linux-kernel - [PATCH] mm/hugetlb: mm/memory_hotplug: use a folio in scan_movable

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Date: Tue, 28 May 2024 15:03:21 -0700
From: Sidhartha Kumar <sidhartha.kumar@...cle.com>
To: linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc: akpm@...ux-foundation.org, vishal.moola@...cle.com, muchun.song@...ux.dev,
        david@...hat.com, osalvador@...e.de, willy@...radead.org,
        Sidhartha Kumar <sidhartha.kumar@...cle.com>
Subject: [PATCH] mm/hugetlb: mm/memory_hotplug: use a folio in scan_movable_pages()

By using a folio in scan_movable_pages(), we convert the last user of the
page-based hugetlb meta-data macro functions to the folio version.
After this conversion, we can safely remove the page-based definitions
from include/linux/hugetlb.h.

Signed-off-by: Sidhartha Kumar <sidhartha.kumar@...cle.com>
---
 include/linux/hugetlb.h | 6 +-----
 mm/memory_hotplug.c     | 9 +++++----
 2 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 15a58f69782c..279aca379b95 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -616,9 +616,7 @@ static __always_inline						\
 bool folio_test_hugetlb_##flname(struct folio *folio)		\
 	{	void *private = &folio->private;		\
 		return test_bit(HPG_##flname, private);		\
-	}							\
-static inline int HPage##uname(struct page *page)		\
-	{ return test_bit(HPG_##flname, &(page->private)); }
+	}
 
 #define SETHPAGEFLAG(uname, flname)				\
 static __always_inline						\
@@ -637,8 +635,6 @@ void folio_clear_hugetlb_##flname(struct folio *folio)		\
 #define TESTHPAGEFLAG(uname, flname)				\
 static inline bool						\
 folio_test_hugetlb_##flname(struct folio *folio)		\
-	{ return 0; }						\
-static inline int HPage##uname(struct page *page)		\
 	{ return 0; }
 
 #define SETHPAGEFLAG(uname, flname)				\
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 431b1f6753c0..3573f39fbaa6 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1731,7 +1731,8 @@ static int scan_movable_pages(unsigned long start, unsigned long end,
 	unsigned long pfn;
 
 	for (pfn = start; pfn < end; pfn++) {
-		struct page *page, *head;
+		struct page *page;
+		struct folio *folio;
 		unsigned long skip;
 
 		if (!pfn_valid(pfn))
@@ -1753,7 +1754,7 @@ static int scan_movable_pages(unsigned long start, unsigned long end,
 
 		if (!PageHuge(page))
 			continue;
-		head = compound_head(page);
+		folio = page_folio(page);
 		/*
 		 * This test is racy as we hold no reference or lock.  The
 		 * hugetlb page could have been free'ed and head is no longer
@@ -1761,9 +1762,9 @@ static int scan_movable_pages(unsigned long start, unsigned long end,
 		 * cases false positives and negatives are possible.  Calling
 		 * code must deal with these scenarios.
 		 */
-		if (HPageMigratable(head))
+		if (folio_test_hugetlb_migratable(folio))
 			goto found;
-		skip = compound_nr(head) - (pfn - page_to_pfn(head));
+		skip = folio_nr_pages(folio) - folio_page_idx(folio, page);
 		pfn += skip - 1;
 	}
 	return -ENOENT;
-- 
2.45.1