On Sun, Dec 13, 2020 at 11:45:33PM +0800, Muchun Song wrote: > For HugeTLB page, there are more metadata to save in the struct page. > But the head struct page cannot meet our needs, so we have to abuse > other tail struct page to store the metadata. In order to avoid > conflicts caused by subsequent use of more tail struct pages, we can > gather these discrete indexes of tail struct page. In this case, it > will be easier to add a new tail page index later. > > There are only (RESERVE_VMEMMAP_SIZE / sizeof(struct page)) struct > page structs can be used when CONFIG_HUGETLB_PAGE_FREE_VMEMMAP, so "that can be..." > add a BUILD_BUG_ON to catch invalid usage of the tail struct page. > > Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> I think this makes the current situation with metadata usage in sub-pages easier to track. Reviewed-by: Oscar Salvador <osalvador@xxxxxxx> -- Oscar Salvador SUSE L3
