mm: zone_reclaim: make isolate_lru_page() filter-aware

In __zone_reclaim case, we don't want to shrink mapped page.  Nonetheless,
we have isolated mapped page and re-add it into LRU's head.  It's
unnecessary CPU overhead and makes LRU churning.

Of course, when we isolate the page, the page might be mapped but when we
try to migrate the page, the page would be not mapped.  So it could be
migrated.  But race is rare and although it happens, it's no big deal.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 80da968798ea4ea7f7f8d6d40b854a0cf46ba7af..0b14943dd0451d8b5543359576e90b56fb22cc19 100644 (file)
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -170,6 +170,8 @@ static inline int is_unevictable_lru(enum lru_list l)
 #define ISOLATE_ACTIVE         ((__force isolate_mode_t)0x2)
 /* Isolate clean file */
 #define ISOLATE_CLEAN          ((__force isolate_mode_t)0x4)
+/* Isolate unmapped file */
+#define ISOLATE_UNMAPPED       ((__force fmode_t)0x8)
 
 /* LRU Isolation modes. */
 typedef unsigned __bitwise__ isolate_mode_t;

diff --git a/mm/vmscan.c b/mm/vmscan.c
index c007e78d7078c58c79908ba862628919780322d3..b68a9342d5a3459fc4ea2d9ec674b142b1311620 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1048,6 +1048,9 @@ int __isolate_lru_page(struct page *page, isolate_mode_t mode, int file)
        if ((mode & ISOLATE_CLEAN) && (PageDirty(page) || PageWriteback(page)))
                return ret;
 
+       if ((mode & ISOLATE_UNMAPPED) && page_mapped(page))
+               return ret;
+
        if (likely(get_page_unless_zero(page))) {
                /*
                 * Be careful not to clear PageLRU until after we're
@@ -1471,6 +1474,12 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
                reclaim_mode |= ISOLATE_ACTIVE;
 
        lru_add_drain();
+
+       if (!sc->may_unmap)
+               reclaim_mode |= ISOLATE_UNMAPPED;
+       if (!sc->may_writepage)
+               reclaim_mode |= ISOLATE_CLEAN;
+
        spin_lock_irq(&zone->lru_lock);
 
        if (scanning_global_lru(sc)) {
@@ -1588,19 +1597,26 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
        struct page *page;
        struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
        unsigned long nr_rotated = 0;
+       isolate_mode_t reclaim_mode = ISOLATE_ACTIVE;
 
        lru_add_drain();
+
+       if (!sc->may_unmap)
+               reclaim_mode |= ISOLATE_UNMAPPED;
+       if (!sc->may_writepage)
+               reclaim_mode |= ISOLATE_CLEAN;
+
        spin_lock_irq(&zone->lru_lock);
        if (scanning_global_lru(sc)) {
                nr_taken = isolate_pages_global(nr_pages, &l_hold,
                                                &pgscanned, sc->order,
-                                               ISOLATE_ACTIVE, zone,
+                                               reclaim_mode, zone,
                                                1, file);
                zone->pages_scanned += pgscanned;
        } else {
                nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold,
                                                &pgscanned, sc->order,
-                                               ISOLATE_ACTIVE, zone,
+                                               reclaim_mode, zone,
                                                sc->mem_cgroup, 1, file);
                /*
                 * mem_cgroup_isolate_pages() keeps track of