1 files changed, 18 insertions, 0 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 3f56c8deb3c0..32c661d66a45 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1916,6 +1916,24 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
                 get_lru_size(lruvec, LRU_INACTIVE_FILE);
 
         /*
+         * Prevent the reclaimer from falling into the cache trap: as
+         * cache pages start out inactive, every cache fault will tip
+         * the scan balance towards the file LRU.  And as the file LRU
+         * shrinks, so does the window for rotation from references.
+         * This means we have a runaway feedback loop where a tiny
+         * thrashing file LRU becomes infinitely more attractive than
+         * anon pages.  Try to detect this based on file LRU size.
+         */
+        if (global_reclaim(sc)) {
+                unsigned long free = zone_page_state(zone, NR_FREE_PAGES);
+
+                if (unlikely(file + free <= high_wmark_pages(zone))) {
+                        scan_balance = SCAN_ANON;
+                        goto out;
+                }
+        }
+
+        /*
          * There is enough inactive page cache, do not reclaim
          * anything from the anonymous working set right now.
          */