[moderation] [fs?] KCSAN: data-race in drop_nlink / generic_fillattr (11)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0131b508c0e2 Merge tag 'ntfs-for-7.2-rc6' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12f36e32580000
kernel config: https://syzkaller.appspot.com/x/.config?x=84b3039e8461eef5
dashboard link: https://syzkaller.appspot.com/bug?extid=5ed997d7a0e87b2edabb
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
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/b49487fe5049/disk-0131b508.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/be72600c4e19/vmlinux-0131b508.xz
kernel image: https://storage.googleapis.com/syzbot-assets/02da1b692ee9/bzImage-0131b508.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5ed997...@syzkaller.appspotmail.com

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

write to 0xffff88818ce46f00 of 4 bytes by task 32681 on cpu 0:
drop_nlink+0x3d/0xa0 fs/inode.c:409
__simple_unlink fs/libfs.c:793 [inline]
simple_unlink+0x60/0x80 fs/libfs.c:807
shmem_unlink+0x12d/0x140 mm/shmem.c:3927
shmem_rename2+0x185/0x310 mm/shmem.c:4008
vfs_rename+0x963/0xac0 fs/namei.c:6074
filename_renameat2+0x3a4/0x6a0 fs/namei.c:6192
__do_sys_rename fs/namei.c:6236 [inline]
__se_sys_rename+0x4a/0x1c0 fs/namei.c:6232
__x64_sys_rename+0x31/0x40 fs/namei.c:6232
x64_sys_call+0x2b3/0x3020 arch/x86/include/generated/asm/syscalls_64.h:83
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88818ce46f00 of 4 bytes by task 24648 on cpu 1:
generic_fillattr+0xfc/0x340 fs/stat.c:91
shmem_getattr+0x181/0x200 mm/shmem.c:1312
vfs_getattr_nosec+0x146/0x1e0 fs/stat.c:213
vfs_getattr fs/stat.c:262 [inline]
vfs_fstat fs/stat.c:281 [inline]
__do_sys_newfstat fs/stat.c:551 [inline]
__se_sys_newfstat+0x96/0x460 fs/stat.c:546
__x64_sys_newfstat+0x31/0x40 fs/stat.c:546
x64_sys_call+0x2773/0x3020 arch/x86/include/generated/asm/syscalls_64.h:6
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000001 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 24648 Comm: udevd Tainted: G W syzkaller #0 PREEMPT(lazy)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
==================================================================
udevd[24648]: inotify_add_watch(7, /dev/loop9p23, 10) failed: No such file or directory


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