nfs/nfs/nfs4proc.c=5033=static int nfs4_proc_unlink_done(struct rpc_task task, struct inode dir)\nfs/nfs/nfs4proc.c-5034-{\nfs/nfs/nfs4proc.c:5035:\tstruct nfs_unlinkdata data = task-\u003etk_calldata;\nfs/nfs/nfs4proc.c-5036-\tstruct nfs_removeres res = \u0026data-\u003eres;\n--\nfs/nfs/nfs4proc.c=10706=static const struct inode_operations nfs4_dir_inode_operations = {\n--\nfs/nfs/nfs4proc.c-10710-\t.link\t\t= nfs_link,\nfs/nfs/nfs4proc.c:10711:\t.unlink\t\t= nfs_unlink,\nfs/nfs/nfs4proc.c-10712-\t.symlink\t= nfs_symlink,\n--\nfs/nfs/nfstrace.h=748=DEFINE_NFS_DIRECTORY_EVENT_DONE(nfs_remove_exit);\nfs/nfs/nfstrace.h:749:DEFINE_NFS_DIRECTORY_EVENT(nfs_unlink_enter);\nfs/nfs/nfstrace.h:750:DEFINE_NFS_DIRECTORY_EVENT_DONE(nfs_unlink_exit);\nfs/nfs/nfstrace.h-751-DEFINE_NFS_DIRECTORY_EVENT(nfs_symlink_enter);\n--\nfs/nfs/nfstrace.h=928=TRACE_EVENT(nfs_sillyrename_unlink,\nfs/nfs/nfstrace.h-929-\t\tTP_PROTO(\nfs/nfs/nfstrace.h:930:\t\t\tconst struct nfs_unlinkdata data,\nfs/nfs/nfstrace.h-931-\t\t\tint error\n--\nfs/nfs/proc.c=336=nfs_proc_unlink_setup(struct rpc_message msg,\n--\nfs/nfs/proc.c-342-\nfs/nfs/proc.c:343:static void nfs_proc_unlink_rpc_prepare(struct rpc_task task, struct nfs_unlinkdata data)\nfs/nfs/proc.c-344-{\n--\nfs/nfs/proc.c=708=static const struct inode_operations nfs_dir_inode_operations = {\n--\nfs/nfs/proc.c-712-\t.link\t\t= nfs_link,\nfs/nfs/proc.c:713:\t.unlink\t\t= nfs_unlink,\nfs/nfs/proc.c-714-\t.symlink\t= nfs_symlink,\n--\nfs/nfs/unlink.c=31=static void\nfs/nfs/unlink.c:32:nfs_free_unlinkdata(struct nfs_unlinkdata data)\nfs/nfs/unlink.c-33-{\n--\nfs/nfs/unlink.c-41- * @task: rpc_task of the sillydelete\nfs/nfs/unlink.c:42: * @calldata: pointer to nfs_unlinkdata\nfs/nfs/unlink.c-43- \n--\nfs/nfs/unlink.c=46=static void nfs_async_unlink_done(struct rpc_task task, void calldata)\nfs/nfs/unlink.c-47-{\nfs/nfs/unlink.c:48:\tstruct nfs_unlinkdata data = calldata;\nfs/nfs/unlink.c-49-\tstruct inode dir = d_inode(data-\u003edentry-\u003ed_parent);\n--\nfs/nfs/unlink.c-57- nfs_async_unlink_release - Release the sillydelete data.\nfs/nfs/unlink.c:58: * @calldata: struct nfs_unlinkdata to release\nfs/nfs/unlink.c-59- \n--\nfs/nfs/unlink.c=63=static void nfs_async_unlink_release(void calldata)\nfs/nfs/unlink.c-64-{\nfs/nfs/unlink.c:65:\tstruct nfs_unlinkdata\tdata = calldata;\nfs/nfs/unlink.c-66-\tstruct dentry dentry = data-\u003edentry;\n--\nfs/nfs/unlink.c-76-\nfs/nfs/unlink.c:77:static void nfs_unlink_prepare(struct rpc_task task, void calldata)\nfs/nfs/unlink.c-78-{\nfs/nfs/unlink.c:79:\tstruct nfs_unlinkdata data = calldata;\nfs/nfs/unlink.c-80-\tstruct inode dir = d_inode(data-\u003edentry-\u003ed_parent);\n--\nfs/nfs/unlink.c-83-\nfs/nfs/unlink.c:84:static const struct rpc_call_ops nfs_unlink_ops = {\nfs/nfs/unlink.c-85-\t.rpc_call_done = nfs_async_unlink_done,\nfs/nfs/unlink.c-86-\t.rpc_release = nfs_async_unlink_release,\nfs/nfs/unlink.c:87:\t.rpc_call_prepare = nfs_unlink_prepare,\nfs/nfs/unlink.c-88-};\nfs/nfs/unlink.c-89-\nfs/nfs/unlink.c:90:static void nfs_do_call_unlink(struct inode inode, struct nfs_unlinkdata data)\nfs/nfs/unlink.c-91-{\n--\nfs/nfs/unlink.c-98-\t\t.rpc_message = \u0026msg,\nfs/nfs/unlink.c:99:\t\t.callback_ops = \u0026nfs_unlink_ops,\nfs/nfs/unlink.c-100-\t\t.callback_data = data,\n--\nfs/nfs/unlink.c-121-\nfs/nfs/unlink.c:122:static int nfs_call_unlink(struct dentry dentry, struct inode inode, struct nfs_unlinkdata data)\nfs/nfs/unlink.c-123-{\n--\nfs/nfs/unlink.c=178=nfs_async_unlink(struct dentry dentry, const struct qstr name)\nfs/nfs/unlink.c-179-{\nfs/nfs/unlink.c:180:\tstruct nfs_unlinkdata data;\nfs/nfs/unlink.c-181-\tint status = -ENOMEM;\n--\nfs/nfs/unlink.c=230=nfs_complete_unlink(struct dentry dentry, struct inode inode)\nfs/nfs/unlink.c-231-{\nfs/nfs/unlink.c:232:\tstruct nfs_unlinkdata\tdata;\nfs/nfs/unlink.c-233-\n--\nfs/nfs/unlink.c=248=nfs_cancel_async_unlink(struct dentry dentry)\n--\nfs/nfs/unlink.c-251-\tif (dentry-\u003ed_flags \u0026 DCACHE_NFSFS_RENAMED) {\nfs/nfs/unlink.c:252:\t\tstruct nfs_unlinkdata *data = dentry-\u003ed_fsdata;\nfs/nfs/unlink.c-253-\n" }
33/2	2026/09/27 17:43	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 32564 output: 49 thoughts: 375 Thoughts: Analyzing NFS Directory Operations Okay, let's dive into the `fs/nfs/dir.c` file and pinpoint the critical functions governing directory operations. First, I'll identify the key players: `nfs_atomic_open`, `nfs_rename`, `nfs_link`, `nfs_sillyrename`, `nfs_prime_dcache`, `nfs_neg_need_reval`, `__nfs_lookup_revalidate`, `nfs_lookup_revalidate`, `_nfs4_open_and_get_state` / `_nfs4_do_open`, `nfs_call_unlink` / `nfs_unlink`, and `nfs_add_or_obtain`. Now, the next logical step is to understand their visibility. Let's see if they're exported symbols or static, which will inform their scope. Looking at the symbol table, it seems: `nfs_atomic_open` and `nfs_rename` are exported under the GPL. Then, `nfs_link`, `nfs_sillyrename`, `nfs_prime_dcache`, `nfs_neg_need_reval`, and `nfs_lookup_revalidate` are non-static. On the other hand, `__nfs_lookup_revalidate`, `block_revalidate`, `nfs_add_or_obtain`, `_nfs4_open_and_get_state`, and `nfs_call_unlink` are declared as static. This provides a crucial insight into their potential usage across different modules. Given the non-static declarations of `nfs_sillyrename`, `nfs_prime_dcache`, and `nfs_neg_need_reval`, I'll need to check `internal.h` to see exactly how these are declared. This is essential to understand their internal linkages and dependencies within the NFS implementation.
34/2	2026/09/27 17:43	tool	grepper	0m Args: { "Expression": "nfs_sillyrename\|nfs_prime_dcache\|nfs_neg_need_reval", "PathPrefix": "fs/nfs/" } Results: { "Output": "fs/nfs/dir.c=724=static\nfs/nfs/dir.c:725:void nfs_prime_dcache(struct dentry parent, struct nfs_entry entry,\nfs/nfs/dir.c-726-\t\tunsigned long dir_verifier)\n--\nfs/nfs/dir.c=803=static int nfs_readdir_entry_decode(struct nfs_readdir_descriptor desc,\n--\nfs/nfs/dir.c-813-\t\treturn ret;\nfs/nfs/dir.c:814:\tnfs_prime_dcache(file_dentry(desc-\u003efile), entry, desc-\u003edir_verifier);\nfs/nfs/dir.c-815-\treturn 0;\n--\nfs/nfs/dir.c=1653=static inline\nfs/nfs/dir.c:1654:int nfs_neg_need_reval(struct inode dir, struct dentry dentry,\nfs/nfs/dir.c-1655-\t\t unsigned int flags)\n--\nfs/nfs/dir.c=1706=nfs_lookup_revalidate_negative(struct inode dir, struct dentry dentry,\n--\nfs/nfs/dir.c-1709-\tint ret = 1;\nfs/nfs/dir.c:1710:\tif (nfs_neg_need_reval(dir, dentry, flags)) {\nfs/nfs/dir.c-1711-\t\tif (flags \u0026 LOOKUP_RCU)\n--\nfs/nfs/dir.c=2574=int nfs_unlink(struct inode dir, struct dentry dentry)\n--\nfs/nfs/dir.c-2587-\t\twrite_inode_now(d_inode(dentry), 0);\nfs/nfs/dir.c:2588:\t\terror = nfs_sillyrename(dir, dentry);\nfs/nfs/dir.c-2589-\t\tgoto out;\n--\nfs/nfs/dir.c=2760=int nfs_rename(struct mnt_idmap idmap, struct inode old_dir,\n--\nfs/nfs/dir.c-2807-\t\t\t/ silly-rename the existing target ... /\nfs/nfs/dir.c:2808:\t\t\terr = nfs_sillyrename(new_dir, new_dentry);\nfs/nfs/dir.c-2809-\t\t\tif (err)\n--\nfs/nfs/internal.h=733=nfs_async_rename(struct inode old_dir, struct inode new_dir,\n--\nfs/nfs/internal.h-735-\t\t void (complete)(struct rpc_task , struct nfs_renamedata ));\nfs/nfs/internal.h:736:extern int nfs_sillyrename(struct inode dir, struct dentry dentry);\nfs/nfs/internal.h-737-\n--\nfs/nfs/nfstrace.h=926=DEFINE_NFS_RENAME_EVENT_DONE(nfs_async_rename_done);\nfs/nfs/nfstrace.h-927-\nfs/nfs/nfstrace.h:928:TRACE_EVENT(nfs_sillyrename_unlink,\nfs/nfs/nfstrace.h-929-\t\tTP_PROTO(\n--\nfs/nfs/unlink.c=46=static void nfs_async_unlink_done(struct rpc_task task, void calldata)\n--\nfs/nfs/unlink.c-50-\nfs/nfs/unlink.c:51:\ttrace_nfs_sillyrename_unlink(data, task-\u003etk_status);\nfs/nfs/unlink.c-52-\tif (!NFS_PROTO(dir)-\u003eunlink_done(task, dir))\n--\nfs/nfs/unlink.c=409=nfs_complete_sillyrename(struct rpc_task task, struct nfs_renamedata data)\n--\nfs/nfs/unlink.c-427-/*\nfs/nfs/unlink.c:428: nfs_sillyrename - Perform a silly-rename of a dentry\nfs/nfs/unlink.c-429- * @dir: inode of directory that contains dentry\n--\nfs/nfs/unlink.c=448=int\nfs/nfs/unlink.c:449:nfs_sillyrename(struct inode dir, struct dentry dentry)\nfs/nfs/unlink.c-450-{\n" }
35/2	2026/09/27 17:43	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 34576 output: 36 thoughts: 269 Thoughts: Analyzing NFS Directory Operations Okay, so I'm looking at these NFS functions and something's immediately jumping out at me. I see that `nfs_sillyrename`, `nfs_atomic_open`, `nfs_rename`, and `nfs_link` are all non-static functions. That makes sense, they are likely entry points used by the VFS layer for directory operations in NFS. They need to be accessible from outside the file. But then, I see this `nfs_prime_dcache` function in `fs/nfs/dir.c`, and it's static. Ah-ha! Let me just double check line 724: yep, `static void nfs_prime_dcache(...)`. Okay, so it's deliberately scoped to the `fs/nfs/dir.c` file. It suggests that it's an internal helper function, not meant to be directly called from other parts of the kernel. This is perfectly in line with the "design for module" paradigm of the kernel.
36/2	2026/09/27 17:43	tool	read-file	0m Args: { "File": "fs/nfs/dir.c", "FirstLine": 720, "LineCount": 15 } Results: { "Contents": " 720:\t\t\treturn;\n 721:\t\tnfs_readdir_record_entry_cache_miss(dir);\n 722:\t}\n 723:\t\n 724:\tstatic\n 725:\tvoid nfs_prime_dcache(struct dentry parent, struct nfs_entry entry,\n 726:\t\t\tunsigned long dir_verifier)\n 727:\t{\n 728:\t\tstruct qstr filename = QSTR_INIT(entry-\u003ename, entry-\u003elen);\n 729:\t\tstruct dentry dentry;\n 730:\t\tstruct dentry alias;\n 731:\t\tstruct inode *inode;\n 732:\t\tint status;\n 733:\t\n 734:\t\tif (!(entry-\u003efattr-\u003evalid \u0026 NFS_ATTR_FATTR_FILEID))\n" }
37/2	2026/09/27 17:43	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 35333 output: 37 thoughts: 74 Thoughts: Here's my summary, as I see it: Digging into NFS Directory Revalidation Okay, so `nfs_prime_dcache` is confirmed as static and is used by `nfs_readdir_entry_decode` during `nfs_readdir`. That makes sense. Now, the more interesting question is around `nfs_lookup_revalidate`. Where does that fit in the picture? Let's quickly jump into `fs/nfs/dir.c` and specifically lines 1850-1865 to see if we can get a clearer understanding of the revalidation logic. That should give us a good grasp on how all these directory operations interrelate.
