Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Thu, 11 Jun 2020 19:11:14 +0200
Message-ID: <s5h8sgtede5.wl-tiwai@suse.de>
From:   Takashi Iwai <tiwai@suse.de>
To:     "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>
Cc:     alsa-devel@alsa-project.org, bp@alien8.de, hch@infradead.org,
        Christoph Hellwig <hch@lst.de>, hpa@zytor.com,
        linux-kernel@vger.kernel.org, mingo@redhat.com,
        Pavel Machek <pavel@ucw.cz>, perex@perex.cz,
        rientjes@google.com, tglx@linutronix.de, tiwai@suse.com,
        x86@kernel.org
Subject: Re: next-0519 on thinkpad x60: sound related? window manager crash
In-Reply-To: <1591885264.uk6f214o4o.none@localhost>
References: <20200520111136.GA3802@amd>
        <1591545088.74ii116nf2.none@localhost>
        <20200608061950.GA17476@lst.de>
        <1591624340.z01ejtod28.none@localhost>
        <20200609114733.GA1621@lst.de>
        <s5hr1uogtna.wl-tiwai@suse.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

On Thu, 11 Jun 2020 16:51:55 +0200,
Alex Xu (Hello71) wrote:
> 
> Excerpts from Takashi Iwai's message of June 9, 2020 11:12 am:
> > On Tue, 09 Jun 2020 13:47:33 +0200,
> > Christoph Hellwig wrote:
> >> 
> >> Alex, can you try this patch?
> > 
> > Also could you check whether just papering over the memset() call
> > alone avoids the crash like below?  For PulseAudio and dmix/dsnoop,
> > it's the only code path that accesses the vmapped buffer, I believe.
> > 
> > If this works more or less, I'll cook a more comprehensive fix.
> > 
> > 
> > thanks,
> > 
> > Takashi
> > 
> > --- a/sound/core/pcm_native.c
> > +++ b/sound/core/pcm_native.c
> > @@ -754,9 +754,11 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
> >  	while (runtime->boundary * 2 <= LONG_MAX - runtime->buffer_size)
> >  		runtime->boundary *= 2;
> >  
> > +#if 0
> >  	/* clear the buffer for avoiding possible kernel info leaks */
> >  	if (runtime->dma_area && !substream->ops->copy_user)
> >  		memset(runtime->dma_area, 0, runtime->dma_bytes);
> > +#endif
> >  
> >  	snd_pcm_timer_resolution_change(substream);
> >  	snd_pcm_set_state(substream, SNDRV_PCM_STATE_SETUP);
> > 
> 
> Sorry, this patch doesn't work for me with SME off using abfbb29297c2. 
> David's newest submitted patch works for me, which I already replied to 
> separately.

Thanks, so something still missing in the mmap handling, I guess.

I've worked on two different branches for potential fixes of your
problems.  Could you test topic/dma-fix and topic/dma-fix2 branches?
  git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git
Just pull one of them onto Linus' git HEAD.

I guess we'll go with David's new patch, but still it's interesting
whether my changes do anything good actually.


Takashi