From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: Generic DMA - BUG_ON Date: Wed, 20 Jan 2010 12:00:31 +0100 Message-ID: <20100120110031.GD8665@amd.com> References: <1263982111-24123-1-git-send-email-monstr@monstr.eu> <20100120105350.GA23394@flint.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: Content-Disposition: inline In-Reply-To: <20100120105350.GA23394@flint.arm.linux.org.uk> Sender: linux-kernel-owner@vger.kernel.org To: monstr@monstr.eu, linux-kernel@vger.kernel.org, michal.simek@petalogix.com, arnd@arndb.de, linux-arch@vger.kernel.org, fujita.tomonori@lab.ntt.co.jp, akpm@linux-foundation.org, mingo@elte.hu List-Id: linux-arch.vger.kernel.org On Wed, Jan 20, 2010 at 10:53:50AM +0000, Russell King wrote: > and ops is NULL, then this code will oops; you will get a full register > dump and backtrace. You can use this information along with markup_oops.pl > to find out where the problem is. You can't rely on the oops if the code runs in process context. The process may have address 0 mapped which would result in a security hole. We had two of these bugs last year. But I don't see any point in checking for dma_ops != NULL too. Any developer would mention such a bug long before init is started. Joerg From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from tx2ehsobe005.messaging.microsoft.com ([65.55.88.15]:31428 "EHLO TX2EHSOBE010.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753146Ab0ATLAt (ORCPT ); Wed, 20 Jan 2010 06:00:49 -0500 Date: Wed, 20 Jan 2010 12:00:31 +0100 From: Joerg Roedel Subject: Re: Generic DMA - BUG_ON Message-ID: <20100120110031.GD8665@amd.com> References: <1263982111-24123-1-git-send-email-monstr@monstr.eu> <20100120105350.GA23394@flint.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20100120105350.GA23394@flint.arm.linux.org.uk> Sender: linux-arch-owner@vger.kernel.org List-ID: To: monstr@monstr.eu, linux-kernel@vger.kernel.org, michal.simek@petalogix.com, arnd@arndb.de, linux-arch@vger.kernel.org, fujita.tomonori@lab.ntt.co.jp, akpm@linux-foundation.org, mingo@elte.hu Message-ID: <20100120110031.db8t-GUnvG_QysLK-iVNJTPJLkvrqpQMQqL-LTQhyNU@z> On Wed, Jan 20, 2010 at 10:53:50AM +0000, Russell King wrote: > and ops is NULL, then this code will oops; you will get a full register > dump and backtrace. You can use this information along with markup_oops.pl > to find out where the problem is. You can't rely on the oops if the code runs in process context. The process may have address 0 mapped which would result in a security hole. We had two of these bugs last year. But I don't see any point in checking for dma_ops != NULL too. Any developer would mention such a bug long before init is started. Joerg