mm/ksm: convert chain series funcs and replace get_ksm_page
authorAlex Shi (tencent) <alexs@kernel.org>
Thu, 11 Apr 2024 06:17:09 +0000 (14:17 +0800)
committerAndrew Morton <akpm@linux-foundation.org>
Mon, 6 May 2024 00:53:34 +0000 (17:53 -0700)
In ksm stable tree all page are single, let's convert them to use and
folios as well as stable_tree_insert/stable_tree_search funcs.  And
replace get_ksm_page() by ksm_get_folio() since there is no more needs.

It could save a few compound_head calls.

Link: https://lkml.kernel.org/r/20240411061713.1847574-9-alexs@kernel.org
Signed-off-by: Alex Shi (tencent) <alexs@kernel.org>
Cc: Izik Eidus <izik.eidus@ravellosystems.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/ksm.c
mm/migrate.c

index 2fdd6586a3a76970b6cfe64d0cf8b2b2298dfe44..61a7b5b037a6be667993b21912061cac9f49c41d 100644 (file)
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -990,14 +990,6 @@ stale:
        return NULL;
 }
 
-static struct page *get_ksm_page(struct ksm_stable_node *stable_node,
-                                enum get_ksm_page_flags flags)
-{
-       struct folio *folio = ksm_get_folio(stable_node, flags);
-
-       return &folio->page;
-}
-
 /*
  * Removing rmap_item from stable or unstable tree.
  * This function will clean the information from the stable/unstable tree.
@@ -1632,10 +1624,10 @@ bool is_page_sharing_candidate(struct ksm_stable_node *stable_node)
        return __is_page_sharing_candidate(stable_node, 0);
 }
 
-static struct page *stable_node_dup(struct ksm_stable_node **_stable_node_dup,
-                                   struct ksm_stable_node **_stable_node,
-                                   struct rb_root *root,
-                                   bool prune_stale_stable_nodes)
+static struct folio *stable_node_dup(struct ksm_stable_node **_stable_node_dup,
+                                    struct ksm_stable_node **_stable_node,
+                                    struct rb_root *root,
+                                    bool prune_stale_stable_nodes)
 {
        struct ksm_stable_node *dup, *found = NULL, *stable_node = *_stable_node;
        struct hlist_node *hlist_safe;
@@ -1748,7 +1740,7 @@ static struct page *stable_node_dup(struct ksm_stable_node **_stable_node_dup,
        }
 
        *_stable_node_dup = found;
-       return &tree_folio->page;
+       return tree_folio;
 }
 
 static struct ksm_stable_node *stable_node_dup_any(struct ksm_stable_node *stable_node,
@@ -1765,7 +1757,7 @@ static struct ksm_stable_node *stable_node_dup_any(struct ksm_stable_node *stabl
 }
 
 /*
- * Like for get_ksm_page, this function can free the *_stable_node and
+ * Like for ksm_get_folio, this function can free the *_stable_node and
  * *_stable_node_dup if the returned tree_page is NULL.
  *
  * It can also free and overwrite *_stable_node with the found
@@ -1778,16 +1770,16 @@ static struct ksm_stable_node *stable_node_dup_any(struct ksm_stable_node *stabl
  * function and will be overwritten in all cases, the caller doesn't
  * need to initialize it.
  */
-static struct page *__stable_node_chain(struct ksm_stable_node **_stable_node_dup,
-                                       struct ksm_stable_node **_stable_node,
-                                       struct rb_root *root,
-                                       bool prune_stale_stable_nodes)
+static struct folio *__stable_node_chain(struct ksm_stable_node **_stable_node_dup,
+                                        struct ksm_stable_node **_stable_node,
+                                        struct rb_root *root,
+                                        bool prune_stale_stable_nodes)
 {
        struct ksm_stable_node *stable_node = *_stable_node;
        if (!is_stable_node_chain(stable_node)) {
                if (is_page_sharing_candidate(stable_node)) {
                        *_stable_node_dup = stable_node;
-                       return get_ksm_page(stable_node, GET_KSM_PAGE_NOLOCK);
+                       return ksm_get_folio(stable_node, GET_KSM_PAGE_NOLOCK);
                }
                /*
                 * _stable_node_dup set to NULL means the stable_node
@@ -1800,24 +1792,24 @@ static struct page *__stable_node_chain(struct ksm_stable_node **_stable_node_du
                               prune_stale_stable_nodes);
 }
 
