Re: futex strangeness in 2.6.23-mm1/UML

[Rik van Riel <riel@redhat.com>]

On Mon, 22 Oct 2007 22:48:51 +0200
Miklos Szeredi <miklos@szeredi.hu> wrote:

> > > I'm getting a process stuck in pthread_rwlock_wrlock(), even
> > > though it looks like the lock is not held by anybody.
> > > 
> > > I think the last -mm was OK.  Any ideas?
> > > 
> > > If not, I'll go searching for the offending patch.
> > 
> > I wonder if that's the same bug that's breaking autofs for me.
> 
> Probably.
> 
> > Oct 22 14:39:01 kenny automount[2299]: cache_readlock: mapent cache
> > rwlock lock failed
> > Oct 22 14:39:01 kenny automount[2299]: unexpected pthreads error:
> > 11 at 65 in cache.c
> > 
> > I'm bisecting 2.6.23-mm1 today to find the problem patch, with
> > some luck I'll have it this afternoon.
> > 
> > With the series applied up to
> > whitespace-fixes-task-exit-handling.patch things work.
> > 
> > It breaks before kswapd-should-only-wait-on-io-if-there-is-io.patch
> > 
> > That leaves only about 60-80 patches to look at :)
> 
> OK, the first patch that breaks something for me is:
> 
>   pid-namespaces-move-alloc_pid-lower-in-copy_process.patch

Confirmed.  That same patch is the point where the bisect
here starts breaking autofs.

Ian, it looks like the autofs code is innocent :)

-- 
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it." - Brian W. Kernighan