Commit f102cd8b authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

swapfile: convert unuse_pte_range() to use a folio 

Delay fetching the precise page from the folio until we're in unuse_pte().
Saves many calls to compound_head().

Link: https://lkml.kernel.org/r/20220902194653.1739778-37-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 2c3f6194

mm/swapfile.c

+19 −14
Original line number Diff line number Diff line
@@ -1758,8 +1758,9 @@ static inline int pte_same_as_swp(pte_t pte, pte_t swp_pte) 
 * force COW, vm_page_prot omits write permission from any private vma.

 */

static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,

		unsigned long addr, swp_entry_t entry, struct page *page)

		unsigned long addr, swp_entry_t entry, struct folio *folio)

{

	struct page *page = folio_file_page(folio, swp_offset(entry));

	struct page *swapcache;

	spinlock_t *ptl;

	pte_t *pte, new_pte;
@@ -1831,17 +1832,18 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, 
			unsigned long addr, unsigned long end,

			unsigned int type)

{

	struct page *page;

	swp_entry_t entry;

	pte_t *pte;

	struct swap_info_struct *si;

	unsigned long offset;

	int ret = 0;

	volatile unsigned char *swap_map;



	si = swap_info[type];

	pte = pte_offset_map(pmd, addr);

	do {

		struct folio *folio;

		unsigned long offset;



		if (!is_swap_pte(*pte))

			continue;
@@ -1852,8 +1854,9 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, 
		offset = swp_offset(entry);

		pte_unmap(pte);

		swap_map = &si->swap_map[offset];

		page = lookup_swap_cache(entry, vma, addr);

		if (!page) {

		folio = swap_cache_get_folio(entry, vma, addr);

		if (!folio) {

			struct page *page;

			struct vm_fault vmf = {

				.vma = vma,

				.address = addr,
@@ -1863,25 +1866,27 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, 


			page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,

						&vmf);

			if (page)

				folio = page_folio(page);

		}

		if (!page) {

		if (!folio) {

			if (*swap_map == 0 || *swap_map == SWAP_MAP_BAD)

				goto try_next;

			return -ENOMEM;

		}



		lock_page(page);

		wait_on_page_writeback(page);

		ret = unuse_pte(vma, pmd, addr, entry, page);

		folio_lock(folio);

		folio_wait_writeback(folio);

		ret = unuse_pte(vma, pmd, addr, entry, folio);

		if (ret < 0) {

			unlock_page(page);

			put_page(page);

			folio_unlock(folio);

			folio_put(folio);

			goto out;

		}



		try_to_free_swap(page);

		unlock_page(page);

		put_page(page);

		folio_free_swap(folio);

		folio_unlock(folio);

		folio_put(folio);

try_next:

		pte = pte_offset_map(pmd, addr);

	} while (pte++, addr += PAGE_SIZE, addr != end);