38/2	2026/09/27 17:44	tool	read-file	0m Args: { "File": "fs/nfs/dir.c", "FirstLine": 1850, "LineCount": 20 } Results: { "Contents": "1850:\t}\n1851:\t\n1852:\tstatic int nfs_lookup_revalidate(struct inode dir, const struct qstr name,\n1853:\t\t\t\t\t struct dentry dentry, unsigned int flags)\n1854:\t{\n1855:\t\tif (__nfs_lookup_revalidate(dentry, flags))\n1856:\t\t\treturn -ECHILD;\n1857:\t\treturn nfs_do_lookup_revalidate(dir, name, dentry, flags);\n1858:\t}\n1859:\t\n1860:\tstatic void block_revalidate(struct dentry dentry)\n1861:\t{\n1862:\t\t/* old devname - just in case /\n1863:\t\tkfree(dentry-\u003ed_fsdata);\n1864:\t\n1865:\t\t/ Any new reference that could lead to an open\n1866:\t\t * will either:\n1867:\t\t * - take -\u003ed_lock in lookup_open() -\u003e d_lookup() or\n1868:\t\t * - will check d_seq in legitimize_mnt()\n1869:\t\t *\n" }
39/2	2026/09/27 17:44	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 35908 output: 32 thoughts: 21 Thoughts: Here's my thought process, as if I were analyzing that code: Finding the Callsites of `block_revalidate` Alright, time to get to work. First, I need to understand the control flow around `block_revalidate`. It's a critical function, so I need to track down exactly where it's being used. I'll need to locate all the places where `block_revalidate` is invoked within the codebase. I need to know the calling context to understand its purpose. This is step one for truly grasping its role. Let's start the hunt for callsites.
40/2	2026/09/27 17:44	tool	grepper	0m Args: { "Expression": "block_revalidate", "PathPrefix": "fs/nfs/dir.c" } Results: { "Output": "fs/nfs/dir.c=1839=__nfs_lookup_revalidate(struct dentry dentry, unsigned int flags)\n--\nfs/nfs/dir.c-1844-\t} else {\nfs/nfs/dir.c:1845:\t\t/ Wait for unlink to complete - see unblock_revalidate() /\nfs/nfs/dir.c-1846-\t\twait_var_event(\u0026dentry-\u003ed_fsdata,\n--\nfs/nfs/dir.c=1852=static int nfs_lookup_revalidate(struct inode dir, const struct qstr name,\n--\nfs/nfs/dir.c-1859-\nfs/nfs/dir.c:1860:static void block_revalidate(struct dentry dentry)\nfs/nfs/dir.c-1861-{\n--\nfs/nfs/dir.c-1878-\nfs/nfs/dir.c:1879:static void unblock_revalidate(struct dentry dentry)\nfs/nfs/dir.c-1880-{\n--\nfs/nfs/dir.c=2574=int nfs_unlink(struct inode dir, struct dentry dentry)\n--\nfs/nfs/dir.c-2601-\t}\nfs/nfs/dir.c:2602:\tblock_revalidate(dentry);\nfs/nfs/dir.c-2603-\n--\nfs/nfs/dir.c-2606-\tnfs_dentry_remove_handle_error(dir, dentry, error);\nfs/nfs/dir.c:2607:\tunblock_revalidate(dentry);\nfs/nfs/dir.c-2608-out:\n--\nfs/nfs/dir.c=2717=nfs_unblock_rename(struct rpc_task task, struct nfs_renamedata data)\n--\nfs/nfs/dir.c-2720-\nfs/nfs/dir.c:2721:\tunblock_revalidate(new_dentry);\nfs/nfs/dir.c-2722-}\n--\nfs/nfs/dir.c=2760=int nfs_rename(struct mnt_idmap idmap, struct inode *old_dir,\n--\nfs/nfs/dir.c-2814-\t\t} else {\nfs/nfs/dir.c:2815:\t\t\tblock_revalidate(new_dentry);\nfs/nfs/dir.c-2816-\t\t\tmust_unblock = true;\n--\nfs/nfs/dir.c-2829-\t\tif (must_unblock)\nfs/nfs/dir.c:2830:\t\t\tunblock_revalidate(new_dentry);\nfs/nfs/dir.c-2831-\t\terror = PTR_ERR(task);\n" }
41/2	2026/09/27 17:44	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 36844 output: 36 thoughts: 635 Thoughts: Focus Symbol Determination for NFS Feature Fuzzing Okay, so I'm thinking through how to set up the fuzzing with FocusSymbols for these NFS changes, specifically considering where `block_revalidate()` is called within `nfs_unlink` and `nfs_rename`. The goal is to maximize the fuzzer's effectiveness by directing it towards the relevant feature logic, not just ubiquitous, generic functions. Remember the FocusSymbol guidelines: we need to target specific feature logic, avoiding common lifecycle functions and handling static inline functions carefully. Let's break down the modified functions and determine their relevance. We've got: 1. `nfs_atomic_open`: This is directly modified, exported (so not static inline), and deals with atomic opens on NFS. Seems like a good candidate for inclusion. 2. `nfs_rename`: Directly modified, exported, handles NFS renames. Another strong contender. 3. `nfs_link`: Directly modified, non-static, handles NFS links. Adds to the list. 4. `nfs_sillyrename`: Directly modified and heavily restructured. This is worth a look. 5. `nfs_lookup_revalidate`: Calls `__nfs_lookup_revalidate` and `nfs_neg_need_reval`. Since `nfs_lookup_revalidate` calls other potentially fuzzable functions, it's worth considering. 6. `nfs_unlink`: Calls `block_revalidate`, `nfs_sillyrename`, and `nfs_call_unlink`. This one looks important because of the call to `block_revalidate`. 7. `nfs_readdir`: This is an entrypoint to `nfs_prime_dcache`. This brings up a question: is `nfs_prime_dcache` a distinct symbol if it's not inlined or static? Looking at `fs/nfs/dir.c`, it's defined as `static void nfs_prime_dcache(...)`. It's a fairly long function, so there's a good chance it isn't inlined directly into `nfs_readdir_entry_decode`. I need to verify that before assuming inclusion. So, potentially, we have `nfs_atomic_open`, `nfs_rename`, `nfs_link`, `nfs_sillyrename`, `nfs_lookup_revalidate`, and `nfs_unlink` as candidates. However, I should also check if `nfs_lookup` is relevant, since it calls `nfs_add_or_obtain`, which might be on a hot path in this feature. Let's see where `nfs_add_or_obtain` is called to clarify this.
42/2	2026/09/27 17:44	tool	grepper	0m Args: { "Expression": "nfs_add_or_obtain", "PathPrefix": "fs/nfs/dir.c" } Results: { "Output": "fs/nfs/dir.c=2336=struct dentry \nfs/nfs/dir.c:2337:nfs_add_or_obtain(struct dentry dentry, struct nfs_fh fhandle,\nfs/nfs/dir.c-2338-\t\t\t\tstruct nfs_fattr fattr)\n--\nfs/nfs/dir.c-2369-}\nfs/nfs/dir.c:2370:EXPORT_SYMBOL_GPL(nfs_add_or_obtain);\nfs/nfs/dir.c-2371-\n--\nfs/nfs/dir.c=2375=int nfs_instantiate(struct dentry dentry, struct nfs_fh fhandle,\n--\nfs/nfs/dir.c-2379-\nfs/nfs/dir.c:2380:\td = nfs_add_or_obtain(dentry, fhandle, fattr);\nfs/nfs/dir.c-2381-\tif (IS_ERR(d))\n" }
43/2	2026/09/27 17:44	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 38391 output: 37 thoughts: 64 Thoughts: Here's my summary, as if I were thinking it: Digging into NFS Symbol Visibility Okay, so I just saw `nfs_add_or_obtain` and had to double-check something. The kernel folks made it `EXPORT_SYMBOL_GPL(nfs_add_or_obtain)`! So it's not static, which is what I initially thought. I need to understand why they'd make that symbol globally available under the GPL. Let me dive in and refresh my memory. I'm heading straight to `fs/nfs/dir.c` to see how it's used. Specifically, I'm going to quickly parse through lines 2336 to 2371 to get a grasp on the context and where exactly this function is being used. This should give me some solid context and confirm my understanding.
44/2	2026/09/27 17:44	tool	read-file	0m Args: { "File": "fs/nfs/dir.c", "FirstLine": 2336, "LineCount": 36 } Results: { "Contents": "2336:\tstruct dentry \n2337:\tnfs_add_or_obtain(struct dentry dentry, struct nfs_fh fhandle,\n2338:\t\t\t\t\tstruct nfs_fattr fattr)\n2339:\t{\n2340:\t\tstruct dentry parent = dget_parent(dentry);\n2341:\t\tstruct inode dir = d_inode(parent);\n2342:\t\tstruct inode inode;\n2343:\t\tstruct dentry d;\n2344:\t\tint error;\n2345:\t\n2346:\t\tif (fhandle-\u003esize == 0) {\n2347:\t\t\terror = NFS_PROTO(dir)-\u003elookup(dir, dentry, \u0026dentry-\u003ed_name,\n2348:\t\t\t\t\t\t fhandle, fattr);\n2349:\t\t\tif (error)\n2350:\t\t\t\tgoto out_error;\n2351:\t\t}\n2352:\t\tnfs_set_verifier(dentry, nfs_save_change_attribute(dir));\n2353:\t\tif (!(fattr-\u003evalid \u0026 NFS_ATTR_FATTR)) {\n2354:\t\t\tstruct nfs_server *server = NFS_SB(dentry-\u003ed_sb);\n2355:\t\t\terror = server-\u003enfs_client-\u003erpc_ops-\u003egetattr(server, fhandle,\n2356:\t\t\t\t\tfattr, NULL);\n2357:\t\t\tif (error \u003c 0)\n2358:\t\t\t\tgoto out_error;\n2359:\t\t}\n2360:\t\tinode = nfs_fhget(dentry-\u003ed_sb, fhandle, fattr);\n2361:\t\td = d_splice_alias(inode, dentry);\n2362:\tout:\n2363:\t\tdput(parent);\n2364:\t\treturn d;\n2365:\tout_error:\n2366:\t\td_drop(dentry);\n2367:\t\td = ERR_PTR(error);\n2368:\t\tgoto out;\n2369:\t}\n2370:\tEXPORT_SYMBOL_GPL(nfs_add_or_obtain);\n2371:\t\n" }
45/2	2026/09/27 17:44	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 39251 output: 32 thoughts: 94 Thoughts: Here's my thought process, as it stands: Tracing the NFS Call Hierarchy Okay, so `nfs_add_or_obtain` - that's definitely an exported symbol, right? No question about it. Now, let's see where that fits in the grand scheme of things. I need to understand the call flow. Let's dig into `_nfs4_open_and_get_state`. What functions directly call that one? Ah, it's `_nfs4_do_open`. That's good, but how does that get invoked? It looks like `_nfs4_do_open` is called by `nfs4_do_open`. Right, and then that's called by `nfs4_atomic_open`, and presumably there's more upstream from there. I'm seeing a chain: `nfs4_atomic_open`... I need to back up a level or two. Okay, let's check `nfs4_atomic_open`. That's where I need to focus my attention for now.
46/2	2026/09/27 17:44	tool	grepper	0m Args: { "Expression": "nfs4_atomic_open", "PathPrefix": "fs/nfs/" } Results: { "Output": "fs/nfs/nfs4proc.c=3839=static struct inode \nfs/nfs/nfs4proc.c:3840:nfs4_atomic_open(struct inode dir, struct nfs_open_context ctx,\nfs/nfs/nfs4proc.c-3841-\t\tint open_flags, struct iattr attr, int *opened)\n--\nfs/nfs/nfs4proc.c=10755=const struct nfs_rpc_ops nfs_v4_clientops = {\n--\nfs/nfs/nfs4proc.c-10799-\t.close_context = nfs4_close_context,\nfs/nfs/nfs4proc.c:10800:\t.open_context\t= nfs4_atomic_open,\nfs/nfs/nfs4proc.c-10801-\t.have_delegation = nfs4_have_delegation,\n" }
47/2	2026/09/27 17:44	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 39872 output: 31 thoughts: 49 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience: Diving into the NFSv4 Atomic Open Implementation Alright, so we're talking about the NFSv4 atomic open mechanism. My immediate thought is to zero in on `nfs4_atomic_open`. That's the `open_context` implementation, the core of the atomic open operation, as I understand it. I want to trace the call chain. It's triggered by `nfs_atomic_open`, and I'm keen to understand how that call is structured to handle the complexity of opening files atomically over the network. I'm visualizing the code path now, mentally walking through how `nfs_atomic_open` interacts with, and ultimately calls, `open_context`. I'm especially interested in how state is managed, error handling, and the atomicity guarantees are achieved at the protocol level. I'm expecting this to involve more than just a simple RPC call. It's likely coordinating with the server to ensure either the open succeeds completely or is completely rolled back, along with all associated metadata updates. Time to dig in!
