syzbot


KCSAN: data-race in dentry_unlink_inode / path_openat (4)

Status: moderation: reported on 2026/07/03 08:35
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+6475b58100630a5b37d9@syzkaller.appspotmail.com
First crash: 19h39m, last: 19h39m
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
321acdbd-07c1-44a5-87cb-261028ac994f assessment-kcsan 💥 KCSAN: data-race in dentry_unlink_inode / path_openat (4) 2026/07/03 08:35 2026/07/03 08:35 2026/07/03 08:58 93f579545ae410f5bccfa141d2e7bf03178f036c
 (RECITATION)
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in dentry_unlink_inode / path_openat (3) prio:low fs 6 1 57d 57d 0/29 auto-obsoleted due to no activity on 2026/07/03 01:59
upstream KCSAN: data-race in dentry_unlink_inode / path_openat (2) fs 6 2 132d 136d 0/29 auto-obsoleted due to no activity on 2026/04/19 00:21
upstream KCSAN: data-race in dentry_unlink_inode / path_openat fs 6 1 197d 197d 0/29 auto-obsoleted due to no activity on 2026/02/13 00:48

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

write to 0xffff88811ac419f0 of 8 bytes by task 5826 on cpu 0:
 __d_clear_type_and_inode fs/dcache.c:420 [inline]
 dentry_unlink_inode+0x65/0x260 fs/dcache.c:464
 dentry_kill+0x184/0x500 fs/dcache.c:826
 finish_dput+0x16/0x1d0 fs/dcache.c:1001
 dput+0x48/0x50 fs/dcache.c:1042
 end_renaming fs/namei.c:4122 [inline]
 filename_renameat2+0x478/0x6a0 fs/namei.c:6190
 __do_sys_rename fs/namei.c:6232 [inline]
 __se_sys_rename+0x4a/0x1c0 fs/namei.c:6228
 __x64_sys_rename+0x31/0x40 fs/namei.c:6228
 x64_sys_call+0x2b3/0x3020 arch/x86/include/generated/asm/syscalls_64.h:83
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811ac419f0 of 8 bytes by task 3287 on cpu 1:
 step_into fs/namei.c:2141 [inline]
 open_last_lookups fs/namei.c:4643 [inline]
 path_openat+0x649/0x2000 fs/namei.c:4856
 do_file_open+0x16c/0x290 fs/namei.c:4888
 do_sys_openat2+0xa0/0x130 fs/open.c:1368
 do_sys_open fs/open.c:1374 [inline]
 __do_sys_openat fs/open.c:1390 [inline]
 __se_sys_openat fs/open.c:1385 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1385
 x64_sys_call+0x1e39/0x3020 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff88811f399bb0 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3287 Comm: udevd Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/03 08:35 upstream 51512e22efe8 58bf2096 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dentry_unlink_inode / path_openat
* Struck through repros no longer work on HEAD.