Re: kern/46402: LWPs created after exit_lwp() is called can hang the process....

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

The following reply was made to PR kern/46402; it has been noted by GNATS.

From: Manuel Bouyer <bouyer%antioche.eu.org@localhost>
To: Greg Oster <oster%cs.usask.ca@localhost>
Cc: gnats-bugs%NetBSD.org@localhost, kern-bug-people%NetBSD.org@localhost, 
gnats-admin%NetBSD.org@localhost,
        netbsd-bugs%NetBSD.org@localhost, oster%NetBSD.org@localhost
Subject: Re: kern/46402: LWPs created after exit_lwp() is called can hang the
 process....
Date: Thu, 3 May 2012 18:31:51 +0200

 On Thu, May 03, 2012 at 10:22:21AM -0600, Greg Oster wrote:
 > On Thu,  3 May 2012 15:00:07 +0000 (UTC)
 > Manuel Bouyer <bouyer%antioche.eu.org@localhost> wrote:
 > 
 > > The following reply was made to PR kern/46402; it has been noted by
 > > GNATS.
 > > 
 > > From: Manuel Bouyer <bouyer%antioche.eu.org@localhost>
 > > To: gnats-bugs%NetBSD.org@localhost
 > > Cc: kern-bug-people%NetBSD.org@localhost, gnats-admin%NetBSD.org@localhost,
 > > netbsd-bugs%NetBSD.org@localhost Subject: Re: kern/46402: LWPs created 
 > > after
 > > exit_lwp() is called can hang the process....
 > > Date: Thu, 3 May 2012 16:57:09 +0200
 > > 
 > >  On Wed, May 02, 2012 at 09:30:00PM +0000, oster%NetBSD.org@localhost 
 > > wrote:
 > >  > While running an extended series of aft-tests I noticed that the
 > >  > test were occasionally hanging.  It turns out they were hanging at
 > >  > the same place, and that the test is repeatable.  Running the
 > >  > following:
 > >  > 
 > >  >  cd /usr/tests/lib/libpthread
 > >  >  foreach i (`jot 10000`)
 > >  >  ./t_cond cond_timedwait_race 
 > >  >  echo $i
 > >  >  end
 > >  > 
 > >  
 > >  Sounds familiar: kern/46168
 > 
 > yes!  That's exactly the same bug....  I ran with a patch very, very
 > similar to the one you had in 46168, but I'd end up with a very hard
 > kernel hang after some time... (couldn't break into ddb as normal,
 > even).
 > 
 > >  Andrew Doran had some improvements to the patch I proposed here, but
 > > it seems he forgot to send me an updated patch (this was a month ago).
 > >  I guess we should get the patch in kern/46168 commited then ...
 > 
 > I don't think it's sufficient, unfortunately... there's still something
 > else missing.. :(  
 
 It may be a different bug; see the thread about hard hang on port-amd64.
 I've never seen these hard hangs myself, and I've tested different hardware ...
 
 -- 
 Manuel Bouyer <bouyer%antioche.eu.org@localhost>
      NetBSD: 26 ans d'experience feront toujours la difference
 --