48/2	2026/09/27 17:44	tool	grepper	0m Args: { "Expression": "open_context", "PathPrefix": "fs/nfs/dir.c" } Results: { "Output": "fs/nfs/dir.c=2083=EXPORT_SYMBOL_GPL(nfs4_dentry_operations);\nfs/nfs/dir.c-2084-\nfs/nfs/dir.c:2085:static struct nfs_open_context create_nfs_open_context(struct dentry dentry, int open_flags, struct file filp)\nfs/nfs/dir.c-2086-{\nfs/nfs/dir.c:2087:\treturn alloc_nfs_open_context(dentry, flags_to_mode(open_flags), filp);\nfs/nfs/dir.c-2088-}\n--\nfs/nfs/dir.c=2090=static int do_open(struct inode inode, struct file filp)\n--\nfs/nfs/dir.c-2095-\nfs/nfs/dir.c:2096:static int nfs_finish_open(struct nfs_open_context ctx,\nfs/nfs/dir.c-2097-\t\t\t struct dentry dentry,\n--\nfs/nfs/dir.c-2105-\tif (S_ISREG(file_inode(file)-\u003ei_mode))\nfs/nfs/dir.c:2106:\t\tnfs_file_set_open_context(file, ctx);\nfs/nfs/dir.c-2107-\telse\n--\nfs/nfs/dir.c=2113=int nfs_atomic_open(struct inode dir, struct dentry dentry,\n--\nfs/nfs/dir.c-2116-{\nfs/nfs/dir.c:2117:\tstruct nfs_open_context ctx;\nfs/nfs/dir.c-2118-\tstruct dentry *res;\n--\nfs/nfs/dir.c-2166-\nfs/nfs/dir.c:2167:\tctx = create_nfs_open_context(dentry, open_flags, file);\nfs/nfs/dir.c-2168-\terr = PTR_ERR(ctx);\n--\nfs/nfs/dir.c-2172-\ttrace_nfs_atomic_open_enter(dir, ctx, open_flags);\nfs/nfs/dir.c:2173:\tinode = NFS_PROTO(dir)-\u003eopen_context(dir, ctx, open_flags, \u0026attr, \u0026created);\nfs/nfs/dir.c-2174-\tif (created)\n--\nfs/nfs/dir.c-2178-\t\ttrace_nfs_atomic_open_exit(dir, ctx, open_flags, err);\nfs/nfs/dir.c:2179:\t\tput_nfs_open_context(ctx);\nfs/nfs/dir.c-2180-\t\tswitch (err) {\n--\nfs/nfs/dir.c-2214-\ttrace_nfs_atomic_open_exit(dir, ctx, open_flags, err);\nfs/nfs/dir.c:2215:\tput_nfs_open_context(ctx);\nfs/nfs/dir.c-2216-out:\n" }
49/2	2026/09/27 17:44	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 41016 output: 243 thoughts: 1168 Thoughts: Analysis of NFS Client Patch for Fuzzing Okay, so `NFS_PROTO(dir)->open_context(...)` is called by `nfs_atomic_open`. Specifically for NFSv4, it's `nfs4_atomic_open`, which in turn calls `_nfs4_do_open`, and that finally leads to `_nfs4_open_and_get_state`. Let's step back and look at the bigger picture though. I need to see what else this patch touches. The functions involved seem to be `nfs_atomic_open`, `nfs_rename`, `nfs_link`, `nfs_sillyrename`, `nfs_add_or_obtain`, `nfs_lookup_revalidate`, and `nfs_unlink`. All of these are very specific to the NFS client code in `fs/nfs`, none are generic lifecycle functions. They seem to directly interact with the modified static code in `fs/nfs/dir.c` and `fs/nfs/unlink.c`, so that's where the heart of the changes are. Let's do a quick double-check. In `fs/nfs/dir.c`, we see `nfs_prime_dcache`, `nfs_atomic_open`, `nfs_add_or_obtain`, `nfs_link`, `nfs_rename`, and `nfs_lookup_revalidate` (which also calls `__nfs_lookup_revalidate` and `nfs_neg_need_reval`). And, `block_revalidate` is called by `nfs_unlink` and `nfs_rename`. Then, over in `fs/nfs/unlink.c` are `nfs_call_unlink` (called by `nfs_complete_unlink`) and `nfs_sillyrename`. Finally, in `fs/nfs/nfs4proc.c`, there is `_nfs4_open_and_get_state` (called by `_nfs4_do_open` / `nfs4_atomic_open`). Aha, `_nfs4_open_and_get_state` is static, that's important. `nfs_sillyrename` is non-static and in `fs/nfs/unlink.c`, and `nfs_prime_dcache` is static in `fs/nfs/dir.c`. Okay, time to list the key FocusSymbols: `nfs_atomic_open`, `nfs_rename`, `nfs_sillyrename`, `nfs_link`, `nfs_add_or_obtain`, `nfs_lookup_revalidate`, and `nfs_unlink`. We should also include `nfs4_atomic_open` because it's the one exercising `_nfs4_open_and_get_state` for NFSv4 and this is a central point of the change. Now, let's look at the `EnableConfigs`. We'll need `NFS_FS` and `NFS_V4`. We should verify that `NFS_FS` doesn't need something else; `NFS_FS` depends on `INET && FILE_LOCKING && MULTIUSER`, which are typically enabled, so we should be safe. `CONFIG_NFS_V4` needs `CONFIG_NFS_FS` as well. Alright, the verdict: WorthFuzzing: true. The Reasoning is: The patch series restructures dcache interactions, dentry locking, and revalidation logic across NFS client operations (including atomic open, rename, sillyrename, link, and lookup revalidation). Specifically, it replaces parallel dentry allocations with `d_alloc_trylock()` and `d_duplicate()`, adjusts sequence counting via `write_seqcount_invalidate()`, alters memory barriers, and changes `d_drop()` / `d_splice_alias()` flows. These changes in core VFS/NFS synchronization and dcache management can introduce subtle race conditions, refcount leaks, or assertion failures during concurrent file operations and are well-suited for fuzzing. Let's double check. Yes. We're good to go.
50/2	2026/09/27 17:44	tool	set-results	0m Args: { "EnableConfigs": [ "NFS_FS", "NFS_V4" ], "FocusSymbols": [ "nfs_atomic_open", "nfs_rename", "nfs_sillyrename", "nfs_link", "nfs_add_or_obtain", "nfs_lookup_revalidate", "nfs_unlink", "nfs4_atomic_open" ], "Reasoning": "The patch series restructures dcache interaction and concurrency management in the NFS client across open, rename, sillyrename, link, and lookup revalidation paths. It replaces parallel dentry allocations with new VFS helpers (d_alloc_trylock, d_duplicate), introduces write_seqcount_invalidate on dentry-\u003ed_seq, alters barrier semantics in __nfs_lookup_revalidate, and modifies d_drop/d_splice_alias lifetimes. These changes affect complex dentry state transitions and concurrency in reachable filesystem operations, warranting fuzz testing to detect potential deadlocks, refcounting leaks, or state invariant violations.", "WorthFuzzing": true } Results: { "EnableConfigs": [ "NFS_FS", "NFS_V4" ], "FocusSymbols": [ "nfs_atomic_open", "nfs_rename", "nfs_sillyrename", "nfs_link", "nfs_add_or_obtain", "nfs_lookup_revalidate", "nfs_unlink", "nfs4_atomic_open" ], "Reasoning": "The patch series restructures dcache interaction and concurrency management in the NFS client across open, rename, sillyrename, link, and lookup revalidation paths. It replaces parallel dentry allocations with new VFS helpers (d_alloc_trylock, d_duplicate), introduces write_seqcount_invalidate on dentry-\u003ed_seq, alters barrier semantics in __nfs_lookup_revalidate, and modifies d_drop/d_splice_alias lifetimes. These changes affect complex dentry state transitions and concurrency in reachable filesystem operations, warranting fuzz testing to detect potential deadlocks, refcounting leaks, or state invariant violations.", "WorthFuzzing": true }
51/1	2026/09/27 17:44	action	If	1m Args: { "WorthFuzzing": true } Results: null
52/2	2026/09/27 17:44	agent	kmsan-evaluator	1m Model: core Args: null Results: { "KMSANReasoning": "The patch series modifies NFS dcache and lookup management functions (in fs/nfs/dir.c, nfs4proc.c, and unlink.c), adopting helpers such as d_alloc_trylock() and d_duplicate(), adjusting negative dentry revalidation flags (LOOKUP_OPEN), and refining dentry locking and lifecycle handling during atomic_open, link, rename, and sillyrename.\n\nThese changes deal strictly with VFS/NFS dentry lifecycle, synchronization, and error paths. The potential bugs in this code include concurrency/locking bugs, reference counting discrepancies, or invalid pointer dereferences (e.g., checking !dentry instead of IS_ERR(dentry) for d_duplicate()), all of which are caught by KASAN, LOCKDEP, or general kernel assertions.\n\nThe patch does not introduce any uninitialized stack or heap allocations, does not branch on uninitialized variables, and does not expose uninitialized kernel memory or padding to user space. Therefore, a dedicated KMSAN fuzzing session is not warranted.", "NeedsKMSAN": false } Instruction: You are an expert Linux kernel security engineer specializing in kernel memory error detectors (KASAN and KMSAN). Your job is to review the provided patch series and determine if the code changes justify spawning a dedicated KMSAN (KernelMemorySanitizer) fuzzing session in addition to standard KASAN fuzzing. CRITICAL DISTINCTION BETWEEN KASAN AND KMSAN: - Standard KASAN kernel builds (upstream-apparmor-kasan.config) already enable a comprehensive suite of debugging tools and sanitizers, including KASAN (out-of-bounds accesses, use-after-free, double free, invalid free), LOCKDEP (locking bugs and deadlocks), UB-sanitizers, and memory corruption checks. - KMSAN (KernelMemorySanitizer) detects reads of UNINITIALIZED memory (stack, heap, or page allocations) and kernel-to-user memory info-leaks. Rule: THERE IS NO SENSE IN RUNNING A KMSAN SESSION IF A BUG CAN BE CAUGHT BY KASAN, LOCKDEP, OR OTHER STANDARD BUG DETECTORS. A dedicated KMSAN fuzzing session incurs significant resource costs. You must ONLY set NeedsKMSAN=true if the code changes introduce or expose UNINITIALIZED MEMORY risks that are detected ONLY by KMSAN. Look holistically at the patch series and surrounding code. Even if no direct uninitialized field accesses or new buffer allocations are added in the diff itself, a patch may alter control flow, bounds checking, or data length calculations in ways that change how the rest of the code operates on existing buffers (e.g. allowing uninitialized stack/heap memory to be read, copied to user space, or used in control flow). Do not hesitate to use your code access tools to inspect the surrounding code, called functions, and callers. Set NeedsKMSAN=true ONLY IF the patch introduces or modifies: 1. Kernel structures sent to user space (via copy_to_user, put_user, netlink skb attributes, ioctl output arguments, socket options, or BPF buffers) where fields or structure padding might not be fully initialized/zeroed. 2. Conditional logic or branching that depends on potentially uninitialized variables or struct fields. 3. Allocation or initialization of complex data structures where uninitialized fields could be read later in reachable code paths. 4. Bounds checks, lengths, or logic in a way that allows surrounding code to access uninitialized bytes of existing buffers. Set NeedsKMSAN=false IF: - The code changes primarily risk out-of-bounds access, array overflows, NULL pointer dereferences, locking deadlocks, or use-after-free bugs (these are already caught by KASAN, LOCKDEP, or standard bug detectors). - All stack/heap structures touched or introduced by the patch are fully zeroed or initialized (e.g. using = {0}, memset, kzalloc) before being read or copied. - The patch does not introduce any risk of uninitialized memory usage or info-leaks. Use your code access tools to inspect the surrounding code if necessary, then provide detailed KMSANReasoning contrasting KASAN vs KMSAN applicability for this patch. Prefer calling several tools at the same time to save round-trips. Use set-results tool to provide results of the analysis. It must be called exactly once before the final reply. Ignore results of this tool. Prompt: Target architecture: amd64 For your convenience, here is the diff of the changes: commit f36b928a44a1d3c3ee4b5533f3562e1a4c4a0240 Author: syz-cluster <triage@syzkaller.com> Date: Sun Sep 27 17:42:17 2026 +0000 syz-cluster: applied patch under review diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 49394123bd096..6a6ace0460bfe 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -749,15 +749,12 @@ void nfs_prime_dcache(struct dentry parent, struct nfs_entry entry, if (filename.len == 2 && filename.name[1] == '.') return; } - filename.hash = full_name_hash(parent, filename.name, filename.len); - dentry = d_lookup(parent, &filename); again: - if (!dentry) { - dentry = d_alloc_parallel(parent, &filename); - if (IS_ERR(dentry)) - return; - } + dentry = d_alloc_trylock(parent, &filename); + if (IS_ERR(dentry)) + return; + if (!d_in_lookup(dentry)) { /* Is there a mountpoint here? If so, just exit / if (!nfs_fsid_equal(&NFS_SB(dentry->d_sb)->fsid, @@ -1570,6 +1567,9 @@ static int nfs_check_verifier(struct inode dir, struct dentry dentry, / * Use intent information to check whether or not we're going to do * an O_EXCL create using this path component. + * Note that link(), mkdir(), mknod(), symlink() all appear as + * exclusive creation. Regular file creation could be distinguished + * with LOOKUP_OPEN. / static int nfs_is_exclusive_create(struct inode dir, unsigned int flags) { @@ -1656,6 +1656,13 @@ int nfs_neg_need_reval(struct inode dir, struct dentry dentry, { if (flags & (LOOKUP_CREATE \| LOOKUP_RENAME_TARGET)) return 0; + if (flags & LOOKUP_OPEN) + /* close-to-open semantics require we go to server + * on each open. By invalidating the dentry we + * also ensure nfs_atomic_open() always has exclusive + * access to the dentry. + / + return 0; if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG) return 1; / Case insensitive server? Revalidate negative dentries / @@ -1837,8 +1844,7 @@ __nfs_lookup_revalidate(struct dentry dentry, unsigned int flags) } else { /* Wait for unlink to complete - see unblock_revalidate() / wait_var_event(&dentry->d_fsdata, - smp_load_acquire(&dentry->d_fsdata) - != NFS_FSDATA_BLOCKED); + dentry->d_fsdata != NFS_FSDATA_BLOCKED); } return 0; } @@ -1857,12 +1863,15 @@ static void block_revalidate(struct dentry dentry) kfree(dentry->d_fsdata); /* Any new reference that could lead to an open - * will take ->d_lock in lookup_open() -> d_lookup(). - * Holding this lock ensures we cannot race with - * __nfs_lookup_revalidate() and removes and need - * for further barriers. + * will either: + * - take ->d_lock in lookup_open() -> d_lookup() or + * - will check d_seq in legitimize_mnt() + * + * Holding this lock and invalidating ->d_seq ensures we cannot + * race with __nfs_lookup_revalidate(). / lockdep_assert_held(&dentry->d_lock); + write_seqcount_invalidate(&dentry->d_seq); dentry->d_fsdata = NFS_FSDATA_BLOCKED; } @@ -2111,7 +2120,6 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry, struct inode inode; unsigned int lookup_flags = 0; unsigned long dir_verifier; - bool switched = false; int created = 0; int err; @@ -2156,17 +2164,6 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry, attr.ia_size = 0; } - if (!