syzbot


KCSAN: data-race in d_invalidate / fast_dput (6)

Status: moderation: reported on 2025/12/11 05:06
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+70bb80293ee8e5c119bf@syzkaller.appspotmail.com
First crash: 48d, last: 7d08h
Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in d_invalidate / fast_dput (4) fs 6 4 444d 484d 0/29 auto-obsoleted due to no activity on 2025/01/05 15:13
upstream KCSAN: data-race in d_invalidate / fast_dput (2) fs 6 1 603d 603d 0/29 auto-obsoleted due to no activity on 2024/07/09 14:03
upstream KCSAN: data-race in d_invalidate / fast_dput (5) fs 6 4 117d 201d 0/29 auto-obsoleted due to no activity on 2025/11/27 20:51
upstream KCSAN: data-race in d_invalidate / fast_dput (3) fs 6 2 529d 539d 0/29 auto-obsoleted due to no activity on 2024/09/21 03:13
upstream KCSAN: data-race in d_invalidate / fast_dput fs 6 4 676d 723d 0/29 auto-obsoleted due to no activity on 2024/04/27 15:57

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

write to 0xffff888110ac1cd0 of 8 bytes by task 10725 on cpu 1:
 __d_drop fs/dcache.c:576 [inline]
 d_invalidate+0x5b/0x200 fs/dcache.c:1691
 lookup_open fs/namei.c:4378 [inline]
 open_last_lookups fs/namei.c:4549 [inline]
 path_openat+0x1670/0x23c0 fs/namei.c:4793
 do_filp_open+0x15d/0x280 fs/namei.c:4823
 do_sys_openat2+0xa6/0x150 fs/open.c:1430
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_openat fs/open.c:1452 [inline]
 __se_sys_openat fs/open.c:1447 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1447
 x64_sys_call+0x2b07/0x3000 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888110ac1cd0 of 8 bytes by task 10721 on cpu 0:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:366 [inline]
 retain_dentry fs/dcache.c:753 [inline]
 fast_dput+0x5f/0x2c0 fs/dcache.c:849
 dput+0x24/0x60 fs/dcache.c:924
 end_dirop fs/namei.c:2898 [inline]
 end_creating include/linux/namei.h:126 [inline]
 end_creating_path fs/namei.c:4931 [inline]
 do_mknodat+0x2c2/0x4f0 fs/namei.c:5062
 __do_sys_mknodat fs/namei.c:5080 [inline]
 __se_sys_mknodat fs/namei.c:5077 [inline]
 __x64_sys_mknodat+0x5e/0x70 fs/namei.c:5077
 x64_sys_call+0x2b33/0x3000 arch/x86/include/generated/asm/syscalls_64.h:260
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff88823741a658 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 10721 Comm: syz.8.2163 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/21 09:51 upstream 6c790212c588 6f1aa2f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_invalidate / fast_dput
2026/01/21 09:49 upstream 6c790212c588 6f1aa2f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_invalidate / fast_dput
2026/01/21 09:48 upstream 6c790212c588 6f1aa2f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_invalidate / fast_dput
2025/12/11 05:05 upstream 0048fbb4011e d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_invalidate / fast_dput
* Struck through repros no longer work on HEAD.