Date: Fri, 8 Jun 2007 15:59:32 -0700 (PDT)
From: Christoph Lameter <clameter@sgi.com>
To: Andi Kleen <ak@suse.de>
cc: Andrew Morton <akpm@linux-foundation.org>,
       "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com>,
       linux-kernel@vger.kernel.org, gregkh@suse.de, muli@il.ibm.com,
       asit.k.mallick@intel.com, suresh.b.siddha@intel.com,
       arjan@linux.intel.com, ashok.raj@intel.com, shaohua.li@intel.com,
       davem@davemloft.net
Subject: Re: [Intel-IOMMU 02/10] Library routine for pre-allocat pool handling
In-Reply-To: <200706090056.49279.ak@suse.de>
Message-ID: <Pine.LNX.4.64.0706081558090.4373@schroedinger.engr.sgi.com>
References: <20070606185658.138237000@askeshav-devel.jf.intel.com>
 <6901450.1181335390183.SLOX.WebMail.wwwrun@imap-dhs.suse.de>
 <Pine.LNX.4.64.0706081534520.3966@schroedinger.engr.sgi.com>
 <200706090056.49279.ak@suse.de>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 943
Lines: 25

On Sat, 9 Jun 2007, Andi Kleen wrote:

> > Why was it not allowed? Because interrupts are disabled?
> 
> Allocating memory during page out under low memory could 
> lead to deadlocks. That is because Linux used to make no attempt
> to limit dirty pages for anonymous mappings and then you could
> end up with most of your memory dirty and not enough 
> memory cleanable for page out and then when page out 
> needs more memory you could be dead.
> 
> [yes that implies that mmap over NFS was always broken]

Right. We got that fixed in 2.6.19.

> Now there is a anon dirty limit since a few releases, but I'm not
> fully convinced it solves the problem completely.

A gut feeling or is there more?

-
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/