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BUG: KCSAN: data-race in copy_process / free_pid

read-write to 0xffffffff86c5c268 of 4 bytes by task 5320 on cpu 1:
 free_pid+0xb3/0x1b0 kernel/pid.c:124
 free_pids+0x9e/0xb0 kernel/pid.c:156
 release_task+0x990/0xb40 kernel/exit.c:300
 exit_notify kernel/exit.c:810 [inline]
 do_exit+0xd79/0x1500 kernel/exit.c:1021
 do_group_exit+0xfe/0x140 kernel/exit.c:1152
 get_signal+0xe07/0xf10 kernel/signal.c:3046
 arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop+0x15d/0x8c0 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x23c/0x3c0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86c5c268 of 4 bytes by task 28456 on cpu 0:
 copy_process+0x1aae/0x2310 kernel/fork.c:2468
 kernel_clone+0x1c0/0x5f0 kernel/fork.c:2748
 user_mode_thread+0x9c/0xd0 kernel/fork.c:2824
 call_usermodehelper_exec_sync kernel/umh.c:132 [inline]
 call_usermodehelper_exec_work+0x7a/0x160 kernel/umh.c:163
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0x4d4/0x9a0 kernel/workqueue.c:3405
 worker_thread+0x569/0x750 kernel/workqueue.c:3486
 kthread+0x221/0x270 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x8000011a -> 0x80000119

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 28456 Comm: kworker/u8:15 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: events_unbound call_usermodehelper_exec_work
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