gpio: mpc8xxx: Prevent NULL pointer deref in demux handler

[pandora-kernel.git] / mm / page_alloc.c

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9dd443d..485be89 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -356,8 +356,8 @@ void prep_compound_page(struct page *page, unsigned long order)
        __SetPageHead(page);
        for (i = 1; i < nr_pages; i++) {
                struct page *p = page + i;
-
                __SetPageTail(p);
+               set_page_count(p, 0);
                p->first_page = page;
        }
 }
@@ -3377,9 +3377,15 @@ static void setup_zone_migrate_reserve(struct zone *zone)
        unsigned long block_migratetype;
        int reserve;
 
-       /* Get the start pfn, end pfn and the number of blocks to reserve */
+       /*
+        * Get the start pfn, end pfn and the number of blocks to reserve
+        * We have to be careful to be aligned to pageblock_nr_pages to
+        * make sure that we always check pfn_valid for the first page in
+        * the block.
+        */
        start_pfn = zone->zone_start_pfn;
        end_pfn = start_pfn + zone->spanned_pages;
+       start_pfn = roundup(start_pfn, pageblock_nr_pages);
        reserve = roundup(min_wmark_pages(zone), pageblock_nr_pages) >>
                                                        pageblock_order;
 
@@ -5602,6 +5608,17 @@ __count_immobile_pages(struct zone *zone, struct page *page, int count)
 bool is_pageblock_removable_nolock(struct page *page)
 {
        struct zone *zone = page_zone(page);
+       unsigned long pfn = page_to_pfn(page);
+
+       /*
+        * We have to be careful here because we are iterating over memory
+        * sections which are not zone aware so we might end up outside of
+        * the zone but still within the section.
+        */
+       if (!zone || zone->zone_start_pfn > pfn ||
+                       zone->zone_start_pfn + zone->spanned_pages <= pfn)
+               return false;
+
        return __count_immobile_pages(zone, page, 0);
 }