Bug#524940: module-init-tools: modprobe starts fork-bombing on executing oss-compat postinst

[Matthew Lockner <mlockner@iastate.edu>]

Marco d'Itri wrote:
> On Apr 22, Matthew Lockner <mlockner@iastate.edu> wrote:
>
>   
> > The strongest evidence is that if I downgrade module-init-tools to the  
> > prior version and hold the prior version and hold the package, the  
> > problem goes away.  I'd find the next most likely candidate to be  
> >     
> Not very compelling evidence.
> This shows that your system was already broken:
>
> WARNING: Deprecated config file /etc/modprobe.conf, all config files belong into /etc/modprobe.d/.
>
> If /etc/modprobe.conf was present, older releases ignored
> /etc/modprobe.d/.
>
>   
> > oss-compat's postinst script, but downgrading that package does nothing  
> > if you still have the newest module-init-tools in place.
> >     
> And what about removing oss-compat?
>   

Since its postinst is my means of demonstrating the problem, then of 
course removing the package will prevent the problem from appearing, at 
least in this context.

It is noteworthy that while I was obtaining the output you requested 
below, I had another hard lockup, and upon rebooting, there were similar 
problems during startup.  The screen displayed the same kinds of 
warnings at points, and the OOM killer was stepping in at points to kill 
modprobe and its child processes.

>   
> > > Please show the content of /etc/modprobe.d/oss-compat.conf.
> > > Are you sure that the processes were related to oss-compat? Please find
> > > out the exact command linux.
> > >       
> I meant "the exact command line" of the processes being run.
>
>   

I got the blocks below from the output of ps.  The first block was 
gathered after dpkg-reconfigure oss-compat started spewing warnings; the 
second block was gathered after a "killall modprobe sh" after running 
ps.  I had to run "killall modprobe sh" again to get rid of the mess, 
but no more modprobe floods came in from that point.  In my other 
window, after each killall invocation, I get something like

/var/lib/dpkg/info/oss-compat.postinst: line 6:  5773 
Terminated              modprobe snd-seq-oss

I conclude that the postinst is hanging on the lines where it calls 
modprobe, specifically for snd_seq_oss and snd_pcm_oss.



/usr/bin/perl -w /usr/sbin/dpkg-reconfigure oss-compat
/bin/sh /var/lib/dpkg/info/oss-compat.postinst configure 0.0.4+nmu3
modprobe snd_seq_oss
sh -c modprobe --ignore-install snd-seq  && { modprobe --quiet 
snd-seq-midi ; modprobe --quiet snd-seq-oss ; : ; }
modprobe --quiet snd_seq_midi
sh -c modprobe --ignore-install snd-seq  && { modprobe --quiet 
snd-seq-midi ; modprobe --quiet snd-seq-oss ; : ; }
modprobe --quiet snd_seq_midi
sh -c modprobe --ignore-install snd-seq  && { modprobe --quiet 
snd-seq-midi ; modprobe --quiet snd-seq-oss ; : ; }
modprobe --quiet snd_seq_midi
sh -c modprobe --ignore-install snd-seq  && { modprobe --quiet 
snd-seq-midi ; modprobe --quiet snd-seq-oss ; : ; }
modprobe --quiet snd_seq_midi
sh -c modprobe --ignore-install snd-seq  && { modprobe --quiet 
snd-seq-midi ; modprobe --quiet snd-seq-oss ; : ; }
modprobe --quiet snd_seq_midi
sh -c modprobe --ignore-install snd-seq  && { modprobe --quiet 
snd-seq-midi ; modprobe --quiet snd-seq-oss ; : ; }
modprobe --quiet snd_seq_midi
sh -c modprobe --ignore-install snd-seq  && { modprobe --quiet 
snd-seq-midi ; modprobe --quiet snd-seq-oss ; : ; }
modprobe --quiet snd_seq_midi
sh -c modprobe --ignore-install snd-seq  && { modprobe --quiet 
snd-seq-midi ; modprobe --quiet snd-seq-oss ; : ; }
modprobe --quiet snd_seq_midi
sh -c modprobe --ignore-install snd-seq  && { modprobe --quiet 
snd-seq-midi ; modprobe --quiet snd-seq-oss ; : ; }
modprobe --quiet snd_seq_midi
sh -c modprobe --ignore-install snd-seq  && { modprobe --quiet 
snd-seq-midi ; modprobe --quiet snd-seq-oss ; : ; }
modprobe --quiet snd_seq_midi
sh -c modprobe --ignore-install snd-seq  && { modprobe --quiet 
snd-seq-midi ; modprobe --quiet snd-seq-oss ; : ; }
modprobe --ignore-install snd_seq
sh -c /sbin/modprobe --ignore-install snd && { /sbin/modprobe --quiet 
snd-ioctl32 ; : ; }
/sbin/modprobe --ignore-install snd


/bin/sh /var/lib/dpkg/info/oss-compat.postinst configure 0.0.4+nmu3
modprobe snd_pcm_oss
sh -c modprobe --ignore-install snd-pcm  && { modprobe --quiet 
snd-pcm-oss ; : ;
modprobe --quiet snd_pcm_oss
sh -c modprobe --ignore-install snd-pcm  && { modprobe --quiet 
snd-pcm-oss ; : ;
modprobe --quiet snd_pcm_oss
sh -c modprobe --ignore-install snd-pcm  && { modprobe --quiet 
snd-pcm-oss ; : ;
modprobe --quiet snd_pcm_oss
sh -c modprobe --ignore-install snd-pcm  && { modprobe --quiet 
snd-pcm-oss ; : ;
modprobe --quiet snd_pcm_oss
sh -c modprobe --ignore-install snd-pcm  && { modprobe --quiet 
snd-pcm-oss ; : ;
modprobe --quiet snd_pcm_oss
sh -c modprobe --ignore-install snd-pcm  && { modprobe --quiet 
snd-pcm-oss ; : ;
modprobe --quiet snd_pcm_oss
sh -c modprobe --ignore-install snd-pcm  && { modprobe --quiet 
snd-pcm-oss ; : ;
modprobe --quiet snd_pcm_oss
sh -c modprobe --ignore-install snd-pcm  && { modprobe --quiet 
snd-pcm-oss ; : ;
modprobe --quiet snd_pcm_oss
sh -c modprobe --ignore-install snd-pcm  && { modprobe --quiet 
snd-pcm-oss ; : ;
modprobe --quiet snd_pcm_oss
sh -c modprobe --ignore-install snd-pcm  && { modprobe --quiet 
snd-pcm-oss ; : ;
modprobe --quiet snd_pcm_oss
sh -c /sbin/modprobe --ignore-install snd && { /sbin/modprobe --quiet 
snd-ioctl3
/sbin/modprobe --quiet snd-ioctl32