Date: Fri, 17 Feb 2006 19:27:37 +0000 (GMT)
From: Hugh Dickins <hugh@veritas.com>
To: Oleg Nesterov <oleg@tv-sign.ru>
cc: "Paul E. McKenney" <paulmck@us.ibm.com>, linux-kernel@vger.kernel.org,
       Dipankar Sarma <dipankar@in.ibm.com>, Andrew Morton <akpm@osdl.org>
Subject: Re: [PATCH] convert sighand_cache to use SLAB_DESTROY_BY_RCU
In-Reply-To: <43F62B96.C54704D1@tv-sign.ru>
Message-ID: <Pine.LNX.4.61.0602171926180.15992@goblin.wat.veritas.com>
References: <43F62B96.C54704D1@tv-sign.ru>
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On Fri, 17 Feb 2006, Oleg Nesterov wrote:
> This patch borrows a clever Hugh's 'struct anon_vma' trick.
> 
> Without tasklist_lock held we can't trust task->sighand until we
> locked it and re-checked that it is still the same.
> 
> But this means we don't need to defer 'kmem_cache_free(sighand)'.
> We can return the memory to slab immediately, all we need is to
> be sure that sighand->siglock can't dissapear inside rcu protected
> section.
> 
> To do so we need to initialize ->siglock inside ctor function,
> SLAB_DESTROY_BY_RCU does the rest.

Yes, that looks a good use of SLAB_DESTROY_BY_RCU to me: thanks!

Hugh
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