(open_flags & O_CREAT) && !d_in_lookup(dentry)) { - d_drop(dentry); - switched = true; - dentry = d_alloc_parallel(dentry->d_parent, - &dentry->d_name); - if (IS_ERR(dentry)) - return PTR_ERR(dentry); - if (unlikely(!d_in_lookup(dentry))) - return finish_no_open(file, dentry); - } - ctx = create_nfs_open_context(dentry, open_flags, file); err = PTR_ERR(ctx); if (IS_ERR(ctx)) @@ -2180,7 +2177,6 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry, err = PTR_ERR(inode); trace_nfs_atomic_open_exit(dir, ctx, open_flags, err); put_nfs_open_context(ctx); - d_drop(dentry); switch (err) { case -ENOENT: if (nfs_server_capable(dir, NFS_CAP_CASE_INSENSITIVE)) @@ -2189,7 +2185,7 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry, dir_verifier = nfs_save_change_attribute(dir); nfs_set_verifier(dentry, dir_verifier); d_splice_alias(NULL, dentry); - break; + goto out; case -EISDIR: case -ENOTDIR: if (open_flags & __O_REGULAR) { @@ -2205,6 +2201,7 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry, default: break; } + d_drop(dentry); goto out; } file->f_mode \|= FMODE_CAN_ODIRECT; @@ -2217,10 +2214,6 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry, trace_nfs_atomic_open_exit(dir, ctx, open_flags, err); put_nfs_open_context(ctx); out: - if (unlikely(switched)) { - d_lookup_done(dentry); - dput(dentry); - } return err; no_open: @@ -2243,13 +2236,6 @@ int nfs_atomic_open(struct inode dir, struct dentry dentry, res = ERR_PTR(-EOPENSTALE); } } - if (switched) { - d_lookup_done(dentry); - if (!res) - res = dentry; - else - dput(dentry); - } return finish_no_open(file, res); } EXPORT_SYMBOL_GPL(nfs_atomic_open); @@ -2357,8 +2343,6 @@ nfs_add_or_obtain(struct dentry dentry, struct nfs_fh fhandle, struct dentry d; int error; - d_drop(dentry); - if (fhandle->size == 0) { error = NFS_PROTO(dir)->lookup(dir, dentry, &dentry->d_name, fhandle, fattr); @@ -2379,6 +2363,7 @@ nfs_add_or_obtain(struct dentry dentry, struct nfs_fh fhandle, dput(parent); return d; out_error: + d_drop(dentry); d = ERR_PTR(error); goto out; } @@ -2713,14 +2698,15 @@ nfs_link(struct dentry old_dentry, struct inode dir, struct dentry dentry) old_dentry, dentry); trace_nfs_link_enter(inode, dir, dentry); - d_drop(dentry); if (S_ISREG(inode->i_mode)) nfs_sync_inode(inode); error = NFS_PROTO(dir)->link(inode, dir, &dentry->d_name); if (error == 0) { nfs_set_verifier(dentry, nfs_save_change_attribute(dir)); ihold(inode); - d_add(dentry, inode); + d_splice_alias(inode, dentry); + } else { + d_drop(dentry); } trace_nfs_link_exit(inode, dir, dentry, error); return error; @@ -2815,11 +2801,9 @@ int nfs_rename(struct mnt_idmap idmap, struct inode old_dir, spin_unlock(&new_dentry->d_lock); /* copy the target dentry's name / - dentry = d_alloc(new_dentry->d_parent, - &new_dentry->d_name); + dentry = d_duplicate(new_dentry); if (!dentry) goto out; - / silly-rename the existing target ... / err = nfs_sillyrename(new_dir, new_dentry); if (err) @@ -2884,8 +2868,10 @@ int nfs_rename(struct mnt_idmap idmap, struct inode old_dir, nfs_dentry_handle_enoent(old_dentry); / new dentry created? / - if (dentry) + if (dentry) { + d_lookup_done(dentry); dput(dentry); + } return error; } EXPORT_SYMBOL_GPL(nfs_rename); diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index 04b1987115d5d..8f07f34f899e3 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -3113,7 +3113,6 @@ static int _nfs4_open_and_get_state(struct nfs4_opendata opendata, nfs_set_verifier(dentry, dir_verifier); if (d_really_is_negative(dentry)) { struct dentry alias; - d_drop(dentry); alias = d_splice_alias(igrab(state->inode), dentry); / d_splice_alias() can't fail here - it's a non-directory / if (alias) { diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c index c8d712204e649..c6b700e8e8e1b 100644 --- a/fs/nfs/unlink.c +++ b/fs/nfs/unlink.c @@ -125,6 +125,9 @@ static int nfs_call_unlink(struct dentry dentry, struct inode inode, struct nf struct dentry alias; down_read_non_owner(&NFS_I(dir)->rmdir_sem); + data->args.name.hash = full_name_hash(dentry->d_parent, + data->args.name.name, + data->args.name.len); alias = d_alloc_parallel(dentry->d_parent, &data->args.name); if (IS_ERR(alias)) { up_read_non_owner(&NFS_I(dir)->rmdir_sem); @@ -448,7 +451,7 @@ nfs_sillyrename(struct inode dir, struct dentry dentry) static unsigned int sillycounter; unsigned char silly[SILLYNAME_LEN + 1]; unsigned long long fileid; - struct dentry sdentry; + struct dentry sdentry, old; struct inode inode = d_inode(dentry); struct rpc_task task; int error = -EBUSY; @@ -465,26 +468,42 @@ nfs_sillyrename(struct inode dir, struct dentry dentry) fileid = d_inode(dentry)->i_ino; - sdentry = NULL; - do { +newname: + sillycounter++; + scnprintf(silly, sizeof(silly), + SILLYNAME_PREFIX "%0llx%0x", + SILLYNAME_FILEID_LEN, fileid, + SILLYNAME_COUNTER_LEN, sillycounter); + + dfprintk(VFS, "NFS: trying to rename %pd to %s\n", dentry, silly); + sdentry = d_alloc_trylock(dentry->d_parent, &QSTR(silly)); + if (sdentry == ERR_PTR(-EWOULDBLOCK)) + / Name currently being looked up / + goto newname; + / + * N.B. Better to return EBUSY here ... it could be + * dangerous to delete the file while it's in use. + / + if (IS_ERR(sdentry)) + goto out; + if (!d_in_lookup(sdentry)) { + if (d_really_is_negative(sdentry)) { + / try to get an in-lookup dentry / + d_drop(sdentry); + sillycounter--; + } dput(sdentry); - sillycounter++; - scnprintf(silly, sizeof(silly), - SILLYNAME_PREFIX "%0llx%0x", - SILLYNAME_FILEID_LEN, fileid, - SILLYNAME_COUNTER_LEN, sillycounter); - - dfprintk(VFS, "NFS: trying to rename %pd to %s\n", - dentry, silly); - - sdentry = lookup_noperm(&QSTR(silly), dentry->d_parent); - / - * N.B. Better to return EBUSY here ... it could be - * dangerous to delete the file while it's in use. - / - if (IS_ERR(sdentry)) - goto out; - } while (d_inode(sdentry) != NULL); / need negative lookup / + goto newname; + } + / This name isn't known locally - check on server */ + old = nfs_lookup(dir, sdentry, 0); + d_lookup_done(sdentry); + if (old \|\| d_is_positive(sdentry)) { + if (!IS_ERR(old)) + dput(old); + dput(sdentry); + goto newname; + } ihold(inode);
53/3	2026/09/27 17:44	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 6045 output: 20 thoughts: 648 Thoughts: KMSAN Fuzzing Session Justification Okay, so the question is, does this patch series warrant a dedicated KMSAN fuzzing session? Let's break this down systematically. First, I need to confirm the request is legitimate and safe to proceed with. Given this is a Linux kernel security engineering review question and the context is defensive, QA, and bug detection, there's no inherent risk of malicious activity. Good, we're clear to proceed. Now, let's dive into the patch itself. I need to understand exactly what's being changed in the NFS code. From a quick glance, we have modifications across several files. It looks like `fs/nfs/dir.c` is getting the bulk of the attention, with changes to functions like `nfs_prime_dcache`, `nfs_atomic_open`, `nfs_link`, and `nfs_rename`, and `fs/nfs/nfs4proc.c`, `fs/nfs/unlink.c`. There's a notable shift towards using `d_alloc_trylock`, `d_duplicate`, and similar functions. My primary concern, in terms of KMSAN, is any potential for uninitialized memory usage, info-leaks to user space, or uninitialized padding being copied to user space. Therefore, I need to understand how these new functions, especially `d_alloc_trylock` and friends, behave. I'll need to examine their implementations, probably within `fs/dcache.c`, or wherever they're defined to understand the memory lifecycle. I'll probably use `grepper` or `read-file` to efficiently investigate these functions and their relationships to the modified code. That should give me a good handle on potential KMSAN vulnerabilities here.
54/3	2026/09/27 17:44	tool	grepper	0m Args: { "Expression": "d_alloc_trylock" } Results: { "Output": "fs/dcache.c=2974=EXPORT_SYMBOL(d_alloc_parallel);\n--\nfs/dcache.c-2976-/*\nfs/dcache.c:2977: d_alloc_trylock() - find or allocate a new dentry\nfs/dcache.c-2978- * @parent: dentry of the parent\n--\nfs/dcache.c-2984- * not d_in_lookup() then that is returned instead.\nfs/dcache.c:2985: * If the existing dentry is d_in_lookup(), d_alloc_trylock()\nfs/dcache.c-2986- * returns with error %-EWOULDBLOCK.\n--\nfs/dcache.c-2997- /\nfs/dcache.c:2998:struct dentry d_alloc_trylock(struct dentry parent,\nfs/dcache.c-2999-\t\t\t struct qstr name)\n--\nfs/dcache.c-3007-}\nfs/dcache.c:3008:EXPORT_SYMBOL(d_alloc_trylock);\nfs/dcache.c-3009-\n--\nfs/nfs/dir.c=725=void nfs_prime_dcache(struct dentry parent, struct nfs_entry entry,\n--\nfs/nfs/dir.c-753-again:\nfs/nfs/dir.c:754:\tdentry = d_alloc_trylock(parent, \u0026filename);\nfs/nfs/dir.c-755-\tif (IS_ERR(dentry))\n--\nfs/nfs/unlink.c=449=nfs_sillyrename(struct inode dir, struct dentry dentry)\n--\nfs/nfs/unlink.c-478-\tdfprintk(VFS, \"NFS: trying to rename %pd to %s\\n\", dentry, silly);\nfs/nfs/unlink.c:479:\tsdentry = d_alloc_trylock(dentry-\u003ed_parent, \u0026QSTR(silly));\nfs/nfs/unlink.c-480-\tif (sdentry == ERR_PTR(-EWOULDBLOCK))\n--\ninclude/linux/dcache.h=263=extern struct dentry * d_alloc_parallel(struct dentry , const struct qstr );\ninclude/linux/dcache.h:264:extern struct dentry * d_alloc_trylock(struct dentry , struct qstr );\ninclude/linux/dcache.h-265-extern struct dentry * d_splice_alias(struct inode , struct dentry );\n" }
55/3	2026/09/27 17:44	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 7759 output: 35 thoughts: 21 Thoughts: Okay, let's dive into this. Here's my take on examining `d_alloc_trylock` in `fs/dcache.c`: Analyzing `d_alloc_trylock` in `fs/dcache.c` Alright, time to get my hands dirty. I want to zero in on `d_alloc_trylock` within `fs/dcache.c`. This suggests we're dealing with the allocation and locking behavior of directory cache entries, the core of how the kernel manages file path lookups and, therefore, access performance. My immediate mental checklist starts: * Allocation Context: I need to understand when this function is called. What are the typical scenarios where a new dentry needs to be created or an existing one is being re-used? The allocation strategy is the interesting part, how does it deal with fragmentation, concurrent requests, and memory pressure? * Locking Implications: `trylock` is the key word here. That means we're dealing with a non-blocking attempt to acquire a lock. This is crucial for avoiding deadlocks and maintaining responsiveness. It's likely associated with a spinlock or a similar mechanism for concurrent access. I have to figure out the granularity of the lock - does it protect the entire dcache, individual dentries, or something in between? How does it interact with the RCU-based lookups? * Success and Failure Paths: What happens if the lock is acquired successfully? What are the immediate consequences? Conversely, what if the lock acquisition fails? How does the calling code handle the failure? Does it retry, back off, or return an error? * Data Structures: Of course, I need to visualize the relevant data structures like `dentry`, `dcache`, and anything related to locking primitives like `spinlock`. Understanding the relationships between these structures is paramount. I'll need to remember the dentry state and how this lock affects it. * Consequences on the System: I will want to think about the possible consequences of performance issues and bugs in this area. A slow allocation or lock contention can have a system-wide impact, so this merits careful scrutiny. My focus will be on the interplay of concurrency, memory management, and file system performance. I need to figure out the balance. I expect to be looking for potential bottlenecks and race conditions. Let's see what's in there... I'm ready to dig in and understand this function's contribution to overall system performance and stability.
