[moderation] [fs?] KCSAN: data-race in __dentry_kill / d_set_d_op (19)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9a6e8c7c3a02 Merge tag 'drm-fixes-2024-12-07' of https://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=165f58df980000
kernel config: https://syzkaller.appspot.com/x/.config?x=ff022027cd3a0001
dashboard link: https://syzkaller.appspot.com/bug?extid=a1d474ed61f16a434868
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/5ee8576e1a96/disk-9a6e8c7c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8ef3af2cd2ee/vmlinux-9a6e8c7c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ccae1dba9cd0/bzImage-9a6e8c7c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a1d474...@syzkaller.appspotmail.com

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

read-write to 0xffff88810693f840 of 4 bytes by task 4124 on cpu 1:
d_set_d_op+0x15b/0x1f0 fs/dcache.c:1818
simple_lookup+0x7c/0xa0 fs/libfs.c:79
lookup_open fs/namei.c:3627 [inline]
open_last_lookups fs/namei.c:3748 [inline]
path_openat+0xd40/0x1fa0 fs/namei.c:3984
do_filp_open+0x107/0x230 fs/namei.c:4014
do_sys_openat2+0xab/0x120 fs/open.c:1402
do_sys_open fs/open.c:1417 [inline]
__do_sys_openat fs/open.c:1433 [inline]
__se_sys_openat fs/open.c:1428 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1428
x64_sys_call+0x2b30/0x2dc0 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 0xffff88810693f840 of 4 bytes by task 3464 on cpu 0:
dentry_unlist fs/dcache.c:595 [inline]
__dentry_kill+0x2af/0x4c0 fs/dcache.c:639
dput+0x5c/0xd0 fs/dcache.c:867
handle_mounts fs/namei.c:1638 [inline]
step_into+0x21a/0x840 fs/namei.c:1950
open_last_lookups fs/namei.c:3775 [inline]
path_openat+0x1234/0x1fa0 fs/namei.c:3984
do_filp_open+0x107/0x230 fs/namei.c:4014
do_sys_openat2+0xab/0x120 fs/open.c:1402
do_sys_open fs/open.c:1417 [inline]
__do_sys_openat fs/open.c:1433 [inline]
__se_sys_openat fs/open.c:1428 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1428
x64_sys_call+0x2b30/0x2dc0 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: 0x10000000 -> 0x00000008

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3464 Comm: udevd Not tainted 6.13.0-rc1-syzkaller-00239-g9a6e8c7c3a02 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================


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[syzbot]

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