can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
		     struct anon_vma *anon_vma, struct file *file,
		     pgoff_t vm_pgoff,
		     struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
{
	if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
		if (vma->vm_pgoff == vm_pgoff)
			return 1;
	}
	return 0;
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.