-static __always_inline struct page *chain_prune(struct ksm_stable_node **s_n_d,
-                                               struct ksm_stable_node **s_n,
-                                               struct rb_root *root)
+static __always_inline struct folio *chain_prune(struct ksm_stable_node **s_n_d,
+                                                struct ksm_stable_node **s_n,
+                                                struct rb_root *root)
 {
        return __stable_node_chain(s_n_d, s_n, root, true);
 }
 
-static __always_inline struct page *chain(struct ksm_stable_node **s_n_d,
-                                         struct ksm_stable_node *s_n,
-                                         struct rb_root *root)
+static __always_inline struct folio *chain(struct ksm_stable_node **s_n_d,
+                                          struct ksm_stable_node *s_n,
+                                          struct rb_root *root)
 {
        struct ksm_stable_node *old_stable_node = s_n;
-       struct page *tree_page;
+       struct folio *tree_folio;
 
-       tree_page = __stable_node_chain(s_n_d, &s_n, root, false);
+       tree_folio = __stable_node_chain(s_n_d, &s_n, root, false);
        /* not pruning dups so s_n cannot have changed */
        VM_BUG_ON(s_n != old_stable_node);
-       return tree_page;
+       return tree_folio;
 }
 
 /*
@@ -1837,28 +1829,30 @@ static struct page *stable_tree_search(struct page *page)
        struct rb_node *parent;
        struct ksm_stable_node *stable_node, *stable_node_dup, *stable_node_any;
        struct ksm_stable_node *page_node;
+       struct folio *folio;
 
-       page_node = page_stable_node(page);
+       folio = page_folio(page);
+       page_node = folio_stable_node(folio);
        if (page_node && page_node->head != &migrate_nodes) {
                /* ksm page forked */
-               get_page(page);
-               return page;
+               folio_get(folio);
+               return &folio->page;
        }
 
-       nid = get_kpfn_nid(page_to_pfn(page));
+       nid = get_kpfn_nid(folio_pfn(folio));
        root = root_stable_tree + nid;
 again:
        new = &root->rb_node;
        parent = NULL;
 
        while (*new) {
-               struct page *tree_page;
+               struct folio *tree_folio;
                int ret;
 
                cond_resched();
                stable_node = rb_entry(*new, struct ksm_stable_node, node);
                stable_node_any = NULL;
-               tree_page = chain_prune(&stable_node_dup, &stable_node, root);
+               tree_folio = chain_prune(&stable_node_dup, &stable_node, root);
                /*
                 * NOTE: stable_node may have been freed by
                 * chain_prune() if the returned stable_node_dup is
@@ -1892,14 +1886,14 @@ again:
                         * write protected at all times. Any will work
                         * fine to continue the walk.
                         */
-                       tree_page = get_ksm_page(stable_node_any,
-                                                GET_KSM_PAGE_NOLOCK);
+                       tree_folio = ksm_get_folio(stable_node_any,
+                                                  GET_KSM_PAGE_NOLOCK);
                }
                VM_BUG_ON(!stable_node_dup ^ !!stable_node_any);
-               if (!tree_page) {
+               if (!tree_folio) {
                        /*
                         * If we walked over a stale stable_node,
-                        * get_ksm_page() will call rb_erase() and it
+                        * ksm_get_folio() will call rb_erase() and it
                         * may rebalance the tree from under us. So
                         * restart the search from scratch. Returning
                         * NULL would be safe too, but we'd generate
@@ -1909,8 +1903,8 @@ again:
                        goto again;
                }
 
