From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ale.deltatee.com (ale.deltatee.com [207.54.116.67]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 2688921951C90 for ; Thu, 27 Apr 2017 08:44:33 -0700 (PDT) References: <1493144468-22493-1-git-send-email-logang@deltatee.com> <1493144468-22493-2-git-send-email-logang@deltatee.com> <20170426074416.GA7936@lst.de> <4736d44e-bbcf-5d59-a1a9-317d0f4da847@deltatee.com> <20170427065338.GA20677@lst.de> From: Logan Gunthorpe Message-ID: <3b7f3aba-d609-dca7-149f-107757d63fb0@deltatee.com> Date: Thu, 27 Apr 2017 09:44:18 -0600 MIME-Version: 1.0 In-Reply-To: <20170427065338.GA20677@lst.de> Subject: Re: [PATCH v2 01/21] scatterlist: Introduce sg_map helper functions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Christoph Hellwig Cc: dri-devel@lists.freedesktop.org, dm-devel@redhat.com, target-devel@vger.kernel.org, Sumit Semwal , devel@driverdev.osuosl.org, "James E.J. Bottomley" , linux-scsi@vger.kernel.org, linux-nvdimm@lists.01.org, linux-rdma@vger.kernel.org, open-iscsi@googlegroups.com, linux-media@vger.kernel.org, intel-gfx@lists.freedesktop.org, sparmaintainer@unisys.com, linux-raid@vger.kernel.org, megaraidlinux.pdl@broadcom.com, Jens Axboe , "Martin K. Petersen" , netdev@vger.kernel.org, Matthew Wilcox , linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, Greg Kroah-Hartman List-ID: On 27/04/17 12:53 AM, Christoph Hellwig wrote: > I think you'll need to follow the existing kmap semantics and never > fail the iomem version either. Otherwise you'll have a special case > that's almost never used that has a different error path. > > Again, wrong way. Suddenly making things fail for your special case > that normally don't fail is a receipe for bugs. I don't disagree but these restrictions make the problem impossible to solve? If there is iomem behind a page in an SGL and someone tries to map it, we either have to fail or we break iomem safety which was your original concern. Logan _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm