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From: Christoph Lameter <cl@linux.com>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: linux-arch@vger.kernel.org, linux-mm@kvack.org,
	"hugh.dickins@tiscali.co.uk" <hugh.dickins@tiscali.co.uk>,
	Parisc List <linux-parisc@vger.kernel.org>
Subject: Re: slub: fix panic with DISCONTIGMEM
Date: Tue, 19 Apr 2011 17:04:31 -0500 (CDT)	[thread overview]
Message-ID: <alpine.DEB.2.00.1104191702400.26867@router.home> (raw)
In-Reply-To: <1303249970.11237.30.camel@mulgrave.site>

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.


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      reply	other threads:[~2011-04-19 22:04 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1303248576.11237.23.camel@mulgrave.site>
     [not found] ` <alpine.DEB.2.00.1104191633250.23077@router.home>
2011-04-19 21:52   ` James Bottomley
2011-04-19 22:04     ` Christoph Lameter [this message]

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