-               ret = memcmp_pages(page, tree_page);
-               put_page(tree_page);
+               ret = memcmp_pages(page, &tree_folio->page);
+               folio_put(tree_folio);
 
                parent = *new;
                if (ret < 0)
@@ -1953,26 +1947,26 @@ again:
                         * It would be more elegant to return stable_node
                         * than kpage, but that involves more changes.
                         */
-                       tree_page = get_ksm_page(stable_node_dup,
-                                                GET_KSM_PAGE_TRYLOCK);
+                       tree_folio = ksm_get_folio(stable_node_dup,
+                                                  GET_KSM_PAGE_TRYLOCK);
 
-                       if (PTR_ERR(tree_page) == -EBUSY)
+                       if (PTR_ERR(tree_folio) == -EBUSY)
                                return ERR_PTR(-EBUSY);
 
-                       if (unlikely(!tree_page))
+                       if (unlikely(!tree_folio))
                                /*
                                 * The tree may have been rebalanced,
                                 * so re-evaluate parent and new.
                                 */
                                goto again;
-                       unlock_page(tree_page);
+                       folio_unlock(tree_folio);
 
                        if (get_kpfn_nid(stable_node_dup->kpfn) !=
                            NUMA(stable_node_dup->nid)) {
-                               put_page(tree_page);
+                               folio_put(tree_folio);
                                goto replace;
                        }
-                       return tree_page;
+                       return &tree_folio->page;
                }
        }
 
@@ -1985,8 +1979,8 @@ again:
        rb_insert_color(&page_node->node, root);
 out:
        if (is_page_sharing_candidate(page_node)) {
-               get_page(page);
-               return page;
+               folio_get(folio);
+               return &folio->page;
        } else
                return NULL;
 
@@ -2011,12 +2005,12 @@ replace:
                                        &page_node->node,
                                        root);
                        if (is_page_sharing_candidate(page_node))
-                               get_page(page);
+                               folio_get(folio);
                        else
-                               page = NULL;
+                               folio = NULL;
                } else {
                        rb_erase(&stable_node_dup->node, root);
-                       page = NULL;
+                       folio = NULL;
                }
        } else {
                VM_BUG_ON(!is_stable_node_chain(stable_node));
@@ -2027,16 +2021,16 @@ replace:
                        DO_NUMA(page_node->nid = nid);
                        stable_node_chain_add_dup(page_node, stable_node);
                        if (is_page_sharing_candidate(page_node))
-                               get_page(page);
+                               folio_get(folio);
                        else
-                               page = NULL;
+                               folio = NULL;
                } else {
-                       page = NULL;
+                       folio = NULL;
                }
        }
        stable_node_dup->head = &migrate_nodes;
        list_add(&stable_node_dup->list, stable_node_dup->head);
-       return page;
+       return &folio->page;
 
 chain_append:
        /* stable_node_dup could be null if it reached the limit */
@@ -2079,7 +2073,7 @@ chain_append:
  * This function returns the stable tree node just allocated on success,
  * NULL otherwise.
  */
-static struct ksm_stable_node *stable_tree_insert(struct page *kpage)
+static struct ksm_stable_node *stable_tree_insert(struct folio *kfolio)
 {
        int nid;
        unsigned long kpfn;
@@ -2089,7 +2083,7 @@ static struct ksm_stable_node *stable_tree_insert(struct page *kpage)
        struct ksm_stable_node *stable_node, *stable_node_dup, *stable_node_any;
        bool need_chain = false;
 
-       kpfn = page_to_pfn(kpage);
+       kpfn = folio_pfn(kfolio);
        nid = get_kpfn_nid(kpfn);
        root = root_stable_tree + nid;
 again:
@@ -2097,13 +2091,13 @@ again:
        new = &root->rb_node;
 
        while (*new) {
-               struct page *tree_page;
+               struct folio *tree_folio;
                int ret;
 
