On Fri, 22 Jun 2007, Christoph Lameter wrote: > > Add VM_BUG_ON in case someone uses page_mapping on a slab page > > Detect slab objects being passed to the page oriented functions of the VM. > > It is not sufficient to simply return NULL because the functions calling > page_mapping may depend on other items of the page_struct also to be setup > properly. Moreover the slab object may not be properly aligned. The page > orientedfunctions of the VM expect to operate on page aligned, page sized > objects. operations on objects straddling page boundaries may only affect > the objects partially which may lead to surprising results. > > It is better to detect eventually remaining uses and eliminate them. > > Signed-off-by: Christoph Lameter <[EMAIL PROTECTED]>
I'm quite happy with this approach for 2.6.23-rc, along with your ARM dma_map patch which (if I understood aright) rmk approved. Except, haven't you misplaced that VM_BUG_ON between an if and its else? And I'd much prefer you to make it an outright BUG_ON, because many testers have those VM_BUG_ONs configured out. Hugh > > --- > include/linux/mm.h | 5 +---- > 1 file changed, 1 insertion(+), 4 deletions(-) > > Index: linux-2.6/include/linux/mm.h > =================================================================== > --- linux-2.6.orig/include/linux/mm.h 2007-06-22 10:33:27.000000000 -0700 > +++ linux-2.6/include/linux/mm.h 2007-06-22 10:34:09.000000000 -0700 > @@ -603,10 +603,7 @@ static inline struct address_space *page > > if (unlikely(PageSwapCache(page))) > mapping = &swapper_space; > -#ifdef CONFIG_SLUB > - else if (unlikely(PageSlab(page))) > - mapping = NULL; > -#endif > + VM_BUG_ON(PageSlab(page)); > else if (unlikely((unsigned long)mapping & PAGE_MAPPING_ANON)) > mapping = NULL; > return mapping; > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
