From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751366AbcFIMdz (ORCPT ); Thu, 9 Jun 2016 08:33:55 -0400 Received: from mail-db3on0145.outbound.protection.outlook.com ([157.55.234.145]:26258 "EHLO emea01-db3-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750810AbcFIMdx (ORCPT ); Thu, 9 Jun 2016 08:33:53 -0400 Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=aryabinin@virtuozzo.com; From: Andrey Ryabinin To: Ingo Molnar , Peter Zijlstra CC: , Andrey Ryabinin Subject: [PATCH v2] kernel/sysrq: reset watchdog on all CPUs while processing sysrq-w Date: Thu, 9 Jun 2016 15:20:05 +0300 Message-ID: <1465474805-14641-1-git-send-email-aryabinin@virtuozzo.com> X-Mailer: git-send-email 2.7.3 In-Reply-To: <1464353394-30528-1-git-send-email-aryabinin@virtuozzo.com> References: <1464353394-30528-1-git-send-email-aryabinin@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [195.214.232.10] X-ClientProxiedBy: AM3PR03CA024.eurprd03.prod.outlook.com (10.141.191.152) To VI1PR0801MB1310.eurprd08.prod.outlook.com (10.167.197.148) X-MS-Office365-Filtering-Correlation-Id: 04c01847-acc5-431e-5447-08d3906048d1 X-Microsoft-Exchange-Diagnostics: 1;VI1PR0801MB1310;2:TCM+6f/wnYxRFJiwXJC0IMetJItiRzypU5cbk5UvD+0plcJib6W3mbNlo5WHUVaQCnmZ0X9/zBoZUQgXrl7lOcEYmACNCOX/3XCCjH68vSFQatRdlQGdoiT9Nw++T8sFq9NwM7b+U6ypKuvAXDX0E5X564p0SCL27dwvcAsD0fG9s7sgNdgf/mcVkSoi1lqi;3:X269gC/3+/IX5RxoMDNcA6+O8coBsBgEJofP6f79xh1rJym4mCA1gogvSw4xeJOVoAbsBJgCw6HAXYDbaWX4XSVQTr5f2S5gJRDJFbrFVMj95wnPHS0ZnionUFjDLMHs;25:sBRs8aO2crBYOPkg5xSsbb2VVLi1YjgXiLrzGaigjiCRamu0qY90xCB2ZIfrDRfJZk8RKybZkMSwlDqDJ/hu4pRInmccJF+spBeFd2DyOlEQc0pEBG3wwDzMG4XuCWn7RG7asxiXxrVUpYkqA64is8ELvJxSLDwoSnYVSBODj+OXZiBaKZDzg9liCdDtROI6PoMPwtuxQ8hXUcVXy9M7+boTXJuJ5E2OjA0SzwnvJsJY71pmvxJeg0BDj0c/jfButwGM81//YZDTiNy7ceAnr6Kl+9enUhFMrZk5OlUxchpOhBTTuZcO/1+7Z/icmXSbBwezUV1VyOYBlnUImXXxe0gswve4x/P8NYLh+xPTFUP7n5sNGgTMXeBUEfDJTPYQP9jmJCW3EYNBV/zaH+g4v8iYm4vyhj1x9wTmF1LavCY= X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:VI1PR0801MB1310; 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Currently we reset NMI-watchdog on the current CPU to avoid spurious lockup messages. Sometimes this doesn't work since softlockup watchdog might trigger on another CPU which is waiting for an IPI to proceed. We reset softlockup watchdogs on all CPUs, but we do this only after listing all tasks, and this may be too late on a busy system. So, reset watchdogs CPUs earlier, in for_each_process_thread() loop. Signed-off-by: Andrey Ryabinin --- Changes since v1: - keep touch_nmi_watchdog() - touch_all_softlockup_watchdogs() after the loop becomes redundant, so remove it. - added comment. kernel/sched/core.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 7f2cae4..32fe0a7 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5133,14 +5133,16 @@ void show_state_filter(unsigned long state_filter) /* * reset the NMI-timeout, listing all files on a slow * console might take a lot of time: + * Also, reset softlockup watchdogs on all CPUs, because + * another CPU might be blocked waiting for us to process + * an IPI. */ touch_nmi_watchdog(); + touch_all_softlockup_watchdogs(); if (!state_filter || (p->state & state_filter)) sched_show_task(p); } - touch_all_softlockup_watchdogs(); - #ifdef CONFIG_SCHED_DEBUG if (!state_filter) sysrq_sched_debug_show(); -- 2.7.3