Subject: Re: Next April 28: boot failure on PowerPC with SLQB

From: Nick Piggin <[email-masked]>
Date: Thu, 30 Apr 2009 12:35:28 +0200

On Thu, Apr 30, 2009 at 03:17:12PM +0530, Sachin Sant wrote:
> Nick Piggin wrote:
> >Hmm, forget that. Actually my last patch had a silly mistake because I
> >forgot MAX_ORDER shift is applied to PAGE_SIZE, rather than 1. So
> >kmalloc(PAGE_SIZE) was failing as too large.
> >
> >This patch should do the trick I hope.
> >  
> Yes this patch fixed the issue for me. Thanks Nick.

Thanks very much for reporting and testing.

Pekka, can you apply this patch please?

--
SLQB: fix slab calculation

SLQB didn't consider MAX_ORDER when defining which sizes of kmalloc
slabs to create. It panics at boot if it tries to create a cache
which exceeds MAX_ORDER-1.

Signed-off-by: Nick Piggin <[email-masked]>
---
 include/linux/slqb_def.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: linux-2.6/include/linux/slqb_def.h
===================================================================
--- linux-2.6.orig/include/linux/slqb_def.h
+++ linux-2.6/include/linux/slqb_def.h
@@ -172,7 +172,8 @@ struct kmem_cache {
 #endif
 
 #define KMALLOC_SHIFT_LOW ilog2(KMALLOC_MIN_SIZE)
-#define KMALLOC_SHIFT_SLQB_HIGH (PAGE_SHIFT + 9)
+#define KMALLOC_SHIFT_SLQB_HIGH (PAGE_SHIFT + 			\
+				 ((9 <= (MAX_ORDER - 1)) ? 9 : (MAX_ORDER - 1)))
 
 extern struct kmem_cache kmalloc_caches[KMALLOC_SHIFT_SLQB_HIGH + 1];
 extern struct kmem_cache kmalloc_caches_dma[KMALLOC_SHIFT_SLQB_HIGH + 1];