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BUG: KCSAN: data-race in complete_signal / futex_wait_queue_me

write to 0xffff88809c931010 of 8 bytes by task 8236 on cpu 0:
 futex_wait_queue_me+0x1f8/0x290 kernel/futex.c:2706
 futex_wait+0x19b/0x3f0 kernel/futex.c:2810
 do_futex+0xe9/0x18d0 kernel/futex.c:3881
 __do_sys_futex kernel/futex.c:3942 [inline]
 __se_sys_futex kernel/futex.c:3910 [inline]
 __x64_sys_futex+0x2cd/0x3f0 kernel/futex.c:3910
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88809c931010 of 8 bytes by task 8239 on cpu 1:
 wants_signal kernel/signal.c:978 [inline]
 complete_signal+0xcd/0x5e0 kernel/signal.c:995
 __send_signal+0x5ea/0x870 kernel/signal.c:1175
 send_signal+0x224/0x2b0 kernel/signal.c:1236
 __group_send_sig_info kernel/signal.c:1275 [inline]
 do_notify_parent+0x55b/0x5e0 kernel/signal.c:1992
 exit_notify kernel/exit.c:670 [inline]
 do_exit+0x16ef/0x18c0 kernel/exit.c:818
 do_group_exit+0xb4/0x1c0 kernel/exit.c:895
 __do_sys_exit_group kernel/exit.c:906 [inline]
 __se_sys_exit_group kernel/exit.c:904 [inline]
 __x64_sys_exit_group+0x2e/0x30 kernel/exit.c:904
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8239 Comm: syz-executor.3 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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