[moderation] [fs?] KCSAN: data-race in d_invalidate / fast_dput (7)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0e0611827f33 Merge tag 'pull-fixes' of gitolite.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1336a986580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e09e0406a0da08d4
dashboard link: https://syzkaller.appspot.com/bug?extid=cf4db856a13fb368457b
compiler: Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
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/0cf6cf9bca9f/disk-0e061182.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/aa6c78f55bcb/vmlinux-0e061182.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8546555a824a/bzImage-0e061182.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cf4db8...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in d_invalidate / fast_dput

write to 0xffff88811afd60d0 of 8 bytes by task 25476 on cpu 1:
__d_drop fs/dcache.c:578 [inline]
d_invalidate+0x5b/0x1f0 fs/dcache.c:1863
lookup_open fs/namei.c:4435 [inline]
open_last_lookups fs/namei.c:4608 [inline]
path_openat+0x13f3/0x2000 fs/namei.c:4856
do_file_open+0x16c/0x290 fs/namei.c:4888
do_sys_openat2+0xa0/0x130 fs/open.c:1395
do_sys_open fs/open.c:1401 [inline]
__do_sys_openat fs/open.c:1417 [inline]
__se_sys_openat fs/open.c:1412 [inline]
__x64_sys_openat+0xf2/0x120 fs/open.c:1412
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+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811afd60d0 of 8 bytes by task 25490 on cpu 0:
hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
d_unhashed include/linux/dcache.h:396 [inline]
retain_dentry fs/dcache.c:872 [inline]
fast_dput+0x64/0x2e0 fs/dcache.c:971
dput+0x1f/0x50 fs/dcache.c:1040
end_dirop fs/namei.c:2956 [inline]
end_creating include/linux/namei.h:117 [inline]
vfs_mkdir+0xb4/0x3e0 fs/namei.c:5284
filename_mkdirat+0x138/0x300 fs/namei.c:5305
__do_sys_mkdir fs/namei.c:5332 [inline]
__se_sys_mkdir+0x31/0xf0 fs/namei.c:5329
__x64_sys_mkdir+0x31/0x40 fs/namei.c:5329
x64_sys_call+0x2eab/0x3020 arch/x86/include/generated/asm/syscalls_64.h:84
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: 0xffff888237b12548 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 25490 Comm: syz.6.3476 Tainted: G W syzkaller #0 PREEMPT(lazy)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
==================================================================


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