[PATCH] mm: VM_BUG_ON

Introduce a VM_BUG_ON, which is turned on with CONFIG_DEBUG_VM.  Use this
in the lightweight, inline refcounting functions; PageLRU and PageActive
checks in vmscan, because they're pretty well confined to vmscan.  And in
page allocate/free fastpaths which can be the hottest parts of the kernel
for kbuilds.

Unlike BUG_ON, VM_BUG_ON must not be used to execute statements with
side-effects, and should not be used outside core mm code.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/mm/swap.c b/mm/swap.c
index 687686a61f7c..600235e43704 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -233,7 +233,7 @@ void fastcall __page_cache_release(struct page *page)
                 struct zone *zone = page_zone(page);
 
                 spin_lock_irqsave(&zone->lru_lock, flags);
-                BUG_ON(!PageLRU(page));
+                VM_BUG_ON(!PageLRU(page));
                 __ClearPageLRU(page);
                 del_page_from_lru(zone, page);
                 spin_unlock_irqrestore(&zone->lru_lock, flags);
@@ -284,7 +284,7 @@ void release_pages(struct page **pages, int nr, int cold)
                                 zone = pagezone;
                                 spin_lock_irq(&zone->lru_lock);
                         }
-                        BUG_ON(!PageLRU(page));
+                        VM_BUG_ON(!PageLRU(page));
                         __ClearPageLRU(page);
                         del_page_from_lru(zone, page);
                 }
@@ -337,7 +337,7 @@ void __pagevec_release_nonlru(struct pagevec *pvec)
         for (i = 0; i < pagevec_count(pvec); i++) {
                 struct page *page = pvec->pages[i];
 
-                BUG_ON(PageLRU(page));
+                VM_BUG_ON(PageLRU(page));
                 if (put_page_testzero(page))
                         pagevec_add(&pages_to_free, page);
         }
@@ -364,7 +364,7 @@ void __pagevec_lru_add(struct pagevec *pvec)
                         zone = pagezone;
                         spin_lock_irq(&zone->lru_lock);
                 }
-                BUG_ON(PageLRU(page));
+                VM_BUG_ON(PageLRU(page));
                 SetPageLRU(page);
                 add_page_to_inactive_list(zone, page);
         }
@@ -391,9 +391,9 @@ void __pagevec_lru_add_active(struct pagevec *pvec)
                         zone = pagezone;
                         spin_lock_irq(&zone->lru_lock);
                 }
-                BUG_ON(PageLRU(page));
+                VM_BUG_ON(PageLRU(page));
                 SetPageLRU(page);
-                BUG_ON(PageActive(page));
+                VM_BUG_ON(PageActive(page));
                 SetPageActive(page);
                 add_page_to_active_list(zone, page);
         }