From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 560E3C33CA4 for ; Fri, 10 Jan 2020 08:25:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2C79A2072E for ; Fri, 10 Jan 2020 08:25:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726962AbgAJIZZ (ORCPT ); Fri, 10 Jan 2020 03:25:25 -0500 Received: from out30-44.freemail.mail.aliyun.com ([115.124.30.44]:47157 "EHLO out30-44.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726561AbgAJIZY (ORCPT ); Fri, 10 Jan 2020 03:25:24 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R761e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01f04446;MF=shile.zhang@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0TnJTHE8_1578644713; Received: from e18g09479.et15sqa.tbsite.net(mailfrom:shile.zhang@linux.alibaba.com fp:SMTPD_---0TnJTHE8_1578644713) by smtp.aliyun-inc.com(127.0.0.1); Fri, 10 Jan 2020 16:25:20 +0800 From: Shile Zhang To: Andrew Morton , Pavel Tatashin Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Shile Zhang Subject: [PATCH 1/1] mm: fix tick_sched timer blocked by pgdat_resize_lock Date: Fri, 10 Jan 2020 16:25:10 +0800 Message-Id: <20200110082510.172517-2-shile.zhang@linux.alibaba.com> X-Mailer: git-send-email 2.24.0.rc2 In-Reply-To: <20200110082510.172517-1-shile.zhang@linux.alibaba.com> References: <20200110082510.172517-1-shile.zhang@linux.alibaba.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When 'CONFIG_DEFERRED_STRUCT_PAGE_INIT' is set, 'pgdat_resize_lock' will be called inside 'pgdatinit' kthread to initialise the deferred pages with local interrupts disabled. Which is introduced by commit 3a2d7fa8a3d5 ("mm: disable interrupts while initializing deferred pages"). But 'pgdatinit' kthread is possible be pined on the boot CPU (CPU#0 by default), especially in small system with NRCPUS <= 2. In this case, the interrupts are disabled on boot CPU during memory initialising, which caused the tick_sched timer be blocked, leading to wall clock stuck. Fixes: commit 3a2d7fa8a3d5 ("mm: disable interrupts while initializing deferred pages") Signed-off-by: Shile Zhang --- include/linux/memory_hotplug.h | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index ba0dca6aac6e..6ffcb5b704bc 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -282,12 +282,22 @@ static inline bool movable_node_is_enabled(void) static inline void pgdat_resize_lock(struct pglist_data *pgdat, unsigned long *flags) { - spin_lock_irqsave(&pgdat->node_size_lock, *flags); + /* + * Disable local interrupts on boot CPU will stop the tick_sched + * timer, which will block jiffies(wall clock) update. + */ + if (current->cpu != get_boot_cpu_id()) + spin_lock_irqsave(&pgdat->node_size_lock, *flags); + else + spin_lock(&pgdat->node_size_lock); } static inline void pgdat_resize_unlock(struct pglist_data *pgdat, unsigned long *flags) { - spin_unlock_irqrestore(&pgdat->node_size_lock, *flags); + if (current->cpu != get_boot_cpu_id()) + spin_unlock_irqrestore(&pgdat->node_size_lock, *flags); + else + spin_unlock(&pgdat->node_size_lock); } static inline void pgdat_resize_init(struct pglist_data *pgdat) -- 2.24.0.rc2