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BUG: KCSAN: data-race in copy_process / free_pid

read-write to 0xffffffff8685f028 of 4 bytes by task 5564 on cpu 0:
 free_pid+0x7e/0x180 kernel/pid.c:125
 free_pids+0x54/0xb0 kernel/pid.c:158
 release_task+0xa32/0xba0 kernel/exit.c:289
 wait_task_zombie kernel/exit.c:1264 [inline]
 wait_consider_task+0x117a/0x16a0 kernel/exit.c:1491
 do_wait_thread kernel/exit.c:1554 [inline]
 __do_wait+0x108/0x520 kernel/exit.c:1672
 do_wait+0xb9/0x270 kernel/exit.c:1706
 kernel_wait4+0x147/0x1d0 kernel/exit.c:1865
 __do_sys_wait4 kernel/exit.c:1893 [inline]
 __se_sys_wait4 kernel/exit.c:1889 [inline]
 __x64_sys_wait4+0x99/0x120 kernel/exit.c:1889
 x64_sys_call+0x25f3/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:62
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff8685f028 of 4 bytes by task 5992 on cpu 1:
 copy_process+0x1754/0x1f60 kernel/fork.c:2587
 kernel_clone+0x168/0x5d0 kernel/fork.c:2844
 __do_sys_clone kernel/fork.c:2987 [inline]
 __se_sys_clone kernel/fork.c:2971 [inline]
 __x64_sys_clone+0xe9/0x120 kernel/fork.c:2971
 x64_sys_call+0x2dc9/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:57
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x800000c6 -> 0x800000c5

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5992 Comm: dhcpcd-run-hook Not tainted 6.15.0-rc3-syzkaller-00032-ga79be02bba5c #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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