From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:35973 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759045AbcDISdL (ORCPT ); Sat, 9 Apr 2016 14:33:11 -0400 Subject: Patch "sched/fair: Avoid using decay_load_missed() with a negative value" has been added to the 4.5-stable tree To: byungchul.park@lge.com, cl@linux.com, cmetcalf@ezchip.com, dietmar.eggemann@arm.com, efault@gmx.de, fweisbec@gmail.com, gregkh@linuxfoundation.org, lcapitulino@redhat.com, mingo@kernel.org, paulmck@linux.vnet.ibm.com, peterz@infradead.org, riel@redhat.com, tglx@linutronix.de, torvalds@linux-foundation.org Cc: , From: Date: Sat, 09 Apr 2016 11:33:10 -0700 Message-ID: <1460226790213211@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled sched/fair: Avoid using decay_load_missed() with a negative value to the 4.5-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: sched-fair-avoid-using-decay_load_missed-with-a-negative-value.patch and it can be found in the queue-4.5 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 7400d3bbaa229eb8e7631d28fb34afd7cd2c96ff Mon Sep 17 00:00:00 2001 From: Byungchul Park Date: Fri, 15 Jan 2016 16:07:49 +0900 Subject: sched/fair: Avoid using decay_load_missed() with a negative value From: Byungchul Park commit 7400d3bbaa229eb8e7631d28fb34afd7cd2c96ff upstream. decay_load_missed() cannot handle nagative values, so we need to prevent using the function with a negative value. Reported-by: Dietmar Eggemann Signed-off-by: Byungchul Park Signed-off-by: Peter Zijlstra (Intel) Cc: Chris Metcalf Cc: Christoph Lameter Cc: Frederic Weisbecker Cc: Linus Torvalds Cc: Luiz Capitulino Cc: Mike Galbraith Cc: Paul E . McKenney Cc: Peter Zijlstra Cc: Rik van Riel Cc: Thomas Gleixner Cc: perterz@infradead.org Fixes: 59543275488d ("sched/fair: Prepare __update_cpu_load() to handle active tickless") Link: http://lkml.kernel.org/r/20160115070749.GA1914@X58A-UD3R Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- kernel/sched/fair.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4459,9 +4459,17 @@ static void __update_cpu_load(struct rq /* scale is effectively 1 << i now, and >> i divides by scale */ - old_load = this_rq->cpu_load[i] - tickless_load; + old_load = this_rq->cpu_load[i]; old_load = decay_load_missed(old_load, pending_updates - 1, i); - old_load += tickless_load; + if (tickless_load) { + old_load -= decay_load_missed(tickless_load, pending_updates - 1, i); + /* + * old_load can never be a negative value because a + * decayed tickless_load cannot be greater than the + * original tickless_load. + */ + old_load += tickless_load; + } new_load = this_load; /* * Round up the averaging division if load is increasing. This Patches currently in stable-queue which might be from byungchul.park@lge.com are queue-4.5/sched-fair-avoid-using-decay_load_missed-with-a-negative-value.patch