Re: lockdep complaints in slab allocator

From: Pekka Enberg
Date: Mon Nov 23 2009 - 14:14:05 EST


Matt Mackall wrote:
This seems like a lot of work to paper over a lockdep false positive in
code that should be firmly in the maintenance end of its lifecycle? I'd
rather the fix or papering over happen in lockdep.

True that. Is __raw_spin_lock() out of question, Peter?-) Passing the state is pretty invasive because of the kmem_cache_free() call in slab_destroy(). We re-enter the slab allocator from the outer edges which makes spin_lock_nested() very inconvenient.

Introducing extra cacheline pressure by passing to_destroy around also
seems like a good way to trickle away SLAB's narrow remaining
performance advantages.

We can probably fix that to affect CONFIG_NUMA only which sucks already.

Pekka
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