[moderation] [fs?] KCSAN: data-race in dentry_unlink_inode / path_openat (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d295082ea672 Merge tag 'spdx-7.0-rc1' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1559a95a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4c7a3cd4d19e835b
dashboard link: https://syzkaller.appspot.com/bug?extid=3f487494b21564066c20
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
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/98356c916efc/disk-d295082e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1bb89f4fd97a/vmlinux-d295082e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/87d64254210a/bzImage-d295082e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3f4874...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in dentry_unlink_inode / path_openat

write to 0xffff888107629db0 of 8 bytes by task 3365 on cpu 0:
__d_clear_type_and_inode fs/dcache.c:420 [inline]
dentry_unlink_inode+0x65/0x260 fs/dcache.c:457
__dentry_kill+0x13f/0x460 fs/dcache.c:670
finish_dput+0x2b/0x200 fs/dcache.c:879
dput+0x52/0x60 fs/dcache.c:928
end_renaming fs/namei.c:4096 [inline]
filename_renameat2+0x493/0x6e0 fs/namei.c:6146
__do_sys_rename fs/namei.c:6188 [inline]
__se_sys_rename+0x4a/0x1c0 fs/namei.c:6184
__x64_sys_rename+0x31/0x40 fs/namei.c:6184
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+0x12c/0x370 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888107629db0 of 8 bytes by task 4988 on cpu 1:
step_into fs/namei.c:2138 [inline]
open_last_lookups fs/namei.c:4618 [inline]
path_openat+0x65f/0x2050 fs/namei.c:4827
do_file_open+0x16c/0x290 fs/namei.c:4859
do_sys_openat2+0x94/0x130 fs/open.c:1366
do_sys_open fs/open.c:1372 [inline]
__do_sys_openat fs/open.c:1388 [inline]
__se_sys_openat fs/open.c:1383 [inline]
__x64_sys_openat+0xf2/0x120 fs/open.c:1383
x64_sys_call+0x1e39/0x3020 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff888113918938 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4988 Comm: udevd Tainted: G W syzkaller #0 PREEMPT(full)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================


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