syzbot


upstream test error: KCSAN: data-race in dont_mount / lookup_fast (2)

Status: moderation: reported on 2025/09/12 22:02
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+a86385c461d30c745f1b@syzkaller.appspotmail.com
First crash: 3h36m, last: 3h36m
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream upstream test error: KCSAN: data-race in dont_mount / lookup_fast fs -1 2 88d 123d 0/29 auto-obsoleted due to no activity on 2025/08/11 09:20

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

read-write to 0xffff88810725f900 of 4 bytes by task 3975 on cpu 0:
 dont_mount+0x2a/0x40 include/linux/dcache.h:377
 vfs_unlink+0x28f/0x420 fs/namei.c:4588
 do_unlinkat+0x24e/0x480 fs/namei.c:4650
 __do_sys_unlink fs/namei.c:4696 [inline]
 __se_sys_unlink fs/namei.c:4694 [inline]
 __x64_sys_unlink+0x2e/0x40 fs/namei.c:4694
 x64_sys_call+0x2dc0/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:88
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810725f900 of 4 bytes by task 2993 on cpu 1:
 d_revalidate fs/namei.c:928 [inline]
 lookup_fast+0xf0/0x320 fs/namei.c:1756
 walk_component+0x3f/0x220 fs/namei.c:2125
 lookup_last fs/namei.c:2630 [inline]
 path_lookupat+0xfe/0x2a0 fs/namei.c:2654
 filename_lookup+0x147/0x340 fs/namei.c:2683
 do_readlinkat+0x7d/0x320 fs/stat.c:576
 __do_sys_readlink fs/stat.c:613 [inline]
 __se_sys_readlink fs/stat.c:610 [inline]
 __x64_sys_readlink+0x47/0x60 fs/stat.c:610
 x64_sys_call+0x28da/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:90
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00300080 -> 0x00004080

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 2993 Comm: udevd Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/12 22:01 upstream 22f20375f5b7 e2beed91 .config console log report [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce upstream test error: KCSAN: data-race in dont_mount / lookup_fast
* Struck through repros no longer work on HEAD.