From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752227AbeCWV2V (ORCPT ); Fri, 23 Mar 2018 17:28:21 -0400 Received: from mail-wr0-f180.google.com ([209.85.128.180]:43083 "EHLO mail-wr0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751595AbeCWV2U (ORCPT ); Fri, 23 Mar 2018 17:28:20 -0400 X-Google-Smtp-Source: AG47ELv8OqLAkrscMYbnOBDmxRsJ/D1ZcX4I2vv2AKPjp5vRthP3ilN5/29W+/x90COX9+0Lgkgmig== To: Vincent Guittot , "Peter Zijlstra (Intel)" Cc: Ingo Molnar , Linux Kernel Mailing List From: Heiner Kallweit Subject: Problem with commit 31e77c93e432 "sched/fair: Update blocked load when newly idle" Message-ID: Date: Fri, 23 Mar 2018 22:28:09 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Recently I started to get the following problems with linux-next: - When working via Putty/SSH on the system the console frequently freezes for few seconds. Sometimes only opening a second console makes the first one react again. - I get "INFO: rcu_sched detected stalls on CPUs/tasks:" warnings as described in [1]. Bisecting the issue resulted in: 31e77c93e432dec79c7d90b888bbfc3652592741 is the first bad commit commit 31e77c93e432dec79c7d90b888bbfc3652592741 Author: Vincent Guittot Date: Wed Feb 14 16:26:46 2018 +0100 sched/fair: Update blocked load when newly idle When NEWLY_IDLE load balance is not triggered, we might need to update the blocked load anyway. We can kick an ilb so an idle CPU will take care of updating blocked load or we can try to update them locally before entering idle. In the latter case, we reuse part of the nohz_idle_balance. After reversing this commit at least the issue with the freezing console is gone. The second one appeared only sporadically, I still have to see whether it pops up again. System is a Zotac CI321 mini PC with Intel Celeron 2961Y CPU. If you need more details, please let me know. Regards, Heiner [1] https://lkml.org/lkml/2018/3/22/605