Date: Fri, 30 Apr 2004 11:27:04 -0700
From: Andrew Morton <akpm@osdl.org>
To: Mikael Pettersson <mikpe@csd.uu.se>
Cc: ak@suse.de, linux-kernel@vger.kernel.org
Subject: Re: [BUG] 2.6.6-rc2-bk5 mm/slab.c change broke x86-64 SMP
Message-Id: <20040430112704.3dca3c4c.akpm@osdl.org>
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Mikael Pettersson <mikpe@csd.uu.se> wrote:
>
> The change to mm/slab.c between 2.6.6-rc2-bk4 and -bk5
> broke x86-64 SMP. The symptoms are general protection
> faults in __switch_to shortly after init starts, and
> then the machine is dead. (Can't be more specific, my
> box can't log early boot oopses.)
> 
> I'm only seeing this with x86-64 SMP; x86-64 UP and i386
> SMP on the same machine (Athlon64 UP) have no problems.
> 
> Reverting 2.6.6-rc2-bk5's change to mm/slab.c eliminates
> the problem.

The "-bk5" terminology doesn't mean much to people who use bitkeeper or who
use http://www.kernel.org/pub/linux/kernel/v2.5/testing/cset/ - I assume
you refer to the alignment changes?

Does this fix?

diff -puN include/asm-x86_64/processor.h~a include/asm-x86_64/processor.h
--- 25/include/asm-x86_64/processor.h~a	Fri Apr 30 11:24:58 2004
+++ 25-akpm/include/asm-x86_64/processor.h	Fri Apr 30 11:25:28 2004
@@ -20,6 +20,8 @@
 #include <asm/mmsegment.h>
 #include <linux/personality.h>
 
+#define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
+
 #define TF_MASK		0x00000100
 #define IF_MASK		0x00000200
 #define IOPL_MASK	0x00003000

_

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