[moderation] [fs?] KCSAN: data-race in __dentry_kill / d_set_d_op (16)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9b6de136b5f0 Merge tag 'loongarch-fixes-6.7-1' of git://gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=120282cce80000
kernel config: https://syzkaller.appspot.com/x/.config?x=8c1151391aefc0c3
dashboard link: https://syzkaller.appspot.com/bug?extid=bb35d724c36857653564
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [amir...@gmail.com ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/66e487a84769/disk-9b6de136.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/68701b15ec8c/vmlinux-9b6de136.xz
kernel image: https://storage.googleapis.com/syzbot-assets/78c7cba56794/bzImage-9b6de136.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bb35d7...@syzkaller.appspotmail.com

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

read-write to 0xffff8881340ff000 of 4 bytes by task 11897 on cpu 0:
d_set_d_op+0x150/0x1e0 fs/dcache.c:1935
simple_lookup+0x7c/0xa0 fs/libfs.c:78
__lookup_slow+0x17a/0x230 fs/namei.c:1694
lookup_slow+0x3c/0x60 fs/namei.c:1711
walk_component+0x1ec/0x230 fs/namei.c:2002
lookup_last fs/namei.c:2459 [inline]
path_lookupat+0x10a/0x2a0 fs/namei.c:2483
filename_lookup+0x126/0x300 fs/namei.c:2512
user_path_at_empty+0x42/0x110 fs/namei.c:2911
user_path_at include/linux/namei.h:57 [inline]
inotify_find_inode fs/notify/inotify/inotify_user.c:378 [inline]
__do_sys_inotify_add_watch fs/notify/inotify/inotify_user.c:777 [inline]
__se_sys_inotify_add_watch+0x119/0x820 fs/notify/inotify/inotify_user.c:730
__x64_sys_inotify_add_watch+0x43/0x50 fs/notify/inotify/inotify_user.c:730
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff8881340ff000 of 4 bytes by task 4613 on cpu 1:
dentry_unlist fs/dcache.c:572 [inline]
__dentry_kill+0x237/0x4a0 fs/dcache.c:603
dentry_kill+0x8d/0x1e0
dput+0x118/0x1f0 fs/dcache.c:913
handle_mounts fs/namei.c:1555 [inline]
step_into+0x21a/0x800 fs/namei.c:1840
walk_component+0x164/0x230 fs/namei.c:2008
lookup_last fs/namei.c:2459 [inline]
path_lookupat+0x10a/0x2a0 fs/namei.c:2483
filename_lookup+0x126/0x300 fs/namei.c:2512
vfs_statx+0xa2/0x430 fs/stat.c:240
vfs_fstatat+0xcd/0x100 fs/stat.c:295
__do_sys_newfstatat fs/stat.c:459 [inline]
__se_sys_newfstatat+0x58/0x260 fs/stat.c:453
__x64_sys_newfstatat+0x55/0x60 fs/stat.c:453
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x10000000 -> 0x00000008

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4613 Comm: udevd Tainted: G W 6.7.0-rc2-syzkaller-00029-g9b6de136b5f0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
==================================================================
udevd[4613]: inotify_add_watch(7, /dev/loop2p1, 10) failed: No such file or directory
udevd[4613]: inotify_add_watch(7, /dev/loop2p1, 10) failed: No such file or directory
blk_print_req_error: 4 callbacks suppressed
I/O error, dev loop4, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 2
udevd[4613]: inotify_add_watch(7, /dev/loop2p1, 10) failed: No such file or directory
I/O error, dev loop2, sector 8064 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 2
udevd[4613]: inotify_add_watch(7, /dev/loop3p1, 10) failed: No such file or directory


---
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.