From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755656Ab0COCcX (ORCPT ); Sun, 14 Mar 2010 22:32:23 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:50947 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751581Ab0COCcV (ORCPT ); Sun, 14 Mar 2010 22:32:21 -0400 Date: Sun, 14 Mar 2010 19:31:14 -0400 From: Andrew Morton To: Alan Stern Cc: Mel Gorman , Markus Rechberger , LKML , Greg KH Subject: Re: USBFS Memory allocation Bug Message-Id: <20100314193114.619a2616.akpm@linux-foundation.org> In-Reply-To: References: <20100310155519.GO4883@csn.ul.ie> X-Mailer: Sylpheed 2.7.1 (GTK+ 2.18.7; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 11 Mar 2010 11:56:22 -0500 (EST) Alan Stern wrote: > On Wed, 10 Mar 2010, Mel Gorman wrote: > > > > > Is there any means for the driver to take the large request, break it up > > > > into multiple smaller requests and submit them one at a time? > > > > > > In theory almost anything is possible. But it would be a big effort > > > and not consistent with the way the rest of the driver works. > > > > > > > Then about the only other suggestion would be a mempool containing a small > > number of largest-possible buffers that is enabled if there is no swap > > available. > > Considering that this is the first report I have heard about this sort > of problem, and that adding swap space would probably fix it, I'm not > inclined to make any changes. Adding swap space is unlikely to help here. For an order-6 allocation the page allocator will go into wtf-youre-kidding-me mode and won't even bother trying. Asking the allocator for 2^6 physically contiguous pages is terribly unreliable and shouldn't be done by any kernel code which wants to be useful.