From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=F/Af=7W=vger.kernel.org=linux-kernel-owner@kernel.org>
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 EDF06C433DF
	for <linux-kernel@archiver.kernel.org>; Tue,  9 Jun 2020 11:38:50 +0000 (UTC)
Received: from vger.kernel.org (vger.kernel.org [23.128.96.18])
	by mail.kernel.org (Postfix) with ESMTP id C06C62064C
	for <linux-kernel@archiver.kernel.org>; Tue,  9 Jun 2020 11:38:50 +0000 (UTC)
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1729044AbgFILit (ORCPT
        <rfc822;linux-kernel@archiver.kernel.org>);
        Tue, 9 Jun 2020 07:38:49 -0400
Received: from mx2.suse.de ([195.135.220.15]:44780 "EHLO mx2.suse.de"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1728903AbgFILis (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 9 Jun 2020 07:38:48 -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 03D30ABCE;
        Tue,  9 Jun 2020 11:38:50 +0000 (UTC)
Date:   Tue, 09 Jun 2020 13:38:46 +0200
Message-ID: <s5h3674ii49.wl-tiwai@suse.de>
From:   Takashi Iwai <tiwai@suse.de>
To:     Christoph Hellwig <hch@lst.de>
Cc:     David Rientjes <rientjes@google.com>,
        "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>,
        alsa-devel@alsa-project.org, bp@alien8.de, hch@infradead.org,
        hpa@zytor.com, linux-kernel@vger.kernel.org, mingo@redhat.com,
        Pavel Machek <pavel@ucw.cz>, 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: <20200609113123.GA547@lst.de>
References: <1591545088.74ii116nf2.none@localhost>
        <20200608061950.GA17476@lst.de>
        <1591624340.z01ejtod28.none@localhost>
        <alpine.DEB.2.22.394.2006081928070.148886@chino.kir.corp.google.com>
        <20200609054306.GA9606@lst.de>
        <s5hsgf4irzt.wl-tiwai@suse.de>
        <20200609084305.GA21671@lst.de>
        <s5hlfkwip1h.wl-tiwai@suse.de>
        <20200609091727.GA23814@lst.de>
        <s5hh7vkio0n.wl-tiwai@suse.de>
        <20200609113123.GA547@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: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Tue, 09 Jun 2020 13:31:23 +0200,
Christoph Hellwig wrote:
> 
> On Tue, Jun 09, 2020 at 11:31:20AM +0200, Takashi Iwai wrote:
> > > > 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...  :-<
> 
> Can you point me to the relevant places (allocation and vmap mostly)
> so that I can take a look at how to fix this mess?

Found in sound/core/sgbuf.c.  It's specific to x86.
Also, for V4L, drivers/media/v4l2-core/videobuf-dma-sg.c.


thanks,

Takashi