Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755678Ab0DNOIt (ORCPT ); Wed, 14 Apr 2010 10:08:49 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:60809 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751127Ab0DNOIs (ORCPT ); Wed, 14 Apr 2010 10:08:48 -0400 Date: Wed, 14 Apr 2010 10:08:47 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Pedro Ribeiro cc: linux-usb@vger.kernel.org, Andi Kleen , , , Greg KH , Subject: Re: USB transfer_buffer allocations on 64bit systems In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1544 Lines: 34 On Wed, 14 Apr 2010, Pedro Ribeiro wrote: > On 14 April 2010 11:09, Daniel Mack wrote: > > > Thanks! So the only thing I can do for now is submit exactly this patch. > > At least, it helps you and it shouldn't break anything. The question > > remains whether this type of memory should be used for all > > transfer_buffers. > > > > Is there any chance you could push this to -stable? I don't care > because I always use the latest kernel, but the next Debian stable and > Ubuntu LTS are going to use 2.6.32. No! Please don't do it: Don't submit the patch and _certainly_ don't submit it to -stable. It doesn't fix anything; it only works around a bug, and at the moment we don't even know if the bug is in the kernel or in Pedro's hardware (and even though it affects two different systems of his, nobody else has reported a similar problem). Papering over it will only remove the incentive to fix it properly. In addition, you'll most likely find that lots of Linux developers will object vociferously to any proposed patch that uses GFP_DMA. That flag is supposed to be _only_ for ISA devices, which really need it. By limiting the memory allocation to the lowest 16 MB of physical memory, it greatly increases the chances that the allocation will fail. Alan Stern -- 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/