Re: [PATCH] module,bug: Add TAINT_OOT_MODULE flag for modules not built in-tree

[Greg KH <greg@kroah.com>]

On Thu, Oct 27, 2011 at 11:41:37AM +1030, Rusty Russell wrote:
> On Wed, 26 Oct 2011 09:08:34 -0400, Nick Bowler <nbowler@elliptictech.com> wrote:
> > On 2011-10-25 22:54 +0200, Greg KH wrote:
> > > On Tue, Oct 25, 2011 at 04:17:24PM -0400, Dave Jones wrote:
> > > > On Tue, Oct 25, 2011 at 10:04:55PM +0200, Greg Kroah-Hartman wrote:
> > > >  > On Tue, Oct 25, 2011 at 12:51:42PM -0400, Nick Bowler wrote:
> > > >  > > This is not the case: lockdep works fine with staging modules.
> > > >  > 
> > > >  > Yes, that was fixed a few kernel versions ago.
> > > >  > 
> > > >  > Now you might want to update that fix for the TAINT_OOT_MODULE flag as
> > > >  > well, if you feel it is needed.
> > > > 
> > > > I'm assuming you mean this patch ?
> > > > 
> > > > commit 7816c45bf13255157c00fb8aca86cb64d825e878
> > > > Author: Roland Vossen <rvossen@broadcom.com>
> > > > Date:   Thu Apr 7 11:20:58 2011 +0200
> > > > 
> > > >     modules: Enabled dynamic debugging for staging modules
> > > 
> > > Hm, this is the patch I was thinking about yes.  But as you point out:
> > [...]
> > > Perhaps the lockdep thing is totally different.  I don't know about that
> > > check.
> > 
> > Lockdep is disabled (for the whole system) by add_taint itself.  The
> > relevant commit that fixes TAINT_CRAP appears to be this one (circa
> > 2.6.30):
> > 
> >   commit 574bbe782057fdf0490dc7dec906a2dc26363e20
> >   Author: Frederic Weisbecker <fweisbec@gmail.com>
> >   Date:   Sat Apr 11 03:17:18 2009 +0200
> >   
> >       lockdep: continue lock debugging despite some taints
> > 
> > I didn't know about the dynamic debug problem.  Is there more breakage
> > that we haven't found yet?  Remind me why we're trying to cripple out
> > of tree module users?
> 
> Gah, people are overloading taint.
> 
> It doesn't mean "don't do stuff", it means "note the taint when
> something goes wrong".

I agree, we shouldn't be changing logic in the kernel due to tainting,
so removing any such checks would be a good idea.

thanks,

greg k-h