syzbot

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BUG: KCSAN: data-race in copy_process / mm_update_next_owner

write to 0xffff888105ed706c of 4 bytes by task 6322 on cpu 0:
 copy_process+0x608/0x2e00 kernel/fork.c:1986
 kernel_clone+0x14b/0x680 kernel/fork.c:2503
 __do_sys_clone kernel/fork.c:2620 [inline]
 __se_sys_clone kernel/fork.c:2604 [inline]
 __x64_sys_clone+0xb4/0xe0 kernel/fork.c:2604
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888105ed706c of 4 bytes by task 6324 on cpu 1:
 mm_update_next_owner+0x1d9/0x520 kernel/exit.c:389
 exit_mm+0x358/0x450 kernel/exit.c:501
 do_exit+0x3ff/0x1560 kernel/exit.c:813
 do_group_exit+0x19b/0x1a0 kernel/exit.c:923
 __do_sys_exit_group+0xb/0x10 kernel/exit.c:934
 __se_sys_exit_group+0x5/0x10 kernel/exit.c:932
 __x64_sys_exit_group+0x16/0x20 kernel/exit.c:932
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 6324 Comm: syz-executor.5 Not tainted 5.13.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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