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BUG: KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step

write to 0xffff8881001d94dc of 4 bytes by task 28 on cpu 1:
 rcu_tasks_trace_pertask_prep kernel/rcu/tasks.h:1784 [inline]
 rcu_tasks_trace_pregp_step+0x1ac/0x920 kernel/rcu/tasks.h:1828
 rcu_tasks_wait_gp+0x8b/0x530 kernel/rcu/tasks.h:826
 rcu_tasks_one_gp+0x7f6/0x8e0 kernel/rcu/tasks.h:622
 rcu_tasks_kthread+0xf7/0x110 kernel/rcu/tasks.h:658
 kthread+0x489/0x510 kernel/kthread.c:463
 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 0:
 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+0x28d/0x360 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: 0 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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