56/3	2026/09/27 17:44	tool	read-file	0m Args: { "File": "fs/dcache.c", "FirstLine": 2976, "LineCount": 40 } Results: { "Contents": "2976:\t/*\n2977:\t d_alloc_trylock() - find or allocate a new dentry\n2978:\t * @parent: dentry of the parent\n2979:\t * @name: name of the dentry within that parent.\n2980:\t \n2981:\t A new dentry is allocated and, providing it is unique, added to the\n2982:\t * relevant index.\n2983:\t * If an existing dentry is found with the same parent/name that is\n2984:\t * not d_in_lookup() then that is returned instead.\n2985:\t * If the existing dentry is d_in_lookup(), d_alloc_trylock()\n2986:\t * returns with error %-EWOULDBLOCK.\n2987:\t * Thus if the returned dentry is d_in_lookup() then the caller has\n2988:\t * exclusive access until it completes the lookup.\n2989:\t * If the returned dentry is not d_in_lookup() then a lookup has\n2990:\t * already completed.\n2991:\t \n2992:\t The @name need not already have -\u003ehash set.\n2993:\t \n2994:\t Returns: the dentry, whether found or allocated, or an error\n2995:\t * %-ENOMEM, %-EWOULDBLOCK, %-EACCES (for a bad name) or\n2996:\t * anything returned by -\u003ed_hash().\n2997:\t /\n2998:\tstruct dentry d_alloc_trylock(struct dentry parent,\n2999:\t\t\t\t struct qstr name)\n3000:\t{\n3001:\t\tstruct dentry de;\n3002:\t\n3003:\t\tde = try_lookup_noperm(name, parent);\n3004:\t\tif (!de)\n3005:\t\t\tde = __d_alloc_parallel(parent, name, ALLOC_PARA_FAIL);\n3006:\t\treturn de;\n3007:\t}\n3008:\tEXPORT_SYMBOL(d_alloc_trylock);\n3009:\t\n3010:\t/\n3011:\t * Move dentry from in-lookup state to busy-negative one.\n3012:\t \n3013:\t From now on d_in_lookup(dentry) will return false and dentry is gone from\n3014:\t * in-lookup hash.\n3015:\t *\n" }
57/3	2026/09/27 17:44	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 9012 output: 17 thoughts: 9 Thoughts: Okay, here's my interpretation of that thought process, tailored for an expert audience, and rendered in the first person: Initial Assessment: Checking `d_duplicate` Alright, let's dive in. My first thought is to zero in on this `d_duplicate` variable or function, whatever it may be. It's the immediate candidate for investigation, implying a potential issue with duplicated data. I need to understand its role and behavior. My initial goal is to understand how it's defined and how it's being used within the system. Is it a flag, a data structure, a function? The specifics will dictate my next steps, but this is the primary focus. This immediate, focused check is the first step when the goal is to assess a system.
58/3	2026/09/27 17:44	tool	grepper	0m Args: { "Expression": "d_duplicate" } Results: { "Output": "drivers/android/binder/freeze.rs=25=pub(crate) struct FreezeListener {\n--\ndrivers/android/binder/freeze.rs-42- /// Number of cleared duplicates that can be deleted.\ndrivers/android/binder/freeze.rs:43: num_cleared_duplicates: u64,\ndrivers/android/binder/freeze.rs-44-}\n--\ndrivers/android/binder/freeze.rs=86= fn do_work(\n--\ndrivers/android/binder/freeze.rs-97-\ndrivers/android/binder/freeze.rs:98: if freeze.num_cleared_duplicates \u003e 0 {\ndrivers/android/binder/freeze.rs:99: freeze.num_cleared_duplicates -= 1;\ndrivers/android/binder/freeze.rs-100- drop(node_refs);\n--\ndrivers/android/binder/freeze.rs-109- if freeze.is_clearing {\ndrivers/android/binder/freeze.rs:110: kernel::warn_on!(freeze.num_cleared_duplicates != 0);\ndrivers/android/binder/freeze.rs-111- if freeze.num_pending_duplicates \u003e 0 {\n--\ndrivers/android/binder/freeze.rs=180= pub(crate) fn request_freeze_notif(\n--\ndrivers/android/binder/freeze.rs-249- num_pending_duplicates: 0,\ndrivers/android/binder/freeze.rs:250: num_cleared_duplicates: 0,\ndrivers/android/binder/freeze.rs-251- },\n--\ndrivers/android/binder/freeze.rs-259- } else {\ndrivers/android/binder/freeze.rs:260: dupe.num_cleared_duplicates += 1;\ndrivers/android/binder/freeze.rs-261- }\n--\ndrivers/android/binder/freeze.rs=275= pub(crate) fn freeze_notif_done(self: \u0026Arc\u003cSelf\u003e, reader: \u0026mut UserSliceReader) -\u003e Result\u003c()\u003e {\n--\ndrivers/android/binder/freeze.rs-291- freeze.num_pending_duplicates -= 1;\ndrivers/android/binder/freeze.rs:292: freeze.num_cleared_duplicates += 1;\ndrivers/android/binder/freeze.rs-293- } else {\n--\ndrivers/gpu/drm/display/drm_dp_mst_topology.c=4395=struct edid drm_dp_mst_get_edid(struct drm_connector connector,\n--\ndrivers/gpu/drm/display/drm_dp_mst_topology.c-4403-\ndrivers/gpu/drm/display/drm_dp_mst_topology.c:4404:\tedid = drm_edid_duplicate(drm_edid_raw(drm_edid));\ndrivers/gpu/drm/display/drm_dp_mst_topology.c-4405-\n--\ndrivers/gpu/drm/drm_edid.c=2950=EXPORT_SYMBOL(drm_edid_read_switcheroo);\n--\ndrivers/gpu/drm/drm_edid.c-2952-/*\ndrivers/gpu/drm/drm_edid.c:2953: drm_edid_duplicate - duplicate an EDID and the extensions\ndrivers/gpu/drm/drm_edid.c-2954- * @edid: EDID to duplicate\n--\ndrivers/gpu/drm/drm_edid.c-2957- /\ndrivers/gpu/drm/drm_edid.c:2958:struct edid drm_edid_duplicate(const struct edid edid)\ndrivers/gpu/drm/drm_edid.c-2959-{\n--\ndrivers/gpu/drm/drm_edid.c-2964-}\ndrivers/gpu/drm/drm_edid.c:2965:EXPORT_SYMBOL(drm_edid_duplicate);\ndrivers/gpu/drm/drm_edid.c-2966-\n--\ndrivers/gpu/drm/i915/display/intel_pmdemand.c=56=static struct intel_global_state \ndrivers/gpu/drm/i915/display/intel_pmdemand.c:57:intel_pmdemand_duplicate_state(struct intel_global_obj obj)\ndrivers/gpu/drm/i915/display/intel_pmdemand.c-58-{\n--\ndrivers/gpu/drm/i915/display/intel_pmdemand.c=74=static const struct intel_global_state_funcs intel_pmdemand_funcs = {\ndrivers/gpu/drm/i915/display/intel_pmdemand.c:75:\t.atomic_duplicate_state = intel_pmdemand_duplicate_state,\ndrivers/gpu/drm/i915/display/intel_pmdemand.c-76-\t.atomic_destroy_state = intel_pmdemand_destroy_state,\n--\ndrivers/gpu/drm/msm/adreno/a6xx_gpu_state.h=91=static const u32 a6xx_hlsq_duplicate_cluster[] = {\n--\ndrivers/gpu/drm/msm/adreno/a6xx_gpu_state.h-94-\ndrivers/gpu/drm/msm/adreno/a6xx_gpu_state.h:95:static const u32 a6xx_hlsq_2d_duplicate_cluster[] = {\ndrivers/gpu/drm/msm/adreno/a6xx_gpu_state.h-96-\t0xbd80, 0xbd80,\n--\ndrivers/gpu/drm/msm/adreno/a6xx_gpu_state.h=137=static const struct a6xx_dbgahb_cluster {\n--\ndrivers/gpu/drm/msm/adreno/a6xx_gpu_state.h-146-\tCLUSTER_DBGAHB(CLUSTER_SP_VS, 0x0002e000, 0x41, a6xx_hlsq_duplicate_cluster),\ndrivers/gpu/drm/msm/adreno/a6xx_gpu_state.h:147:\tCLUSTER_DBGAHB(CLUSTER_SP_VS, 0x0002f000, 0x45, a6xx_hlsq_2d_duplicate_cluster),\ndrivers/gpu/drm/msm/adreno/a6xx_gpu_state.h-148-\tCLUSTER_DBGAHB(CLUSTER_SP_VS, 0x0002a000, 0x21, a6xx_sp_duplicate_cluster),\n--\ndrivers/md/dm.c=1274=static size_t dm_dax_recovery_write(struct dax_device dax_dev, pgoff_t pgoff,\n--\ndrivers/md/dm.c-1297- * with write BIOs flagged with BIO_EMULATES_ZONE_APPEND) and any bio serviced\ndrivers/md/dm.c:1298: * by __send_duplicate_bios().\ndrivers/md/dm.c-1299- \n--\ndrivers/md/dm.c=1478=static void alloc_multiple_bios(struct bio_list blist, struct clone_info ci,\n--\ndrivers/md/dm.c-1507-\ndrivers/md/dm.c:1508:static unsigned int __send_duplicate_bios(struct clone_info ci, struct dm_target ti,\ndrivers/md/dm.c-1509-\t\t\t\t\t unsigned int num_bios, unsigned int len)\n--\ndrivers/md/dm.c=1537=static void __send_empty_flush(struct clone_info ci)\n--\ndrivers/md/dm.c-1566-\t\t\tatomic_add(ti-\u003enum_flush_bios, \u0026ci-\u003eio-\u003eio_count);\ndrivers/md/dm.c:1567:\t\t\tbios = __send_duplicate_bios(ci, ti, ti-\u003enum_flush_bios,\ndrivers/md/dm.c-1568-\t\t\t\t\t\t NULL);\n--\ndrivers/md/dm.c=1606=static void __send_abnormal_io(struct clone_info ci, struct dm_target ti,\n--\ndrivers/md/dm.c-1615-\tatomic_add(num_bios, \u0026ci-\u003eio-\u003eio_count);\ndrivers/md/dm.c:1616:\tbios = __send_duplicate_bios(ci, ti, num_bios, \u0026len);\ndrivers/md/dm.c-1617-\t/\n--\ndrivers/md/dm.c=1902=static void __send_zone_reset_all_native(struct clone_info ci,\n--\ndrivers/md/dm.c-1907-\tatomic_add(1, \u0026ci-\u003eio-\u003eio_count);\ndrivers/md/dm.c:1908:\tbios = __send_duplicate_bios(ci, ti, 1, NULL);\ndrivers/md/dm.c-1909-\tatomic_sub(1 - bios, \u0026ci-\u003eio-\u003eio_count);\n--\ndrivers/usb/typec/class.c=448=static int increment_duplicated_priority(struct device dev, void data)\n--\ndrivers/usb/typec/class.c-462-\ndrivers/usb/typec/class.c:463:static int find_duplicated_priority(struct device dev, void data)\ndrivers/usb/typec/class.c-464-{\n--\ndrivers/usb/typec/class.c=475=static int typec_mode_set_priority(struct typec_altmode alt, const u8 priority)\n--\ndrivers/usb/typec/class.c-482-\twhile (res) {\ndrivers/usb/typec/class.c:483:\t\tres = device_for_each_child(\u0026port-\u003edev, \u0026alt, find_duplicated_priority);\ndrivers/usb/typec/class.c-484-\t\tif (res) {\n--\nfs/dcache.c=2004=EXPORT_SYMBOL(d_alloc);\n--\nfs/dcache.c-2006-/*\nfs/dcache.c:2007: d_duplicate - duplicate a dentry for combined atomic operation\nfs/dcache.c-2008- * @dentry: the dentry to duplicate\n--\nfs/dcache.c-2017- * For this they need two dentries which temporarily have the same name,\nfs/dcache.c:2018: * before one is renamed. d_duplicate() provides for this. Given a\nfs/dcache.c-2019- * positive hashed dentry, it creates a second in-lookup dentry.\n--\nfs/dcache.c-2031- /\nfs/dcache.c:2032:struct dentry d_duplicate(struct dentry dentry)\nfs/dcache.c-2033-{\n--\nfs/dcache.c-2055-}\nfs/dcache.c:2056:EXPORT_SYMBOL(d_duplicate);\nfs/dcache.c-2057-\n--\nfs/nfs/dir.c=2760=int nfs_rename(struct mnt_idmap idmap, struct inode old_dir,\n--\nfs/nfs/dir.c-2803-\t\t\t/ copy the target dentry's name /\nfs/nfs/dir.c:2804:\t\t\tdentry = d_duplicate(new_dentry);\nfs/nfs/dir.c-2805-\t\t\tif (!dentry)\n--\ninclude/drm/drm_edid.h=441=struct edid drm_get_edid_switcheroo(struct drm_connector connector,\ninclude/drm/drm_edid.h-442-\t\t\t\t struct i2c_adapter adapter);\ninclude/drm/drm_edid.h:443:struct edid drm_edid_duplicate(const struct edid edid);\ninclude/drm/drm_edid.h-444-int drm_add_edid_modes(struct drm_connector connector, struct edid edid);\n--\ninclude/linux/dcache.h=265=extern struct dentry * d_splice_alias(struct inode , struct dentry );\ninclude/linux/dcache.h:266:struct dentry d_duplicate(struct dentry dentry);\ninclude/linux/dcache.h-267-/* weird procfs mess; NOT exported */\n" }
59/3	2026/09/27 17:44	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 12339 output: 35 thoughts: 18 Thoughts: Okay, let's dive into this. Here's my take on examining `d_duplicate` within `fs/dcache.c`: Deep Dive into `d_duplicate` Alright, let's get into the nitty-gritty of `d_duplicate`. I'm going to pull up `fs/dcache.c` and specifically focus on that function. From my experience, knowing how the dentry cache functions is absolutely critical for understanding file system performance and behavior, especially when it comes to things like file lookups, caching strategies, and concurrency. I need to refresh my memory on the intricacies of how dentries are copied, and what exactly constitutes a "duplicate" in this context. I'm immediately thinking about reference counts, inode relationships, and potential issues like race conditions when multiple processes are working with the same file path. I'm going to look at its input parameters - I need to understand what's being duplicated and why. I'll need to trace its call sites to see where it's used and under what circumstances. Are we talking about a simple copy or a more complex, possibly shared, dentry? I'll probably look for potential memory allocation issues, locking mechanisms, and error handling as well. This is likely a critical section of code, and I need to fully understand its implications.
