ksm: use a folio inside cmp_and_merge_page()

This removes the last call to page_stable_node(), so delete the wrapper.
It also removes a call to trylock_page() and saves a call to
compound_head(), as well as removing a reference to folio->page.

Link: https://lkml.kernel.org/r/20250916181219.2400258-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Longlong Xia <xialonglong@kylinos.cn>
Cc: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/ksm.c b/mm/ksm.c
index 2ef29802a49b9e6cb996d76634291155e8456f7e..2dbe92e3dd52a1d91726e8ce722ec74dc882fe8a 100644 (file)
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1061,11 +1061,6 @@ struct ksm_stable_node *folio_stable_node(const struct folio *folio)
        return folio_test_ksm(folio) ? folio_raw_mapping(folio) : NULL;
 }
 
-static inline struct ksm_stable_node *page_stable_node(struct page *page)
-{
-       return folio_stable_node(page_folio(page));
-}
-
 static inline void folio_set_stable_node(struct folio *folio,
                                         struct ksm_stable_node *stable_node)
 {
@@ -2225,6 +2220,7 @@ static void stable_tree_append(struct ksm_rmap_item *rmap_item,
  */
 static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_item)
 {
+       struct folio *folio = page_folio(page);
        struct ksm_rmap_item *tree_rmap_item;
        struct page *tree_page = NULL;
        struct ksm_stable_node *stable_node;
@@ -2233,7 +2229,7 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite
        int err;
        bool max_page_sharing_bypass = false;
 
-       stable_node = page_stable_node(page);
+       stable_node = folio_stable_node(folio);
        if (stable_node) {
                if (stable_node->head != &migrate_nodes &&
                    get_kpfn_nid(READ_ONCE(stable_node->kpfn)) !=
@@ -2272,7 +2268,7 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite
 
        /* Start by searching for the folio in the stable tree */
        kfolio = stable_tree_search(page);
-       if (&kfolio->page == page && rmap_item->head == stable_node) {
+       if (kfolio == folio && rmap_item->head == stable_node) {
                folio_put(kfolio);
                return;
        }
@@ -2353,10 +2349,11 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite
                         * the page is locked, it is better to skip it and
                         * perhaps try again later.
                         */
-                       if (!trylock_page(page))
+                       if (!folio_trylock(folio))
                                return;
                        split_huge_page(page);
-                       unlock_page(page);
+                       folio = page_folio(page);
+                       folio_unlock(folio);
                }
        }
 }