Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965625AbbD0Vec (ORCPT ); Mon, 27 Apr 2015 17:34:32 -0400 Received: from ip4-83-240-67-251.cust.nbox.cz ([83.240.67.251]:49721 "EHLO ip4-83-240-18-248.cust.nbox.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S965301AbbD0Vc7 (ORCPT ); Mon, 27 Apr 2015 17:32:59 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Tejun Heo , Wu Fengguang , Jens Axboe , Jens Axboe , Jiri Slaby Subject: [PATCH 3.12 25/83] writeback: add missing INITIAL_JIFFIES init in global_update_bandwidth() Date: Mon, 27 Apr 2015 23:31:56 +0200 Message-Id: <0d4958ffdbf7a14e58ea822968a40c05b3c9de0f.1430159990.git.jslaby@suse.cz> X-Mailer: git-send-email 2.3.5 In-Reply-To: <3426bb8de3a655aa6668e92ee92eb35f0db86582.1430159990.git.jslaby@suse.cz> References: <3426bb8de3a655aa6668e92ee92eb35f0db86582.1430159990.git.jslaby@suse.cz> In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1901 Lines: 52 From: Tejun Heo 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit 7d70e15480c0450d2bfafaad338a32e884fc215e upstream. 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 Signed-off-by: Jens Axboe Signed-off-by: Jiri Slaby --- mm/page-writeback.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 9f45f87a5859..d3653325a255 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -943,7 +943,7 @@ static void global_update_bandwidth(unsigned long thresh, 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 -- 2.3.5 -- 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/