From d6da1a5abc2bf3a06a5bda08e0f6833409234666 Mon Sep 17 00:00:00 2001 From: KOSAKI Motohiro Date: Tue, 6 Apr 2010 14:34:56 -0700 Subject: [PATCH] mm: revert "vmscan: get_scan_ratio() cleanup" Shaohua Li reported his tmpfs streaming I/O test can lead to make oom. The test uses a 6G tmpfs in a system with 3G memory. In the tmpfs, there are 6 copies of kernel source and the test does kbuild for each copy. His investigation shows the test has a lot of rotated anon pages and quite few file pages, so get_scan_ratio calculates percent[0] (i.e. scanning percent for anon) to be zero. Actually the percent[0] shoule be a big value, but our calculation round it to zero. Although before commit 84b18490 ("vmscan: get_scan_ratio() cleanup") , we have the same problem too. But the old logic can rescue percent[0]==0 case only when priority==0. It had hided the real issue. I didn't think merely streaming io can makes percent[0]==0 && priority==0 situation. but I was wrong. So, definitely we have to fix such tmpfs streaming io issue. but anyway I revert the regression commit at first. This reverts commit 84b18490d1f1bc7ed5095c929f78bc002eb70f26. Signed-off-by: KOSAKI Motohiro Reported-by: Shaohua Li Cc: Rik van Riel Cc: KAMEZAWA Hiroyuki Cc: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 23 +++++++++-------------- 1 file changed, 9 insertions(+), 14 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index e0e5f15..3ff3311 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1535,13 +1535,6 @@ static void get_scan_ratio(struct zone *zone, struct scan_control *sc, unsigned long ap, fp; struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); - /* If we have no swap space, do not bother scanning anon pages. */ - if (!sc->may_swap || (nr_swap_pages <= 0)) { - percent[0] = 0; - percent[1] = 100; - return; - } - anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) + zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON); file = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) + @@ -1639,20 +1632,22 @@ static void shrink_zone(int priority, struct zone *zone, unsigned long nr_reclaimed = sc->nr_reclaimed; unsigned long nr_to_reclaim = sc->nr_to_reclaim; struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); + int noswap = 0; - get_scan_ratio(zone, sc, percent); + /* If we have no swap space, do not bother scanning anon pages. */ + if (!sc->may_swap || (nr_swap_pages <= 0)) { + noswap = 1; + percent[0] = 0; + percent[1] = 100; + } else + get_scan_ratio(zone, sc, percent); for_each_evictable_lru(l) { int file = is_file_lru(l); unsigned long scan; - if (percent[file] == 0) { - nr[l] = 0; - continue; - } - scan = zone_nr_lru_pages(zone, sc, l); - if (priority) { + if (priority || noswap) { scan >>= priority; scan = (scan * percent[file]) / 100; } -- 2.7.4