On Wed, Nov 22, 2023 at 11:21:50PM -0800, Christoph Hellwig wrote: > That alone sounds like a good reason to not bother. So unless more > qualified people have a different opinion I'm fine with this patch > as long as you leave a comment in place, and ammend the commit message > with some of the very useful information from your mail. Will do, thanks. This is what I will squash into the same patch in the new version, as the current plan: +/* + * NOTE: currently hugepd is only used in hugetlbfs file systems on Power, + * which does not have issue with folio writeback against GUP updates. + * When hugepd will be extended to support non-hugetlbfs or even anonymous + * memory, we need to do extra check as what we do with most of the other + * folios. See writable_file_mapping_allowed() and folio_fast_pin_allowed() + * for more information. + */ static int gup_huge_pd(hugepd_t hugepd, unsigned long addr, unsigned int pdshift, unsigned long end, unsigned int flags, struct page **pages, int *nr) -- Peter Xu