Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933655Ab1CXSGP (ORCPT ); Thu, 24 Mar 2011 14:06:15 -0400 Received: from mail-yx0-f174.google.com ([209.85.213.174]:32858 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933572Ab1CXSGL (ORCPT ); Thu, 24 Mar 2011 14:06:11 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; b=AzrpDP/3psZVgyXbFV5HMwgm+L+xfyoj7kxxAZzNV4o/p3JkB6G5y2QsWyJ4NVfk8Z zyhgvHrrlYlUiutuRpVW4v+D/ABp7EFE40aIbi2SP/tZlXPwpuwYEwkI036B+yv89vA3 tHtsTO98nW0GSegRICjPR5Ig4utUoHcYuAxno= MIME-Version: 1.0 In-Reply-To: References: <20110324142146.GA11682@elte.hu> <20110324172653.GA28507@elte.hu> Date: Thu, 24 Mar 2011 20:06:10 +0200 X-Google-Sender-Auth: YUXc8fCmbbBXs3F6guA67D8dlfw Message-ID: Subject: Re: [GIT PULL] SLAB changes for v2.6.39-rc1 From: Pekka Enberg To: Christoph Lameter Cc: Ingo Molnar , torvalds@linux-foundation.org, akpm@linux-foundation.org, tj@kernel.org, npiggin@kernel.dk, rientjes@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1528 Lines: 31 On Thu, Mar 24, 2011 at 8:01 PM, Christoph Lameter wrote: > On Thu, 24 Mar 2011, Pekka Enberg wrote: > >> On Thu, Mar 24, 2011 at 7:43 PM, Christoph Lameter wrote: >> > The bug should only trigger on old AMD64 boxes that do not support >> > cmpxchg16b. >> >> Yup. Ingo is it possible to see /proc/cpuinfo of one of the affected >> boxes? I'll try your config but I'm pretty sure the problem doesn't >> trigger here. Like I said, I think the problem is that alternative >> instructions are not patched early enough for cmpxchg16b emulation to >> work for kmem_cache_init(). I tried my check_bugs() patch but it hangs >> during boot. I'll see if I can cook up a patch that does >> alternative_instructions() before kmem_cache_init() because I think >> those *should* be available during boot too. > > I forced the fallback to the _emu function to occur but could not trigger > the bug in kvm. That's not the problem. I'm sure the fallback is just fine. What I'm saying is that the fallback is *not patched* to kernel text on Ingo's machines because alternative_instructions() happens late in the boot! So the problem is that on Ingo's boxes (that presumably have old AMD CPUs) we execute cmpxchg16b, not the fallback code. Pekka -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/