syzbot

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BUG: KCSAN: data-race in memcpy_and_pad / release_task

write to 0xffff888100211638 of 8 bytes by task 1265 on cpu 1:
 __list_del include/linux/list.h:195 [inline]
 __list_del_entry include/linux/list.h:218 [inline]
 list_del_init include/linux/list.h:287 [inline]
 __unhash_process kernel/exit.c:150 [inline]
 __exit_signal kernel/exit.c:212 [inline]
 release_task+0x779/0xb60 kernel/exit.c:267
 exit_notify kernel/exit.c:778 [inline]
 do_exit+0xd81/0x15c0 kernel/exit.c:973
 call_usermodehelper_exec_async+0x247/0x250 kernel/umh.c:122
 ret_from_fork+0xdd/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff888100211080 of 3264 bytes by task 2 on cpu 0:
 memcpy_and_pad+0x48/0x80 lib/string_helpers.c:1007
 arch_dup_task_struct+0x2c/0x40 arch/x86/kernel/process.c:98
 dup_task_struct+0x83/0x6a0 kernel/fork.c:874
 copy_process+0x399/0x2000 kernel/fork.c:2001
 kernel_clone+0x16c/0x5c0 kernel/fork.c:2602
 kernel_thread+0xac/0xe0 kernel/fork.c:2664
 create_kthread kernel/kthread.c:486 [inline]
 kthreadd+0x28d/0x360 kernel/kthread.c:846
 ret_from_fork+0xdd/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 2 Comm: kthreadd Tainted: G        W           6.16.0-syzkaller-11699-g7e161a991ea7 #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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