Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932432AbbDUPed (ORCPT ); Tue, 21 Apr 2015 11:34:33 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:57530 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932148AbbDUPeV (ORCPT ); Tue, 21 Apr 2015 11:34:21 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Tejun Heo , Wu Fengguang , Jens Axboe , Jens Axboe , Luis Henriques Subject: [PATCH 3.16.y-ckt 084/144] writeback: add missing INITIAL_JIFFIES init in global_update_bandwidth() Date: Tue, 21 Apr 2015 16:31:09 +0100 Message-Id: <1429630329-21748-85-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1429630329-21748-1-git-send-email-luis.henriques@canonical.com> References: <1429630329-21748-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1920 Lines: 49 3.16.7-ckt10 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Tejun Heo 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: Luis Henriques --- 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 dfe512e911c8..001d86441639 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -925,7 +925,7 @@ 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 -- 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/