[alsa-devel] [PATCH 0/2] PCM OSS fixes

[Takashi Iwai]

On Mon, 08 Jan 2018 16:37:32 +0100,
Lars-Peter Clausen wrote:
> 
> On 01/08/2018 04:05 PM, Takashi Iwai wrote:
> > On Mon, 08 Jan 2018 15:58:47 +0100,
> > Lars-Peter Clausen wrote:
> >>
> >> On 01/08/2018 03:25 PM, Takashi Iwai wrote:
> >>> Hi,
> >>>
> >>> this contains two fixes for PCM OSS bugs that have been triggered by
> >>> syzbot.  These are simple and straightforward, and I'm going to queue
> >>> for 4.15-rc8.
> >>
> >> I tried to reproduce the issue as well with the reproducer generated by
> >> syzbot. But what syzbot reported was that the CPU didn't sleep for 140
> >> seconds. But with a long write() we'll go to sleep in between frames. So
> >> when I tried the lockup detector never triggered.
> >>
> >> Were you able to reproduce the same CPU lockup as syzbot?
> > 
> > Yes, I could reproduce RCU stalls with two reproducers
> > (001a113ece5c2b600d05620b097a at google.com and
> >  001a1147e1988b160a05620552eb at google.com)
> > 
> > The patches seem curing them, so far, in combination with other
> > patches in for-linus branch of sound.git tree.
> > 
> 
> Hm, interesting. Are you using aloop for the backend or real hardware?

The RCU stall happened also with dummy driver.  Just feeding a GB of
chunk to /dev/audio and aborting the stream concurrently, then it
stalls at that point.


Takashi