From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756789Ab3APXO1 (ORCPT ); Wed, 16 Jan 2013 18:14:27 -0500 Received: from caramon.arm.linux.org.uk ([78.32.30.218]:48107 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752120Ab3APXO0 (ORCPT ); Wed, 16 Jan 2013 18:14:26 -0500 Date: Wed, 16 Jan 2013 23:14:01 +0000 From: Russell King - ARM Linux To: James Bottomley Cc: Subhash Jadavani , martin.petersen@oracle.com, linux-scsi@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, tj@kernel.org, asias@redhat.com, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2 1/1] block: blk-merge: don't merge the pages with non-contiguous descriptors Message-ID: <20130116231401.GV23505@n2100.arm.linux.org.uk> References: <1358265681-25671-1-git-send-email-subhashj@codeaurora.org> <1358266794.10591.8.camel@dabdike.int.hansenpartnership.com> <50F64AC1.3040304@codeaurora.org> <1358332355.2384.11.camel@dabdike.int.hansenpartnership.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1358332355.2384.11.camel@dabdike.int.hansenpartnership.com> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 16, 2013 at 10:32:35AM +0000, James Bottomley wrote: > On Wed, 2013-01-16 at 12:07 +0530, Subhash Jadavani wrote: > > > Now consider this call stack from MMC block driver (this is on the ARmv7 > > based board): > > [ 98.918174] [] (v7_dma_inv_range+0x30/0x48) from > > [] (dma_cache_maint_page+0x1c4/0x24c) > > [ 98.927819] [] (dma_cache_maint_page+0x1c4/0x24c) from > > [] (___dma_page_cpu_to_dev+0x14/0x1c) > > [ 98.937982] [] (___dma_page_cpu_to_dev+0x14/0x1c) from > > [] (dma_map_sg+0x3c/0x114) > > OK, so this is showing that ARM itself is making the assumption that the > pages are contiguous in the page offset map. > > Fix this by doing the increment via the pfn, which will do the right > thing whatever the memory model. > > Signed-off-by: James Bottomley Ok. What would you like the patch summary line for this to be - the existing one seems to be a little wrong given the content of this patch... > > --- > > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > index 6b2fb87..ab88c5b 100644 > --- a/arch/arm/mm/dma-mapping.c > +++ b/arch/arm/mm/dma-mapping.c > @@ -809,7 +809,7 @@ static void dma_cache_maint_page(struct page *page, unsigned long offset, > op(vaddr, len, dir); > } > offset = 0; > - page++; > + page = pfn_to_page(page_to_pfn(page) + 1); > left -= len; > } while (left); > } > > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel