KCSAN: data-race in d_lru_del / dentry_kill (2)

Status: moderation: reported on 2026/10/04 19:05
Subsystems: fs
Labels: race:benign
[Documentation on labels]
Reported-by: syzbot+e74549a899a4f360e328@syzkaller.appspotmail.com
First crash: 5h46m, last: 5h46m
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
07ec819a assessment-kcsan Benign: ✅ ❓ KCSAN: data-race in d_lru_del / dentry_kill (2) 2026/10/04 19:05 2026/10/04 19:05 2026/10/04 19:44 57bbd979
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in d_lru_del / dentry_kill race:benign prio:low fs 6 3 57d 104d 0/29 auto-obsoleted due to no activity on 2026/10/03 11:03

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

write to 0xffff8881059a7a80 of 4 bytes by task 2986 on cpu 1:
 d_lru_del+0x4c/0x100 fs/dcache.c:515
 dentry_kill+0x10a/0x500 fs/dcache.c:821
 finish_dput+0x16/0x1d0 fs/dcache.c:1001
 dput+0x48/0x50 fs/dcache.c:1042
 lookup_fast+0x29f/0x320 fs/namei.c:1886
 walk_component fs/namei.c:2278 [inline]
 lookup_last fs/namei.c:2789 [inline]
 path_lookupat+0x120/0x4c0 fs/namei.c:2813
 filename_lookup+0x18f/0x390 fs/namei.c:2842
 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+0x1d41/0x2550 arch/x86/include/generated/asm/syscalls_64.h:90
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881059a7a80 of 4 bytes by task 3530 on cpu 0:
 dentry_unlist fs/dcache.c:694 [inline]
 dentry_kill+0x2d3/0x500 fs/dcache.c:840
 finish_dput+0x16/0x1d0 fs/dcache.c:1001
 dput+0x48/0x50 fs/dcache.c:1042
 lookup_fast+0x29f/0x320 fs/namei.c:1886
 walk_component fs/namei.c:2278 [inline]
 lookup_last fs/namei.c:2789 [inline]
 path_lookupat+0x120/0x4c0 fs/namei.c:2813
 filename_lookup+0x18f/0x390 fs/namei.c:2842
 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+0xee6/0x2550 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00140004 -> 0x00000004

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3530 Comm: udevd Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/04 19:04 upstream 6addb4f38557 57bbd979 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_lru_del / dentry_kill
* Struck through repros no longer work on HEAD.