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BUG: KCSAN: data-race in alloc_pid / copy_process

read-write to 0xffffffff8685ffc8 of 4 bytes by task 15483 on cpu 1:
 alloc_pid+0x54c/0x760 kernel/pid.c:281
 copy_process+0xdd1/0x1ef0 kernel/fork.c:2237
 kernel_clone+0x16c/0x5c0 kernel/fork.c:2651
 user_mode_thread+0x7d/0xb0 kernel/fork.c:2727
 call_usermodehelper_exec_sync kernel/umh.c:132 [inline]
 call_usermodehelper_exec_work+0x7a/0x160 kernel/umh.c:163
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3340
 worker_thread+0x582/0x770 kernel/workqueue.c:3421
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

read to 0xffffffff8685ffc8 of 4 bytes by task 15500 on cpu 0:
 copy_process+0x16d4/0x1ef0 kernel/fork.c:2394
 kernel_clone+0x16c/0x5c0 kernel/fork.c:2651
 user_mode_thread+0x7d/0xb0 kernel/fork.c:2727
 call_usermodehelper_exec_sync kernel/umh.c:132 [inline]
 call_usermodehelper_exec_work+0x7a/0x160 kernel/umh.c:163
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3340
 worker_thread+0x582/0x770 kernel/workqueue.c:3421
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

value changed: 0x80000125 -> 0x80000126

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 15500 Comm: kworker/u8:50 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: events_unbound call_usermodehelper_exec_work
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