From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH] block: set the bounce_pfn to the actual DMA limit rather than to max memory Date: Fri, 24 Sep 2010 15:58:00 +0200 Message-ID: <4C9CAE68.4060706@fusionio.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-scsi-owner@vger.kernel.org To: Malahal Naineni Cc: "dm-devel@redhat.com" , "linux-scsi@vger.kernel.org" List-Id: dm-devel.ids On 2010-09-22 00:22, Malahal Naineni wrote: > The bounce_pfn of the request queue in 64 bit systems is set to the > current max_low_pfn. Adding more memory later makes this incorrect. Clearly correct. > Memory allocated beyond this boot time max_low_pfn appear to require > bounce buffers (bounce buffers are actually not allocated but used in > calculating segments that may result in "over max segments limit" > errors). But I can't quite convince myself that the change is fully correct. You don't really explain in your own words what the patch does, just what it fixes. -- Jens Axboe