syzbot

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BUG: KCSAN: data-race in alloc_pid / copy_process

read-write to 0xffffffff8685f0b0 of 4 bytes by task 51 on cpu 0:
 alloc_pid+0x539/0x720 kernel/pid.c:280
 copy_process+0xe0e/0x1f90 kernel/fork.c:2445
 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+0x4ce/0x9d0 kernel/workqueue.c:3319
 worker_thread+0x582/0x770 kernel/workqueue.c:3400
 kthread+0x489/0x510 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

read to 0xffffffff8685f0b0 of 4 bytes by task 5639 on cpu 1:
 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+0x4ce/0x9d0 kernel/workqueue.c:3319
 worker_thread+0x582/0x770 kernel/workqueue.c:3400
 kthread+0x489/0x510 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: 0x80000109 -> 0x8000010a

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5639 Comm: kworker/u8:13 Not tainted 6.15.0-rc6-syzkaller-00188-gfee3e843b309 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Workqueue: events_unbound call_usermodehelper_exec_work
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bridge0: port 1(bridge_slave_0) entered blocking state
bridge0: port 1(bridge_slave_0) entered forwarding state