ksm-abstract-the-function-try_to_get_old_rmap_item-v6

ksm-abstract-the-function-try_to_get_old_rmap_item-v6

modify some comments according to David's suggestions.

Link: https://lkml.kernel.org/r/202302100916423431376@zte.com.cn
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Reviewed-by: Xiaokai Ran <ran.xiaokai@zte.com.cn>
Reviewed-by: Yang Yang <yang.yang29@zte.com.cn>
Cc: David Hildenbrand <david@redhat.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Xuexin Jiang <jiang.xuexin@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>