Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752664Ab0LWK6U (ORCPT ); Thu, 23 Dec 2010 05:58:20 -0500 Received: from mailout4.samsung.com ([203.254.224.34]:29232 "EHLO mailout4.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752378Ab0LWK6T (ORCPT ); Thu, 23 Dec 2010 05:58:19 -0500 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> 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 Message-id: <00ea01cba290$4d67f500$e837df00$%szyprowski@samsung.com> MIME-version: 1.0 X-Mailer: Microsoft Office Outlook 12.0 Content-type: text/plain; charset=us-ascii Content-language: pl Content-transfer-encoding: 7BIT Thread-index: AcuiiWPfhnfwa0RHTauoouex3IdUTQABZHLQ References: <20101223100642.GD3636@n2100.arm.linux.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1557 Lines: 41 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 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/