[PATCH] mm: restore vm_normal_page check

Hugh is rightly concerned that the CONFIG_DEBUG_VM coverage has gone too
far in vm_normal_page, considering that we expect production kernels to be
shipped with the option turned off, and that the code has been under some
large changes recently.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 80c3fb370f91..e347e106ca3a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -395,12 +395,16 @@ struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_
                         return NULL;
         }
 
-#ifdef CONFIG_DEBUG_VM
+        /*
+         * Add some anal sanity checks for now. Eventually,
+         * we should just do "return pfn_to_page(pfn)", but
+         * in the meantime we check that we get a valid pfn,
+         * and that the resulting page looks ok.
+         */
         if (unlikely(!pfn_valid(pfn))) {
                 print_bad_pte(vma, pte, addr);
                 return NULL;
         }
-#endif
 
         /*
          * NOTE! We still have PageReserved() pages in the page