On Tue, Jul 23, 2019 at 01:08:42PM +0800, Huang, Ying wrote:
> @@ -2489,6 +2491,14 @@ static void __split_huge_page(struct page *page,
> struct list_head *list,
> /* complete memcg works before add pages to LRU */
> mem_cgroup_split_huge_fixup(head);
>
> + if (PageAnon(head) && PageSwapCache(head)) {
> + swp_entry_t entry = { .val = page_private(head) };
> +
> + offset = swp_offset(entry);
> + swap_cache = swap_address_space(entry);
> + xa_lock(&swap_cache->i_pages);
> + }
> +
> for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
> __split_huge_page_tail(head, i, lruvec, list);
> /* Some pages can be beyond i_size: drop them from page cache */
> @@ -2501,6 +2511,9 @@ static void __split_huge_page(struct page *page, struct
> list_head *list,
> } else if (!PageAnon(page)) {
> __xa_store(&head->mapping->i_pages, head[i].index,
> head + i, 0);
> + } else if (swap_cache) {
> + __xa_store(&swap_cache->i_pages, offset + i,
> + head + i, 0);
I tried something along these lines (though I think I messed up the offset
calculation which is why it wasn't working for me). My other concern
was with the case where SWAPFILE_CLUSTER was less than HPAGE_PMD_NR.
Don't we need to drop the lock and look up a new swap_cache if offset >=
SWAPFILE_CLUSTER?
