KCSAN: data-race in __d_instantiate / path_openat (2)

Status: auto-obsoleted due to no activity on 2026/02/06 09:23
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+63e0988e071251a5d8e9@syzkaller.appspotmail.com
First crash: 285d, last: 244d
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
a38b48d7 assessment-kcsan Benign: ✅ Confident: ✅ ❓ KCSAN: data-race in __d_instantiate / path_openat (2) 2026/01/14 18:43 2026/01/14 18:43 2026/01/14 19:07 a9d6a792
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __d_instantiate / path_openat (3) prio:low fs 6 2 105d 120d 0/29 auto-obsoleted due to no activity on 2026/06/25 07:42
upstream KCSAN: data-race in __d_instantiate / path_openat fs 6 1 436d 436d 0/29 auto-obsoleted due to no activity on 2025/07/28 17:11

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

write to 0xffff888106133870 of 8 bytes by task 15722 on cpu 1:
 __d_set_inode_and_type fs/dcache.c:407 [inline]
 __d_instantiate+0x1db/0x390 fs/dcache.c:1975
 d_make_persistent+0x78/0x110 fs/dcache.c:2793
 shmem_mknod+0x15f/0x170 mm/shmem.c:3892
 shmem_create+0x34/0x50 mm/shmem.c:3943
 lookup_open fs/namei.c:4440 [inline]
 open_last_lookups fs/namei.c:4540 [inline]
 path_openat+0x1115/0x23b0 fs/namei.c:4784
 do_filp_open+0x109/0x230 fs/namei.c:4814
 do_sys_openat2+0xa6/0x150 fs/open.c:1430
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_open fs/open.c:1444 [inline]
 __se_sys_open fs/open.c:1440 [inline]
 __x64_sys_open+0xe6/0x110 fs/open.c:1440
 x64_sys_call+0x166f/0x3000 arch/x86/include/generated/asm/syscalls_64.h:3
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888106133870 of 8 bytes by task 15723 on cpu 0:
 lookup_fast_for_open fs/namei.c:4483 [inline]
 open_last_lookups fs/namei.c:4511 [inline]
 path_openat+0x443/0x23b0 fs/namei.c:4784
 do_filp_open+0x109/0x230 fs/namei.c:4814
 do_sys_openat2+0xa6/0x150 fs/open.c:1430
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_open fs/open.c:1444 [inline]
 __se_sys_open fs/open.c:1440 [inline]
 __x64_sys_open+0xe6/0x110 fs/open.c:1440
 x64_sys_call+0x166f/0x3000 arch/x86/include/generated/asm/syscalls_64.h:3
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff88811e5897c0

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 15723 Comm: syz.7.2908 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 (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/12 09:23 upstream d358e5254674 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __d_instantiate / path_openat
2025/11/01 01:40 upstream 58fdd8484c05 2c50b6a9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __d_instantiate / path_openat
* Struck through repros no longer work on HEAD.