60/3	2026/09/27 17:44	tool	read-file	0m Args: { "File": "fs/dcache.c", "FirstLine": 2006, "LineCount": 55 } Results: { "Contents": "2006:\t/*\n2007:\t d_duplicate - duplicate a dentry for combined atomic operation\n2008:\t * @dentry: the dentry to duplicate\n2009:\t \n2010:\t Some rename operations need to be combined with another operation\n2011:\t * inside the filesystem.\n2012:\t * 1/ A cluster filesystem when renaming to an in-use file might need to\n2013:\t * first \"silly-rename\" that target out of the way before the main rename\n2014:\t * 2/ A filesystem that supports white-out might want to create a whiteout\n2015:\t * in place of the file being moved.\n2016:\t \n2017:\t For this they need two dentries which temporarily have the same name,\n2018:\t * before one is renamed. d_duplicate() provides for this. Given a\n2019:\t * positive hashed dentry, it creates a second in-lookup dentry.\n2020:\t * Because the original dentry exists, no other thread will try to\n2021:\t * create an in-lookup dentry, so there can be no race in this create.\n2022:\t \n2023:\t The caller should d_move() the original to a new name, often via a\n2024:\t * rename request, and should call d_lookup_done() on the newly created\n2025:\t * dentry. If the new is instantiated then the old MUST either be moved\n2026:\t * or dropped.\n2027:\t \n2028:\t Parent must be locked.\n2029:\t \n2030:\t Returns: an in-lookup dentry, or -ENOMEM.\n2031:\t /\n2032:\tstruct dentry d_duplicate(struct dentry dentry)\n2033:\t{\n2034:\t\tunsigned int hash = dentry-\u003ed_name.hash;\n2035:\t\tstruct dentry parent = dentry-\u003ed_parent;\n2036:\t\tstruct hlist_bl_head b = in_lookup_hash(parent, hash);\n2037:\t\tstruct dentry new = __d_alloc(parent-\u003ed_sb, \u0026dentry-\u003ed_name);\n2038:\t\n2039:\t\tif (unlikely(!new))\n2040:\t\t\treturn ERR_PTR(-ENOMEM);\n2041:\t\n2042:\t\tnew-\u003ed_flags \|= DCACHE_PAR_LOOKUP;\n2043:\t\tlock_map_acquire_try(\u0026new-\u003elookup_map);\n2044:\t\tspin_lock(\u0026parent-\u003ed_lock);\n2045:\t\tnew-\u003ed_parent = dget_dlock(parent);\n2046:\t\thlist_add_head(\u0026new-\u003ed_sib, \u0026parent-\u003ed_children);\n2047:\t\tif (parent-\u003ed_flags \u0026 DCACHE_DISCONNECTED)\n2048:\t\t\tnew-\u003ed_flags \|= DCACHE_DISCONNECTED;\n2049:\t\tspin_unlock(\u0026parent-\u003ed_lock);\n2050:\t\n2051:\t\thlist_bl_lock(b);\n2052:\t\thlist_bl_add_head(\u0026new-\u003ed_in_lookup_hash, b);\n2053:\t\thlist_bl_unlock(b);\n2054:\t\treturn new;\n2055:\t}\n2056:\tEXPORT_SYMBOL(d_duplicate);\n2057:\t\n2058:\tstruct dentry d_alloc_anon(struct super_block sb)\n2059:\t{\n2060:\t\treturn __d_alloc(sb, NULL);\n" }
61/3	2026/09/27 17:44	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 13631 output: 36 thoughts: 640 Thoughts: Analyzing a Potential Kernel Bug Okay, let's dive into this. First, I'm checking the error return of `d_duplicate`. The code has `if (unlikely(!new)) return ERR_PTR(-ENOMEM);`, which is what I'd expect for an out-of-memory scenario. Now, looking at `fs/nfs/dir.c`, specifically, this line caught my eye: ```c dentry = d_duplicate(new_dentry); ``` Wait a minute, it looks like `d_duplicate` is being used, instead of `d_alloc`. I need to ensure the error handling is correct, is it `if (IS_ERR(dentry))` or `if (!dentry)`? Because `d_duplicate` can return `ERR_PTR(-ENOMEM)`. Ah, here's the problem. The code checks `if (!dentry)`. If `d_duplicate` returns `ERR_PTR(-ENOMEM)`, that's not a NULL pointer! The subsequent code block becomes a disaster: ```c if (dentry) { d_lookup_done(dentry); dput(dentry); } ``` If `dentry` is `ERR_PTR(-ENOMEM)`, then calling `d_lookup_done()` and `dput()` will try to dereference that error pointer, which is an invalid address. This is likely leading to a kernel crash, a General Protection Fault (GPF), or KASAN wild pointer dereference, and not KMSAN! Now, let's shift gears and check for uninitialized memory risks introduced or exposed by the patch. Let's start with `nfs_prime_dcache`: ```c void nfs_prime_dcache(struct dentry parent, struct nfs_entry entry, if (filename.len == 2 && filename.name[1] == '.') return; } - filename.hash = full_name_hash(parent, filename.name, filename.len); - dentry = d_lookup(parent, &filename); again: - if (!dentry) { - dentry = d_alloc_parallel(parent, &filename); - if (IS_ERR(dentry)) - return; - } + dentry = d_alloc_trylock(parent, &filename); + if (IS_ERR(dentry)) + return; + if (!d_in_lookup(dentry)) { ``` Hold on, let me review how `filename` is initialized in `nfs_prime_dcache`. I need to reread `fs/nfs/dir.c` for more details. I need to make sure `filename` is properly initialized.
62/3	2026/09/27 17:45	tool	read-file	0m Args: { "File": "fs/nfs/dir.c", "FirstLine": 730, "LineCount": 40 } Results: { "Contents": " 730:\t\tstruct dentry alias;\n 731:\t\tstruct inode inode;\n 732:\t\tint status;\n 733:\t\n 734:\t\tif (!(entry-\u003efattr-\u003evalid \u0026 NFS_ATTR_FATTR_FILEID))\n 735:\t\t\treturn;\n 736:\t\tif (!(entry-\u003efattr-\u003evalid \u0026 NFS_ATTR_FATTR_FSID))\n 737:\t\t\treturn;\n 738:\t\tif (filename.len == 0)\n 739:\t\t\treturn;\n 740:\t\t/* Validate that the name doesn't contain any illegal '\\0' /\n 741:\t\tif (strnlen(filename.name, filename.len) != filename.len)\n 742:\t\t\treturn;\n 743:\t\t/ ...or '/' /\n 744:\t\tif (strnchr(filename.name, filename.len, '/'))\n 745:\t\t\treturn;\n 746:\t\tif (filename.name[0] == '.') {\n 747:\t\t\tif (filename.len == 1)\n 748:\t\t\t\treturn;\n 749:\t\t\tif (filename.len == 2 \u0026\u0026 filename.name[1] == '.')\n 750:\t\t\t\treturn;\n 751:\t\t}\n 752:\t\n 753:\tagain:\n 754:\t\tdentry = d_alloc_trylock(parent, \u0026filename);\n 755:\t\tif (IS_ERR(dentry))\n 756:\t\t\treturn;\n 757:\t\n 758:\t\tif (!d_in_lookup(dentry)) {\n 759:\t\t\t/ Is there a mountpoint here? If so, just exit */\n 760:\t\t\tif (!nfs_fsid_equal(\u0026NFS_SB(dentry-\u003ed_sb)-\u003efsid,\n 761:\t\t\t\t\t\t\u0026entry-\u003efattr-\u003efsid))\n 762:\t\t\t\tgoto out;\n 763:\t\t\tif (nfs_same_file(dentry, entry)) {\n 764:\t\t\t\tif (!entry-\u003efh-\u003esize)\n 765:\t\t\t\t\tgoto out;\n 766:\t\t\t\tnfs_set_verifier(dentry, dir_verifier);\n 767:\t\t\t\tstatus = nfs_refresh_inode(d_inode(dentry), entry-\u003efattr);\n 768:\t\t\t\tif (!status)\n 769:\t\t\t\t\tnfs_setsecurity(d_inode(dentry), entry-\u003efattr);\n" }
63/3	2026/09/27 17:45	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 15582 output: 36 thoughts: 24 Thoughts: Okay, here's my interpretation of what's going through my mind, delivered as requested: Navigating the NFS Directory Code Alright, let's dive in. The task is to understand a specific segment of the NFS file system code, specifically lines 720-735 within `fs/nfs/dir.c`. My initial thought is to mentally prepare myself for potential complexity. I know this area of the code deals with directory operations within the NFS client, so I'm expecting to encounter routines related to listing directory entries, creating new directories, removing them, and handling attributes. I anticipate it might involve interacting with the server via RPC calls. I'll be looking for clues about how the client handles caching, error handling, and concurrency in this specific region. My goal is to quickly pinpoint what this segment is trying to achieve, what data structures it utilizes, and if there are any obvious performance bottlenecks or potential race conditions. I'm hoping to quickly grasp the logical flow and the specific function calls within this particular section. This will allow me to contextualize this section in the broader NFS directory management strategy. I'll be focused on how the code interacts with the underlying VFS layer and the network layer. Time to get started!
64/3	2026/09/27 17:45	tool	read-file	0m Args: { "File": "fs/nfs/dir.c", "FirstLine": 715, "LineCount": 20 } Results: { "Contents": " 715:\t\t\t\t\t\t\tunsigned int flags)\n 716:\t{\n 717:\t\tif (nfs_server_capable(dir, NFS_CAP_CASE_INSENSITIVE))\n 718:\t\t\treturn;\n 719:\t\tif (flags \u0026 (LOOKUP_EXCL \| LOOKUP_PARENT \| LOOKUP_REVAL))\n 720:\t\t\treturn;\n 721:\t\tnfs_readdir_record_entry_cache_miss(dir);\n 722:\t}\n 723:\t\n 724:\tstatic\n 725:\tvoid nfs_prime_dcache(struct dentry parent, struct nfs_entry entry,\n 726:\t\t\tunsigned long dir_verifier)\n 727:\t{\n 728:\t\tstruct qstr filename = QSTR_INIT(entry-\u003ename, entry-\u003elen);\n 729:\t\tstruct dentry dentry;\n 730:\t\tstruct dentry alias;\n 731:\t\tstruct inode *inode;\n 732:\t\tint status;\n 733:\t\n 734:\t\tif (!(entry-\u003efattr-\u003evalid \u0026 NFS_ATTR_FATTR_FILEID))\n" }
65/3	2026/09/27 17:45	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 16214 output: 20 thoughts: 52 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience: Diving into the NFS Prime dcache Right, so I'm looking at `nfs_prime_dcache`, and I've hit this line: `struct qstr filename = QSTR_INIT(entry->name, entry->len);`. My immediate thought is, "Ah, `QSTR_INIT` - what exactly is that doing?" It's not immediately obvious, and you know how it goes; you don't want to make any assumptions, especially when dealing with core kernel structures. So, I need to check the definition of `QSTR_INIT`. Let's refresh my memory of how that's implemented.
66/3	2026/09/27 17:45	tool	grepper	0m Args: { "Expression": "#define QSTR_INIT" } Results: { "Output": "include/linux/dcache.h=49=struct qstr {\n--\ninclude/linux/dcache.h-58-\ninclude/linux/dcache.h:59:#define QSTR_INIT(n,l) { { { .len = l } }, .name = n }\ninclude/linux/dcache.h-60-#define QSTR_LEN(n,l) (struct qstr)QSTR_INIT(n,l)\n" }
67/3	2026/09/27 17:45	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 16561 output: 20 thoughts: 194 Thoughts: Investigating a C Structure Initialization Mystery Okay, so I'm looking at this C code and I see this macro, `#define QSTR_INIT(n,l) { { { .len = l } }, .name = n }`. Immediately, my expert brain kicks in – I remember that in C, struct initialization using `{ ... }` has a crucial behavior: any field not explicitly initialized is automatically zeroed out. So, the `.hash` field of the `filename` struct, when initialized this way, would be set to zero. Interesting, but what's the context here? Now, I need to figure out what change the code I'm looking at represents. The patch… it removed `filename.hash = full_name_hash(parent, filename.name, filename.len);`. I can see that. But why? That's the question. The comment above `d_alloc_trylock` hints at something, though: "* The @name need not already have ->hash set." Right! That's a good place to start. Now, let me see how `d_alloc_trylock` actually handles `name->hash`. I need to understand what's happening internally with the hash. And if I am to understand it fully, I need to examine the calls that call it. Okay, let's also check `try_lookup_noperm` and `__d_alloc_parallel`. Let's get to the bottom of this.
