[moderation] [fs?] KCSAN: data-race in dentry_unlink_inode / path_openat (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fcee7d82f27d Merge tag 'net-7.1-rc3' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14181dce580000
kernel config: https://syzkaller.appspot.com/x/.config?x=2e40c0f41e01837e
dashboard link: https://syzkaller.appspot.com/bug?extid=fdbe96d95ed5185a602f
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/31910c967428/disk-fcee7d82.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6f44180a7937/vmlinux-fcee7d82.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5c0a47f18a08/bzImage-fcee7d82.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fdbe96...@syzkaller.appspotmail.com

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

write to 0xffff8881005e1e70 of 8 bytes by task 6072 on cpu 0:
__d_clear_type_and_inode fs/dcache.c:420 [inline]
dentry_unlink_inode+0x6a/0x290 fs/dcache.c:457
__dentry_kill+0x145/0x4d0 fs/dcache.c:718
finish_dput+0x2b/0x200 fs/dcache.c:927
dput+0x52/0x60 fs/dcache.c:976
end_renaming fs/namei.c:4124 [inline]
filename_renameat2+0x493/0x6e0 fs/namei.c:6174
__do_sys_rename fs/namei.c:6216 [inline]
__se_sys_rename+0x4a/0x1c0 fs/namei.c:6212
__x64_sys_rename+0x31/0x40 fs/namei.c:6212
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/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881005e1e70 of 8 bytes by task 6039 on cpu 1:
step_into fs/namei.c:2137 [inline]
open_last_lookups fs/namei.c:4646 [inline]
path_openat+0x65f/0x2050 fs/namei.c:4855
do_file_open+0x16c/0x290 fs/namei.c:4887
do_sys_openat2+0x94/0x130 fs/open.c:1364
do_sys_open fs/open.c:1370 [inline]
__do_sys_openat fs/open.c:1386 [inline]
__se_sys_openat fs/open.c:1381 [inline]
__x64_sys_openat+0xf2/0x120 fs/open.c:1381
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/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff88811b9e20b8 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 6039 Comm: udevd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
==================================================================


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