Re: SLOB lockup (was: Re: [tip:core/locking] lockdep: annotatereclaim context (__GFP_NOFS), fix SLOB)

[Ingo Molnar]

* Nick Piggin <nickpiggin@xxxxxxxxxxxx> wrote:

> On Sunday 15 March 2009 17:48:18 Ingo Molnar wrote:
> 
> > > Cc: Nick Piggin <npiggin@xxxxxxx>
> > > Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> > > LKML-Reference: <20090128135457.350751756@xxxxxxxxx>
> > > Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
> >
> > and with this fixed, and with SLOB now being tested in -tip, the
> > new lockdep assert attached below (followed by a real lockup)
> > pops up.
> >
> > Seems like a genuine SLOB bug, probably present upstream as
> > well.
> 
> Hmmf. debugobjects calls back into the slab allocator from the 
> page allocator. The following patch would improve SLOB, but I 
> think it would be a good idea to avoid a dependency in that 
> direction. Can debugobjects defer this freeing?

dunno - that's a question for Thomas.

this lockup does not trigger under any of the other allocators.

	Ingo
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