KCSAN: data-race in do_task_stat / handle_mm_fault (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 85a2c56c Merge tag 'pm-5.10-rc6' of git://git.kernel.org/p..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10bb268b500000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9b19d1bde60f8d
dashboard link: https://syzkaller.appspot.com/bug?extid=ba2362d5a0758ad2de50
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [adob...@gmail.com ak...@linux-foundation.org ebie...@xmission.com gladkov...@gmail.com kees...@chromium.org linux-...@vger.kernel.org linux-...@vger.kernel.org rp...@kernel.org]

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+ba2362...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in do_task_stat / handle_mm_fault

read-write to 0xffff88802dde8678 of 8 bytes by task 27902 on cpu 1:
mm_account_fault mm/memory.c:4557 [inline]
handle_mm_fault+0x1572/0x1770 mm/memory.c:4621
do_user_addr_fault+0x33e/0x730 arch/x86/mm/fault.c:1372
handle_page_fault arch/x86/mm/fault.c:1429 [inline]
exc_page_fault+0x91/0x290 arch/x86/mm/fault.c:1485
asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:583

read to 0xffff88802dde8678 of 8 bytes by task 1 on cpu 0:
do_task_stat+0x61d/0x1070 fs/proc/array.c:504
proc_tgid_stat+0x2f/0x40 fs/proc/array.c:633
proc_single_show+0x84/0x100 fs/proc/base.c:775
seq_read_iter+0x2ef/0x8e0 fs/seq_file.c:228
seq_read+0x221/0x260 fs/seq_file.c:159
vfs_read+0x154/0x5c0 fs/read_write.c:494
ksys_read+0xce/0x180 fs/read_write.c:634
__do_sys_read fs/read_write.c:644 [inline]
__se_sys_read fs/read_write.c:642 [inline]
__x64_sys_read+0x3e/0x50 fs/read_write.c:642
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: 0 PID: 1 Comm: systemd Not tainted 5.10.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

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