Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756699Ab2HWGRk (ORCPT ); Thu, 23 Aug 2012 02:17:40 -0400 Received: from hqemgate04.nvidia.com ([216.228.121.35]:2016 "EHLO hqemgate04.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754017Ab2HWGRg (ORCPT ); Thu, 23 Aug 2012 02:17:36 -0400 X-PGP-Universal: processed; by hqnvupgp05.nvidia.com on Wed, 22 Aug 2012 23:17:29 -0700 Date: Thu, 23 Aug 2012 09:15:19 +0300 From: Hiroshi Doyu To: Marek Szyprowski CC: "pullip.cho@samsung.com" , "linux-arm-kernel@lists.infradead.org" , "linaro-mm-sig@lists.linaro.org" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "kyungmin.park@samsung.com" , "arnd@arndb.de" , "linux@arm.linux.org.uk" , "chunsang.jeong@linaro.org" , Krishna Reddy , "konrad.wilk@oracle.com" , "subashrp@gmail.com" , "minchan@kernel.org" Subject: Re: [RFC 2/4] ARM: dma-mapping: IOMMU allocates pages from pool with GFP_ATOMIC Message-ID: <20120823091519.804aeae4ba93bcfe011e787c@nvidia.com> In-Reply-To: <012401cd80f4$59727020$0c575060$%szyprowski@samsung.com> References: <1345630830-9586-1-git-send-email-hdoyu@nvidia.com> <1345630830-9586-3-git-send-email-hdoyu@nvidia.com> <20120822.163648.3800987367886904.hdoyu@nvidia.com> <012401cd80f4$59727020$0c575060$%szyprowski@samsung.com> X-Mailer: Sylpheed 3.2.0beta3 (GTK+ 2.24.6; x86_64-pc-linux-gnu) X-NVConfidentiality: public 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 Content-Length: 1493 Lines: 35 Hi, On Thu, 23 Aug 2012 07:58:34 +0200 Marek Szyprowski wrote: > Hello, > > On Wednesday, August 22, 2012 3:37 PM Hiroshi Doyu wrote: > > > KyongHo Cho wrote @ Wed, 22 Aug 2012 14:47:00 +0200: > > > > > vzalloc() call in __iommu_alloc_buffer() also causes BUG() in atomic context. > > > > Right. > > > > I've been thinking that kzalloc() may be enough here, since > > vzalloc() was introduced to avoid allocation failure for big chunk of > > memory, but I think that it's unlikely that the number of page array > > can be so big. So I propose to drop vzalloc() here, and just simply to > > use kzalloc only as below(*1). > > We already had a discussion about this, so I don't think it makes much sense to > change it back to kzalloc. This vmalloc() call won't hurt anyone. It should not > be considered a problem for atomic allocations, because no sane driver will try > to allocate buffers larger than a dozen KiB with GFP_ATOMIC flag. I would call > such try a serious bug, which we should not care here. Ok, I've already sent v2 just now, where, instead of changing it back, just with GFP_ATOMIC, kzalloc() would be selected, just in case. I guess that this would be ok(a bit safer?) -- 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/