From patchwork Thu Jun 25 06:13:15 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sai Harshini Nimmala X-Patchwork-Id: 194562 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=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 24346C433E0 for ; Thu, 25 Jun 2020 06:13:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F38FD206FA for ; Thu, 25 Jun 2020 06:13:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="LRUs5CEq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389693AbgFYGNy (ORCPT ); Thu, 25 Jun 2020 02:13:54 -0400 Received: from mail29.static.mailgun.info ([104.130.122.29]:52190 "EHLO mail29.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727800AbgFYGNy (ORCPT ); Thu, 25 Jun 2020 02:13:54 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1593065634; h=Message-Id: Date: Subject: Cc: To: From: Sender; bh=OokbzRGBh4vM/wAytBHd5gph7Yx4DvpSixDVA2ZxHJ4=; b=LRUs5CEqZU6046Y8yCVVmc+wUOh/uxrb2H/cBpaOGw2bVPg8jvUNFP95asJXNu6OgHdEkkr1 KGjQxsceBeSzKCRmmD5b9VbJqYQNT39w0idhcPSSh+faeRw0+1WYu0IS/sl1Lx9XXEvk2lSK MzNm64P/x2ih77g6RBtm/CYptzY= X-Mailgun-Sending-Ip: 104.130.122.29 X-Mailgun-Sid: WyI1MzIzYiIsICJsaW51eC1hcm0tbXNtQHZnZXIua2VybmVsLm9yZyIsICJiZTllNGEiXQ== Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n12.prod.us-east-1.postgun.com with SMTP id 5ef4408ba6e154319f53344c (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Thu, 25 Jun 2020 06:13:31 GMT Received: by smtp.codeaurora.org (Postfix, from userid 1001) id A6ABCC43395; Thu, 25 Jun 2020 06:13:29 +0000 (UTC) Received: from snimmala-linux.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: snimmala) by smtp.codeaurora.org (Postfix) with ESMTPSA id EECCCC433C6; Thu, 25 Jun 2020 06:13:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org EECCCC433C6 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=none smtp.mailfrom=snimmala@codeaurora.org From: Sai Harshini Nimmala To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arm-msm-owner@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Sai Harshini Nimmala , adharmap@codeaurora.org, shalagra@codeaurora.org, dickey@codeaurora.org, satyap@codeaurora.org, pkondeti@codeaurora.org, clingutla@codeaurora.org, aiquny@codeaurora.org, rgottimu@codeaurora.org, Puja Gupta Subject: [PATCH] Revert "sched/deadline: Remove cpu_active_mask from cpudl_find()" Date: Wed, 24 Jun 2020 23:13:15 -0700 Message-Id: <1593065595-17794-1-git-send-email-snimmala@codeaurora.org> X-Mailer: git-send-email 2.7.4 Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org The original commit 9659e1ee removes checking the cpu_active_mask while finding the best cpu to place a deadline task, citing the reason that this mask rarely changes and removing the check will give performance gains. However, on hotplugging, the cpu dying path has a brief duration between the CPUHP_TEARDOWN_CPU and CPUHP_AP_SCHED_STARTING hotplug states where the DL task can be scheduled on this cpu because the corresponding cpu bit in cpu->free_cpus has not been cleared yet. Without the cpu_active_mask check we could end up putting a DL task on such cpus leading to a BUG. The cpu_active_mask will be updated promptly before either of these states and will provide a more accurate check for the use case above. Signed-off-by: Puja Gupta Signed-off-by: Sai Harshini Nimmala --- kernel/sched/cpudeadline.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c index 5cc4012..0346837 100644 --- a/kernel/sched/cpudeadline.c +++ b/kernel/sched/cpudeadline.c @@ -120,7 +120,8 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p, const struct sched_dl_entity *dl_se = &p->dl; if (later_mask && - cpumask_and(later_mask, cp->free_cpus, p->cpus_ptr)) { + cpumask_and(later_mask, cp->free_cpus, p->cpus_ptr) && + cpumask_and(later_mask, later_mask, cpu_active_mask)) { return 1; } else { int best_cpu = cpudl_maximum(cp); @@ -128,6 +129,7 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p, WARN_ON(best_cpu != -1 && !cpu_present(best_cpu)); if (cpumask_test_cpu(best_cpu, p->cpus_ptr) && + cpumask_test_cpu(best_cpu, cpu_active_mask) && dl_time_before(dl_se->deadline, cp->elements[0].dl)) { if (later_mask) cpumask_set_cpu(best_cpu, later_mask);