static inline bool can_do_pageout(struct vm_area_struct *vma)
{
	if (vma_is_anonymous(vma))
		return true;
	if (!vma->vm_file)
		return false;
	/*
	 * paging out pagecache only for non-anonymous mappings that correspond
	 * to the files the calling process could (if tried) open for writing;
	 * otherwise we'd be including shared non-exclusive mappings, which
	 * opens a side channel.
	 */
	return inode_owner_or_capable(file_inode(vma->vm_file)) ||
		inode_permission(file_inode(vma->vm_file), MAY_WRITE) == 0;
}
static inline bool can_do_pageout(struct vm_area_struct *vma)
{
	if (vma_is_anonymous(vma))
		return true;
	if (!vma->vm_file)
		return false;
	 
	return inode_owner_or_capable(file_inode(vma->vm_file)) ||
		inode_permission(file_inode(vma->vm_file), MAY_WRITE) == 0;
}