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BUG: KCSAN: data-race in memcpy_and_pad / zap_other_threads

read-write to 0xffff888150ff1618 of 8 bytes by task 21969 on cpu 0:
 task_clear_jobctl_pending kernel/signal.c:339 [inline]
 zap_other_threads+0x114/0x290 kernel/signal.c:1345
 do_group_exit+0xe3/0x140 kernel/exit.c:1113
 __do_sys_exit_group kernel/exit.c:1129 [inline]
 __se_sys_exit_group kernel/exit.c:1127 [inline]
 __x64_sys_exit_group+0x1f/0x20 kernel/exit.c:1127
 x64_sys_call+0x3008/0x3020 arch/x86/include/generated/asm/syscalls_64.h:232
 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 0xffff888150ff10c0 of 3328 bytes by task 21970 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
 create_io_thread+0x8f/0xc0 kernel/fork.c:2601
 create_io_worker+0xde/0x360 io_uring/io-wq.c:917
 io_wq_create_worker io_uring/io-wq.c:341 [inline]
 io_wq_enqueue+0x461/0x540 io_uring/io-wq.c:1059
 io_queue_iowq+0x24e/0x350 io_uring/io_uring.c:431
 io_queue_sqe_fallback+0xe6/0x140 io_uring/io_uring.c:1661
 io_submit_sqe io_uring/io_uring.c:1915 [inline]
 io_submit_sqes+0xdd0/0x1230 io_uring/io_uring.c:2043
 __do_sys_io_uring_enter io_uring/io_uring.c:2604 [inline]
 __se_sys_io_uring_enter+0x1c9/0xf50 io_uring/io_uring.c:2539
 __x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:2539
 x64_sys_call+0x1e16/0x3020 arch/x86/include/generated/asm/syscalls_64.h:427
 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: 21970 Comm: syz.1.6392 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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