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KCSAN: data-race in __dentry_kill / __dentry_kill (7)

Status: moderation: reported on 2026/02/02 12:42
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+32c4ce311ae1ea106e44@syzkaller.appspotmail.com
First crash: 112d, last: 2d13h
▶ ▼ ✨ AI Jobs (4)
ID Workflow Result Correct Bug Created Started Finished Revision Error
4491a883-17f6-4d8e-8ca5-d3d2f4e7a547 assessment-security 💥 KCSAN: data-race in __dentry_kill / __dentry_kill (7) 2026/05/15 05:37 2026/05/15 05:37 2026/05/15 05:38 6ccb967e465e832a7bfd7a116ad00d52a0923a5d failed to run ["git" "pull" "origin" "HEAD" "--depth=1" "--allow-unrelated-histories"]: exit status 128 From /app/workdir/repo/linux * branch HEAD -> FETCH_HEAD Updating files: 19% (17935/93693) Updating files: 20% (18739/93693) Updating files: 21% (19676/93693) Updating files: 22% (20613/93693) Updating files: 23% (21550/93693) Updating files: 24% (22487/93693) error: unable to write file arch/parisc/include/asm/hardirq.h error: unable to write file arch/parisc/include/asm/hardware.h error: unable to write file arch/parisc/include/asm/hash.h error: unable to write file arch/parisc/include/asm/hugetlb.h error: unable to write file arch/parisc/include/asm/io.h error: unable to write file arch/parisc/include/asm/irq.h error: unable to write file arch/parisc/include/asm/irqflags.h error: unable to write file arch/parisc/include/asm/jump_label.h error: unable to write file arch/parisc/include/asm/kbdleds.h error: unable to write file arch/parisc/include/asm/kexec.h error: unable to write file arch/parisc/include/asm/kfence.h error: unable to write file arch/parisc/include/asm/kgdb.h error: unable to write file arch/parisc/include/asm/kprobes.h error: unable to write file arch/parisc/include/asm/ldcw.h error: unable to write file arch/parisc/include/asm/led.h error: unable to write file arch/parisc/include/asm/linkage.h error: unable to write file arch/parisc/include/asm/mman.h error: unable to write file arch/parisc/include/asm/mmu.h error: unable to write file arch/parisc/include/asm/mmu_context.h error: unable to write file arch/parisc/include/asm/mmzone.h error: unable to write file arch/parisc/include/asm/module.h error: unable to write file arch/parisc/include/asm/page.h error: unable to write file arch/parisc/include/asm/parisc-device.h error: unable to write file arch/parisc/include/asm/parport.h error: unable to write file arch/parisc/include/asm/pci.h error: unable to write file arch/parisc/include/asm/pdc.h error: unable to write file arch/parisc/include/asm/pdc_chassis.h error: unable to write file arch/parisc/include/asm/pdcpat.h error: unable to write file arch/parisc/include/asm/perf.h error: unable to write file arch/parisc/include/asm/perf_event.h error: unable to write file arch/parisc/include/asm/pgalloc.h error: unable to write file arch/parisc/include/asm/pgtable.h error: unable to write file arch/parisc/include/asm/prefetch.h error: unable to write file arch/parisc/include/asm/processor.h error: unable to write file arch/parisc/include/asm/psw.h error: unable to write file arch/parisc/include/asm/ptrace.h error: unable to write file arch/parisc/include/asm/ropes.h error: unable to write file arch/parisc/include/asm/rt_sigframe.h error: unable to write file arch/parisc/include/asm/runway.h error: unable to write file arch/parisc/include/asm/seccomp.h error: unable to write file arch/parisc/include/asm/sections.h error: unable to write file arch/parisc/include/asm/serial.h error: unable to write file arch/parisc/include/asm/shmparam.h error: unable to write file arch/parisc/include/asm/signal.h error: unable to write file arch/parisc/include/asm/smp.h error: unable to write file arch/parisc/include/asm/socket.h error: unable to write file arch/parisc/include/asm/sparsemem.h error: unable to write file arch/parisc/include/asm/special_insns.h error: unable to write file arch/parisc/include/asm/spinlock.h error: unable to write file arch/parisc/include/asm/spinlock_types.h error: unable to write file arch/parisc/include/asm/string.h error: unable to write file arch/parisc/include/asm/superio.h error: unable to write file arch/parisc/include/asm/switch_to.h error: unable to write file arch/parisc/include/asm/syscall.h error: unable to write file arch/parisc/include/asm/text-patching.h error: unable to write file arch/parisc/include/asm/thread_info.h error: unable to write file arch/parisc/include/asm/timex.h error: unable to write file arch/parisc/include/asm/tlb.h error: unable to write file arch/parisc/include/asm/tlbflush.h error: unable to write file arch/parisc/include/asm/topo
1fc03653-f781-4f9b-88b9-0764266a73d2 repro ❓ KCSAN: data-race in __dentry_kill / __dentry_kill (7) 2026/03/07 03:29 2026/03/07 03:29 2026/03/07 03:37 31e9c887f7dc24e04b3ca70d0d54fc34141844b0
982b89e5-2f52-49a5-a022-9678d450ee0d assessment-kcsan Benign: ✅ Confident: ✅ ❓ KCSAN: data-race in __dentry_kill / __dentry_kill (7) 2026/02/02 12:41 2026/02/02 12:41 2026/02/02 12:55 2186dcabcd743737b50c1a9f99a8bf0d3a5a7914
93880a73-eb05-473c-9a94-3f1f0d0a66b5 assessment-kcsan Benign: ✅ Confident: ✅ ❓ KCSAN: data-race in __dentry_kill / __dentry_kill (7) 2026/02/02 12:41 2026/02/02 12:41 2026/02/02 13:10 63a5f77ffe6c631f8781efb082e741722cdf8c6a+
▶ ▼ Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __dentry_kill / __dentry_kill (6) fs 6 7 275d 345d 0/29 auto-obsoleted due to no activity on 2025/10/18 15:44
upstream KCSAN: data-race in __dentry_kill / __dentry_kill (2) fs 6 1 711d 711d 0/29 auto-obsoleted due to no activity on 2024/07/18 14:41
upstream KCSAN: data-race in __dentry_kill / __dentry_kill (3) fs 6 1 652d 652d 0/29 auto-obsoleted due to no activity on 2024/09/15 09:01
upstream KCSAN: data-race in __dentry_kill / __dentry_kill (5) fs 6 1 514d 514d 0/29 auto-obsoleted due to no activity on 2025/02/21 02:11
upstream KCSAN: data-race in __dentry_kill / __dentry_kill (4) fs 6 2 575d 581d 0/29 auto-obsoleted due to no activity on 2024/12/22 05:35
upstream KCSAN: data-race in __dentry_kill / __dentry_kill fs 6 1 775d 775d 0/29 auto-obsoleted due to no activity on 2024/05/15 11:32

