[moderation] [fs?] KCSAN: data-race in d_invalidate / fast_dput (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e32cde8d2bd7 Merge tag 'sched_ext-for-6.12-rc1-fixes-1' of..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=128e139f980000
kernel config: https://syzkaller.appspot.com/x/.config?x=13af6e9c27c7bbbf
dashboard link: https://syzkaller.appspot.com/bug?extid=ece4b976a38eaf570d93
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/e728901b4154/disk-e32cde8d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e662806fa232/vmlinux-e32cde8d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ed885d1a3f98/bzImage-e32cde8d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ece4b9...@syzkaller.appspotmail.com

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

write to 0xffff8881069136d0 of 8 bytes by task 3598 on cpu 0:
__d_drop fs/dcache.c:521 [inline]
d_invalidate+0x5c/0x1c0 fs/dcache.c:1597
lookup_fast+0x254/0x2a0 fs/namei.c:1697
walk_component fs/namei.c:2049 [inline]
link_path_walk+0x464/0x820 fs/namei.c:2418
path_openat+0x1af/0x1fa0 fs/namei.c:3929
do_filp_open+0xf7/0x200 fs/namei.c:3960
do_sys_openat2+0xab/0x120 fs/open.c:1415
do_sys_open fs/open.c:1430 [inline]
__do_sys_openat fs/open.c:1446 [inline]
__se_sys_openat fs/open.c:1441 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1441
x64_sys_call+0x1025/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881069136d0 of 8 bytes by task 4289 on cpu 1:
hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
d_unhashed include/linux/dcache.h:354 [inline]
retain_dentry fs/dcache.c:698 [inline]
fast_dput+0x65/0x2c0 fs/dcache.c:794
dput+0x24/0xd0 fs/dcache.c:851
handle_mounts fs/namei.c:1579 [inline]
step_into+0x21a/0x810 fs/namei.c:1891
walk_component fs/namei.c:2059 [inline]
link_path_walk+0x54c/0x820 fs/namei.c:2418
path_openat+0x1af/0x1fa0 fs/namei.c:3929
do_filp_open+0xf7/0x200 fs/namei.c:3960
do_sys_openat2+0xab/0x120 fs/open.c:1415
do_sys_open fs/open.c:1430 [inline]
__do_sys_openat fs/open.c:1446 [inline]
__se_sys_openat fs/open.c:1441 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1441
x64_sys_call+0x1025/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff888237963e88 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4289 Comm: udevd Not tainted 6.12.0-rc1-syzkaller-00031-ge32cde8d2bd7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.