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

write to 0xffff888103e3cb60 of 8 bytes by task 12716 on cpu 1:
 __change_pid kernel/pid.c:414 [inline]
 detach_pid+0xf0/0x1a0 kernel/pid.c:426
 __unhash_process kernel/exit.c:140 [inline]
 __exit_signal kernel/exit.c:211 [inline]
 release_task+0x67c/0xb90 kernel/exit.c:272
 wait_task_zombie kernel/exit.c:1316 [inline]
 wait_consider_task+0x10ef/0x15f0 kernel/exit.c:1543
 do_wait_thread kernel/exit.c:1606 [inline]
 __do_wait+0xf1/0x500 kernel/exit.c:1724
 do_wait+0xb6/0x230 kernel/exit.c:1758
 kernel_wait4+0x19f/0x210 kernel/exit.c:1917
 __do_sys_wait4 kernel/exit.c:1945 [inline]
 __se_sys_wait4 kernel/exit.c:1941 [inline]
 __x64_sys_wait4+0x91/0x120 kernel/exit.c:1941
 x64_sys_call+0x108f/0x2550 arch/x86/include/generated/asm/syscalls_64.h:62
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888103e3cb60 of 8 bytes by task 12692 on cpu 0:
 pid_alive include/linux/pid.h:267 [inline]
 perf_event_pid_type kernel/events/core.c:1534 [inline]
 perf_event_tid kernel/events/core.c:1546 [inline]
 perf_event_switch_output+0x207/0x370 kernel/events/core.c:10132
 perf_iterate_sb_cpu kernel/events/core.c:9023 [inline]
 perf_iterate_sb+0x369/0x650 kernel/events/core.c:9052
 perf_event_switch kernel/events/core.c:10177 [inline]
 __perf_event_task_sched_in+0xa41/0xae0 kernel/events/core.c:4330
 perf_event_task_sched_in include/linux/perf_event.h:1639 [inline]
 finish_task_switch+0x2bd/0x340 kernel/sched/core.c:5372
 context_switch kernel/sched/core.c:5529 [inline]
 __schedule+0x79e/0xd20 kernel/sched/core.c:7277
 preempt_schedule_irq+0x2c/0x50 kernel/sched/core.c:7599
 raw_irqentry_exit_cond_resched+0x49/0x60 kernel/entry/common.c:145
 irqentry_exit_to_kernel_mode_preempt+0x2b/0x40 include/linux/irq-entry-common.h:468
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
 irqentry_exit+0x7d/0x610 kernel/entry/common.c:167
 sysvec_apic_timer_interrupt+0x44/0x80 arch/x86/kernel/apic/apic.c:1062
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
 its_return_thunk+0x0/0x10
 __scm_recv_common+0x228/0x340 net/core/scm.c:-1
 scm_recv_unix+0x4a/0x270 net/core/scm.c:566
 __unix_dgram_recvmsg+0x76d/0x860 net/unix/af_unix.c:2669
 unix_dgram_recvmsg+0x7e/0x90 net/unix/af_unix.c:2689
 sock_recvmsg_nosec+0xc2/0xf0 net/socket.c:1151
 ____sys_recvmsg+0x26f/0x280 net/socket.c:2931
 ___sys_recvmsg+0x11f/0x3a0 net/socket.c:2975
 do_recvmmsg+0x1e5/0x560 net/socket.c:3070
 __sys_recvmmsg net/socket.c:3144 [inline]
 __do_sys_recvmmsg net/socket.c:3167 [inline]
 __se_sys_recvmmsg net/socket.c:3160 [inline]
 __x64_sys_recvmmsg+0xe5/0x170 net/socket.c:3160
 x64_sys_call+0x77f/0x2550 arch/x86/include/generated/asm/syscalls_64.h:300
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff88813b909300 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 12692 Comm: syz.3.12291 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
==================================================================