mm/compaction: correctly return failure with bogus compound_order in strict mode

[linux-2.6-block.git] / mm / compaction.c

diff --git a/mm/compaction.c b/mm/compaction.c
index a40550a33aee691b08bbebec36336b30abcd65d6..9ecbfbc695e5f68d8a211f32032beb75b32093eb 100644 (file)
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -626,11 +626,12 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
                if (PageCompound(page)) {
                        const unsigned int order = compound_order(page);
 
-                       if (likely(order <= MAX_ORDER)) {
+                       if (blockpfn + (1UL << order) <= end_pfn) {
                                blockpfn += (1UL << order) - 1;
                                page += (1UL << order) - 1;
                                nr_scanned += (1UL << order) - 1;
                        }
+
                        goto isolate_fail;
                }
 
@@ -678,8 +679,7 @@ isolate_fail:
                spin_unlock_irqrestore(&cc->zone->lock, flags);
 
        /*
-        * There is a tiny chance that we have read bogus compound_order(),
-        * so be careful to not go outside of the pageblock.
+        * Be careful to not go outside of the pageblock.
         */
        if (unlikely(blockpfn > end_pfn))
                blockpfn = end_pfn;