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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 4AAB5C4360C for ; Sun, 6 Oct 2019 17:22:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 20D7820867 for ; Sun, 6 Oct 2019 17:22:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570382578; bh=AA3UGzytwFlaFFB0h7c09QGX5TW/ljwxPmgI+tY/N1Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=lvlHbkbjG6cgrvLKGKAri3FM1YxBg37/rRglrUafSabH/zSa19gBAlAMXfm2j1zrh uaaTDgPw3hGeIk38FiRsATsMiiDTvTUNq9qeXdJ//oI1rfudXC7DnRFyQLrKMKtUPO rXK7yTTyrHYEMYYP+gUA+MdqHE6U0hoUb9o2q6wY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727063AbfJFRW5 (ORCPT ); Sun, 6 Oct 2019 13:22:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:47194 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726508AbfJFRW5 (ORCPT ); Sun, 6 Oct 2019 13:22:57 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 299282080F; Sun, 6 Oct 2019 17:22:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570382576; bh=AA3UGzytwFlaFFB0h7c09QGX5TW/ljwxPmgI+tY/N1Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L/HGCrcJqWCBQ7WDDXuFCEz7HGK3Gxp7aA7p43ZVIP1Yj6KCcPblza3jvg0UPg+WB YjjGCzJqTepM6jtYc7W5Wy6sZ65+0ETpfM3mh7aW3Tl+OxxwHJKkUZ72grX23u5jh/ p2227y3QBIkDnI8wUoiGhDxtvl9yQBdd4k2iikRo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nathan Lynch , Michael Ellerman , Sasha Levin Subject: [PATCH 4.9 10/47] powerpc/pseries/mobility: use cond_resched when updating device tree Date: Sun, 6 Oct 2019 19:20:57 +0200 Message-Id: <20191006172017.431913166@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191006172016.873463083@linuxfoundation.org> References: <20191006172016.873463083@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Nathan Lynch [ Upstream commit ccfb5bd71d3d1228090a8633800ae7cdf42a94ac ] After a partition migration, pseries_devicetree_update() processes changes to the device tree communicated from the platform to Linux. This is a relatively heavyweight operation, with multiple device tree searches, memory allocations, and conversations with partition firmware. There's a few levels of nested loops which are bounded only by decisions made by the platform, outside of Linux's control, and indeed we have seen RCU stalls on large systems while executing this call graph. Use cond_resched() in these loops so that the cpu is yielded when needed. Signed-off-by: Nathan Lynch Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190802192926.19277-4-nathanl@linux.ibm.com Signed-off-by: Sasha Levin --- arch/powerpc/platforms/pseries/mobility.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c index 3784a7abfcc80..74791e8382d22 100644 --- a/arch/powerpc/platforms/pseries/mobility.c +++ b/arch/powerpc/platforms/pseries/mobility.c @@ -11,6 +11,7 @@ #include #include +#include #include #include #include @@ -206,7 +207,11 @@ static int update_dt_node(__be32 phandle, s32 scope) prop_data += vd; } + + cond_resched(); } + + cond_resched(); } while (rtas_rc == 1); of_node_put(dn); @@ -282,8 +287,12 @@ int pseries_devicetree_update(s32 scope) add_dt_node(phandle, drc_index); break; } + + cond_resched(); } } + + cond_resched(); } while (rc == 1); kfree(rtas_buf); -- 2.20.1