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BUG: KCSAN: data-race in acct_collect / do_exit

write to 0xffff888029d8a4dc of 4 bytes by task 17404 on cpu 0:
 reparent_leader kernel/exit.c:582 [inline]
 forget_original_parent kernel/exit.c:634 [inline]
 exit_notify kernel/exit.c:650 [inline]
 do_exit+0x8de/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

read to 0xffff888029d8a4dc of 4 bytes by task 17405 on cpu 1:
 thread_group_leader include/linux/sched/signal.h:654 [inline]
 acct_collect+0x14c/0x360 kernel/acct.c:556
 do_exit+0x373/0x15a0 kernel/exit.c:785
 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: 1 PID: 17405 Comm: syz-executor.3 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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