syzbot

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BUG: KCSAN: data-race in memcpy_and_pad / release_task

write to 0xffff8881001d9638 of 8 bytes by task 2658 on cpu 0:
 __list_del include/linux/list.h:203 [inline]
 __list_del_entry include/linux/list.h:226 [inline]
 list_del_init include/linux/list.h:295 [inline]
 __unhash_process kernel/exit.c:150 [inline]
 __exit_signal kernel/exit.c:212 [inline]
 release_task+0x76f/0xb60 kernel/exit.c:265
 exit_notify kernel/exit.c:777 [inline]
 do_exit+0xd4d/0x1590 kernel/exit.c:983
 call_usermodehelper_exec_async+0x247/0x250 kernel/umh.c:122
 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 0xffff8881001d9080 of 3264 bytes by task 2 on cpu 1:
 memcpy_and_pad+0x48/0x80 lib/string_helpers.c:1007
 arch_dup_task_struct+0x2c/0x40 arch/x86/kernel/process.c:108
 dup_task_struct+0x6e/0x950 kernel/fork.c:919
 copy_process+0x37d/0x1ef0 kernel/fork.c:2052
 kernel_clone+0x16c/0x5c0 kernel/fork.c:2651
 kernel_thread+0xad/0xe0 kernel/fork.c:2712
 create_kthread kernel/kthread.c:486 [inline]
 kthreadd+0x26c/0x340 kernel/kthread.c:844
 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 2 Comm: kthreadd Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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