linux-kernel - [PATCH 1/2] mm/hugetlb: Use a folio in copy_hugetlb_page

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Date:   Fri, 2 Jun 2023 09:54:07 +0800
From:   Peng Zhang <zhangpeng362@...wei.com>
To:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <akpm@...ux-foundation.org>, <willy@...radead.org>,
        <mike.kravetz@...cle.com>
CC:     <muchun.song@...ux.dev>, <sidhartha.kumar@...cle.com>,
        <vishal.moola@...il.com>, <wangkefeng.wang@...wei.com>,
        <sunnanyong@...wei.com>, ZhangPeng <zhangpeng362@...wei.com>
Subject: [PATCH 1/2] mm/hugetlb: Use a folio in copy_hugetlb_page_range()

From: ZhangPeng <zhangpeng362@...wei.com>

We can replace five implict calls to compound_head() with one by using
pte_folio. However, we still need to keep ptepage because we need to know
which page in the folio we are copying.

Suggested-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Signed-off-by: ZhangPeng <zhangpeng362@...wei.com>
---
 mm/hugetlb.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ea24718db4af..0b774dd3d57b 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5017,6 +5017,7 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
 {
 	pte_t *src_pte, *dst_pte, entry;
 	struct page *ptepage;
+	struct folio *pte_folio;
 	unsigned long addr;
 	bool cow = is_cow_mapping(src_vma->vm_flags);
 	struct hstate *h = hstate_vma(src_vma);
@@ -5116,7 +5117,8 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
 		} else {
 			entry = huge_ptep_get(src_pte);
 			ptepage = pte_page(entry);
-			get_page(ptepage);
+			pte_folio = page_folio(ptepage);
+			folio_get(pte_folio);
 
 			/*
 			 * Failing to duplicate the anon rmap is a rare case
@@ -5128,7 +5130,7 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
 			 * need to be without the pgtable locks since we could
 			 * sleep during the process.
 			 */
-			if (!PageAnon(ptepage)) {
+			if (!folio_test_anon(pte_folio)) {
 				page_dup_file_rmap(ptepage, true);
 			} else if (page_try_dup_anon_rmap(ptepage, true,
 							  src_vma)) {
@@ -5140,14 +5142,14 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
 				/* Do not use reserve as it's private owned */
 				new_folio = alloc_hugetlb_folio(dst_vma, addr, 1);
 				if (IS_ERR(new_folio)) {
-					put_page(ptepage);
+					folio_put(pte_folio);
 					ret = PTR_ERR(new_folio);
 					break;
 				}
 				ret = copy_user_large_folio(new_folio,
-						      page_folio(ptepage),
-						      addr, dst_vma);
-				put_page(ptepage);
+							    pte_folio,
+							    addr, dst_vma);
+				folio_put(pte_folio);
 				if (ret) {
 					folio_put(new_folio);
 					break;
-- 
2.25.1