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BUG: KCSAN: data-race in copy_process / free_pid

read-write to 0xffffffff868608e0 of 4 bytes by task 19022 on cpu 0:
 free_pid+0x77/0x180 kernel/pid.c:126
 free_pids+0x9e/0xb0 kernel/pid.c:159
 release_task+0x9a9/0xb60 kernel/exit.c:295
 exit_notify kernel/exit.c:782 [inline]
 do_exit+0xd81/0x1590 kernel/exit.c:976
 do_group_exit+0xff/0x140 kernel/exit.c:1105
 get_signal+0xe59/0xf70 kernel/signal.c:3034
 arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x7a/0x100 kernel/entry/common.c:111
 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
 do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff868608e0 of 4 bytes by task 2 on cpu 1:
 copy_process+0x1790/0x1f90 kernel/fork.c:2342
 kernel_clone+0x16c/0x5b0 kernel/fork.c:2599
 kernel_thread+0xac/0xe0 kernel/fork.c:2661
 create_kthread kernel/kthread.c:487 [inline]
 kthreadd+0x28d/0x360 kernel/kthread.c:847
 ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x80000116 -> 0x80000115

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 2 Comm: kthreadd Not tainted 6.16.0-rc6-syzkaller-00002-g155a3c003e55 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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