Subject: Re: [MM PATCH V4.1 5/6] slub: support for bulk free with SLUB freelists

From: Jesper Dangaard Brouer <[email-masked]>
Date: Fri, 2 Oct 2015 12:40:01 +0200

On Fri, 2 Oct 2015 05:10:02 -0500 (CDT)
Christoph Lameter <[email-masked]> wrote:

> On Fri, 2 Oct 2015, Jesper Dangaard Brouer wrote:
> 
> > Thus, I need introducing new code like this patch and at the same time
> > have to reduce the number of instruction-cache misses/usage.  In this
> > case we solve the problem by kmem_cache_free_bulk() not getting called
> > too often. Thus, +17 bytes will hopefully not matter too much... but on
> > the other hand we sort-of know that calling kmem_cache_free_bulk() will
> > cause icache misses.
> 
> Can we just drop the WARN/BUG here? Nothing untoward happens if size == 0
> right?

I think we crash if size == 0, as we deref p[--size] in build_detached_freelist().

(aside note: The code do handles if pointers in the p array are NULL)
-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer

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