syzbot

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BUG: KCSAN: data-race in detach_pid / perf_event_switch_output

write to 0xffff888151c5c6c0 of 8 bytes by task 11179 on cpu 1:
 __change_pid kernel/pid.c:350 [inline]
 detach_pid+0xdb/0x160 kernel/pid.c:361
 __unhash_process kernel/exit.c:126 [inline]
 __exit_signal kernel/exit.c:199 [inline]
 release_task+0x62c/0xb70 kernel/exit.c:256
 wait_task_zombie kernel/exit.c:1210 [inline]
 wait_consider_task+0x115e/0x1670 kernel/exit.c:1437
 do_wait_pid kernel/exit.c:1568 [inline]
 do_wait+0x2e7/0x650 kernel/exit.c:1610
 kernel_wait+0x52/0xc0 kernel/exit.c:1797
 call_usermodehelper_exec_sync kernel/umh.c:137 [inline]
 call_usermodehelper_exec_work+0x9c/0x150 kernel/umh.c:164
 process_one_work kernel/workqueue.c:2630 [inline]
 process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
 worker_thread+0x525/0x730 kernel/workqueue.c:2784
 kthread+0x1d7/0x210 kernel/kthread.c:388
 ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

read to 0xffff888151c5c6c0 of 8 bytes by task 9234 on cpu 0:
 pid_alive include/linux/sched.h:1607 [inline]
 perf_event_pid_type kernel/events/core.c:1323 [inline]
 perf_event_tid kernel/events/core.c:1335 [inline]
 perf_event_switch_output+0x228/0x390 kernel/events/core.c:8971
 perf_iterate_sb_cpu kernel/events/core.c:7911 [inline]
 perf_iterate_sb+0x353/0x640 kernel/events/core.c:7940
 perf_event_switch kernel/events/core.c:9016 [inline]
 __perf_event_task_sched_in+0x72e/0x790 kernel/events/core.c:3983
 perf_event_task_sched_in include/linux/perf_event.h:1459 [inline]
 finish_task_switch+0x1ec/0x280 kernel/sched/core.c:5249
 context_switch kernel/sched/core.c:5385 [inline]
 __schedule+0x63b/0x8c0 kernel/sched/core.c:6695
 schedule+0x51/0x80 kernel/sched/core.c:6771
 do_nanosleep+0xa2/0x2f0 kernel/time/hrtimer.c:2047
 hrtimer_nanosleep+0xe7/0x1e0 kernel/time/hrtimer.c:2100
 common_nsleep+0x68/0x80 kernel/time/posix-timers.c:1350
 __do_sys_clock_nanosleep kernel/time/posix-timers.c:1396 [inline]
 __se_sys_clock_nanosleep+0x202/0x230 kernel/time/posix-timers.c:1373
 __x64_sys_clock_nanosleep+0x55/0x60 kernel/time/posix-timers.c:1373
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0xffff88816f2d6600 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 9234 Comm: syz-executor.0 Not tainted 6.6.0-rc1-syzkaller-00115-g9fdfb15a3dbf #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
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