Commit 27763eda authored by Kairui Song's avatar Kairui Song Committed by Andrew Morton
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mm/mincore, swap: consolidate swap cache checking for mincore 

Patch series "mm/mincore: minor clean up for swap cache checking".

This series cleans up a swap cache helper only used by mincore, move it
back into mincore code.  Also separate the swap cache related logics out
of shmem / page cache logics in mincore.

With this series we have less lines of code and better performance.

Before this series:
mincore on a swaped out 16G anon mmap range:
Took 488220 us
mincore on 16G shmem mmap range:
Took 530272 us.

After this series:
mincore on a swaped out 16G anon mmap range:
Took 446763 us
mincore on 16G shmem mmap range:
Took 460496 us.

About ~10% faster.


This patch (of 2):

The filemap_get_incore_folio (previously find_get_incore_page) helper was
introduced by commit 61ef1865 ("mm: factor find_get_incore_page out of
mincore_page") to be used by later commit f5df8635 ("mm: use
find_get_incore_page in memcontrol"), so memory cgroup charge move code
can be simplified.

But commit 6b611388 ("memcg-v1: remove charge move code") removed that
user completely, it's only used by mincore now.

So this commit basically reverts commit 61ef1865 ("mm: factor
find_get_incore_page out of mincore_page").  Move it back to mincore side
to simplify the code.

Link: https://lkml.kernel.org/r/20250811172018.48901-1-ryncsn@gmail.com
Link: https://lkml.kernel.org/r/20250811172018.48901-2-ryncsn@gmail.com


Signed-off-by: default avatarKairui Song <kasong@tencent.com>
Acked-by: default avatarNhat Pham <nphamcs@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 7bca1760

mm/mincore.c

+27 −2
Original line number Diff line number Diff line
@@ -64,8 +64,33 @@ static unsigned char mincore_page(struct address_space *mapping, pgoff_t index) 
	 * any other file mapping (ie. marked !present and faulted in with

	 * tmpfs's .fault). So swapped out tmpfs mappings are tested here.

	 */

	folio = filemap_get_incore_folio(mapping, index);

	if (!IS_ERR(folio)) {

	if (IS_ENABLED(CONFIG_SWAP) && shmem_mapping(mapping)) {

		folio = filemap_get_entry(mapping, index);

		/*

		 * shmem/tmpfs may return swap: account for swapcache

		 * page too.

		 */

		if (xa_is_value(folio)) {

			struct swap_info_struct *si;

			swp_entry_t swp = radix_to_swp_entry(folio);

			/* There might be swapin error entries in shmem mapping. */

			if (non_swap_entry(swp))

				return 0;

			/* Prevent swap device to being swapoff under us */

			si = get_swap_device(swp);

			if (si) {

				folio = filemap_get_folio(swap_address_space(swp),

							  swap_cache_index(swp));

				put_swap_device(si);

			} else {

				return 0;

			}

		}

	} else {

		folio = filemap_get_folio(mapping, index);

	}



	if (!IS_ERR_OR_NULL(folio)) {

		present = folio_test_uptodate(folio);

		folio_put(folio);

	}

mm/swap.h

+0 −10
Original line number Diff line number Diff line
@@ -64,9 +64,6 @@ void clear_shadow_from_swap_cache(int type, unsigned long begin, 
void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry, int nr);

struct folio *swap_cache_get_folio(swp_entry_t entry,

		struct vm_area_struct *vma, unsigned long addr);

struct folio *filemap_get_incore_folio(struct address_space *mapping,

		pgoff_t index);



struct folio *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,

		struct vm_area_struct *vma, unsigned long addr,

		struct swap_iocb **plug);
@@ -178,13 +175,6 @@ static inline struct folio *swap_cache_get_folio(swp_entry_t entry, 
	return NULL;

}



static inline

struct folio *filemap_get_incore_folio(struct address_space *mapping,

		pgoff_t index)

{

	return filemap_get_folio(mapping, index);

}



static inline void *get_shadow_from_swap_cache(swp_entry_t entry)

{

	return NULL;

mm/swap_state.c

+0 −38
Original line number Diff line number Diff line
@@ -323,44 +323,6 @@ struct folio *swap_cache_get_folio(swp_entry_t entry, 
	return folio;

}



/**

 * filemap_get_incore_folio - Find and get a folio from the page or swap caches.

 * @mapping: The address_space to search.

 * @index: The page cache index.

 *

 * This differs from filemap_get_folio() in that it will also look for the

 * folio in the swap cache.

 *

 * Return: The found folio or %NULL.

 */

struct folio *filemap_get_incore_folio(struct address_space *mapping,

		pgoff_t index)

{

	swp_entry_t swp;

	struct swap_info_struct *si;

	struct folio *folio = filemap_get_entry(mapping, index);



	if (!folio)

		return ERR_PTR(-ENOENT);

	if (!xa_is_value(folio))

		return folio;

	if (!shmem_mapping(mapping))

		return ERR_PTR(-ENOENT);



	swp = radix_to_swp_entry(folio);

	/* There might be swapin error entries in shmem mapping. */

	if (non_swap_entry(swp))

		return ERR_PTR(-ENOENT);

	/* Prevent swapoff from happening to us */

	si = get_swap_device(swp);

	if (!si)

		return ERR_PTR(-ENOENT);

	index = swap_cache_index(swp);

	folio = filemap_get_folio(swap_address_space(swp), index);

	put_swap_device(si);

	return folio;

}



struct folio *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,

		struct mempolicy *mpol, pgoff_t ilx, bool *new_page_allocated,

		bool skip_if_exists)