On Tue 12-02-19 10:34:54, Matthew Wilcox wrote: > Transparent Huge Pages are currently stored in i_pages as pointers to > consecutive subpages. This patch changes that to storing consecutive > pointers to the head page in preparation for storing huge pages more > efficiently in i_pages. > > Large parts of this are "inspired" by Kirill's patch > https://lore.kernel.org/lkml/20170126115819.58875-2-kirill.shutemov@xxxxxxxxxxxxxxx/ > > Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxx> I like the idea! > @@ -1778,33 +1767,27 @@ unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start, > > rcu_read_lock(); > xas_for_each(&xas, page, end) { > - struct page *head; > if (xas_retry(&xas, page)) > continue; > /* Skip over shadow, swap and DAX entries */ > if (xa_is_value(page)) > continue; > > - head = compound_head(page); > - if (!page_cache_get_speculative(head)) > + if (!page_cache_get_speculative(page)) > goto retry; > > - /* The page was split under us? */ > - if (compound_head(page) != head) > - goto put_page; > - > - /* Has the page moved? */ > + /* Has the page moved or been split? */ > if (unlikely(page != xas_reload(&xas))) > goto put_page; > > - pages[ret] = page; > + pages[ret] = find_subpage(page, xas.xa_index); > if (++ret == nr_pages) { > *start = page->index + 1; > goto out; > } So this subtly changes the behavior because now we will be returning in '*start' a different index. So you should rather use 'pages[ret]->index' instead. > @@ -1923,26 +1899,21 @@ unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index, > if (xa_is_value(page)) > continue; > > - head = compound_head(page); > - if (!page_cache_get_speculative(head)) > + if (!page_cache_get_speculative(page)) > goto retry; > > - /* The page was split under us? */ > - if (compound_head(page) != head) > - goto put_page; > - > - /* Has the page moved? */ > + /* Has the page moved or been split? */ > if (unlikely(page != xas_reload(&xas))) > goto put_page; > > - pages[ret] = page; > + pages[ret] = find_subpage(page, xas.xa_index); > if (++ret == nr_pages) { > *index = page->index + 1; > goto out; > } Ditto here. Otherwise the patch looks good to me so feel free to add: Acked-by: Jan Kara <jack@xxxxxxx> after fixing these two. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
