Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932171Ab3FLUzH (ORCPT ); Wed, 12 Jun 2013 16:55:07 -0400 Received: from mail-pa0-f48.google.com ([209.85.220.48]:52995 "EHLO mail-pa0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756646Ab3FLUzE (ORCPT ); Wed, 12 Jun 2013 16:55:04 -0400 Date: Wed, 12 Jun 2013 13:55:00 -0700 From: Kent Overstreet To: Tejun Heo Cc: linux-kernel@vger.kernel.org, Rusty Russell , Oleg Nesterov , Christoph Lameter Subject: Re: [PATCH percpu/for-3.11] percpu-refcount: consistently use plain (non-sched) RCU Message-ID: <20130612205500.GE6151@google.com> References: <20130612204031.GA15092@htj.dyndns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130612204031.GA15092@htj.dyndns.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1103 Lines: 24 On Wed, Jun 12, 2013 at 01:40:32PM -0700, Tejun Heo wrote: > From e96262150a513ce3d54ff221d4ace8aeec96e0bf Mon Sep 17 00:00:00 2001 > From: Tejun Heo > Date: Wed, 12 Jun 2013 13:37:42 -0700 > > percpu_ref_get/put() are using preempt_disable/enable() while > percpu_ref_kill() is using plain call_rcu() instead of > call_rcu_sched(). This is buggy as grace periods of the two may not > match. Fix it by using plain RCU in percpu_ref_get/put(). > > (I suggested using sched RCU in the first place but there's no actual > benefit in doing so unless we're gonna introduce different variants > of get/put to be called while preemption is alredy disabled, which we > definitely shouldn't.) > > Signed-off-by: Tejun Heo > Reported-by: Rusty Russell Acked-by: Kent Overstreet -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/