syzbot

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

write to 0xffff888217ccc064 of 4 bytes by task 14612 on cpu 0:
 io_worker_exit fs/io-wq.c:208 [inline]
 io_wqe_worker+0x5bb/0xa10 fs/io-wq.c:590
 kthread+0x1cb/0x1f0 kernel/kthread.c:255
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

read to 0xffff888217ccc064 of 4 bytes by task 14727 on cpu 1:
 mm_update_next_owner+0x376/0x5a0 kernel/exit.c:389
 exit_mm kernel/exit.c:484 [inline]
 do_exit+0x638/0x1880 kernel/exit.c:788
 do_group_exit+0xae/0x1a0 kernel/exit.c:899
 get_signal+0x2a7/0x1290 kernel/signal.c:2734
 do_signal+0x2b/0x670 arch/x86/kernel/signal.c:813
 exit_to_usermode_loop+0x24a/0x2c0 arch/x86/entry/common.c:160
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x36e/0x390 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 14727 Comm: syz-executor.1 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 14727 Comm: syz-executor.1 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x11d/0x187 lib/dump_stack.c:118
 panic+0x210/0x640 kernel/panic.c:221
 kcsan_report.cold+0xc/0xf kernel/kcsan/report.c:599
 kcsan_setup_watchpoint+0x3fb/0x440 kernel/kcsan/core.c:507
 mm_update_next_owner+0x376/0x5a0 kernel/exit.c:389
 exit_mm kernel/exit.c:484 [inline]
 do_exit+0x638/0x1880 kernel/exit.c:788
 do_group_exit+0xae/0x1a0 kernel/exit.c:899
 get_signal+0x2a7/0x1290 kernel/signal.c:2734
 do_signal+0x2b/0x670 arch/x86/kernel/signal.c:813
 exit_to_usermode_loop+0x24a/0x2c0 arch/x86/entry/common.c:160
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x36e/0x390 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45c889
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fe0ec51ccf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 0000000000000000 RBX: 000000000076bf08 RCX: 000000000045c889
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000076bf08
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000076bf0c
R13: 00007ffcfaa2b66f R14: 00007fe0ec51d9c0 R15: 000000000076bf0c
Shutting down cpus with NMI
Kernel Offset: disabled
Rebooting in 86400 seconds..