From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753459AbZHGJUB (ORCPT ); Fri, 7 Aug 2009 05:20:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752918AbZHGJUA (ORCPT ); Fri, 7 Aug 2009 05:20:00 -0400 Received: from smtp.nokia.com ([192.100.105.134]:61481 "EHLO mgw-mx09.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752709AbZHGJUA (ORCPT ); Fri, 7 Aug 2009 05:20:00 -0400 Message-ID: <4A7BF1C3.4050602@nokia.com> Date: Fri, 07 Aug 2009 12:20:03 +0300 From: Adrian Hunter User-Agent: Thunderbird 2.0.0.21 (X11/20090318) MIME-Version: 1.0 To: JiSheng Zhang CC: "linux-mtd@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "dwmw2@infradead.org" , "rmk@arm.linux.org.uk" , "Bityutskiy Artem (Nokia-D/Helsinki)" Subject: Re: [UBI UBIFS] replace vmalloc with kmalloc References: <2df346410908070202i6c16008ckc145559a474129c6@mail.gmail.com> In-Reply-To: <2df346410908070202i6c16008ckc145559a474129c6@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 07 Aug 2009 09:19:34.0182 (UTC) FILETIME=[2D7A5C60:01CA1740] X-Nokia-AV: Clean Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org JiSheng Zhang wrote: > If nandflash driver use DMA to support UBI and UBIFS i/o, there will > be panic like > the following. This is because UBI and UBIFS use vmalloced buffer > somewhere while > nandflash driver put the buffer under DMA and DMA support doesn't like vmalloced > memory. > [ 412.369280] UBIFS: default file-system created > [ 412.374879] Unable to handle kernel NULL pointer dereference at > virtual address 00000000 > [ 412.383177] UBIFS: background thread "ubifs_bgt0_0" started, PID 887 > [ 412.389656] pgd = c0004000 > [ 412.392419] [00000000] *pgd=00000000 > [ 412.396117] Internal error: Oops: 817 [#1] PREEMPT > > Yes, I know kmalloc may fail when memory get fragmented, but I grep the UBI and > UBIFS's source, there are six .c files and seven .c files using > vmalloc, the function > which call vmalloc are all called during the ubi being attached and > the volume being > mounted. In embedded system, this mainly happen during kernel boot, it > should succeed. > > After replacing vmalloc with kmalloc, ubi and ubifs runs fine on my > board. I can alos upload > a patch. > > Comments are welcomed! vmalloc allows large (> 128KiB) buffers, but kmalloc doesn't. So we presently have no choice but to use vmalloc. I do not know what hardware you have or exactly what driver you are using, but we have UBIFS on OneNAND using DMA. See drivers/mtd/onenand/omap2.c