From: Christoph Lameter NR_FILE_PAGES must be accounted for depending on the zone that the page belongs to. If we replace the page in the radix tree then we may have to shift the count to another zone. Suggested-by: Ethan Solomita Eventually-typed-in-by: Christoph Lameter Cc: Martin Bligh Cc: Signed-off-by: Christoph Lameter Signed-off-by: Andrew Morton --- mm/migrate.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff -puN mm/migrate.c~page-migration-fix-nr_file_pages-accounting mm/migrate.c --- a/mm/migrate.c~page-migration-fix-nr_file_pages-accounting +++ a/mm/migrate.c @@ -297,7 +297,7 @@ static int migrate_page_move_mapping(str void **pslot; if (!mapping) { - /* Anonymous page */ + /* Anonymous page without mapping */ if (page_count(page) != 1) return -EAGAIN; return 0; @@ -333,6 +333,19 @@ static int migrate_page_move_mapping(str */ __put_page(page); + /* + * If moved to a different zone then also account + * the page for that zone. Other VM counters will be + * taken care of when we establish references to the + * new page and drop references to the old page. + * + * Note that anonymous pages are accounted for + * via NR_FILE_PAGES and NR_ANON_PAGES if they + * are mapped to swap space. + */ + __dec_zone_page_state(page, NR_FILE_PAGES); + __inc_zone_page_state(newpage, NR_FILE_PAGES); + write_unlock_irq(&mapping->tree_lock); return 0; _