syzbot

==================================================================
BUG: KCSAN: data-race in __perf_event_header__init_id / detach_pid

write to 0xffff88812d5515d8 of 8 bytes by task 8 on cpu 1:
 __change_pid kernel/pid.c:347 [inline]
 detach_pid+0xd7/0x160 kernel/pid.c:358
 __unhash_process kernel/exit.c:75 [inline]
 __exit_signal kernel/exit.c:148 [inline]
 release_task+0x6d8/0xbe0 kernel/exit.c:199
 wait_task_zombie kernel/exit.c:1107 [inline]
 wait_consider_task+0x10ce/0x19e0 kernel/exit.c:1334
 do_wait_thread kernel/exit.c:1397 [inline]
 do_wait+0x1b1/0x4a0 kernel/exit.c:1468
 kernel_wait+0x4e/0xc0 kernel/exit.c:1647
 call_usermodehelper_exec_sync kernel/umh.c:137 [inline]
 call_usermodehelper_exec_work+0x98/0x150 kernel/umh.c:164
 process_one_work+0x3e9/0x8f0 kernel/workqueue.c:2275
 worker_thread+0x636/0xae0 kernel/workqueue.c:2421
 kthread+0x1d0/0x1f0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff88812d5515d8 of 8 bytes by interrupt on cpu 0:
 pid_alive include/linux/sched.h:1442 [inline]
 perf_event_pid_type kernel/events/core.c:1414 [inline]
 perf_event_tid kernel/events/core.c:1426 [inline]
 __perf_event_header__init_id+0x16c/0x2d0 kernel/events/core.c:6647
 perf_prepare_sample+0xcd/0x1080 kernel/events/core.c:7147
 __perf_event_output kernel/events/core.c:7325 [inline]
 perf_event_output_backward+0x36/0xb0 kernel/events/core.c:7353
 __perf_event_overflow kernel/events/core.c:9019 [inline]
 perf_swevent_hrtimer+0x351/0x4a0 kernel/events/core.c:10419
 __run_hrtimer+0x160/0x480 kernel/time/hrtimer.c:1537
 __hrtimer_run_queues kernel/time/hrtimer.c:1601 [inline]
 hrtimer_interrupt+0x380/0xaf0 kernel/time/hrtimer.c:1663
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1089 [inline]
 __sysvec_apic_timer_interrupt+0x6f/0x1c0 arch/x86/kernel/apic/apic.c:1106
 sysvec_apic_timer_interrupt+0x64/0x80 arch/x86/kernel/apic/apic.c:1100
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:632
 is_atomic kernel/kcsan/core.c:233 [inline]
 should_watch kernel/kcsan/core.c:261 [inline]
 check_access kernel/kcsan/core.c:627 [inline]
 __tsan_read8+0x11a/0x180 kernel/kcsan/core.c:840
 stack_not_used include/linux/sched/task_stack.h:101 [inline]
 check_stack_usage kernel/exit.c:710 [inline]
 do_exit+0x1030/0x1560 kernel/exit.c:868
 do_group_exit+0xa4/0x1a0 kernel/exit.c:922
 __do_sys_exit_group+0xb/0x10 kernel/exit.c:933
 __se_sys_exit_group+0x5/0x10 kernel/exit.c:931
 __x64_sys_exit_group+0x16/0x20 kernel/exit.c:931
 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 9595 Comm: modprobe Tainted: G        W         5.12.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================