From patchwork Fri Jan 15 12:27:44 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 364544 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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 93D37C4332E for ; Fri, 15 Jan 2021 13:04:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6397F22473 for ; Fri, 15 Jan 2021 13:04:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732801AbhAOMbq (ORCPT ); Fri, 15 Jan 2021 07:31:46 -0500 Received: from mail.kernel.org ([198.145.29.99]:37452 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732787AbhAOMbp (ORCPT ); Fri, 15 Jan 2021 07:31:45 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id A882C23136; Fri, 15 Jan 2021 12:31:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1610713890; bh=tC6JJM1vmnXYySKfv9b0mXJx7CTs1lpaCXJ6pG71VEA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zd9q0MD00j7HtiBLIwvzxxSOYv54HMpWh2TQzp04uRJW3dPBUqaG/4z4CtJlooXU0 CdO3VJnaHsdjUwI3KKD3HYtaS0AqB5nY4Anm8T6k/f/YSX7q6mU/CtO8Ggolw+CJOP 8qrr0EzaN1fHElPjv/vd8+/NWcPowljtoIhAs3dw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Shakeel Butt , Fenghua Yu , Reinette Chatre , Borislav Petkov , Tony Luck Subject: [PATCH 4.14 07/28] x86/resctrl: Dont move a task to the same resource group Date: Fri, 15 Jan 2021 13:27:44 +0100 Message-Id: <20210115121957.106181858@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210115121956.731354372@linuxfoundation.org> References: <20210115121956.731354372@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Fenghua Yu commit a0195f314a25582b38993bf30db11c300f4f4611 upstream Shakeel Butt reported in [1] that a user can request a task to be moved to a resource group even if the task is already in the group. It just wastes time to do the move operation which could be costly to send IPI to a different CPU. Add a sanity check to ensure that the move operation only happens when the task is not already in the resource group. [1] https://lore.kernel.org/lkml/CALvZod7E9zzHwenzf7objzGKsdBmVwTgEJ0nPgs0LUFU3SN5Pw@mail.gmail.com/ Backporting notes: Since upstream commit fa7d949337cc ("x86/resctrl: Rename and move rdt files to a separate directory"), the file arch/x86/kernel/cpu/intel_rdt_rdtgroup.c has been renamed and moved to arch/x86/kernel/cpu/resctrl/rdtgroup.c. Apply the change against file arch/x86/kernel/cpu/intel_rdt_rdtgroup.c for older stable trees. Fixes: e02737d5b826 ("x86/intel_rdt: Add tasks files") Reported-by: Shakeel Butt Signed-off-by: Fenghua Yu Signed-off-by: Reinette Chatre Signed-off-by: Borislav Petkov Reviewed-by: Tony Luck Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/962ede65d8e95be793cb61102cca37f7bb018e66.1608243147.git.reinette.chatre@intel.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c +++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c @@ -432,6 +432,13 @@ static void update_task_closid_rmid(stru static int __rdtgroup_move_task(struct task_struct *tsk, struct rdtgroup *rdtgrp) { + /* If the task is already in rdtgrp, no need to move the task. */ + if ((rdtgrp->type == RDTCTRL_GROUP && tsk->closid == rdtgrp->closid && + tsk->rmid == rdtgrp->mon.rmid) || + (rdtgrp->type == RDTMON_GROUP && tsk->rmid == rdtgrp->mon.rmid && + tsk->closid == rdtgrp->mon.parent->closid)) + return 0; + /* * Set the task's closid/rmid before the PQR_ASSOC MSR can be * updated by them.