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BUG: KCSAN: data-race in copy_process / free_pid

read-write to 0xffffffff86e5c368 of 4 bytes by task 38 on cpu 0:
 free_pid+0xb3/0x1b0 kernel/pid.c:124
 free_pids+0x7a/0xb0 kernel/pid.c:156
 release_task+0xa28/0xb90 kernel/exit.c:302
 wait_task_zombie kernel/exit.c:1317 [inline]
 wait_consider_task+0x10ef/0x15f0 kernel/exit.c:1544
 do_wait_pid kernel/exit.c:1683 [inline]
 __do_wait+0x33c/0x500 kernel/exit.c:1718
 do_wait+0xb6/0x230 kernel/exit.c:1759
 kernel_wait+0x72/0x100 kernel/exit.c:1935
 call_usermodehelper_exec_sync kernel/umh.c:134 [inline]
 call_usermodehelper_exec_work+0x9c/0x160 kernel/umh.c:161
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0x56a/0xa50 kernel/workqueue.c:3479
 worker_thread+0x569/0x750 kernel/workqueue.c:3560
 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 0xffffffff86e5c368 of 4 bytes by task 17997 on cpu 1:
 copy_process+0x1ae0/0x2350 kernel/fork.c:2489
 kernel_clone+0x1c0/0x5f0 kernel/fork.c:2769
 __do_sys_clone kernel/fork.c:2911 [inline]
 __se_sys_clone kernel/fork.c:2895 [inline]
 __x64_sys_clone+0x143/0x180 kernel/fork.c:2895
 x64_sys_call+0x2479/0x2550 arch/x86/include/generated/asm/syscalls_64.h:57
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x800001aa -> 0x800001a9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 17997 Comm: dhcpcd-run-hook Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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