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BUG: KCSAN: data-race in memcpy_and_pad / rcu_tasks_pertask

write to 0xffff888103fc6c38 of 8 bytes by task 28 on cpu 1:
 __list_add include/linux/list.h:172 [inline]
 list_add include/linux/list.h:192 [inline]
 rcu_tasks_pertask+0x103/0x160 kernel/rcu/tasks.h:1021
 rcu_tasks_wait_gp+0x184/0x530 kernel/rcu/tasks.h:837
 rcu_tasks_one_gp+0x7f9/0x8e0 kernel/rcu/tasks.h:621
 rcu_tasks_kthread+0xf6/0x110 kernel/rcu/tasks.h:657
 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 0xffff888103fc6780 of 3456 bytes by task 23720 on cpu 0:
 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+0x6d/0x750 kernel/fork.c:926
 copy_process+0x5a0/0x2340 kernel/fork.c:2133
 kernel_clone+0x1c0/0x5f0 kernel/fork.c:2766
 __do_sys_clone kernel/fork.c:2908 [inline]
 __se_sys_clone kernel/fork.c:2892 [inline]
 __x64_sys_clone+0x143/0x180 kernel/fork.c:2892
 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 23720 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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