From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754734Ab3KTRYU (ORCPT ); Wed, 20 Nov 2013 12:24:20 -0500 Received: from mail-yh0-f53.google.com ([209.85.213.53]:63527 "EHLO mail-yh0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754424Ab3KTRYS (ORCPT ); Wed, 20 Nov 2013 12:24:18 -0500 Date: Wed, 20 Nov 2013 12:24:13 -0500 From: Tejun Heo To: Hong Zhiguo Cc: vgoyal@redhat.com, cgroups@vger.kernel.org, axboe@kernel.dk, linux-kernel@vger.kernel.org, Hong Zhiguo Subject: Re: [PATCH] blkcg: have bh disable for 32bit UP system reading 64bit stats Message-ID: <20131120172413.GN28946@htj.dyndns.org> References: <1383736484-393-1-git-send-email-zhiguohong@tencent.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1383736484-393-1-git-send-email-zhiguohong@tencent.com> 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 On Wed, Nov 06, 2013 at 07:14:44PM +0800, Hong Zhiguo wrote: > From: Hong Zhiguo > > Update of blkg_stat and blkg_rwstat may happen in bh context. > While u64_stats_fetch_retry is only preempt_disable on 32bit > UP system. This is not enough to avoid preemption by bh and > may read strange 64 bit value. > > Signed-off-by: Hong Zhiguo Acked-by: Tejun Heo Jens, can you please pick this one up? This probably needs to be tagged for stable too. Thanks! -- tejun