From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B7DE7C433E0 for ; Tue, 9 Jun 2020 11:02:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8BF9D207F9 for ; Tue, 9 Jun 2020 11:02:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728471AbgFILCx (ORCPT ); Tue, 9 Jun 2020 07:02:53 -0400 Received: from mx2.suse.de ([195.135.220.15]:49540 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727002AbgFILCv (ORCPT ); Tue, 9 Jun 2020 07:02:51 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id B66DFACF2; Tue, 9 Jun 2020 11:02:52 +0000 (UTC) Date: Tue, 09 Jun 2020 13:02:46 +0200 Message-ID: From: Takashi Iwai To: Christoph Hellwig Cc: David Rientjes , "Alex Xu (Hello71)" , alsa-devel@alsa-project.org, bp@alien8.de, hch@infradead.org, hpa@zytor.com, linux-kernel@vger.kernel.org, mingo@redhat.com, Pavel Machek , perex@perex.cz, tglx@linutronix.de, tiwai@suse.com, x86@kernel.org Subject: Re: next-0519 on thinkpad x60: sound related? window manager crash In-Reply-To: References: <20200520111136.GA3802@amd> <1591545088.74ii116nf2.none@localhost> <20200608061950.GA17476@lst.de> <1591624340.z01ejtod28.none@localhost> <20200609054306.GA9606@lst.de> <20200609084305.GA21671@lst.de> <20200609091727.GA23814@lst.de> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 09 Jun 2020 11:31:20 +0200, Takashi Iwai wrote: > > On Tue, 09 Jun 2020 11:17:27 +0200, > Christoph Hellwig wrote: > > > > On Tue, Jun 09, 2020 at 11:09:14AM +0200, Takashi Iwai wrote: > > > On Tue, 09 Jun 2020 10:43:05 +0200, > > > Christoph Hellwig wrote: > > > > > > > > On Tue, Jun 09, 2020 at 10:05:26AM +0200, Takashi Iwai wrote: > > > > > > >From the disassembly it seems like a vmalloc allocation is NULL, which > > > > > > seems really weird as this patch shouldn't make a difference for them, > > > > > > and I also only see a single places that allocates the field, and that > > > > > > checks for an allocation failure. But the sound code is a little > > > > > > hard to unwind sometimes. > > > > > > > > > > It's not clear which sound device being affected, but if it's > > > > > HD-audio on x86, runtime->dma_area points to a vmapped buffer from > > > > > SG-pages allocated by dma_alloc_coherent(). > > > > > > > > > > OTOH, if it's a USB-audio, runtime->dma_area is a buffer by > > > > > vmalloc(). > > > > > > > > Err, you can't just vmap a buffer returned from dma_alloc_coherent, > > > > dma_alloc_coherent returns values are opaque and can't be used > > > > for virt_to_page. Whatever that code did has already been broken > > > > per the DMA API contract and on many architectures and just happend > > > > to work on x86 by accident. > > > > > > Hmm, that's bad. > > > > > > How would be a proper way to get the virtually mapped SG-buffer pages > > > with coherent memory? (Also allowing user-space mmap, too) > > > > dma_mmap_coherent / dma_mmap_attrs for userspace. We don't really > > have a good way for kernel space mappings. > > And that's the missing piece right now... :-< BTW, this kind of usage is not specific to sound, but also V4L also does vmap() over SG pages from dma_alloc_coherent(). It seems done only on selected devices, though. Takashi