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BUG: KCSAN: data-race in copy_process / free_pid

read-write to 0xffffffff86860008 of 4 bytes by task 5314 on cpu 1:
 free_pid+0xb9/0x1d0 kernel/pid.c:126
 free_pids+0x7a/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
 kthread_exit+0x94/0x190 kernel/kthread.c:336
 kthread+0x491/0x510 kernel/kthread.c:465
 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

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: 0x80000178 -> 0x80000177

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 2 Comm: kthreadd Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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