Re: [patch] lockdep: more annotations for mm/slab.c

[Arjan van de Ven <arjan@infradead.org>]

On Thu, 2006-07-13 at 12:44 +0200, Arjan van de Ven wrote:
> On Thu, 2006-07-13 at 11:18 +0200, Ingo Molnar wrote:
> > * Andrew Morton <akpm@osdl.org> wrote:
> > 
> > > > ---
> > > >  mm/slab.c |   45 +++++++++++++++++++++++++--------------------
> > > 
> > > geeze, what fuss.  Can't we just tell lockdep "the locking here is 
> > > correct, so buzz off"?
> > 
> > well, lockdep already found a locking bug in slab.c, so by telling 
> > lockdep to buzz off we lose the proof of correctness :-)
> > 
> > but i agree that this is getting a bit too intrusive. This patch is 
> > really just another expression of: 'slab locking is too complex', but i 
> > digress. Not all hope is lost though: Arjan thinks he can do a much 
> > simpler annotation.
> 
> 
> I am hoping I can get away with just this patch; the idea is to give the
> cache_cache slab a special lock type since it'll be nested all the time
> (and has a natural ordering due to it's special position in the slab
> code). I'm not yet sure I found all places where this stuff is
> initialized (the slab code has gotten terribly complex with all the numa
> stuff added to it); I've started to test this now at least and so far it
> seems to work on my test box.
> 

fwiw the slab where off-slab datastructures get stored needs this
treatment as well, I've yet to decipher the slab code where this slab is
though ;)