linux-kernel - [PATCH v2 6/6] mm/hugetlb: use folio->lru int demote_free_hugetlb

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Message-ID: <20250113131611.2554758-7-david@redhat.com>
Date: Mon, 13 Jan 2025 14:16:11 +0100
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org,
	David Hildenbrand <david@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Muchun Song <muchun.song@...ux.dev>,
	"Matthew Wilcox (Oracle)" <willy@...radead.org>
Subject: [PATCH v2 6/6] mm/hugetlb: use folio->lru int demote_free_hugetlb_folios()

We are demoting hugetlb folios to smaller hugetlb folios; let's avoid
messing with pages where avoidable and handle it more similar to
__split_huge_page_tail().

Signed-off-by: David Hildenbrand <david@...hat.com>
---
 mm/hugetlb.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index bc4ab45d9b93b..a94d52dd53728 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3822,13 +3822,15 @@ static long demote_free_hugetlb_folios(struct hstate *src, struct hstate *dst,
 
 		for (i = 0; i < pages_per_huge_page(src); i += pages_per_huge_page(dst)) {
 			struct page *page = folio_page(folio, i);
+			/* Careful: see __split_huge_page_tail() */
+			struct folio *new_folio = (struct folio *)page;
 
-			page->mapping = NULL;
 			clear_compound_head(page);
 			prep_compound_page(page, dst->order);
 
-			init_new_hugetlb_folio(dst, page_folio(page));
-			list_add(&page->lru, &dst_list);
+			new_folio->mapping = NULL;
+			init_new_hugetlb_folio(dst, new_folio);
+			list_add(&new_folio->lru, &dst_list);
 		}
 	}
 
-- 
2.47.1