From patchwork Wed Mar 4 15:37:43 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tejun Heo X-Patchwork-Id: 5937291 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 2827E9F318 for ; Wed, 4 Mar 2015 15:38:07 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 4544420253 for ; Wed, 4 Mar 2015 15:38:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 71BBE2024F for ; Wed, 4 Mar 2015 15:38:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758837AbbCDPhs (ORCPT ); Wed, 4 Mar 2015 10:37:48 -0500 Received: from mail-qg0-f47.google.com ([209.85.192.47]:33148 "EHLO mail-qg0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758642AbbCDPhr (ORCPT ); Wed, 4 Mar 2015 10:37:47 -0500 Received: by qgef51 with SMTP id f51so123869qge.0; Wed, 04 Mar 2015 07:37:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=DY8Wyy88y38BtHJ1++4weCW/D+KpMOGGxZC8k7GEBXc=; b=mXEooEMtxnwZ+yfa8h5yJ2q9aPyfsOKtu4VHgtCbV17rQvWrYR2ksmlgxjDQO76mgZ vONvCIdVZ2F85FKLp4krrd8oSTKHfHf01xnuadTfZY4cECAOdrNIgjy/sFhExMjgdIqS Mj3/7sjxQPw6Jq4qv6nkFxtx0+leLYxPSZTdMtmZPQOIulUPmDbcn1KhYl/lMfWvvq0f IoT6qQQQse/+70kRqiGLhXcYI3l912QWUh8NtpwS/oLCqgM6ilLPSiS5bS/zh3U9KSIW E4ncmmnky7GhSzztUcud9Z/mNJhyXei7DjuH42HZ8pGr+beGrbeebS/4EcD66vjI+zni LgGQ== X-Received: by 10.55.20.8 with SMTP id e8mr8101386qkh.37.1425483466868; Wed, 04 Mar 2015 07:37:46 -0800 (PST) Received: from htj.duckdns.org (207-38-238-8.c3-0.wsd-ubr1.qens-wsd.ny.cable.rcn.com. [207.38.238.8]) by mx.google.com with ESMTPSA id n34sm2382768qge.27.2015.03.04.07.37.44 (version=TLSv1.2 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 04 Mar 2015 07:37:46 -0800 (PST) Date: Wed, 4 Mar 2015 10:37:43 -0500 From: Tejun Heo To: Jens Axboe Cc: Jan Kara , Wu Fengguang , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: [PATCH block/for-4.0-fixes] writeback: add missing INITIAL_JIFFIES init in global_update_bandwidth() Message-ID: <20150304153743.GH3122@htj.duckdns.org> References: <20150304152243.GG3122@htj.duckdns.org> <20150304153050.GA1249@quack.suse.cz> <54F72567.3060406@kernel.dk> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <54F72567.3060406@kernel.dk> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Spam-Status: No, score=-6.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID,T_RP_MATCHES_RCVD,UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Subject: writeback: add missing INITIAL_JIFFIES init in global_update_bandwidth() global_update_bandwidth() uses static variable update_time as the timestamp for the last update but forgets to initialize it to INITIALIZE_JIFFIES. This means that global_dirty_limit will be 5 mins into the future on 32bit and some large amount jiffies into the past on 64bit. This isn't critical as the only effect is that global_dirty_limit won't be updated for the first 5 mins after booting on 32bit machines, especially given the auxiliary nature of global_dirty_limit's role - protecting against global dirty threshold's sudden dips; however, it does lead to unintended suboptimal behavior. Fix it. Fixes: c42843f2f0bb ("writeback: introduce smoothed global dirty limit") Signed-off-by: Tejun Heo Acked-by: Jan Kara Cc: Wu Fengguang Cc: Jens Axboe Cc: stable@vger.kernel.org --- Added the "fixes" tag. Jens, can you please route this one? Thanks. mm/page-writeback.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -922,7 +922,7 @@ static void global_update_bandwidth(unsi unsigned long now) { static DEFINE_SPINLOCK(dirty_lock); - static unsigned long update_time; + static unsigned long update_time = INITIAL_JIFFIES; /* * check locklessly first to optimize away locking for the most time