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __dentry_kill / __dentry_kill

write to 0xffff88811a7acc00 of 4 bytes by task 2983 on cpu 1:
 d_lru_del fs/dcache.c:513 [inline]
 __dentry_kill+0xab/0x4d0 fs/dcache.c:713
 finish_dput+0x2b/0x200 fs/dcache.c:927
 dput+0x52/0x60 fs/dcache.c:976
 lookup_fast+0x29e/0x320 fs/namei.c:1881
 walk_component fs/namei.c:2274 [inline]
 lookup_last fs/namei.c:2785 [inline]
 path_lookupat+0x15c/0x500 fs/namei.c:2809
 filename_lookup+0x190/0x390 fs/namei.c:2838
 do_readlinkat+0x74/0x2f0 fs/stat.c:571
 __do_sys_readlink fs/stat.c:605 [inline]
 __se_sys_readlink fs/stat.c:602 [inline]
 __x64_sys_readlink+0x47/0x60 fs/stat.c:602
 x64_sys_call+0x2b51/0x3020 arch/x86/include/generated/asm/syscalls_64.h:90
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811a7acc00 of 4 bytes by task 16474 on cpu 0:
 dentry_unlist fs/dcache.c:688 [inline]
 __dentry_kill+0x28d/0x4d0 fs/dcache.c:732
 finish_dput+0x2b/0x200 fs/dcache.c:927
 dput+0x52/0x60 fs/dcache.c:976
 lookup_fast+0x29e/0x320 fs/namei.c:1881
 walk_component fs/namei.c:2274 [inline]
 lookup_last fs/namei.c:2785 [inline]
 path_lookupat+0x15c/0x500 fs/namei.c:2809
 filename_lookup+0x190/0x390 fs/namei.c:2838
 vfs_statx+0x96/0x170 fs/stat.c:353
 vfs_fstatat+0x118/0x170 fs/stat.c:373
 __do_sys_newfstatat fs/stat.c:538 [inline]
 __se_sys_newfstatat+0x55/0x3e0 fs/stat.c:532
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:532
 x64_sys_call+0x2c64/0x3020 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00140004 -> 0x00000004

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 16474 Comm: udevd Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
==================================================================

Crashes (12):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/23 05:16 upstream 79bd2dded182 c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __dentry_kill / __dentry_kill
2026/05/22 23:23 upstream 45255ea1ca09 5f091fcc .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __dentry_kill / __dentry_kill
2026/05/09 18:04 upstream 27a26ccfd528 29233ece .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __dentry_kill / __dentry_kill
2026/05/06 00:25 upstream 9207d47f966b 26da2c66 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __dentry_kill / __dentry_kill
2026/05/03 04:05 upstream 66edb901bf87 a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __dentry_kill / __dentry_kill
2026/03/26 20:54 upstream 0138af2472df 766b6434 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __dentry_kill / __dentry_kill
2026/03/19 05:58 upstream 8a30aeb0d1b4 0199f9a1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __dentry_kill / __dentry_kill
2026/03/07 00:28 upstream 651690480a96 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __dentry_kill / __dentry_kill
2026/02/22 08:38 upstream fa5c82f4d2bb 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __dentry_kill / __dentry_kill
2026/02/20 23:52 upstream a95f71ad3e2e 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __dentry_kill / __dentry_kill
2026/02/08 02:37 upstream e7aa57247700 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __dentry_kill / __dentry_kill
2026/02/02 12:41 upstream 18f7fcd5e69a 018ebef2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __dentry_kill / __dentry_kill
* Struck through repros no longer work on HEAD.