1 files changed, 83 insertions, 69 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index a9c74b409681..32c661d66a45 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -224,15 +224,15 @@ shrink_slab_node(struct shrink_control *shrinkctl, struct shrinker *shrinker,
 	unsigned long freed = 0;
 	unsigned long long delta;
 	long total_scan;
-	long max_pass;
+	long freeable;
 	long nr;
 	long new_nr;
 	int nid = shrinkctl->nid;
 	long batch_size = shrinker->batch ? shrinker->batch
 					  : SHRINK_BATCH;
 
-	max_pass = shrinker->count_objects(shrinker, shrinkctl);
-	if (max_pass == 0)
+	freeable = shrinker->count_objects(shrinker, shrinkctl);
+	if (freeable == 0)
 		return 0;
 
 	/*
@@ -244,14 +244,14 @@ shrink_slab_node(struct shrink_control *shrinkctl, struct shrinker *shrinker,
 
 	total_scan = nr;
 	delta = (4 * nr_pages_scanned) / shrinker->seeks;
-	delta *= max_pass;
+	delta *= freeable;
 	do_div(delta, lru_pages + 1);
 	total_scan += delta;
 	if (total_scan < 0) {
 		printk(KERN_ERR
 		"shrink_slab: %pF negative objects to delete nr=%ld\n",
 		       shrinker->scan_objects, total_scan);
-		total_scan = max_pass;
+		total_scan = freeable;
 	}
 
 	/*
@@ -260,26 +260,26 @@ shrink_slab_node(struct shrink_control *shrinkctl, struct shrinker *shrinker,
 	 * shrinkers to return -1 all the time. This results in a large
 	 * nr being built up so when a shrink that can do some work
 	 * comes along it empties the entire cache due to nr >>>
-	 * max_pass.  This is bad for sustaining a working set in
+	 * freeable. This is bad for sustaining a working set in
 	 * memory.
 	 *
 	 * Hence only allow the shrinker to scan the entire cache when
 	 * a large delta change is calculated directly.
 	 */
-	if (delta < max_pass / 4)
-		total_scan = min(total_scan, max_pass / 2);
+	if (delta < freeable / 4)
+		total_scan = min(total_scan, freeable / 2);
 
 	/*
 	 * Avoid risking looping forever due to too large nr value:
 	 * never try to free more than twice the estimate number of
 	 * freeable entries.
 	 */
-	if (total_scan > max_pass * 2)
-		total_scan = max_pass * 2;
+	if (total_scan > freeable * 2)
+		total_scan = freeable * 2;
 
 	trace_mm_shrink_slab_start(shrinker, shrinkctl, nr,
 				nr_pages_scanned, lru_pages,
-				max_pass, delta, total_scan);
+				freeable, delta, total_scan);
 
 	/*
 	 * Normally, we should not scan less than batch_size objects in one
@@ -292,12 +292,12 @@ shrink_slab_node(struct shrink_control *shrinkctl, struct shrinker *shrinker,
 	 *
 	 * We detect the "tight on memory" situations by looking at the total
 	 * number of objects we want to scan (total_scan). If it is greater
-	 * than the total number of objects on slab (max_pass), we must be
+	 * than the total number of objects on slab (freeable), we must be
 	 * scanning at high prio and therefore should try to reclaim as much as
 	 * possible.
 	 */
 	while (total_scan >= batch_size ||
-	       total_scan >= max_pass) {
+	       total_scan >= freeable) {
 		unsigned long ret;
 		unsigned long nr_to_scan = min(batch_size, total_scan);
 
@@ -523,7 +523,8 @@ static pageout_t pageout(struct page *page, struct address_space *mapping,
  * Same as remove_mapping, but if the page is removed from the mapping, it
  * gets returned with a refcount of 0.
  */
-static int __remove_mapping(struct address_space *mapping, struct page *page)
+static int __remove_mapping(struct address_space *mapping, struct page *page,
+			    bool reclaimed)
 {
 	BUG_ON(!PageLocked(page));
 	BUG_ON(mapping != page_mapping(page));
@@ -569,10 +570,23 @@ static int __remove_mapping(struct address_space *mapping, struct page *page)
 		swapcache_free(swap, page);
 	} else {
 		void (*freepage)(struct page *);
+		void *shadow = NULL;
 
 		freepage = mapping->a_ops->freepage;
-
-		__delete_from_page_cache(page);
+		/*
+		 * Remember a shadow entry for reclaimed file cache in
+		 * order to detect refaults, thus thrashing, later on.
+		 *
+		 * But don't store shadows in an address space that is
+		 * already exiting.  This is not just an optizimation,
+		 * inode reclaim needs to empty out the radix tree or
+		 * the nodes are lost.  Don't plant shadows behind its
+		 * back.
+		 */
+		if (reclaimed && page_is_file_cache(page) &&
+		    !mapping_exiting(mapping))
+			shadow = workingset_eviction(mapping, page);
+		__delete_from_page_cache(page, shadow);
 		spin_unlock_irq(&mapping->tree_lock);
 		mem_cgroup_uncharge_cache_page(page);
 
