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BUG: KCSAN: data-race in alloc_pid / copy_process

read-write to 0xffffffff86e5c328 of 4 bytes by task 348 on cpu 1:
 alloc_pid+0x6da/0x960 kernel/pid.c:334
 copy_process+0x11cb/0x2340 kernel/fork.c:2323
 kernel_clone+0x1c0/0x5f0 kernel/fork.c:2766
 user_mode_thread+0xab/0xe0 kernel/fork.c:2843
 call_usermodehelper_exec_sync kernel/umh.c:130 [inline]
 call_usermodehelper_exec_work+0x7a/0x160 kernel/umh.c:161
 process_one_work kernel/workqueue.c:3387 [inline]
 process_scheduled_works+0x56a/0xa50 kernel/workqueue.c:3470
 worker_thread+0x569/0x750 kernel/workqueue.c:3551
 kthread+0x223/0x270 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

read to 0xffffffff86e5c328 of 4 bytes by task 38 on cpu 0:
 copy_process+0x1acf/0x2340 kernel/fork.c:2486
 kernel_clone+0x1c0/0x5f0 kernel/fork.c:2766
 user_mode_thread+0xab/0xe0 kernel/fork.c:2843
 call_usermodehelper_exec_sync kernel/umh.c:130 [inline]
 call_usermodehelper_exec_work+0x7a/0x160 kernel/umh.c:161
 process_one_work kernel/workqueue.c:3387 [inline]
 process_scheduled_works+0x56a/0xa50 kernel/workqueue.c:3470
 worker_thread+0x569/0x750 kernel/workqueue.c:3551
 kthread+0x223/0x270 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: 0x80000093 -> 0x80000094

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 38 Comm: kworker/u8:2 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: events_unbound call_usermodehelper_exec_work
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bridge0: port 2(bridge_slave_1) entered blocking state
bridge0: port 2(bridge_slave_1) entered forwarding state