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BUG: KCSAN: data-race in do_notify_parent_cldstop / wait_consider_task

write to 0xffff88813a3704d0 of 4 bytes by task 26058 on cpu 1:
 wait_task_stopped kernel/exit.c:1185 [inline]
 wait_consider_task+0xbaf/0x1a10 kernel/exit.c:1371
 ptrace_do_wait kernel/exit.c:1411 [inline]
 do_wait+0x1f4/0x640 kernel/exit.c:1518
 kernel_wait4+0x14b/0x1b0 kernel/exit.c:1677
 __do_sys_wait4 kernel/exit.c:1705 [inline]
 __se_sys_wait4 kernel/exit.c:1701 [inline]
 __x64_sys_wait4+0x90/0x120 kernel/exit.c:1701
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88813a3704d0 of 4 bytes by task 26054 on cpu 0:
 do_notify_parent_cldstop+0x1b7/0x290 kernel/signal.c:2143
 ptrace_stop+0x2e2/0x670 kernel/signal.c:2287
 ptrace_signal kernel/signal.c:2576 [inline]
 get_signal+0xbbc/0x15d0 kernel/signal.c:2756
 arch_do_signal_or_restart+0x8c/0x280 arch/x86/kernel/signal.c:865
 handle_signal_work kernel/entry/common.c:148 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x109/0x190 kernel/entry/common.c:209
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:302
 do_syscall_64+0x50/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000005 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 26054 Comm: syz-executor.0 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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