@@ -595,7 +609,7 @@ cannot_free:
  */
 int remove_mapping(struct address_space *mapping, struct page *page)
 {
-	if (__remove_mapping(mapping, page)) {
+	if (__remove_mapping(mapping, page, false)) {
 		/*
 		 * Unfreezing the refcount with 1 rather than 2 effectively
 		 * drops the pagecache ref for us without requiring another
@@ -1065,7 +1079,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 			}
 		}
 
-		if (!mapping || !__remove_mapping(mapping, page))
+		if (!mapping || !__remove_mapping(mapping, page, true))
 			goto keep_locked;
 
 		/*
@@ -1144,7 +1158,7 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone,
 			TTU_UNMAP|TTU_IGNORE_ACCESS,
 			&dummy1, &dummy2, &dummy3, &dummy4, &dummy5, true);
 	list_splice(&clean_pages, page_list);
-	__mod_zone_page_state(zone, NR_ISOLATED_FILE, -ret);
+	mod_zone_page_state(zone, NR_ISOLATED_FILE, -ret);
 	return ret;
 }
 
@@ -1848,7 +1862,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
 	struct zone *zone = lruvec_zone(lruvec);
 	unsigned long anon_prio, file_prio;
 	enum scan_balance scan_balance;
-	unsigned long anon, file, free;
+	unsigned long anon, file;
 	bool force_scan = false;
 	unsigned long ap, fp;
 	enum lru_list lru;
@@ -1902,13 +1916,17 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
 		get_lru_size(lruvec, LRU_INACTIVE_FILE);
 
 	/*
-	 * If it's foreseeable that reclaiming the file cache won't be
-	 * enough to get the zone back into a desirable shape, we have
-	 * to swap.  Better start now and leave the - probably heavily
-	 * thrashing - remaining file pages alone.
+	 * 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)) {
-		free = zone_page_state(zone, NR_FREE_PAGES);
+		unsigned long free = zone_page_state(zone, NR_FREE_PAGES);
+
 		if (unlikely(file + free <= high_wmark_pages(zone))) {
 			scan_balance = SCAN_ANON;
 			goto out;
@@ -2297,16 +2315,26 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
 	struct zone *zone;
 	unsigned long nr_soft_reclaimed;
 	unsigned long nr_soft_scanned;
+	unsigned long lru_pages = 0;
 	bool aborted_reclaim = false;
+	struct reclaim_state *reclaim_state = current->reclaim_state;
+	gfp_t orig_mask;
+	struct shrink_control shrink = {
+		.gfp_mask = sc->gfp_mask,
+	};
+	enum zone_type requested_highidx = gfp_zone(sc->gfp_mask);
 
 	/*
 	 * If the number of buffer_heads in the machine exceeds the maximum
 	 * allowed level, force direct reclaim to scan the highmem zone as
 	 * highmem pages could be pinning lowmem pages storing buffer_heads
 	 */
+	orig_mask = sc->gfp_mask;
 	if (buffer_heads_over_limit)
 		sc->gfp_mask |= __GFP_HIGHMEM;
 
+	nodes_clear(shrink.nodes_to_scan);
+
 	for_each_zone_zonelist_nodemask(zone, z, zonelist,
 					gfp_zone(sc->gfp_mask), sc->nodemask) {
 		if (!populated_zone(zone))
@@ -2318,6 +2346,10 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
 		if (global_reclaim(sc)) {
 			if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
 				continue;
+
+			lru_pages += zone_reclaimable_pages(zone);
+			node_set(zone_to_nid(zone), shrink.nodes_to_scan);
+
 			if (sc->priority != DEF_PRIORITY &&
 			    !zone_reclaimable(zone))
 				continue;	/* Let kswapd poll it */
@@ -2331,7 +2363,8 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
 				 * noticeable problem, like transparent huge
 				 * page allocations.
 				 */
-				if (compaction_ready(zone, sc)) {
+				if ((zonelist_zone_idx(z) <= requested_highidx)
+				    && compaction_ready(zone, sc)) {
 					aborted_reclaim = true;
 					continue;
 				}
@@ -2354,6 +2387,26 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
 		shrink_zone(zone, sc);
 	}
 
