From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755044Ab3G2GIc (ORCPT ); Mon, 29 Jul 2013 02:08:32 -0400 Received: from mga03.intel.com ([143.182.124.21]:36388 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752933Ab3G2GIb (ORCPT ); Mon, 29 Jul 2013 02:08:31 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.89,767,1367996400"; d="scan'208";a="274642823" Date: Mon, 29 Jul 2013 10:59:30 +0530 From: Vinod Koul To: Xiang Wang Cc: Dan Williams , "linux-kernel@vger.kernel.org" , cxie4@marvell.com, Xiang Wang Subject: Re: [PATCH v2] dma: mmp_pdma: fix a memory alloc error Message-ID: <20130729052930.GC29095@intel.com> References: <1371536519-7837-1-git-send-email-wangxfdu@gmail.com> <20130705064549.GD10947@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 25, 2013 at 10:22:50AM +0800, Xiang Wang wrote: Btw its generally a good idea to remove the parts not required for further discussion > Would you please explain a little more about why we should use > GFP_NOWAIT here? This memory is not dedicated for DMA controller. Do > we have special reasons to use GFP_NOWAIT? Thanks! There are few reasons - the dma requests can be triggered from atomic context - so for above you can argue to use the GFP_ATOMIC and the guideline for dma drivers [1] was discussed briefly ~Vinod [1]: http://lkml.indiana.edu/hypermail/linux/kernel/0911.1/02316.html --