linux-kernel - Re: [RFC][PATCH 1/3] slub: Drop lock at the end of free_debug

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Date:	Tue, 26 Jan 2016 10:19:08 -0600 (CST)
From:	Christoph Lameter <cl@...ux.com>
To:	Laura Abbott <labbott@...oraproject.org>
cc:	Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Joonsoo Kim <js1304@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com,
	Kees Cook <keescook@...omium.org>
Subject: Re: [RFC][PATCH 1/3] slub: Drop lock at the end of
 free_debug_processing

On Mon, 25 Jan 2016, Laura Abbott wrote:

> Currently, free_debug_processing has a comment "Keep node_lock to preserve
> integrity until the object is actually freed". In actuallity,
> the lock is dropped immediately in __slab_free. Rather than wait until
> __slab_free and potentially throw off the unlikely marking, just drop
> the lock in __slab_free. This also lets free_debug_processing take
> its own copy of the spinlock flags rather than trying to share the ones
> from __slab_free. Since there is no use for the node afterwards, change
> the return type of free_debug_processing to return an int like
> alloc_debug_processing.

Acked-by: Christoph Lameter <cl@...ux.com>\