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 61ef18655704 ("mm: factor find_get_incore_page out of
mincore_page") to be used by later commit f5df8635c5a3 ("mm: use
find_get_incore_page in memcontrol"), so memory cgroup charge move code
can be simplified.

But commit 6b611388b626 ("memcg-v1: remove charge move code") removed that
user completely, it's only used by mincore now.

So this commit basically reverts commit 61ef18655704 ("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: Kairui Song <kasong@tencent.com>
Acked-by: Nhat 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: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/mincore.c b/mm/mincore.c
index 10dabefc3accb56f86e47e971ca95d8034c5c8ff..20fd0967d3cbca54c337d324d9eaee67c19c84ce 100644 (file)
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -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);
        }

diff --git a/mm/swap.h b/mm/swap.h
index 911ad5ff0f89fd3b6ddceb3cf603158887e77f7d..1ae44d4193b1cac29c47fcac2397734cdb67ff58 100644 (file)
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -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;

diff --git a/mm/swap_state.c b/mm/swap_state.c
index c354435a0923d3309f0a778e4f64fa0a08a2109c..99513b74b5d8160b942c29a6fb1ef90ec0a2000e 100644 (file)
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -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)