[moderation] [fs?] KCSAN: data-race in d_alloc_parallel / d_set_d_op (10)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 2f91ff27b0ee Merge tag 'sound-6.12-rc2' of git://git.kerne..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1324d380580000
kernel config: https://syzkaller.appspot.com/x/.config?x=95098faba89c70c9
dashboard link: https://syzkaller.appspot.com/bug?extid=2c167a88c95ba9499bdb
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/14933c4ac457/disk-2f91ff27.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6725831fc1a1/vmlinux-2f91ff27.xz
kernel image: https://storage.googleapis.com/syzbot-assets/98d64e038e72/bzImage-2f91ff27.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2c167a...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in d_alloc_parallel / d_set_d_op

read-write to 0xffff888106ca06c0 of 4 bytes by task 5929 on cpu 1:
d_set_d_op+0xfb/0x1f0 fs/dcache.c:1804
proc_ns_instantiate fs/proc/namespaces.c:114 [inline]
proc_ns_dir_lookup+0x180/0x220 fs/proc/namespaces.c:172
lookup_open fs/namei.c:3573 [inline]
open_last_lookups fs/namei.c:3694 [inline]
path_openat+0xd40/0x1fa0 fs/namei.c:3930
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 0xffff888106ca06c0 of 4 bytes by task 5928 on cpu 0:
d_in_lookup include/linux/dcache.h:378 [inline]
d_wait_lookup fs/dcache.c:2459 [inline]
d_alloc_parallel+0x60b/0xc80 fs/dcache.c:2547
lookup_open fs/namei.c:3517 [inline]
open_last_lookups fs/namei.c:3694 [inline]
path_openat+0x6c8/0x1fa0 fs/namei.c:3930
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: 0x10000000 -> 0x1000000c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 5928 Comm: syz.2.803 Not tainted 6.12.0-rc1-syzkaller-00257-g2f91ff27b0ee #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup