KCSAN: data-race in exit_signals / task_dump_owner (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c2e7554e Merge tag 'gfs2-v5.10-rc4-fixes' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17a67fdc500000
kernel config: https://syzkaller.appspot.com/x/.config?x=e9a6e9171a00e85a
dashboard link: https://syzkaller.appspot.com/bug?extid=fef1fca3947c120bc9e0
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [ax...@kernel.dk chri...@brauner.io ebie...@xmission.com linux-...@vger.kernel.org liuzhi...@huawei.com ol...@redhat.com]

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fef1fc...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in exit_signals / task_dump_owner

read-write to 0xffff888020807024 of 4 bytes by task 11213 on cpu 0:
exit_signals+0x108/0x530 kernel/signal.c:2846
do_exit+0x158/0x15a0 kernel/exit.c:765
do_group_exit+0x16f/0x170 kernel/exit.c:906
__do_sys_exit_group+0xb/0x10 kernel/exit.c:917
__se_sys_exit_group+0x5/0x10 kernel/exit.c:915
__x64_sys_exit_group+0x16/0x20 kernel/exit.c:915
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888020807024 of 4 bytes by task 11216 on cpu 1:
task_dump_owner+0x2b/0x1b0 fs/proc/base.c:1823
pid_update_inode fs/proc/base.c:1965 [inline]
pid_revalidate+0x69/0x110 fs/proc/base.c:1988
lookup_fast+0x208/0x370 fs/namei.c:768
walk_component+0x5c/0x350 fs/namei.c:1857
link_path_walk+0x451/0x710 fs/namei.c:2180
path_openat+0x19f/0x20a0 fs/namei.c:3365
do_filp_open+0xbd/0x1d0 fs/namei.c:3396
do_sys_openat2+0xa3/0x240 fs/open.c:1168
do_sys_open fs/open.c:1184 [inline]
__do_sys_open fs/open.c:1192 [inline]
__se_sys_open fs/open.c:1188 [inline]
__x64_sys_open+0xe2/0x110 fs/open.c:1188
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 11216 Comm: syz-executor.5 Not tainted 5.10.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


---
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.

[syzbot]

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