KCSAN: data-race in io_wqe_worker / mm_update_next

KCSAN: data-race in io_wqe_worker / mm_update_next_owner (3)
Status: auto-closed as invalid on 2021/01/17 04:50
Reported-by: syzbot+d9e50e3e137a44331160@syzkaller.appspotmail.com
First crash: 55d, last: 43d

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in io_wqe_worker / mm_update_next_owner				1	289d	289d	0/17	auto-closed as invalid on 2020/06/18 13:53
upstream	KCSAN: data-race in io_wqe_worker / mm_update_next_owner (2)				3	97d	111d	0/17	auto-closed as invalid on 2020/11/23 20:14

Sample crash report:

==================================================================
BUG: KCSAN: data-race in io_wqe_worker / mm_update_next_owner

read-write to 0xffff8881443d0024 of 4 bytes by task 15405 on cpu 0:
 io_worker_exit fs/io-wq.c:234 [inline]
 io_wqe_worker+0x55d/0x810 fs/io-wq.c:641
 kthread+0x1fd/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff8881443d0024 of 4 bytes by task 15408 on cpu 1:
 mm_update_next_owner+0x1d9/0x4e0 kernel/exit.c:387
 exit_mm+0x2ff/0x370 kernel/exit.c:485
 do_exit+0x3c8/0x1630 kernel/exit.c:796
 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 15408 Comm: syz-executor.4 Not tainted 5.10.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Maintainers
ci2-upstream-kcsan-gce	2020/12/13 04:50	upstream	7b1b868e	bca53db9	.config	log	report			info	axboe@kernel.dk, io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-upstream-kcsan-gce	2020/11/30 11:36	upstream	b6505459	76831598	.config	log	report			info	axboe@kernel.dk, io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk