From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id A1EB86B0087 for ; Thu, 23 Dec 2010 05:58:19 -0500 (EST) Received: from epmmp1 (mailout4.samsung.com [203.254.224.34]) by mailout4.samsung.com (Oracle Communications Messaging Exchange Server 7u4-19.01 64bit (built Sep 7 2010)) with ESMTP id <0LDV00F0VNT5Y010@mailout4.samsung.com> for linux-mm@kvack.org; Thu, 23 Dec 2010 19:58:17 +0900 (KST) Received: from AMDC159 ([106.116.37.153]) by mmp1.samsung.com (iPlanet Messaging Server 5.2 Patch 2 (built Jul 14 2004)) with ESMTPA id <0LDV00873NSXWU@mmp1.samsung.com> for linux-mm@kvack.org; Thu, 23 Dec 2010 19:58:17 +0900 (KST) Date: Thu, 23 Dec 2010 11:58:08 +0100 From: Marek Szyprowski Subject: RE: [PATCHv8 00/12] Contiguous Memory Allocator In-reply-to: <20101223100642.GD3636@n2100.arm.linux.org.uk> Message-id: <00ea01cba290$4d67f500$e837df00$%szyprowski@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii Content-language: pl Content-transfer-encoding: 7BIT References: <20101223100642.GD3636@n2100.arm.linux.org.uk> Sender: owner-linux-mm@kvack.org To: 'Russell King - ARM Linux' , 'Kyungmin Park' Cc: 'Michal Nazarewicz' , linux-arm-kernel@lists.infradead.org, 'Daniel Walker' , 'Johan MOSSBERG' , 'Mel Gorman' , linux-kernel@vger.kernel.org, 'Michal Nazarewicz' , linux-mm@kvack.org, 'Ankita Garg' , 'Andrew Morton' , linux-media@vger.kernel.org, 'KAMEZAWA Hiroyuki' , Marek Szyprowski List-ID: Hello, On Thursday, December 23, 2010 11:07 AM Russell King - ARM Linux wrote: > On Thu, Dec 23, 2010 at 06:30:57PM +0900, Kyungmin Park wrote: > > Hi Andrew, > > > > any comments? what's the next step to merge it for 2.6.38 kernel. we > > want to use this feature at mainline kernel. > > Has anyone addressed my issue with it that this is wide-open for > abuse by allocating large chunks of memory, and then remapping > them in some way with different attributes, thereby violating the > ARM architecture specification? Actually this contiguous memory allocator is a better replacement for alloc_pages() which is used by dma_alloc_coherent(). It is a generic framework that is not tied only to ARM architecture. > In other words, do we _actually_ have a use for this which doesn't > involve doing something like allocating 32MB of memory from it, > remapping it so that it's DMA coherent, and then performing DMA > on the resulting buffer? This is an arm specific problem, also related to dma_alloc_coherent() allocator. To be 100% conformant with ARM specification we would probably need to unmap all pages used by the dma_coherent allocator from the LOW MEM area. This is doable, but completely not related to the CMA and this patch series. Best regards -- Marek Szyprowski Samsung Poland R&D Center -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org