linux-kernel - [PATCH v2 3/5] mm/khugepaged: Convert is_refcount

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Message-Id: <20231018203213.50224-4-vishal.moola@gmail.com>
Date:   Wed, 18 Oct 2023 13:32:11 -0700
From:   "Vishal Moola (Oracle)" <vishal.moola@...il.com>
To:     linux-mm@...ck.org
Cc:     linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        shy828301@...il.com,
        "Vishal Moola (Oracle)" <vishal.moola@...il.com>
Subject: [PATCH v2 3/5] mm/khugepaged: Convert is_refcount_suitable() to use folios

Both callers of is_refcount_suitable() have been converted to use
folios, so convert it to take in a folio. Both callers only operate on
head pages of folios so mapcount/refcount conversions here are trivial.

Removes 3 calls to compound head, and removes 315 bytes of kernel text.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@...il.com>
---
 mm/khugepaged.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 6c4b5af43371..9efd8ff68f06 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -524,15 +524,15 @@ static void release_pte_pages(pte_t *pte, pte_t *_pte,
 	}
 }
 
-static bool is_refcount_suitable(struct page *page)
+static bool is_refcount_suitable(struct folio *folio)
 {
 	int expected_refcount;
 
-	expected_refcount = total_mapcount(page);
-	if (PageSwapCache(page))
-		expected_refcount += compound_nr(page);
+	expected_refcount = folio_mapcount(folio);
+	if (folio_test_swapcache(folio))
+		expected_refcount += folio_nr_pages(folio);
 
-	return page_count(page) == expected_refcount;
+	return folio_ref_count(folio) == expected_refcount;
 }
 
 static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
@@ -625,7 +625,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
 		 * but not from this process. The other process cannot write to
 		 * the page, only trigger CoW.
 		 */
-		if (!is_refcount_suitable(&folio->page)) {
+		if (!is_refcount_suitable(folio)) {
 			folio_unlock(folio);
 			result = SCAN_PAGE_COUNT;
 			goto out;
@@ -1371,7 +1371,7 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm,
 		 * has excessive GUP pins (i.e. 512).  Anyway the same check
 		 * will be done again later the risk seems low.
 		 */
-		if (!is_refcount_suitable(&folio->page)) {
+		if (!is_refcount_suitable(folio)) {
 			result = SCAN_PAGE_COUNT;
 			goto out_unmap;
 		}
-- 
2.40.1