1 files changed, 41 insertions, 35 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 514fd8008114..822babd808fe 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2301,7 +2301,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
 {
         struct zone *last_compact_zone = NULL;
         unsigned long compact_result;
-
+        struct page *page;
 
         if (!order)
                 return NULL;
@@ -2313,49 +2313,55 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
                                                 &last_compact_zone);
         current->flags &= ~PF_MEMALLOC;
 
-        if (compact_result > COMPACT_DEFERRED)
-                count_vm_event(COMPACTSTALL);
-        else
+        switch (compact_result) {
+        case COMPACT_DEFERRED:
                 *deferred_compaction = true;
+                /* fall-through */
+        case COMPACT_SKIPPED:
+                return NULL;
+        default:
+                break;
+        }
 
-        if (compact_result > COMPACT_SKIPPED) {
-                struct page *page;
+        /*
+         * At least in one zone compaction wasn't deferred or skipped, so let's
+         * count a compaction stall
+         */
+        count_vm_event(COMPACTSTALL);
 
-                /* Page migration frees to the PCP lists but we want merging */
-                drain_pages(get_cpu());
-                put_cpu();
+        /* Page migration frees to the PCP lists but we want merging */
+        drain_pages(get_cpu());
+        put_cpu();
 
-                page = get_page_from_freelist(gfp_mask, nodemask,
-                                order, zonelist, high_zoneidx,
-                                alloc_flags & ~ALLOC_NO_WATERMARKS,
-                                preferred_zone, classzone_idx, migratetype);
+        page = get_page_from_freelist(gfp_mask, nodemask,
+                        order, zonelist, high_zoneidx,
+                        alloc_flags & ~ALLOC_NO_WATERMARKS,
+                        preferred_zone, classzone_idx, migratetype);
 
-                if (page) {
-                        struct zone *zone = page_zone(page);
+        if (page) {
+                struct zone *zone = page_zone(page);
 
-                        zone->compact_blockskip_flush = false;
-                        compaction_defer_reset(zone, order, true);
-                        count_vm_event(COMPACTSUCCESS);
-                        return page;
-                }
+                zone->compact_blockskip_flush = false;
+                compaction_defer_reset(zone, order, true);
+                count_vm_event(COMPACTSUCCESS);
+                return page;
+        }
 
-                /*
-                 * last_compact_zone is where try_to_compact_pages thought
-                 * allocation should succeed, so it did not defer compaction.
-                 * But now we know that it didn't succeed, so we do the defer.
-                 */
-                if (last_compact_zone && mode != MIGRATE_ASYNC)
-                        defer_compaction(last_compact_zone, order);
+        /*
+         * last_compact_zone is where try_to_compact_pages thought allocation
+         * should succeed, so it did not defer compaction. But here we know
+         * that it didn't succeed, so we do the defer.
+         */
+        if (last_compact_zone && mode != MIGRATE_ASYNC)
+                defer_compaction(last_compact_zone, order);
 
-                /*
-                 * It's bad if compaction run occurs and fails.
-                 * The most likely reason is that pages exist,
-                 * but not enough to satisfy watermarks.
-                 */
-                count_vm_event(COMPACTFAIL);
+        /*
+         * It's bad if compaction run occurs and fails. The most likely reason
+         * is that pages exist, but not enough to satisfy watermarks.
+         */
+        count_vm_event(COMPACTFAIL);
 
-                cond_resched();
-        }
+        cond_resched();
 
         return NULL;
 }