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Date: Wed, 9 Sep 2015 20:47:50 -0500 (CDT)
From: Christoph Lameter <cl@linux.com>
Subject: Re: Store Buffers (was Re: Is it OK to pass non-acquired objects to
 kfree?)
In-Reply-To: <20150910011028.GY4029@linux.vnet.ibm.com>
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To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>, Pekka Enberg <penberg@kernel.org>, David Rientjes <rientjes@google.com>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Andrew Morton <akpm@linux-foundation.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>, Andrey Konovalov <andreyknvl@google.com>, Alexander Potapenko <glider@google.com>

On Wed, 9 Sep 2015, Paul E. McKenney wrote:

> > But then again kfree() contains a barrier() which would block the compiler
> > from moving anything into the free path.
>
> That barrier() is implicit in the fact that kfree() is an external
> function?  Or are my eyes failing me?

kfree at some point calls slab_free(). That function has a barrier. All
free operations go through it.

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