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ksm: convert cmp_and_merge_page() to use a folio

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By making try_to_merge_two_pages() and stable_tree_search() return a
folio, we can replace kpage with kfolio.  This replaces 7 calls to
compound_head() with one.

[cuigaosheng1@huawei.com: add IS_ERR_OR_NULL check for stable_tree_search()]
  Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Link: https://lkml.kernel.org/r/20241002152533.1350629-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2024-10-02 16:25:28 +01:00 committed by Andrew Morton
parent 9c0a1b99e3
commit 98c3ca0015
1 changed files with 26 additions and 25 deletions
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51
mm/ksm.c
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@ -1582,7 +1582,7 @@ static int try_to_merge_with_ksm_page(struct ksm_rmap_item *rmap_item,
* Note that this function upgrades page to ksm page: if one of the pages
* is already a ksm page, try_to_merge_with_ksm_page should be used.
*/
static struct page *try_to_merge_two_pages(struct ksm_rmap_item *rmap_item,
static struct folio *try_to_merge_two_pages(struct ksm_rmap_item *rmap_item,
struct page *page,
struct ksm_rmap_item *tree_rmap_item,
struct page *tree_page)
@ -1600,7 +1600,7 @@ static struct page *try_to_merge_two_pages(struct ksm_rmap_item *rmap_item,
if (err)
break_cow(rmap_item);
}
return err ? NULL : page;
return err ? NULL : page_folio(page);
}
static __always_inline
@ -1787,9 +1787,9 @@ static __always_inline struct folio *chain(struct ksm_stable_node **s_n_d,
* with identical content to the page that we are scanning right now.
*
* This function returns the stable tree node of identical content if found,
* NULL otherwise.
* -EBUSY if the stable node's page is being migrated, NULL otherwise.
*/
static struct page *stable_tree_search(struct page *page)
static struct folio *stable_tree_search(struct page *page)
{
int nid;
struct rb_root *root;
@ -1804,7 +1804,7 @@ static struct page *stable_tree_search(struct page *page)
if (page_node && page_node->head != &migrate_nodes) {
/* ksm page forked */
folio_get(folio);
return &folio->page;
return folio;
}
nid = get_kpfn_nid(folio_pfn(folio));
@ -1899,7 +1899,7 @@ static struct page *stable_tree_search(struct page *page)
folio_put(tree_folio);
goto replace;
}
return &tree_folio->page;
return tree_folio;
}
}
@ -1913,7 +1913,7 @@ static struct page *stable_tree_search(struct page *page)
out:
if (is_page_sharing_candidate(page_node)) {
folio_get(folio);
return &folio->page;
return folio;
} else
return NULL;
@ -1963,7 +1963,7 @@ static struct page *stable_tree_search(struct page *page)
}
stable_node_dup->head = &migrate_nodes;
list_add(&stable_node_dup->list, stable_node_dup->head);
return &folio->page;
return folio;
chain_append:
/*
@ -2217,7 +2217,7 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite
struct ksm_rmap_item *tree_rmap_item;
struct page *tree_page = NULL;
struct ksm_stable_node *stable_node;
struct page *kpage;
struct folio *kfolio;
unsigned int checksum;
int err;
bool max_page_sharing_bypass = false;
@ -2259,31 +2259,32 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite
return;
}
/* We first start with searching the page inside the stable tree */
kpage = stable_tree_search(page);
if (kpage == page && rmap_item->head == stable_node) {
put_page(kpage);
/* Start by searching for the folio in the stable tree */
kfolio = stable_tree_search(page);
if (!IS_ERR_OR_NULL(kfolio) && &kfolio->page == page &&
rmap_item->head == stable_node) {
folio_put(kfolio);
return;
}
remove_rmap_item_from_tree(rmap_item);
if (kpage) {
if (PTR_ERR(kpage) == -EBUSY)
if (kfolio) {
if (kfolio == ERR_PTR(-EBUSY))
return;
err = try_to_merge_with_ksm_page(rmap_item, page, kpage);
err = try_to_merge_with_ksm_page(rmap_item, page, &kfolio->page);
if (!err) {
/*
* The page was successfully merged:
* add its rmap_item to the stable tree.
*/
lock_page(kpage);
stable_tree_append(rmap_item, page_stable_node(kpage),
folio_lock(kfolio);
stable_tree_append(rmap_item, folio_stable_node(kfolio),
max_page_sharing_bypass);
unlock_page(kpage);
folio_unlock(kfolio);
}
put_page(kpage);
folio_put(kfolio);
return;
}
@ -2292,7 +2293,7 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite
if (tree_rmap_item) {
bool split;
kpage = try_to_merge_two_pages(rmap_item, page,
kfolio = try_to_merge_two_pages(rmap_item, page,
tree_rmap_item, tree_page);
/*
* If both pages we tried to merge belong to the same compound
@ -2307,20 +2308,20 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite
split = PageTransCompound(page)
&& compound_head(page) == compound_head(tree_page);
put_page(tree_page);
if (kpage) {
if (kfolio) {
/*
* The pages were successfully merged: insert new
* node in the stable tree and add both rmap_items.
*/
lock_page(kpage);
stable_node = stable_tree_insert(page_folio(kpage));
folio_lock(kfolio);
stable_node = stable_tree_insert(kfolio);
if (stable_node) {
stable_tree_append(tree_rmap_item, stable_node,
false);
stable_tree_append(rmap_item, stable_node,
false);
}
unlock_page(kpage);
folio_unlock(kfolio);
/*
* If we fail to insert the page into the stable tree,