mm/lru: Add folio LRU functions

Handle arbitrary-order folios being added to the LRU.  By definition,
all pages being added to the LRU were already head or base pages, but
call page_folio() on them anyway to get the type right and avoid the
buried calls to compound_head().

Saves 783 bytes of kernel text; no functions grow.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>

Documentation/core-api/mm-api.rst

@@ -95,6 +95,7 @@ More Memory Management Functions
 .. kernel-doc:: mm/mempolicy.c
 .. kernel-doc:: include/linux/mm_types.h
    :internal:
+.. kernel-doc:: include/linux/mm_inline.h
 .. kernel-doc:: include/linux/page-flags.h
 .. kernel-doc:: include/linux/mm.h
    :internal:

include/linux/mm_inline.h

@@ -6,27 +6,33 @@
 #include <linux/swap.h>
 
 /**
- * page_is_file_lru - should the page be on a file LRU or anon LRU?
- * @page: the page to test
- *
- * Returns 1 if @page is a regular filesystem backed page cache page or a lazily
- * freed anonymous page (e.g. via MADV_FREE).  Returns 0 if @page is a normal
- * anonymous page, a tmpfs page or otherwise ram or swap backed page.  Used by
- * functions that manipulate the LRU lists, to sort a page onto the right LRU
- * list.
+ * folio_is_file_lru - Should the folio be on a file LRU or anon LRU?
+ * @folio: The folio to test.
  *
  * We would like to get this info without a page flag, but the state
- * needs to survive until the page is last deleted from the LRU, which
+ * needs to survive until the folio is last deleted from the LRU, which
  * could be as far down as __page_cache_release.
+ *
+ * Return: An integer (not a boolean!) used to sort a folio onto the
+ * right LRU list and to account folios correctly.
+ * 1 if @folio is a regular filesystem backed page cache folio
+ * or a lazily freed anonymous folio (e.g. via MADV_FREE).
+ * 0 if @folio is a normal anonymous folio, a tmpfs folio or otherwise
+ * ram or swap backed folio.
  */
+static inline int folio_is_file_lru(struct folio *folio)
+{
+	return !folio_test_swapbacked(folio);
+}
+
 static inline int page_is_file_lru(struct page *page)
 {
-	return !PageSwapBacked(page);
+	return folio_is_file_lru(page_folio(page));
 }
 
 static __always_inline void update_lru_size(struct lruvec *lruvec,
 				enum lru_list lru, enum zone_type zid,
-				int nr_pages)
+				long nr_pages)
 {
 	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
 
@@ -39,69 +45,94 @@ static __always_inline void update_lru_size(struct lruvec *lruvec,
 }
 
 /**
- * __clear_page_lru_flags - clear page lru flags before releasing a page
- * @page: the page that was on lru and now has a zero reference
+ * __folio_clear_lru_flags - Clear page lru flags before releasing a page.
+ * @folio: The folio that was on lru and now has a zero reference.
  */
-static __always_inline void __clear_page_lru_flags(struct page *page)
+static __always_inline void __folio_clear_lru_flags(struct folio *folio)
 {
-	VM_BUG_ON_PAGE(!PageLRU(page), page);
+	VM_BUG_ON_FOLIO(!folio_test_lru(folio), folio);
 
-	__ClearPageLRU(page);
+	__folio_clear_lru(folio);
 
 	/* this shouldn't happen, so leave the flags to bad_page() */
-	if (PageActive(page) && PageUnevictable(page))
+	if (folio_test_active(folio) && folio_test_unevictable(folio))
 		return;
 
-	__ClearPageActive(page);
-	__ClearPageUnevictable(page);
+	__folio_clear_active(folio);
+	__folio_clear_unevictable(folio);
+}
+
+static __always_inline void __clear_page_lru_flags(struct page *page)
+{
+	__folio_clear_lru_flags(page_folio(page));
 }
 
 /**
- * page_lru - which LRU list should a page be on?
- * @page: the page to test
+ * folio_lru_list - Which LRU list should a folio be on?
+ * @folio: The folio to test.
  *
- * Returns the LRU list a page should be on, as an index
+ * Return: The LRU list a folio should be on, as an index
  * into the array of LRU lists.
  */
-static __always_inline enum lru_list page_lru(struct page *page)
+static __always_inline enum lru_list folio_lru_list(struct folio *folio)
 {
 	enum lru_list lru;
 
-	VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page);
+	VM_BUG_ON_FOLIO(folio_test_active(folio) && folio_test_unevictable(folio), folio);
 
-	if (PageUnevictable(page))
+	if (folio_test_unevictable(folio))
 		return LRU_UNEVICTABLE;
 
-	lru = page_is_file_lru(page) ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON;
-	if (PageActive(page))
+	lru = folio_is_file_lru(folio) ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON;
+	if (folio_test_active(folio))
 		lru += LRU_ACTIVE;
 
 	return lru;
 }
 
+static __always_inline
+void lruvec_add_folio(struct lruvec *lruvec, struct folio *folio)
+{
+	enum lru_list lru = folio_lru_list(folio);
+
+	update_lru_size(lruvec, lru, folio_zonenum(folio),
+			folio_nr_pages(folio));
+	list_add(&folio->lru, &lruvec->lists[lru]);
+}
+
 static __always_inline void add_page_to_lru_list(struct page *page,
 				struct lruvec *lruvec)
 {
-	enum lru_list lru = page_lru(page);
+	lruvec_add_folio(lruvec, page_folio(page));
+}
 
-	update_lru_size(lruvec, lru, page_zonenum(page), thp_nr_pages(page));
-	list_add(&page->lru, &lruvec->lists[lru]);
+static __always_inline
+void lruvec_add_folio_tail(struct lruvec *lruvec, struct folio *folio)
+{
+	enum lru_list lru = folio_lru_list(folio);
+
+	update_lru_size(lruvec, lru, folio_zonenum(folio),
+			folio_nr_pages(folio));
+	list_add_tail(&folio->lru, &lruvec->lists[lru]);
 }
 
 static __always_inline void add_page_to_lru_list_tail(struct page *page,
 				struct lruvec *lruvec)
 {
-	enum lru_list lru = page_lru(page);
+	lruvec_add_folio_tail(lruvec, page_folio(page));
+}
 
-	update_lru_size(lruvec, lru, page_zonenum(page), thp_nr_pages(page));
-	list_add_tail(&page->lru, &lruvec->lists[lru]);
+static __always_inline
+void lruvec_del_folio(struct lruvec *lruvec, struct folio *folio)
+{
+	list_del(&folio->lru);
+	update_lru_size(lruvec, folio_lru_list(folio), folio_zonenum(folio),
+			-folio_nr_pages(folio));
 }
 
 static __always_inline void del_page_from_lru_list(struct page *page,
 				struct lruvec *lruvec)
 {
-	list_del(&page->lru);
-	update_lru_size(lruvec, page_lru(page), page_zonenum(page),
-			-thp_nr_pages(page));
+	lruvec_del_folio(lruvec, page_folio(page));
 }
 #endif

include/trace/events/pagemap.h

@@ -41,7 +41,7 @@ TRACE_EVENT(mm_lru_insertion,
 	TP_fast_assign(
 		__entry->page	= page;
 		__entry->pfn	= page_to_pfn(page);
-		__entry->lru	= page_lru(page);
+		__entry->lru	= folio_lru_list(page_folio(page));
 		__entry->flags	= trace_pagemap_flags(page);
 	),