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

read-write to 0xffffffff8685f030 of 4 bytes by task 15774 on cpu 1:
 free_pid+0x77/0x180 kernel/pid.c:125
 free_pids+0x7a/0xb0 kernel/pid.c:158
 release_task+0x9d0/0xbb0 kernel/exit.c:289
 exit_notify kernel/exit.c:790 [inline]
 do_exit+0xee3/0x17c0 kernel/exit.c:973
 call_usermodehelper_exec_async+0x247/0x250 kernel/umh.c:122
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffffffff8685f030 of 4 bytes by task 3705 on cpu 0:
 copy_process+0x1790/0x1f90 kernel/fork.c:2587
 kernel_clone+0x16c/0x5b0 kernel/fork.c:2844
 user_mode_thread+0x7d/0xb0 kernel/fork.c:2922
 call_usermodehelper_exec_work+0x41/0x160 kernel/umh.c:171
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3319
 worker_thread+0x582/0x770 kernel/workqueue.c:3400
 kthread+0x486/0x510 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x800000c2 -> 0x800000c1

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3705 Comm: kworker/u8:12 Tainted: G        W           6.15.0-rc4-syzkaller-00256-g95d3481af6dc #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Workqueue: events_unbound call_usermodehelper_exec_work
==================================================================
bridge0: port 2(bridge_slave_1) entered blocking state
bridge0: port 2(bridge_slave_1) entered forwarding state
bridge0: port 1(bridge_slave_0) entered blocking state
bridge0: port 1(bridge_slave_0) entered forwarding state
bridge0: port 2(bridge_slave_1) entered blocking state
bridge0: port 2(bridge_slave_1) entered forwarding state