What the differences between "__GFP_NOFAIL" and "__GFP_REPEAT"?

As per the documentation( https://www.linuxjournal.com/article/6930), which says: Flag Description __GFP_REPEAT The kernel repeats the allocation if it fails. __GFP_NOFAIL The kernel can repeat the allocation. So, both of them may cause the kernel to repeat the allocation operation. How can I choose between them? What are the major differences? Thank you for your attention to this matter. Looking forward to hearing from you.