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BUG: KCSAN: data-race in memcpy_and_pad / rcu_tasks_trace_pregp_step

write to 0xffff8881036a845c of 4 bytes by task 28 on cpu 0:
 rcu_tasks_trace_pertask_prep kernel/rcu/tasks.h:1783 [inline]
 rcu_tasks_trace_pregp_step+0x1ac/0x920 kernel/rcu/tasks.h:1827
 rcu_tasks_wait_gp+0x88/0x530 kernel/rcu/tasks.h:825
 rcu_tasks_one_gp+0x7f3/0x8e0 kernel/rcu/tasks.h:621
 rcu_tasks_kthread+0xf7/0x110 kernel/rcu/tasks.h:657
 kthread+0x486/0x510 kernel/kthread.c:464
 ret_from_fork+0x4e/0x60 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff8881036a8000 of 3200 bytes by task 12722 on cpu 1:
 memcpy_and_pad+0x48/0x80 lib/string_helpers.c:1004
 arch_dup_task_struct+0x2c/0x40 arch/x86/kernel/process.c:98
 dup_task_struct+0x83/0x6a0 kernel/fork.c:1133
 copy_process+0x399/0x1fe0 kernel/fork.c:2259
 kernel_clone+0x16c/0x5b0 kernel/fork.c:2859
 __do_sys_clone3 kernel/fork.c:3163 [inline]
 __se_sys_clone3+0x1c2/0x200 kernel/fork.c:3142
 __x64_sys_clone3+0x31/0x40 kernel/fork.c:3142
 x64_sys_call+0x10c9/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:436
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1b0 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: 12722 Comm: syz.9.3135 Not tainted 6.15.0-syzkaller-01958-g785cdec46e92 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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