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 8243437..d57b376 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1575,10 +1575,10 @@ retry:
                 */
                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 @@ retry:
                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 @@ retry:
                        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 @@ retry:
                                 * 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 @@ retry:
                        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;