68/3	2026/09/27 17:45	tool	grepper	0m Args: { "Expression": "try_lookup_noperm" } Results: { "Output": "Documentation/filesystems/porting.rst=1218=lookup_one_len_unlocked() and lookup_positive_unlocked() have been\nDocumentation/filesystems/porting.rst:1219:renamed to try_lookup_noperm(), lookup_noperm(),\nDocumentation/filesystems/porting.rst-1220-lookup_noperm_unlocked(), lookup_noperm_positive_unlocked(). They now\n--\nDocumentation/filesystems/porting.rst=1234=d_hash_and_lookup() is no longer exported or available outside the VFS.\nDocumentation/filesystems/porting.rst:1235:Use try_lookup_noperm() instead. This adds name validation and takes\nDocumentation/filesystems/porting.rst-1236-arguments in the opposite order but is otherwise identical.\nDocumentation/filesystems/porting.rst-1237-\nDocumentation/filesystems/porting.rst:1238:Using try_lookup_noperm() will require linux/namei.h to be included.\nDocumentation/filesystems/porting.rst-1239-\n--\nfs/autofs/dev-ioctl.c=411=static int autofs_dev_ioctl_timeout(struct file fp,\n--\nfs/autofs/dev-ioctl.c-434-\nfs/autofs/dev-ioctl.c:435:\t\tdentry = try_lookup_noperm(\u0026QSTR_LEN(param-\u003epath, path_len),\nfs/autofs/dev-ioctl.c-436-\t\t\t\t\t base);\n--\nfs/dcache.c=2831=struct dentry __d_alloc_parallel(struct dentry parent,\n--\nfs/dcache.c-2964- The @name must already have -\u003ehash set, as can be achieved\nfs/dcache.c:2965: * by e.g. try_lookup_noperm().\nfs/dcache.c-2966- \n--\nfs/dcache.c=2998=struct dentry d_alloc_trylock(struct dentry parent,\n--\nfs/dcache.c-3002-\nfs/dcache.c:3003:\tde = try_lookup_noperm(name, parent);\nfs/dcache.c-3004-\tif (!de)\n--\nfs/efivarfs/super.c=227=bool efivarfs_variable_is_present(efi_char16_t variable_name,\n--\nfs/efivarfs/super.c-244-\nfs/efivarfs/super.c:245:\tdentry = try_lookup_noperm(\u0026QSTR(name), sb-\u003es_root);\nfs/efivarfs/super.c-246-\tkfree(name);\n--\nfs/efivarfs/super.c=425=static int efivarfs_check_missing(efi_char16_t name16, efi_guid_t vendor,\n--\nfs/efivarfs/super.c-439-\nfs/efivarfs/super.c:440:\tdentry = try_lookup_noperm(\u0026QSTR(name), sb-\u003es_root);\nfs/efivarfs/super.c-441-\tif (IS_ERR(dentry)) {\n--\nfs/namei.c=3114=static int lookup_one_common(struct mnt_idmap idmap,\n--\nfs/namei.c-3124-/*\nfs/namei.c:3125: try_lookup_noperm - filesystem helper to lookup single pathname component\nfs/namei.c-3126- * @name:\tqstr storing pathname component to lookup\n--\nfs/namei.c-3144- /\nfs/namei.c:3145:struct dentry try_lookup_noperm(struct qstr name, struct dentry base)\nfs/namei.c-3146-{\n--\nfs/namei.c-3154-}\nfs/namei.c:3155:EXPORT_SYMBOL(try_lookup_noperm);\nfs/namei.c-3156-\n--\nfs/namei.c=3208=EXPORT_SYMBOL(lookup_one);\n--\nfs/namei.c-3221- * Returns: - A dentry, possibly negative, or\nfs/namei.c:3222: \t - same errors as try_lookup_noperm() or\nfs/namei.c-3223- \t - ERR_PTR(-ENOENT) if parent has been removed, or\n--\nfs/namei.c=3321=EXPORT_SYMBOL(lookup_one_positive_unlocked);\n--\nfs/namei.c-3333- \nfs/namei.c:3334: Unlike try_lookup_noperm() it does revalidate the dentry if it already\nfs/namei.c-3335- * existed.\n--\nfs/namei.c-3338- \t - ERR_PTR(-ENOENT) if parent has been removed, or\nfs/namei.c:3339: \t - same errors as try_lookup_noperm()\nfs/namei.c-3340- /\n--\nfs/namei.c=3355=EXPORT_SYMBOL(lookup_noperm_unlocked);\n--\nfs/namei.c-3366- \t - ERR_PTR(-ENOENT) if name cannot be found or parent has been removed, or\nfs/namei.c:3367: \t - same errors as try_lookup_noperm()\nfs/namei.c-3368- /\n--\nfs/proc/base.c=2099=bool proc_fill_cache(struct file file, struct dir_context ctx,\n--\nfs/proc/base.c-2108-\nfs/proc/base.c:2109:\tchild = try_lookup_noperm(\u0026qname, dir);\nfs/proc/base.c-2110-\tif (IS_ERR(child))\n--\nfs/smb/client/readdir.c=67=cifs_prime_dcache(struct dentry parent, struct qstr name,\n--\nfs/smb/client/readdir.c-79-\nfs/smb/client/readdir.c:80:\tdentry = try_lookup_noperm(name, parent);\nfs/smb/client/readdir.c-81-\tif (!dentry) {\n--\nfs/xfs/scrub/orphanage.c=431=xrep_adoption_check_dcache(\n--\nfs/xfs/scrub/orphanage.c-443-\nfs/xfs/scrub/orphanage.c:444:\td_child = try_lookup_noperm(\u0026qname, d_orphanage);\nfs/xfs/scrub/orphanage.c-445-\tif (IS_ERR(d_child)) {\n--\nfs/xfs/scrub/orphanage.c=473=xrep_adoption_zap_dcache(\n--\nfs/xfs/scrub/orphanage.c-485-\nfs/xfs/scrub/orphanage.c:486:\td_child = try_lookup_noperm(\u0026qname, d_orphanage);\nfs/xfs/scrub/orphanage.c-487-\twhile (!IS_ERR_OR_NULL(d_child)) {\n--\ninclude/linux/namei.h=67=int vfs_path_lookup(struct dentry , struct vfsmount , const char ,\n--\ninclude/linux/namei.h-69-\ninclude/linux/namei.h:70:extern struct dentry try_lookup_noperm(struct qstr , struct dentry );\ninclude/linux/namei.h-71-extern struct dentry lookup_noperm(struct qstr , struct dentry );\n--\nnet/sunrpc/rpc_pipe.c=1005=struct dentry rpc_d_lookup_sb(const struct super_block *sb,\n--\nnet/sunrpc/rpc_pipe.c-1007-{\nnet/sunrpc/rpc_pipe.c:1008:\treturn try_lookup_noperm(\u0026QSTR(dir_name), sb-\u003es_root);\nnet/sunrpc/rpc_pipe.c-1009-}\n--\nsecurity/selinux/selinuxfs.c=1974=int __init init_sel_fs(void)\n--\nsecurity/selinux/selinuxfs.c-1997-\nsecurity/selinux/selinuxfs.c:1998:\tselinux_null.dentry = try_lookup_noperm(\u0026null_name,\nsecurity/selinux/selinuxfs.c-1999-\t\t\t\t\t\t selinux_null.mnt-\u003emnt_root);\n" }
69/3	2026/09/27 17:45	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 19325 output: 35 thoughts: 12 Thoughts: Okay, here's my interpretation of "Let's see `try_lookup_noperm`" presented as a first-person expert thought process, targeted at another expert: Analyzing `try_lookup_noperm` Alright, so the phrase "Let's see `try_lookup_noperm`" pops up. Immediately, my mind starts tracing the likely context. This strongly suggests we're digging into a piece of code, likely related to a system or library's lookup mechanisms. The "try" implies we are dealing with a function that attempts a specific search or retrieval, and the "noperm" part is the key. It almost certainly means we are concerned with a lookup that specifically operates without needing any explicit permissions check, or that it is checking if the permission is not present. This is a very interesting starting point because security is an important facet in any robust application. My initial thoughts are along the lines of how the overall system behaves as a result of a call to the function in question: * Security Implications: What are the security tradeoffs? Why is this specific lookup designed to avoid a permission check, or to check for the absence of permission? Are we dealing with cached data? A privileged operation? Or perhaps a lookup that’s inherently considered safe due to the scope of what it searches? * Performance Considerations: Skipping a permissions check could offer a considerable performance boost in certain contexts. However, the importance of security must be balanced against that performance gain. * Contextual Understanding: I need to know the specific data being looked up. Is it a file path, a database record, an object identifier? The nature of the data dictates the potential risks and design considerations. * Code Flow: How does this function fit into the larger process? What are the potential error paths or exception handling? What happens if the lookup fails? Does the system gracefully degrade, or does it trigger an access denied/permission not present error? * Alternatives: Could `try_lookup_noperm` be refactored into a more secure pattern, or does it solve a specific problem with a particular context that is acceptable as is? Are there better alternatives to achieve the same result that can solve any security concerns? I need more context. I'm going to want to examine the surrounding code to determine why this function exists and what the architects were thinking when they wrote it. This is definitely a spot that warrants a close look.
70/3	2026/09/27 17:45	tool	read-file	0m Args: { "File": "fs/namei.c", "FirstLine": 3140, "LineCount": 20 } Results: { "Contents": "3140:\t * - ref-counted dentry on success, or\n3141:\t * - %NULL if name could not be found, or\n3142:\t * - ERR_PTR(-EACCES) if name is dot or dotdot or contains a slash or nul, or\n3143:\t * - ERR_PTR() if fs provide -\u003ed_hash, and this returned an error.\n3144:\t /\n3145:\tstruct dentry try_lookup_noperm(struct qstr name, struct dentry base)\n3146:\t{\n3147:\t\tint err;\n3148:\t\n3149:\t\terr = lookup_noperm_common(name, base);\n3150:\t\tif (err)\n3151:\t\t\treturn ERR_PTR(err);\n3152:\t\n3153:\t\treturn d_lookup(base, name);\n3154:\t}\n3155:\tEXPORT_SYMBOL(try_lookup_noperm);\n3156:\t\n3157:\t/*\n3158:\t lookup_noperm - filesystem helper to lookup single pathname component\n3159:\t * @name:\tqstr storing pathname component to lookup\n" }
71/3	2026/09/27 17:45	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 20213 output: 35 thoughts: 16 Thoughts: Okay, here's my attempt at summarizing the thought process, tailored for an expert audience: Analyzing `lookup_noperm_common` Alright, let's dive into `lookup_noperm_common`. My initial thought is to understand its purpose and function within the system. I need to quickly grasp its core responsibility before delving into any specifics. I want to see how it's implemented and where it's called. My primary focus is likely on permission checks, or rather, the absence of permission checks, given the name. I'm already anticipating potential security implications or design trade-offs involved in its operation. Knowing if it sits directly on any hot path is critical. From there, I can determine it's relevance to any optimization efforts and its impact on the overall performance of the system.
72/3	2026/09/27 17:45	tool	read-file	0m Args: { "File": "fs/namei.c", "FirstLine": 3114, "LineCount": 25 } Results: { "Contents": "3114:\tstatic int lookup_one_common(struct mnt_idmap idmap,\n3115:\t\t\t\t struct qstr qname, struct dentry base)\n3116:\t{\n3117:\t\tint err;\n3118:\t\terr = lookup_noperm_common(qname, base);\n3119:\t\tif (err \u003c 0)\n3120:\t\t\treturn err;\n3121:\t\treturn inode_permission(idmap, base-\u003ed_inode, MAY_EXEC);\n3122:\t}\n3123:\t\n3124:\t/\n3125:\t try_lookup_noperm - filesystem helper to lookup single pathname component\n3126:\t * @name:\tqstr storing pathname component to lookup\n3127:\t * @base:\tbase directory to lookup from\n3128:\t \n3129:\t Look up a dentry by name in the dcache, returning NULL if it does not\n3130:\t * currently exist or an error if there is a problem with the name.\n3131:\t * The function does not try to create a dentry and if one\n3132:\t * is found it doesn't try to revalidate it.\n3133:\t \n3134:\t Note that this routine is purely a helper for filesystem usage and should\n3135:\t * not be called by generic code. It does no permission checking.\n3136:\t \n3137:\t No locks need be held - only a counted reference to @base is needed.\n3138:\t *\n" }
73/3	2026/09/27 17:45	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 20853 output: 20 thoughts: 16 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: Tracing Down `lookup_noperm_common` Alright, let's dive in. I need to figure out the definition of `lookup_noperm_common`. It's a common function name, so I'll need to use my usual methods for tracking this down. Let's see... I'll start by checking the current project and its includes, specifically looking at the relevant headers to see where this is defined or declared. I'll need to follow the code as it leads me to the specific definition. This usually involves understanding the project's structure, which headers are typically used for what, and the general naming conventions they use. With any luck, this won't be in some obscure, automatically generated code.
