linux-kernel - [PATCH 01/11] mm/ksm: Convert get_ksm

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Date: Wed, 20 Mar 2024 15:40:37 +0800
From: alexs@...nel.org
To: Izik Eidus <izik.eidus@...ellosystems.com>,
	Matthew Wilcox <willy@...radead.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Hugh Dickins <hughd@...gle.com>,
	Chris Wright <chrisw@...s-sol.org>,
	kasong@...cent.com,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-mm@...ck.org (open list:MEMORY MANAGEMENT),
	linux-kernel@...r.kernel.org (open list)
Cc: linux-kernel@...r.kernel.org,
	"Alex Shi (tencent)" <alexs@...nel.org>
Subject: [PATCH 01/11] mm/ksm: Convert get_ksm_page to return a folio

From: "Alex Shi (tencent)" <alexs@...nel.org>

The ksm only contains single pages, so use folio instead of pages to
save a couple of compound_head calls.

Signed-off-by: Alex Shi (tencent) <alexs@...nel.org>
Cc: Izik Eidus <izik.eidus@...ellosystems.com>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: Hugh Dickins <hughd@...gle.com>
Cc: Chris Wright <chrisw@...s-sol.org>
---
 mm/ksm.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/mm/ksm.c b/mm/ksm.c
index 8c001819cf10..fda291b054c2 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -915,10 +915,10 @@ enum get_ksm_page_flags {
  * a page to put something that might look like our key in page->mapping.
  * is on its way to being freed; but it is an anomaly to bear in mind.
  */
-static struct page *get_ksm_page(struct ksm_stable_node *stable_node,
+static void *get_ksm_page(struct ksm_stable_node *stable_node,
 				 enum get_ksm_page_flags flags)
 {
-	struct page *page;
+	struct folio *folio;
 	void *expected_mapping;
 	unsigned long kpfn;
 
@@ -926,8 +926,8 @@ static struct page *get_ksm_page(struct ksm_stable_node *stable_node,
 					PAGE_MAPPING_KSM);
 again:
 	kpfn = READ_ONCE(stable_node->kpfn); /* Address dependency. */
-	page = pfn_to_page(kpfn);
-	if (READ_ONCE(page->mapping) != expected_mapping)
+	folio = pfn_folio(kpfn);
+	if (READ_ONCE(folio->mapping) != expected_mapping)
 		goto stale;
 
 	/*
@@ -940,7 +940,7 @@ static struct page *get_ksm_page(struct ksm_stable_node *stable_node,
 	 * in folio_migrate_mapping(), it might still be our page,
 	 * in which case it's essential to keep the node.
 	 */
-	while (!get_page_unless_zero(page)) {
+	while (!folio_try_get(folio)) {
 		/*
 		 * Another check for page->mapping != expected_mapping would
 		 * work here too.  We have chosen the !PageSwapCache test to
@@ -949,32 +949,32 @@ static struct page *get_ksm_page(struct ksm_stable_node *stable_node,
 		 * in the ref_freeze section of __remove_mapping(); but Anon
 		 * page->mapping reset to NULL later, in free_pages_prepare().
 		 */
-		if (!PageSwapCache(page))
+		if (!folio_test_swapcache(folio))
 			goto stale;
 		cpu_relax();
 	}
 
-	if (READ_ONCE(page->mapping) != expected_mapping) {
-		put_page(page);
+	if (READ_ONCE(folio->mapping) != expected_mapping) {
+		folio_put(folio);
 		goto stale;
 	}
 
 	if (flags == GET_KSM_PAGE_TRYLOCK) {
-		if (!trylock_page(page)) {
-			put_page(page);
+		if (!folio_trylock(folio)) {
+			folio_put(folio);
 			return ERR_PTR(-EBUSY);
 		}
 	} else if (flags == GET_KSM_PAGE_LOCK)
-		lock_page(page);
+		folio_lock(folio);
 
 	if (flags != GET_KSM_PAGE_NOLOCK) {
-		if (READ_ONCE(page->mapping) != expected_mapping) {
-			unlock_page(page);
-			put_page(page);
+		if (READ_ONCE(folio->mapping) != expected_mapping) {
+			folio_unlock(folio);
+			folio_put(folio);
 			goto stale;
 		}
 	}
-	return page;
+	return folio;
 
 stale:
 	/*
-- 
2.43.0