                cond_resched();
                stable_node = rb_entry(*new, struct ksm_stable_node, node);
                stable_node_any = NULL;
-               tree_page = chain(&stable_node_dup, stable_node, root);
+               tree_folio = chain(&stable_node_dup, stable_node, root);
                if (!stable_node_dup) {
                        /*
                         * Either all stable_node dups were full in
@@ -2125,14 +2119,14 @@ again:
                         * write protected at all times. Any will work
                         * fine to continue the walk.
                         */
-                       tree_page = get_ksm_page(stable_node_any,
-                                                GET_KSM_PAGE_NOLOCK);
+                       tree_folio = ksm_get_folio(stable_node_any,
+                                                  GET_KSM_PAGE_NOLOCK);
                }
                VM_BUG_ON(!stable_node_dup ^ !!stable_node_any);
-               if (!tree_page) {
+               if (!tree_folio) {
                        /*
                         * If we walked over a stale stable_node,
-                        * get_ksm_page() will call rb_erase() and it
+                        * ksm_get_folio() will call rb_erase() and it
                         * may rebalance the tree from under us. So
                         * restart the search from scratch. Returning
                         * NULL would be safe too, but we'd generate
@@ -2142,8 +2136,8 @@ again:
                        goto again;
                }
 
-               ret = memcmp_pages(kpage, tree_page);
-               put_page(tree_page);
+               ret = memcmp_pages(&kfolio->page, &tree_folio->page);
+               folio_put(tree_folio);
 
                parent = *new;
                if (ret < 0)
@@ -2162,7 +2156,7 @@ again:
 
        INIT_HLIST_HEAD(&stable_node_dup->hlist);
        stable_node_dup->kpfn = kpfn;
-       set_page_stable_node(kpage, stable_node_dup);
+       folio_set_stable_node(kfolio, stable_node_dup);
        stable_node_dup->rmap_hlist_len = 0;
        DO_NUMA(stable_node_dup->nid = nid);
        if (!need_chain) {
@@ -2440,7 +2434,7 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite
                         * node in the stable tree and add both rmap_items.
                         */
                        lock_page(kpage);
-                       stable_node = stable_tree_insert(kpage);
+                       stable_node = stable_tree_insert(page_folio(kpage));
                        if (stable_node) {
                                stable_tree_append(tree_rmap_item, stable_node,
                                                   false);
@@ -3244,7 +3238,7 @@ void folio_migrate_ksm(struct folio *newfolio, struct folio *folio)
                /*
                 * newfolio->mapping was set in advance; now we need smp_wmb()
                 * to make sure that the new stable_node->kpfn is visible
-                * to get_ksm_page() before it can see that folio->mapping
+                * to ksm_get_folio() before it can see that folio->mapping
                 * has gone stale (or that folio_test_swapcache has been cleared).
                 */
                smp_wmb();
@@ -3271,7 +3265,7 @@ static bool stable_node_dup_remove_range(struct ksm_stable_node *stable_node,
        if (stable_node->kpfn >= start_pfn &&
            stable_node->kpfn < end_pfn) {
                /*
-                * Don't get_ksm_page, page has already gone:
+                * Don't ksm_get_folio, page has already gone:
                 * which is why we keep kpfn instead of page*
                 */
                remove_node_from_stable_tree(stable_node);
@@ -3359,7 +3353,7 @@ static int ksm_memory_callback(struct notifier_block *self,
                 * Most of the work is done by page migration; but there might
                 * be a few stable_nodes left over, still pointing to struct
                 * pages which have been offlined: prune those from the tree,
-                * otherwise get_ksm_page() might later try to access a
+                * otherwise ksm_get_folio() might later try to access a
                 * non-existent struct page.
                 */
                ksm_check_stable_tree(mn->start_pfn,
index d87ce32645d4fafb8db0cf070e6825cff2ab1d7a..c7692f303fa7333642871164f9656f057720f6e0 100644 (file)
@@ -616,7 +616,7 @@ void folio_migrate_flags(struct folio *newfolio, struct folio *folio)
        folio_migrate_ksm(newfolio, folio);
        /*
         * Please do not reorder this without considering how mm/ksm.c's
-        * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache().
+        * ksm_get_folio() depends upon ksm_migrate_page() and PageSwapCache().
         */
        if (folio_test_swapcache(folio))
                folio_clear_swapcache(folio);