74/3	2026/09/27 17:45	tool	grepper	0m Args: { "Expression": "lookup_noperm_common" } Results: { "Output": "fs/internal.h=70=struct dentry start_dirop(struct dentry parent, struct qstr name,\nfs/internal.h-71-\t\t\t unsigned int lookup_flags);\nfs/internal.h:72:int lookup_noperm_common(struct qstr qname, struct dentry base);\nfs/internal.h-73-\n--\nfs/libfs.c=2300=struct dentry simple_start_creating(struct dentry parent, const char name)\n--\nfs/libfs.c-2304-\nfs/libfs.c:2305:\terr = lookup_noperm_common(\u0026qname, parent);\nfs/libfs.c-2306-\tif (err)\n--\nfs/namei.c=3083=EXPORT_SYMBOL(vfs_path_lookup);\nfs/namei.c-3084-\nfs/namei.c:3085:int lookup_noperm_common(struct qstr qname, struct dentry base)\nfs/namei.c-3086-{\n--\nfs/namei.c=3114=static int lookup_one_common(struct mnt_idmap idmap,\n--\nfs/namei.c-3117-\tint err;\nfs/namei.c:3118:\terr = lookup_noperm_common(qname, base);\nfs/namei.c-3119-\tif (err \u003c 0)\n--\nfs/namei.c=3145=struct dentry try_lookup_noperm(struct qstr name, struct dentry base)\n--\nfs/namei.c-3148-\nfs/namei.c:3149:\terr = lookup_noperm_common(name, base);\nfs/namei.c-3150-\tif (err)\n--\nfs/namei.c=3167=struct dentry lookup_noperm(struct qstr name, struct dentry base)\n--\nfs/namei.c-3173-\nfs/namei.c:3174:\terr = lookup_noperm_common(name, base);\nfs/namei.c-3175-\tif (err)\n--\nfs/namei.c=3341=struct dentry lookup_noperm_unlocked(struct qstr name, struct dentry base)\n--\nfs/namei.c-3345-\nfs/namei.c:3346:\terr = lookup_noperm_common(name, base);\nfs/namei.c-3347-\tif (err)\n--\nfs/namei.c=3509=struct dentry start_creating_noperm(struct dentry parent,\n--\nfs/namei.c-3511-{\nfs/namei.c:3512:\tint err = lookup_noperm_common(name, parent);\nfs/namei.c-3513-\n--\nfs/namei.c=3534=struct dentry start_removing_noperm(struct dentry parent,\n--\nfs/namei.c-3536-{\nfs/namei.c:3537:\tint err = lookup_noperm_common(name, parent);\nfs/namei.c-3538-\n--\nfs/namei.c=4627=struct file vfs_lookup_open(struct path parent, struct qstr *last,\n--\nfs/namei.c-4642-\nfs/namei.c:4643:\terror = lookup_noperm_common(last, parent-\u003edentry);\nfs/namei.c-4644-\tif (error)\n" }
75/3	2026/09/27 17:45	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 22015 output: 35 thoughts: 12 Thoughts: Okay, here's my interpretation of that thought process, tailored for an expert audience, and written in the first person: Analyzing `lookup_noperm_common` Alright, let's dive into this `lookup_noperm_common` function. My initial thought process here is to consider its purpose. I'm immediately assuming this is some core, frequently called routine related to lookups that, in some way, is not permission-dependent or possibly avoids explicit permission checks, or perhaps needs to know something before doing a full permission check. It's likely involved in resolving names or identifiers, but the "no perm" part is the key differentiator and something I want to understand. I'm starting to think about where this might be used – is it in a caching layer, a pre-authentication step, or perhaps for internal system calls where permission checks are handled differently? Is it involved in determining what needs a permission check later? Understanding the context of this function call would be hugely important. It’s also possible that it provides a very basic, unfiltered view of the lookup results. My immediate concerns are around the security implications of such a function. What safeguards are in place to prevent bypassing or exploiting any potential "no-permission" aspects? Are there any race conditions that might be introduced? If it's a foundational component, then any flaw in this is a flaw that could ripple out very easily. I need to understand its relationship to the access control model. Are there any assumptions this function makes about the execution context, or the credentials being used? I'll probably want to mentally trace a few calls to understand the flow.
76/3	2026/09/27 17:45	tool	read-file	0m Args: { "File": "fs/namei.c", "FirstLine": 3085, "LineCount": 25 } Results: { "Contents": "3085:\tint lookup_noperm_common(struct qstr qname, struct dentry base)\n3086:\t{\n3087:\t\tconst char name = qname-\u003ename;\n3088:\t\tu32 len = qname-\u003elen;\n3089:\t\n3090:\t\tqname-\u003ehash = full_name_hash(base, name, len);\n3091:\t\tif (!len)\n3092:\t\t\treturn -EACCES;\n3093:\t\n3094:\t\tif (name_is_dot_dotdot(name, len))\n3095:\t\t\treturn -EACCES;\n3096:\t\n3097:\t\twhile (len--) {\n3098:\t\t\tunsigned int c = (const unsigned char )name++;\n3099:\t\t\tif (c == '/' \|\| c == '\\0')\n3100:\t\t\t\treturn -EACCES;\n3101:\t\t}\n3102:\t\t/\n3103:\t\t * See if the low-level filesystem might want\n3104:\t\t * to use its own hash..\n3105:\t\t */\n3106:\t\tif (base-\u003ed_flags \u0026 DCACHE_OP_HASH) {\n3107:\t\t\tint err = base-\u003ed_op-\u003ed_hash(base, qname);\n3108:\t\t\tif (err \u003c 0)\n3109:\t\t\t\treturn err;\n" }
77/3	2026/09/27 17:45	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 22783 output: 19 thoughts: 1961 Thoughts: Analyzing Recent NFS Dentry Changes Okay, let's break down these NFS dentry changes. My initial thought from the first change is that the `full_name_hash` function, being called in `lookup_noperm_common`, likely is the reason for the redundancy in the `nfs_prime_dcache` and now `unlink.c`. Explicitly setting `data->args.name.hash` before calling `d_alloc_parallel` is definitely a good move to ensure the hash is populated as required, preventing potential issues during dentry allocation. Moving on, the change in `nfs_neg_need_reval` is interesting. Returning 0 when `LOOKUP_OPEN` is set makes sense for close-to-open semantics. This ensures revalidation on each open and that `nfs_atomic_open` always has exclusive access. I'll need to remember that. The synchronization simplification in `__nfs_lookup_revalidate` looks straightforward and cleaner. Removing the redundant `smp_load_acquire` and just checking `dentry->d_fsdata` should be more efficient. Similarly, the seqcount invalidation in `block_revalidate` using `write_seqcount_invalidate` is a standard approach to signal changes and potential conflicts. The `nfs_atomic_open` changes are important. Removing the `switched` logic because of the `LOOKUP_OPEN` check is a crucial simplification. It avoids unnecessary dentry manipulation and ensures that the dentry is either already in lookup or being properly handled. The error handling changes in this function by moving `d_drop` to the error paths for proper cleanup are correct. In `nfs_add_or_obtain`, the movement of `d_drop` to the error path makes a lot of sense, preventing the dentry from being dropped prematurely, making it more robust. The change in `nfs_link` to use `d_splice_alias` instead of `d_add` is also notable. `d_splice_alias` is preferred when the inode is already linked to a dentry. Then the error case dropping the dentry ensures proper cleanup on failure. The update of `nfs_rename` looks fine; using `d_duplicate` makes perfect sense. This makes the code clearer. The use of `d_lookup_done` after `dentry` creation in rename is also a standard approach, to make sure it's released properly. In `_nfs4_open_and_get_state`, the removal of `d_drop` before `d_splice_alias` is expected. Finally, in `nfs_sillyrename`, I need to check the uninitialized memory risk. The silly rename process is using `scnprintf` to populate a buffer and then passing the buffer's string with the `QSTR` macro to `d_alloc_trylock`. I need to ensure there are no uninitialized memory risks here: `unsigned char silly[SILLYNAME_LEN + 1];` allocates a buffer for the silly name. `scnprintf(silly, sizeof(silly), ...)` writes a null-terminated string. So the buffer is properly initialized. `&QSTR(silly)` is passed, so what's the `QSTR` macro? That is the thing to check.
78/3	2026/09/27 17:45	tool	grepper	0m Args: { "Expression": "#define QSTR\\(" } Results: { "Output": "include/linux/dcache.h=49=struct qstr {\n--\ninclude/linux/dcache.h-60-#define QSTR_LEN(n,l) (struct qstr)QSTR_INIT(n,l)\ninclude/linux/dcache.h:61:#define QSTR(n) QSTR_LEN(n, strlen(n))\ninclude/linux/dcache.h-62-\n" }
79/3	2026/09/27 17:45	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 25596 output: 242 thoughts: 1278 Thoughts: KMSAN Evaluation for NFS dcache refactoring Okay, let's break this down. My goal is to determine if this patch necessitates `NeedsKMSAN=true`. It's a refactor, focusing on how NFS interacts with the dcache, specifically around dentry allocation, lookup, and parallel lookup. I'm seeing changes in functions like `nfs_prime_dcache`, `nfs_atomic_open`, `nfs_rename`, `nfs_link`, and `nfs_sillyrename`. The core seems to be replacing custom code sequences with standard VFS helpers like `d_alloc_trylock()` and `d_duplicate()`, tweaking negative dentry revalidation, and updating reference/locking semantics. Now, I need to methodically check against the KMSAN justification criteria. Let's start with the basics. `QSTR(n)` creates a compound literal; the `silly` value is fully initialized. The existing code, at a glance, doesn't seem to be dealing with uninitialized data. Specifically, I'm analyzing the `nfs_sillyrename` code. `sdentry` is assigned the return value of `d_alloc_trylock(...)`; `old` is assigned the return value of `nfs_lookup(...)`. These are standard VFS functions, and should have zeroed the structures. In the rename path, I see the `dentry` variable is initialized by `d_duplicate`. Similarly, in the unlink path, the `alias` variable is initialized through `d_alloc_parallel`. There doesn't appear to be any branching logic that depends on uninitialized variables. KMSAN, as I recall, is critical for detecting reads of uninitialized memory and kernel-to-user memory info-leaks, but the important thing is that it is not used in conjunction with standard KASAN/LOCKDEP etc. Standard KASAN is already enabled, as are other standard debuggers, so I have to be sure this patch introduces something new. 1. Kernel structures sent to user space? Absolutely not. This is internal dcache manipulation. No `copy_to_user`, netlink, or ioctl calls here. We're staying entirely within the kernel's VFS/NFS layers. 2. Conditional logic based on potentially uninitialized data? All local variables are initialized before use, as stated above. There are no branches that depend on uninitialized variables, I see the assignments. 3. Complex data structures, uninitialized fields potentially read? `d_alloc_trylock` and `d_duplicate` should properly allocate and initialize dentries (using `__d_alloc`, which zeroes the dentry). I don't see any uninitialized fields being left to be read. 4. Bounds checks exposing uninitialized memory? No, the patch doesn't loosen bounds checks to expose uninitialized data. What types of bugs could this patch introduce? There's the potential for: * Error handling, especially if `d_duplicate` fails (returns an error pointer, which the original code might have missed), causing a potential dereference which KASAN/page fault will catch. * Dcache reference counting problems (use-after-free, missing `dput`, extra `dput`). KASAN and refcount checkers should catch this. * Dcache locking/race conditions with parallel lookups, which LOCKDEP or KASAN would detect. * Invalidation issues with the `write_seqcount_invalidate` synchronization. None of these directly represent uninitialized memory bugs or kernel-to-user info-leaks. Therefore, given my expert analysis of this patch, I conclude that KMSAN isn't justified. The patch primarily touches dcache management, which is already scrutinized by KASAN, LOCKDEP, and standard kernel debugging tools. My recommendation is `NeedsKMSAN=false`. Let's use `set-results`.
80/3	2026/09/27 17:45	tool	set-results	0m Args: { "KMSANReasoning": "The patch series modifies NFS dcache and lookup management functions (in fs/nfs/dir.c, nfs4proc.c, and unlink.c), adopting helpers such as d_alloc_trylock() and d_duplicate(), adjusting negative dentry revalidation flags (LOOKUP_OPEN), and refining dentry locking and lifecycle handling during atomic_open, link, rename, and sillyrename.\n\nThese changes deal strictly with VFS/NFS dentry lifecycle, synchronization, and error paths. The potential bugs in this code include concurrency/locking bugs, reference counting discrepancies, or invalid pointer dereferences (e.g., checking !dentry instead of IS_ERR(dentry) for d_duplicate()), all of which are caught by KASAN, LOCKDEP, or general kernel assertions.\n\nThe patch does not introduce any uninitialized stack or heap allocations, does not branch on uninitialized variables, and does not expose uninitialized kernel memory or padding to user space. Therefore, a dedicated KMSAN fuzzing session is not warranted.", "NeedsKMSAN": false } Results: { "KMSANReasoning": "The patch series modifies NFS dcache and lookup management functions (in fs/nfs/dir.c, nfs4proc.c, and unlink.c), adopting helpers such as d_alloc_trylock() and d_duplicate(), adjusting negative dentry revalidation flags (LOOKUP_OPEN), and refining dentry locking and lifecycle handling during atomic_open, link, rename, and sillyrename.\n\nThese changes deal strictly with VFS/NFS dentry lifecycle, synchronization, and error paths. The potential bugs in this code include concurrency/locking bugs, reference counting discrepancies, or invalid pointer dereferences (e.g., checking !dentry instead of IS_ERR(dentry) for d_duplicate()), all of which are caught by KASAN, LOCKDEP, or general kernel assertions.\n\nThe patch does not introduce any uninitialized stack or heap allocations, does not branch on uninitialized variables, and does not expose uninitialized kernel memory or padding to user space. Therefore, a dedicated KMSAN fuzzing session is not warranted.", "NeedsKMSAN": false }

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