syzbot

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BUG: KCSAN: data-race in do_exit / get_signal

read-write to 0xffff888109e7f064 of 4 bytes by task 7654 on cpu 1:
 get_signal+0xee7/0x1510 kernel/signal.c:2737
 arch_do_signal+0x25/0x260 arch/x86/kernel/signal.c:811
 exit_to_user_mode_loop kernel/entry/common.c:161 [inline]
 exit_to_user_mode_prepare+0xde/0x170 kernel/entry/common.c:191
 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888109e7f064 of 4 bytes by task 7645 on cpu 0:
 find_alive_thread kernel/exit.c:493 [inline]
 find_new_reaper kernel/exit.c:542 [inline]
 forget_original_parent kernel/exit.c:617 [inline]
 exit_notify kernel/exit.c:650 [inline]
 do_exit+0x530/0x15a0 kernel/exit.c:826
 do_group_exit+0xc8/0x170 kernel/exit.c:903
 get_signal+0xf9b/0x1510 kernel/signal.c:2757
 arch_do_signal+0x25/0x260 arch/x86/kernel/signal.c:811
 exit_to_user_mode_loop kernel/entry/common.c:161 [inline]
 exit_to_user_mode_prepare+0xde/0x170 kernel/entry/common.c:191
 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7645 Comm: syz-executor.4 Not tainted 5.10.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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