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

read-write to 0xffffffff86c5c268 of 4 bytes by task 3303 on cpu 0:
 free_pid+0xb3/0x1b0 kernel/pid.c:124
 free_pids+0x54/0xb0 kernel/pid.c:156
 release_task+0x990/0xb40 kernel/exit.c:295
 wait_task_zombie kernel/exit.c:1309 [inline]
 wait_consider_task+0x10ef/0x15f0 kernel/exit.c:1536
 do_wait_thread kernel/exit.c:1599 [inline]
 __do_wait+0xf1/0x500 kernel/exit.c:1717
 do_wait+0xb6/0x230 kernel/exit.c:1751
 kernel_wait4+0x19f/0x210 kernel/exit.c:1910
 __do_sys_wait4 kernel/exit.c:1938 [inline]
 __se_sys_wait4 kernel/exit.c:1934 [inline]
 __x64_sys_wait4+0x91/0x120 kernel/exit.c:1934
 x64_sys_call+0x2aee/0x3020 arch/x86/include/generated/asm/syscalls_64.h:62
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86c5c268 of 4 bytes by task 49 on cpu 1:
 copy_process+0x1ae2/0x2350 kernel/fork.c:2466
 kernel_clone+0x1c0/0x5f0 kernel/fork.c:2746
 user_mode_thread+0x9c/0xd0 kernel/fork.c:2822
 call_usermodehelper_exec_work+0x41/0x160 kernel/umh.c:171
 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: 0x800000f0 -> 0x800000ef

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 49 Comm: kworker/u8:3 Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Workqueue: events_unbound call_usermodehelper_exec_work
==================================================================