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BUG: KCSAN: data-race in memcpy_and_pad / release_task

write to 0xffff8881040ad8b0 of 8 bytes by task 3313 on cpu 0:
 __list_del include/linux/list.h:203 [inline]
 __list_del_entry include/linux/list.h:226 [inline]
 list_del_rcu include/linux/rculist.h:178 [inline]
 __unhash_process kernel/exit.c:149 [inline]
 __exit_signal kernel/exit.c:212 [inline]
 release_task+0x6ef/0xb60 kernel/exit.c:265
 wait_task_zombie kernel/exit.c:1280 [inline]
 wait_consider_task+0x1160/0x1670 kernel/exit.c:1507
 do_wait_thread kernel/exit.c:1570 [inline]
 __do_wait+0xf9/0x510 kernel/exit.c:1688
 do_wait+0xb6/0x260 kernel/exit.c:1722
 kernel_wait4+0x19f/0x210 kernel/exit.c:1881
 __do_sys_wait4 kernel/exit.c:1909 [inline]
 __se_sys_wait4 kernel/exit.c:1905 [inline]
 __x64_sys_wait4+0x91/0x120 kernel/exit.c:1905
 x64_sys_call+0x2aee/0x3020 arch/x86/include/generated/asm/syscalls_64.h:62
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881040ad3c0 of 3328 bytes by task 8563 on cpu 1:
 memcpy_and_pad+0x48/0x80 lib/string_helpers.c:1008
 arch_dup_task_struct+0x2c/0x40 arch/x86/kernel/process.c:108
 dup_task_struct+0x6e/0x950 kernel/fork.c:920
 copy_process+0x37e/0x20b0 kernel/fork.c:2050
 kernel_clone+0x16b/0x5d0 kernel/fork.c:2653
 __do_sys_clone3 kernel/fork.c:2955 [inline]
 __se_sys_clone3+0x1f5/0x230 kernel/fork.c:2934
 __x64_sys_clone3+0x31/0x40 kernel/fork.c:2934
 x64_sys_call+0x580/0x3020 arch/x86/include/generated/asm/syscalls_64.h:436
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 8563 Comm: syz.4.1678 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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