From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Lameter Subject: Re: slub: fix panic with DISCONTIGMEM Date: Tue, 19 Apr 2011 17:04:31 -0500 (CDT) Message-ID: References: <1303248576.11237.23.camel@mulgrave.site> <1303249970.11237.30.camel@mulgrave.site> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: In-Reply-To: <1303249970.11237.30.camel@mulgrave.site> Sender: linux-parisc-owner@vger.kernel.org To: James Bottomley Cc: linux-arch@vger.kernel.org, linux-mm@kvack.org, "hugh.dickins@tiscali.co.uk" , Parisc List List-Id: linux-arch.vger.kernel.org On Tue, 19 Apr 2011, James Bottomley wrote: > On Tue, 2011-04-19 at 16:38 -0500, Christoph Lameter wrote: > > On Tue, 19 Apr 2011, James Bottomley wrote: > > > > > Slub makes assumptions about page_to_nid() which are violated by > > > DISCONTIGMEM and !NUMA. This violation results in a panic because > > > > Fix this by stating correctly by saying "The kernel makes assumptions in > > various subsystems ..." > > Slub is a subset of the kernel, so the original wording is a bit more > precise. F.e. hugepage support does the same thing. So it not slub specific. > Well, we can discuss how to proceed going forwards. The current fact is > that any prior kernel that enables SLUB with DISCONTIGMEM and !NUMA will > eventually go boom when the page allocator returns a page not in the > first pfn array. That has to be fixed in -stable. I don't really think > a DISCONTIGMEM re-engineering effort would be the best thing for the > -stable series. As far as I can tell: It will go boom even with other subsystems. I am surprised that we have never seen this before. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp110.prem.mail.ac4.yahoo.com ([76.13.13.93]:22873 "HELO smtp110.prem.mail.ac4.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753569Ab1DSWEe (ORCPT ); Tue, 19 Apr 2011 18:04:34 -0400 Date: Tue, 19 Apr 2011 17:04:31 -0500 (CDT) From: Christoph Lameter Subject: Re: slub: fix panic with DISCONTIGMEM In-Reply-To: <1303249970.11237.30.camel@mulgrave.site> Message-ID: References: <1303248576.11237.23.camel@mulgrave.site> <1303249970.11237.30.camel@mulgrave.site> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-arch-owner@vger.kernel.org List-ID: To: James Bottomley Cc: linux-arch@vger.kernel.org, linux-mm@kvack.org, "hugh.dickins@tiscali.co.uk" , Parisc List Message-ID: <20110419220431.B615MwFhUc-Ns4aRHr4Gzgusgk6o6Kvm9zUvEvaqyMQ@z> On Tue, 19 Apr 2011, James Bottomley wrote: > On Tue, 2011-04-19 at 16:38 -0500, Christoph Lameter wrote: > > On Tue, 19 Apr 2011, James Bottomley wrote: > > > > > Slub makes assumptions about page_to_nid() which are violated by > > > DISCONTIGMEM and !NUMA. This violation results in a panic because > > > > Fix this by stating correctly by saying "The kernel makes assumptions in > > various subsystems ..." > > Slub is a subset of the kernel, so the original wording is a bit more > precise. F.e. hugepage support does the same thing. So it not slub specific. > Well, we can discuss how to proceed going forwards. The current fact is > that any prior kernel that enables SLUB with DISCONTIGMEM and !NUMA will > eventually go boom when the page allocator returns a page not in the > first pfn array. That has to be fixed in -stable. I don't really think > a DISCONTIGMEM re-engineering effort would be the best thing for the > -stable series. As far as I can tell: It will go boom even with other subsystems. I am surprised that we have never seen this before.