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BUG: KCSAN: data-race in alloc_pid / copy_process

read-write to 0xffffffff8685f028 of 4 bytes by task 31 on cpu 0:
 alloc_pid+0x566/0x760 kernel/pid.c:280
 copy_process+0xe1a/0x1f60 kernel/fork.c:2445
 kernel_clone+0x168/0x5d0 kernel/fork.c:2844
 user_mode_thread+0x7f/0xb0 kernel/fork.c:2922
 call_usermodehelper_exec_sync kernel/umh.c:132 [inline]
 call_usermodehelper_exec_work+0x7a/0x150 kernel/umh.c:163
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4de/0xa20 kernel/workqueue.c:3319
 worker_thread+0x52c/0x710 kernel/workqueue.c:3400
 kthread+0x4b7/0x540 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 0xffffffff8685f028 of 4 bytes by task 339 on cpu 1:
 copy_process+0x1754/0x1f60 kernel/fork.c:2587
 kernel_clone+0x168/0x5d0 kernel/fork.c:2844
 user_mode_thread+0x7f/0xb0 kernel/fork.c:2922
 call_usermodehelper_exec_sync kernel/umh.c:132 [inline]
 call_usermodehelper_exec_work+0x7a/0x150 kernel/umh.c:163
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4de/0xa20 kernel/workqueue.c:3319
 worker_thread+0x52c/0x710 kernel/workqueue.c:3400
 kthread+0x4b7/0x540 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: 0x800000a5 -> 0x800000a6

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 339 Comm: kworker/u8:6 Not tainted 6.15.0-rc2-syzkaller-00404-g8560697b23dc #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: events_unbound call_usermodehelper_exec_work
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