+	/*
+	 * Don't shrink slabs when reclaiming memory from over limit cgroups
+	 * but do shrink slab at least once when aborting reclaim for
+	 * compaction to avoid unevenly scanning file/anon LRU pages over slab
+	 * pages.
+	 */
+	if (global_reclaim(sc)) {
+		shrink_slab(&shrink, sc->nr_scanned, lru_pages);
+		if (reclaim_state) {
+			sc->nr_reclaimed += reclaim_state->reclaimed_slab;
+			reclaim_state->reclaimed_slab = 0;
+		}
+	}
+
+	/*
+	 * Restore to original mask to avoid the impact on the caller if we
+	 * promoted it to __GFP_HIGHMEM.
+	 */
+	sc->gfp_mask = orig_mask;
+
 	return aborted_reclaim;
 }
 
@@ -2394,13 +2447,9 @@ static bool all_unreclaimable(struct zonelist *zonelist,
  * 		else, the number of pages reclaimed
  */
 static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
-					struct scan_control *sc,
-					struct shrink_control *shrink)
+					  struct scan_control *sc)
 {
 	unsigned long total_scanned = 0;
-	struct reclaim_state *reclaim_state = current->reclaim_state;
-	struct zoneref *z;
-	struct zone *zone;
 	unsigned long writeback_threshold;
 	bool aborted_reclaim;
 
@@ -2415,32 +2464,6 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
 		sc->nr_scanned = 0;
 		aborted_reclaim = shrink_zones(zonelist, sc);
 
-		/*
-		 * Don't shrink slabs when reclaiming memory from over limit
-		 * cgroups but do shrink slab at least once when aborting
-		 * reclaim for compaction to avoid unevenly scanning file/anon
-		 * LRU pages over slab pages.
-		 */
-		if (global_reclaim(sc)) {
-			unsigned long lru_pages = 0;
-
-			nodes_clear(shrink->nodes_to_scan);
-			for_each_zone_zonelist(zone, z, zonelist,
-					gfp_zone(sc->gfp_mask)) {
-				if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
-					continue;
-
-				lru_pages += zone_reclaimable_pages(zone);
-				node_set(zone_to_nid(zone),
-					 shrink->nodes_to_scan);
-			}
-
-			shrink_slab(shrink, sc->nr_scanned, lru_pages);
-			if (reclaim_state) {
-				sc->nr_reclaimed += reclaim_state->reclaimed_slab;
-				reclaim_state->reclaimed_slab = 0;
-			}
-		}
 		total_scanned += sc->nr_scanned;
 		if (sc->nr_reclaimed >= sc->nr_to_reclaim)
 			goto out;
@@ -2602,9 +2625,6 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 		.target_mem_cgroup = NULL,
 		.nodemask = nodemask,
 	};
-	struct shrink_control shrink = {
-		.gfp_mask = sc.gfp_mask,
-	};
 
 	/*
 	 * Do not enter reclaim if fatal signal was delivered while throttled.
@@ -2618,7 +2638,7 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 				sc.may_writepage,
 				gfp_mask);
 
-	nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink);
+	nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
 
 	trace_mm_vmscan_direct_reclaim_end(nr_reclaimed);
 
@@ -2685,9 +2705,6 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
 		.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
 				(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK),
 	};
-	struct shrink_control shrink = {
-		.gfp_mask = sc.gfp_mask,
-	};
 
 	/*
 	 * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't
@@ -2702,7 +2719,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
 					    sc.may_writepage,
 					    sc.gfp_mask);
 
-	nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink);
+	nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
 
 	trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
 
@@ -3337,9 +3354,6 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
 		.order = 0,
 		.priority = DEF_PRIORITY,
 	};
-	struct shrink_control shrink = {
-		.gfp_mask = sc.gfp_mask,
-	};
 	struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
 	struct task_struct *p = current;
 	unsigned long nr_reclaimed;
@@ -3349,7 +3363,7 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
 	reclaim_state.reclaimed_slab = 0;
 	p->reclaim_state = &reclaim_state;
 
-	nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink);
+	nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
 
 	p->reclaim_state = NULL;
 	lockdep_clear_current_reclaim_state();