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BUG: KCSAN: data-race in copy_mm / vm_mmap_pgoff

read-write to 0xffff888128390208 of 4 bytes by task 28450 on cpu 0:
 do_raw_write_seqcount_begin include/linux/seqlock.h:432 [inline]
 mm_lock_seqcount_begin include/linux/mmap_lock.h:125 [inline]
 mmap_write_lock_killable include/linux/mmap_lock.h:556 [inline]
 vm_mmap_pgoff+0x12f/0x2d0 mm/util.c:579
 ksys_mmap_pgoff+0xc1/0x310 mm/mmap.c:606
 x64_sys_call+0x14df/0x3020 arch/x86/include/generated/asm/syscalls_64.h:10
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888128390000 of 1728 bytes by task 28451 on cpu 1:
 dup_mm kernel/fork.c:1532 [inline]
 copy_mm+0xd6/0x340 kernel/fork.c:1590
 copy_process+0x10cd/0x2350 kernel/fork.c:2288
 kernel_clone+0x1c0/0x5f0 kernel/fork.c:2746
 __do_sys_clone kernel/fork.c:2887 [inline]
 __se_sys_clone kernel/fork.c:2871 [inline]
 __x64_sys_clone+0x143/0x180 kernel/fork.c:2871
 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+0x136/0x3c0 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: 28451 Comm: syz.1.7631 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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