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 information macro functions to the folio version. 
After this conversion, we can safely remove the page-based definitions
from include/linux/hugetlb.h.

Link: https://lkml.kernel.org/r/20240530171427.242018-1-sidhartha.kumar@oracle.comSigned-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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)				\

mm/memory_hotplug.c

@@ -1731,8 +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;
-		unsigned long skip;
+		struct page *page;
+		struct folio *folio;
 
 		if (!pfn_valid(pfn))
 			continue;
@@ -1753,7 +1753,7 @@ 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
@@ -1761,10 +1761,9 @@ 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));
-		pfn += skip - 1;
+		pfn |= folio_nr_pages(folio) - 1;
 	}
 	return -ENOENT;
 found: