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BUG: KCSAN: data-race in copy_mm / copy_page_range

read-write to 0xffff88810546aaf8 of 4 bytes by task 28286 on cpu 0:
 do_raw_write_seqcount_begin include/linux/seqlock.h:432 [inline]
 copy_page_range+0x2a2/0x3d00 mm/memory.c:1542
 dup_mmap+0x892/0x10c0 mm/mmap.c:1841
 dup_mm kernel/fork.c:1530 [inline]
 copy_mm+0x119/0x370 kernel/fork.c:1582
 copy_process+0xe22/0x20d0 kernel/fork.c:2223
 kernel_clone+0x16b/0x5d0 kernel/fork.c:2654
 __do_sys_clone kernel/fork.c:2795 [inline]
 __se_sys_clone kernel/fork.c:2779 [inline]
 __x64_sys_clone+0x143/0x180 kernel/fork.c:2779
 x64_sys_call+0x1222/0x3020 arch/x86/include/generated/asm/syscalls_64.h:57
 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 0xffff88810546a880 of 1664 bytes by task 28285 on cpu 1:
 dup_mm kernel/fork.c:1524 [inline]
 copy_mm+0xe1/0x370 kernel/fork.c:1582
 copy_process+0xe22/0x20d0 kernel/fork.c:2223
 kernel_clone+0x16b/0x5d0 kernel/fork.c:2654
 __do_sys_clone3 kernel/fork.c:2956 [inline]
 __se_sys_clone3+0x1f5/0x230 kernel/fork.c:2935
 __x64_sys_clone3+0x31/0x40 kernel/fork.c:2935
 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: 28285 Comm: syz.9.6052 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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