==================================================================
BUG: KCSAN: data-race in copy_process / free_pid

read-write to 0xffffffff86860008 of 4 bytes by task 17379 on cpu 1:
 free_pid+0xb9/0x1d0 kernel/pid.c:126
 free_pids+0x9e/0xb0 kernel/pid.c:159
 release_task+0x9a7/0xb60 kernel/exit.c:295
 exit_notify kernel/exit.c:777 [inline]
 do_exit+0xd4d/0x1590 kernel/exit.c:983
 do_group_exit+0xff/0x140 kernel/exit.c:1112
 get_signal+0xe58/0xf70 kernel/signal.c:3034
 arch_do_signal_or_restart+0x96/0x450 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
 exit_to_user_mode_loop+0x6a/0x740 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x1e1/0x2b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86860008 of 4 bytes by task 2 on cpu 0:
 copy_process+0x16d4/0x1ef0 kernel/fork.c:2394
 kernel_clone+0x16c/0x5c0 kernel/fork.c:2651
 kernel_thread+0xad/0xe0 kernel/fork.c:2712
 create_kthread kernel/kthread.c:486 [inline]
 kthreadd+0x26c/0x340 kernel/kthread.c:844
 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

value changed: 0x80000126 -> 0x80000125

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 2 Comm: kthreadd Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================