1 files changed, 23 insertions, 1 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 03fef8d987f6..676aec93d699 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -159,8 +159,13 @@ EXPORT_SYMBOL(nr_node_ids);
 #endif
 
 #ifdef CONFIG_PAGE_GROUP_BY_MOBILITY
+int page_group_by_mobility_disabled __read_mostly;
+
 static inline int get_pageblock_migratetype(struct page *page)
 {
+        if (unlikely(page_group_by_mobility_disabled))
+                return MIGRATE_UNMOVABLE;
+
         return get_pageblock_flags_group(page, PB_migrate, PB_migrate_end);
 }
 
@@ -174,6 +179,9 @@ static inline int allocflags_to_migratetype(gfp_t gfp_flags, int order)
 {
         WARN_ON((gfp_flags & GFP_MOVABLE_MASK) == GFP_MOVABLE_MASK);
 
+        if (unlikely(page_group_by_mobility_disabled))
+                return MIGRATE_UNMOVABLE;
+
         /* Cluster high-order atomic allocations together */
         if (unlikely(order > 0) &&
                         (!(gfp_flags & __GFP_WAIT) || in_interrupt()))
@@ -2375,9 +2383,23 @@ void build_all_zonelists(void)
                 /* cpuset refresh routine should be here */
         }
         vm_total_pages = nr_free_pagecache_pages();
-        printk("Built %i zonelists in %s order.  Total pages: %ld\n",
+        /*
+         * Disable grouping by mobility if the number of pages in the
+         * system is too low to allow the mechanism to work. It would be
+         * more accurate, but expensive to check per-zone. This check is
+         * made on memory-hotadd so a system can start with mobility
+         * disabled and enable it later
+         */
+        if (vm_total_pages < (MAX_ORDER_NR_PAGES * MIGRATE_TYPES))
+                page_group_by_mobility_disabled = 1;
+        else
+                page_group_by_mobility_disabled = 0;
+
+        printk("Built %i zonelists in %s order, mobility grouping %s.  "
+                "Total pages: %ld\n",
                         num_online_nodes(),
                         zonelist_order_name[current_zonelist_order],
+                        page_group_by_mobility_disabled ? "off" : "on",
                         vm_total_pages);
 #ifdef CONFIG_NUMA
         printk("Policy zone: %s\n", zone_names[policy_zone]);