syzbot

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BUG: KCSAN: data-race in exit_signals / mm_update_next_owner

write to 0xffff8880954510a4 of 4 bytes by task 23260 on cpu 1:
 exit_signals+0x135/0x4c0 kernel/signal.c:2827
 do_exit+0x17b/0x11e0 kernel/exit.c:744
 do_group_exit+0xae/0x1a0 kernel/exit.c:893
 __do_sys_exit_group kernel/exit.c:904 [inline]
 __se_sys_exit_group kernel/exit.c:902 [inline]
 __x64_sys_exit_group+0x2b/0x30 kernel/exit.c:902
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880954510a4 of 4 bytes by task 23262 on cpu 0:
 mm_update_next_owner+0x376/0x5a0 kernel/exit.c:383
 exit_mm kernel/exit.c:478 [inline]
 do_exit+0x63c/0x11e0 kernel/exit.c:782
 do_group_exit+0xae/0x1a0 kernel/exit.c:893
 __do_sys_exit_group kernel/exit.c:904 [inline]
 __se_sys_exit_group kernel/exit.c:902 [inline]
 __x64_sys_exit_group+0x2b/0x30 kernel/exit.c:902
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 23262 Comm: syz-executor.3 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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