1 files changed, 42 insertions, 45 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index eea668d..a9c74b4 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -147,7 +147,7 @@ static bool global_reclaim(struct scan_control *sc)
 }
 #endif
 
-unsigned long zone_reclaimable_pages(struct zone *zone)
+static unsigned long zone_reclaimable_pages(struct zone *zone)
 {
 	int nr;
 
@@ -281,17 +281,34 @@ shrink_slab_node(struct shrink_control *shrinkctl, struct shrinker *shrinker,
 				nr_pages_scanned, lru_pages,
 				max_pass, delta, total_scan);
 
-	while (total_scan >= batch_size) {
+	/*
+	 * Normally, we should not scan less than batch_size objects in one
+	 * pass to avoid too frequent shrinker calls, but if the slab has less
+	 * than batch_size objects in total and we are really tight on memory,
+	 * we will try to reclaim all available objects, otherwise we can end
+	 * up failing allocations although there are plenty of reclaimable
+	 * objects spread over several slabs with usage less than the
+	 * batch_size.
+	 *
+	 * 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
+	 * scanning at high prio and therefore should try to reclaim as much as
+	 * possible.
+	 */
+	while (total_scan >= batch_size ||
+	       total_scan >= max_pass) {
 		unsigned long ret;
+		unsigned long nr_to_scan = min(batch_size, total_scan);
 
-		shrinkctl->nr_to_scan = batch_size;
+		shrinkctl->nr_to_scan = nr_to_scan;
 		ret = shrinker->scan_objects(shrinker, shrinkctl);
 		if (ret == SHRINK_STOP)
 			break;
 		freed += ret;
 
-		count_vm_events(SLABS_SCANNED, batch_size);
-		total_scan -= batch_size;
+		count_vm_events(SLABS_SCANNED, nr_to_scan);
+		total_scan -= nr_to_scan;
 
 		cond_resched();
 	}
@@ -352,16 +369,17 @@ unsigned long shrink_slab(struct shrink_control *shrinkctl,
 	}
 
 	list_for_each_entry(shrinker, &shrinker_list, list) {
-		for_each_node_mask(shrinkctl->nid, shrinkctl->nodes_to_scan) {
-			if (!node_online(shrinkctl->nid))
-				continue;
-
-			if (!(shrinker->flags & SHRINKER_NUMA_AWARE) &&
-			    (shrinkctl->nid != 0))
-				break;
-
+		if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) {
+			shrinkctl->nid = 0;
 			freed += shrink_slab_node(shrinkctl, shrinker,
-				 nr_pages_scanned, lru_pages);
+					nr_pages_scanned, lru_pages);
+			continue;
+		}
+
+		for_each_node_mask(shrinkctl->nid, shrinkctl->nodes_to_scan) {
+			if (node_online(shrinkctl->nid))
+				freed += shrink_slab_node(shrinkctl, shrinker,
+						nr_pages_scanned, lru_pages);
 
 		}
 	}
@@ -603,7 +621,7 @@ void putback_lru_page(struct page *page)
 	bool is_unevictable;
 	int was_unevictable = PageUnevictable(page);
 
-	VM_BUG_ON(PageLRU(page));
+	VM_BUG_ON_PAGE(PageLRU(page), page);
 
 redo:
 	ClearPageUnevictable(page);
@@ -794,8 +812,8 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		if (!trylock_page(page))
 			goto keep;
 
-		VM_BUG_ON(PageActive(page));
-		VM_BUG_ON(page_zone(page) != zone);
+		VM_BUG_ON_PAGE(PageActive(page), page);
+		VM_BUG_ON_PAGE(page_zone(page) != zone, page);
 
 		sc->nr_scanned++;
 
@@ -1079,14 +1097,14 @@ activate_locked:
 		/* Not a candidate for swapping, so reclaim swap space. */
 		if (PageSwapCache(page) && vm_swap_full())
 			try_to_free_swap(page);
-		VM_BUG_ON(PageActive(page));
+		VM_BUG_ON_PAGE(PageActive(page), page);
 		SetPageActive(page);
 		pgactivate++;
 keep_locked:
 		unlock_page(page);
 keep:
 		list_add(&page->lru, &ret_pages);
-		VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
+		VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page), page);
 	}
 
 	free_hot_cold_page_list(&free_pages, 1);
@@ -1240,7 +1258,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 		page = lru_to_page(src);
 		prefetchw_prev_lru_page(page, src, flags);
 
-		VM_BUG_ON(!PageLRU(page));
+		VM_BUG_ON_PAGE(!PageLRU(page), page);
 
 		switch (__isolate_lru_page(page, mode)) {
 		case 0:
@@ -1295,7 +1313,7 @@ int isolate_lru_page(struct page *page)
 {
 	int ret = -EBUSY;
 
-	VM_BUG_ON(!page_count(page));
+	VM_BUG_ON_PAGE(!page_count(page), page);
 
 	if (PageLRU(page)) {
 		struct zone *zone = page_zone(page);
@@ -1366,7 +1384,7 @@ putback_inactive_pages(struct lruvec *lruvec, struct list_head *page_list)
 		struct page *page = lru_to_page(page_list);
 		int lru;
 
-		VM_BUG_ON(PageLRU(page));
+		VM_BUG_ON_PAGE(PageLRU(page), page);
 		list_del(&page->lru);
 		if (unlikely(!page_evictable(page))) {
 			spin_unlock_irq(&zone->lru_lock);
@@ -1586,7 +1604,7 @@ static void move_active_pages_to_lru(struct lruvec *lruvec,
 		page = lru_to_page(list);
 		lruvec = mem_cgroup_page_lruvec(page, zone);
 
-		VM_BUG_ON(PageLRU(page));
+		VM_BUG_ON_PAGE(PageLRU(page), page);
 		SetPageLRU(page);
 
 		nr_pages = hpage_nr_pages(page);
@@ -3297,27 +3315,6 @@ void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
 	wake_up_interruptible(&pgdat->kswapd_wait);
 }
 
-/*
- * The reclaimable count would be mostly accurate.
- * The less reclaimable pages may be
- * - mlocked pages, which will be moved to unevictable list when encountered
- * - mapped pages, which may require several travels to be reclaimed
- * - dirty pages, which is not "instantly" reclaimable
- */
-unsigned long global_reclaimable_pages(void)
-{
-	int nr;
-
-	nr = global_page_state(NR_ACTIVE_FILE) +
-	     global_page_state(NR_INACTIVE_FILE);
-
-	if (get_nr_swap_pages() > 0)
-		nr += global_page_state(NR_ACTIVE_ANON) +
-		      global_page_state(NR_INACTIVE_ANON);
-
-	return nr;
-}
-
 #ifdef CONFIG_HIBERNATION
 /*
  * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of
@@ -3701,7 +3698,7 @@ void check_move_unevictable_pages(struct page **pages, int nr_pages)
 		if (page_evictable(page)) {
 			enum lru_list lru = page_lru_base_type(page);
 
-			VM_BUG_ON(PageActive(page));
+			VM_BUG_ON_PAGE(PageActive(page), page);
 			ClearPageUnevictable(page);
 			del_page_from_lru_list(page, lruvec, LRU_UNEVICTABLE);
 			add_page_to_lru_list(page, lruvec, lru);