[moderation] [fs?] KCSAN: data-race in drop_nlink / generic_fillattr (6)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 86c4d58a99ab Merge tag 'for-linus-iommufd' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1417bdc7e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=fba13658254d98c5
dashboard link: https://syzkaller.appspot.com/bug?extid=9dc2ccbd936c49eb2ec0
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/ea096ab752ff/disk-86c4d58a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1627df201d3b/vmlinux-86c4d58a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/70af53538f2a/bzImage-86c4d58a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9dc2cc...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in drop_nlink / generic_fillattr

write to 0xffff88813a6603b8 of 4 bytes by task 24 on cpu 1:
drop_nlink+0x3b/0x90 fs/inode.c:332
shmem_unlink+0x169/0x180 mm/shmem.c:3370
vfs_unlink+0x261/0x3e0 fs/namei.c:4334
handle_remove drivers/base/devtmpfs.c:339 [inline]
handle drivers/base/devtmpfs.c:386 [inline]
devtmpfs_work_loop+0x85f/0x8e0 drivers/base/devtmpfs.c:399
devtmpfsd+0x43/0x50 drivers/base/devtmpfs.c:441
kthread+0x1d7/0x210 kernel/kthread.c:388
ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242

read to 0xffff88813a6603b8 of 4 bytes by task 3188 on cpu 0:
generic_fillattr+0xf8/0x2f0 fs/stat.c:55
shmem_getattr+0x17b/0x200 mm/shmem.c:1139
vfs_getattr_nosec fs/stat.c:135 [inline]
vfs_getattr+0x198/0x1e0 fs/stat.c:176
vfs_statx+0x140/0x320 fs/stat.c:248
vfs_fstatat+0xcd/0x100 fs/stat.c:304
__do_sys_newfstatat fs/stat.c:468 [inline]
__se_sys_newfstatat+0x58/0x260 fs/stat.c:462
__x64_sys_newfstatat+0x55/0x60 fs/stat.c:462
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000001 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3188 Comm: udevd Not tainted 6.7.0-syzkaller-11889-g86c4d58a99ab #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
==================================================================
udevd[3188]: inotify_add_watch(7, /dev/loop11, 10) failed: No such file or directory
udevd[3188]: inotify_add_watch(7, /dev/loop11, 10) failed: No such file or directory
udevd[3188]: inotify_add_watch(7, /dev/loop11, 10) failed: No such file or directory
udevd[3188]: inotify_add_watch(7, /dev/loop11, 10) failed: No such file or directory
udevd[3188]: inotify_add_watch(7, /dev/loop11, 10) failed: No such file or directory
udevd[3188]: inotify_add_watch(7, /dev/loop11, 10) failed: No such file or directory
udevd[3188]: inotify_add_watch(7, /dev/loop11, 10) failed: No such file or directory
udevd[3188]: inotify_add_watch(7, /dev/loop11, 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.