mm/page_alloc: add a VM_BUG in __free_one_page() if the zone is uninitialized.

Freeing pages to uninitialized zones is not handled by
__free_one_page(), and should never happen when the code is correct.

Ran into this while writing some code that dynamically onlines extra
zones.

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Cc: David Hansen <dave@linux.vnet.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a3687afc5917..9614aabee8c5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -538,6 +538,8 @@ static inline void __free_one_page(struct page *page,
         unsigned long uninitialized_var(buddy_idx);
         struct page *buddy;
 
+        VM_BUG_ON(!zone_is_initialized(zone));
+
         if (unlikely(PageCompound(page)))
                 if (unlikely(destroy_compound_page(page, order)))
                         return;