[moderation] [fs?] KCSAN: data-race in __dentry_kill / lookup_fast (12)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7758b206117d Merge tag 'tracefs-v6.12-rc6' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1630df40580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8028551073794907
dashboard link: https://syzkaller.appspot.com/bug?extid=cc0d7c280a30e1e2e347
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [bra...@kernel.org ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1ee9943bd133/disk-7758b206.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9edb15a0c4b5/vmlinux-7758b206.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a602adbca7b6/bzImage-7758b206.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cc0d7c...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __dentry_kill / lookup_fast

read-write to 0xffff888119186600 of 4 bytes by task 23188 on cpu 0:
dentry_unlist fs/dcache.c:560 [inline]
__dentry_kill+0x22e/0x4c0 fs/dcache.c:629
dput+0x5c/0xd0 fs/dcache.c:857
do_unlinkat+0x257/0x4c0 fs/namei.c:4536
__do_sys_unlink fs/namei.c:4581 [inline]
__se_sys_unlink fs/namei.c:4579 [inline]
__x64_sys_unlink+0x2e/0x40 fs/namei.c:4579
x64_sys_call+0x280f/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:88
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888119186600 of 4 bytes by task 3015 on cpu 1:
d_revalidate fs/namei.c:867 [inline]
lookup_fast+0xd9/0x2a0 fs/namei.c:1681
walk_component+0x3f/0x230 fs/namei.c:2049
lookup_last fs/namei.c:2556 [inline]
path_lookupat+0x10a/0x2b0 fs/namei.c:2580
filename_lookup+0x127/0x300 fs/namei.c:2609
do_readlinkat+0x89/0x210 fs/stat.c:537
__do_sys_readlink fs/stat.c:574 [inline]
__se_sys_readlink fs/stat.c:571 [inline]
__x64_sys_readlink+0x47/0x60 fs/stat.c:571
x64_sys_call+0x13c3/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:90
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00600008 -> 0x00008008

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3015 Comm: udevd Not tainted 6.12.0-rc6-syzkaller-00099-g7758b206117d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.