From: Matthew Wilcox (Oracle) <willy@infradead.org>
Date: Mon, 17 Jan 2022 19:46:55 +0000 (-0500)
Subject: mm/vmscan: Account large folios correctly
X-Git-Tag: v5.18-rc1~167^2~13
X-Git-Url: https://gentwo.org/gitweb/?a=commitdiff_plain;h=c79b7b96db8b1240887686720cd149f2c5d979d6;p=linux%2F.git

mm/vmscan: Account large folios correctly

The statistics we gather should count the number of pages, not the
number of folios.  The logic in this function is somewhat convoluted,
but even if we split the folio, I think the accounting is now correct.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 8243437e5c5f..d57b376593f8 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1575,10 +1575,10 @@ static unsigned int shrink_page_list(struct list_head *page_list,
 		 */
 		folio_check_dirty_writeback(folio, &dirty, &writeback);
 		if (dirty || writeback)
-			stat->nr_dirty++;
+			stat->nr_dirty += nr_pages;
 
 		if (dirty && !writeback)
-			stat->nr_unqueued_dirty++;
+			stat->nr_unqueued_dirty += nr_pages;
 
 		/*
 		 * Treat this page as congested if the underlying BDI is or if
@@ -1590,7 +1590,7 @@ static unsigned int shrink_page_list(struct list_head *page_list,
 		if (((dirty || writeback) && mapping &&
 		     inode_write_congested(mapping->host)) ||
 		    (writeback && PageReclaim(page)))
-			stat->nr_congested++;
+			stat->nr_congested += nr_pages;
 
 		/*
 		 * If a page at the tail of the LRU is under writeback, there
@@ -1639,7 +1639,7 @@ static unsigned int shrink_page_list(struct list_head *page_list,
 			if (current_is_kswapd() &&
 			    PageReclaim(page) &&
 			    test_bit(PGDAT_WRITEBACK, &pgdat->flags)) {
-				stat->nr_immediate++;
+				stat->nr_immediate += nr_pages;
 				goto activate_locked;
 
 			/* Case 2 above */
@@ -1657,7 +1657,7 @@ static unsigned int shrink_page_list(struct list_head *page_list,
 				 * and it's also appropriate in global reclaim.
 				 */
 				SetPageReclaim(page);
-				stat->nr_writeback++;
+				stat->nr_writeback += nr_pages;
 				goto activate_locked;
 
 			/* Case 3 above */
@@ -1823,7 +1823,7 @@ static unsigned int shrink_page_list(struct list_head *page_list,
 			case PAGE_ACTIVATE:
 				goto activate_locked;
 			case PAGE_SUCCESS:
-				stat->nr_pageout += thp_nr_pages(page);
+				stat->nr_pageout += nr_pages;
 
 				if (PageWriteback(page))
 					goto keep;