[moderation] [fs?] KCSAN: data-race in d_alloc_parallel / d_set_d_op (9)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5c24e4e9e708 Merge tag 'hid-for-linus-2024020101' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=166fa660180000
kernel config: https://syzkaller.appspot.com/x/.config?x=4aab723d3dfffc44
dashboard link: https://syzkaller.appspot.com/bug?extid=dbe6eb55737b9f0f18bb
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/939a791831ca/disk-5c24e4e9.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0ffa996f3841/vmlinux-5c24e4e9.xz
kernel image: https://storage.googleapis.com/syzbot-assets/00a87458e25f/bzImage-5c24e4e9.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+dbe6eb...@syzkaller.appspotmail.com

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

read-write to 0xffff88811dbc3c00 of 4 bytes by task 4975 on cpu 1:
d_set_d_op+0xfb/0x1f0 fs/dcache.c:1792
proc_lookup_de+0x1b9/0x210 fs/proc/generic.c:256
proc_tgid_net_lookup+0x42/0xc0 fs/proc/proc_net.c:296
lookup_open fs/namei.c:3474 [inline]
open_last_lookups fs/namei.c:3565 [inline]
path_openat+0xc6f/0x1d40 fs/namei.c:3795
do_filp_open+0xf6/0x200 fs/namei.c:3825
do_sys_openat2+0xab/0x110 fs/open.c:1404
do_sys_open fs/open.c:1419 [inline]
__do_sys_openat fs/open.c:1435 [inline]
__se_sys_openat fs/open.c:1430 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1430
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff88811dbc3c00 of 4 bytes by task 4976 on cpu 0:
d_in_lookup include/linux/dcache.h:365 [inline]
d_wait_lookup fs/dcache.c:2443 [inline]
d_alloc_parallel+0x5f9/0xc60 fs/dcache.c:2531
lookup_open fs/namei.c:3421 [inline]
open_last_lookups fs/namei.c:3565 [inline]
path_openat+0x658/0x1d40 fs/namei.c:3795
do_filp_open+0xf6/0x200 fs/namei.c:3825
do_sys_openat2+0xab/0x110 fs/open.c:1404
do_sys_open fs/open.c:1419 [inline]
__do_sys_openat fs/open.c:1435 [inline]
__se_sys_openat fs/open.c:1430 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1430
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x10000000 -> 0x1000000c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4976 Comm: syz-executor.4 Not tainted 6.8.0-rc2-syzkaller-00084-g5c24e4e9e708 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================


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