[moderation] [fs?] KCSAN: data-race in __dentry_kill / __dentry_kill (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5189dafa4cf9 Merge tag 'nfsd-6.11-1' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12aac96d980000
kernel config: https://syzkaller.appspot.com/x/.config?x=cb57e6ebf675f9d2
dashboard link: https://syzkaller.appspot.com/bug?extid=34019d184c3556865841
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/5cc1a3a50a1f/disk-5189dafa.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/00e1812dbd03/vmlinux-5189dafa.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b15bac66be14/bzImage-5189dafa.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+34019d...@syzkaller.appspotmail.com

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

write to 0xffff8881069ccb40 of 4 bytes by task 7223 on cpu 1:
d_lru_del fs/dcache.c:444 [inline]
__dentry_kill+0xa3/0x4c0 fs/dcache.c:605
dput+0x5c/0xd0 fs/dcache.c:852
lookup_fast+0x25c/0x2a0 fs/namei.c:1684
walk_component fs/namei.c:2035 [inline]
link_path_walk+0x464/0x820 fs/namei.c:2404
path_openat+0x1aa/0x1f10 fs/namei.c:3882
do_filp_open+0xf7/0x200 fs/namei.c:3913
do_sys_openat2+0xab/0x120 fs/open.c:1416
do_sys_open fs/open.c:1431 [inline]
__do_sys_openat fs/open.c:1447 [inline]
__se_sys_openat fs/open.c:1442 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1442
x64_sys_call+0x1025/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:258
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 0xffff8881069ccb40 of 4 bytes by task 3534 on cpu 0:
dentry_unlist fs/dcache.c:580 [inline]
__dentry_kill+0x2af/0x4c0 fs/dcache.c:624
dput+0x5c/0xd0 fs/dcache.c:852
lookup_fast+0x25c/0x2a0 fs/namei.c:1684
walk_component fs/namei.c:2035 [inline]
link_path_walk+0x464/0x820 fs/namei.c:2404
path_openat+0x1aa/0x1f10 fs/namei.c:3882
do_filp_open+0xf7/0x200 fs/namei.c:3913
do_sys_openat2+0xab/0x120 fs/open.c:1416
do_sys_open fs/open.c:1431 [inline]
__do_sys_openat fs/open.c:1447 [inline]
__se_sys_openat fs/open.c:1442 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1442
x64_sys_call+0x1025/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:258
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: 0x00280004 -> 0x00000004

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3534 Comm: udevd Not tainted 6.11.0-rc2-syzkaller-00257-g5189dafa4cf9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
==================================================================
udevd[3534]: inotify_add_watch(7, /dev/loop2p1, 10) failed: No such file or directory
udevd[3534]: inotify_add_watch(7, /dev/loop2p1, 10) failed: No such file or directory
udevd[3534]: inotify_add_watch(7, /dev/loop2p1, 10) failed: No such file or directory


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[syzbot]

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