Re: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock()

Dave Jones
2008-08-04T14:55:24Z

On Mon, Aug 04, 2008 at 04:32:12PM +0200, Peter Zijlstra wrote:
> On Mon, 2008-08-04 at 07:26 -0700, Roland Dreier wrote:
> > > No more than 48 locks (mutexes, rwlocks, spinlock, RCU, everything
> > > covered by lockdep) held by any one code-path; including nested
> > > interrupt contexts.
> >
> > Does that mean that something like the new mm_take_all_locks() operation
> > is going to explode if someone tries to use it with lockdep on?
>
> Gah - yes, clearly nobody tried this.. :-/
>
> Just looking at the code it will not only run into this limit, but it
> would warn about recursion on the second file/anon vma due to utter lack
> of annotation.
>
> Why are people still developing without lockdep?

More puzzling, is why hasn't this triggered in the Fedora rawhide kernels,
which do have lockdep enabled.

Dave

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