The patch titled
vmscan: handle may_swap more strictly
has been added to the -mm tree. Its filename is
vmscan-handle-may_swap-more-strictly.patch
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------------------------------------------------------
Subject: vmscan: handle may_swap more strictly
From: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Commit 2e2e425989080cc534fc0fca154cae515f971cf5 ("vmscan,memcg:
reintroduce sc->may_swap) add may_swap flag and handle it at
get_scan_ratio().
But the result of get_scan_ratio() is ignored when priority == 0, so anon
lru is scanned even if may_swap == 0 or nr_swap_pages == 0. IMHO, this is
not an expected behavior.
As for memcg especially, because of this behavior many and many pages are
swapped-out just in vain when oom is invoked by mem+swap limit.
This patch is for handling may_swap flag more strictly.
Signed-off-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Lee Schermerhorn <lee.schermerhorn@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff -puN mm/vmscan.c~vmscan-handle-may_swap-more-strictly mm/vmscan.c
--- a/mm/vmscan.c~vmscan-handle-may_swap-more-strictly
+++ a/mm/vmscan.c
@@ -1430,13 +1430,6 @@ static void get_scan_ratio(struct zone *
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_pages(zone, sc, LRU_ACTIVE_ANON) +
zone_nr_pages(zone, sc, LRU_INACTIVE_ANON);
file = zone_nr_pages(zone, sc, LRU_ACTIVE_FILE) +
@@ -1534,15 +1527,22 @@ static void shrink_zone(int priority, st
enum lru_list l;
unsigned long nr_reclaimed = sc->nr_reclaimed;
unsigned long swap_cluster_max = sc->swap_cluster_max;
+ 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;
scan = zone_nr_pages(zone, sc, l);
- if (priority) {
+ if (priority || noswap) {
scan >>= priority;
scan = (scan * percent[file]) / 100;
}
_
Patches currently in -mm which might be from nishimura@xxxxxxxxxxxxxxxxx are
mm-add-swap-cache-interface-for-swap-reference.patch
mm-modify-swap_map-and-add-swap_has_cache-flag.patch
mm-modify-swap_map-and-add-swap_has_cache-flag-update.patch
mm-reuse-unused-swap-entry-if-necessary.patch
mm-reuse-unused-swap-entry-if-necessary-update.patch
vmscan-handle-may_swap-more-strictly.patch
memcg-add-file-based-rss-accounting.patch
memcg-add-file-based-rss-accounting-fix-mem_cgroup_update_mapped_file_stat-oops.patch
memcg-remove-mem_cgroup_cache_charge_swapin.patch
memcg-fix-swap-accounting.patch
memcg-fix-swap-accounting-update.patch
memcg-fix-behavior-under-memorylimit-equals-to-memswlimit.patch
memcg-add-interface-to-reset-limits.patch
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