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BUG: KCSAN: data-race in alloc_pid / copy_process

read-write to 0xffffffff86c5c268 of 4 bytes by task 6455 on cpu 0:
 alloc_pid+0x6bb/0x930 kernel/pid.c:332
 copy_process+0x11aa/0x2310 kernel/fork.c:2305
 kernel_clone+0x1c0/0x5f0 kernel/fork.c:2748
 user_mode_thread+0x9c/0xd0 kernel/fork.c:2824
 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:3322 [inline]
 process_scheduled_works+0x4d4/0x9a0 kernel/workqueue.c:3405
 worker_thread+0x569/0x750 kernel/workqueue.c:3486
 kthread+0x221/0x270 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 0xffffffff86c5c268 of 4 bytes by task 2 on cpu 1:
 copy_process+0x1aae/0x2310 kernel/fork.c:2468
 kernel_clone+0x1c0/0x5f0 kernel/fork.c:2748
 kernel_thread+0xe5/0x120 kernel/fork.c:2809
 create_kthread kernel/kthread.c:459 [inline]
 kthreadd+0x25b/0x320 kernel/kthread.c:817
 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: 0x800000fb -> 0x800000fc

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 2 Comm: kthreadd Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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