From patchwork Fri Nov 25 15:54:27 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zqiang X-Patchwork-Id: 13056094 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 24D11C4332F for ; Fri, 25 Nov 2022 15:48:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229453AbiKYPsp (ORCPT ); Fri, 25 Nov 2022 10:48:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36756 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229529AbiKYPso (ORCPT ); Fri, 25 Nov 2022 10:48:44 -0500 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9B9F322516; Fri, 25 Nov 2022 07:48:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1669391318; x=1700927318; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=YL+ZrS8YaYyzd70/eAm0Uh+wmNDQlivpxdI7bvBiGwo=; b=PqEkLrmb7QFmeDZ52Z5Z+fuNbv8l95sNZoXcfw1NJlUk6dL5NeFAgWIC bEZ9XNC17q7IAImYGlHUzlAFwiBydGo4O+WXEf8pEE8SYSKs5Xjd7EGQm 3tRtQbu+Sc3rIBDn4VrzyTuCJxIfNFWbk7td7VGCVVEsDEeIDdeigVjyp cHuYYhGgi4WAflY9i86eK18C7AP39OKSj58aTPdifmzo8wh8RCiW1JreI t6paq+bSMb1+hnYo/Ns02ACS15nfVihVbHl2sIhFX1PDye6uAjkRhPLzL pQvzAh4It7jkbK2l4ybfZWOgcG09Ny/04Z0BzjacLITU8PcvNk3dPPpRW A==; X-IronPort-AV: E=McAfee;i="6500,9779,10542"; a="341407124" X-IronPort-AV: E=Sophos;i="5.96,193,1665471600"; d="scan'208";a="341407124" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Nov 2022 07:48:38 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10542"; a="644834099" X-IronPort-AV: E=Sophos;i="5.96,193,1665471600"; d="scan'208";a="644834099" Received: from zq-optiplex-7090.bj.intel.com ([10.238.156.129]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Nov 2022 07:48:36 -0800 From: Zqiang To: paulmck@kernel.org, frederic@kernel.org, joel@joelfernandes.org Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] rcu-tasks: Make rude RCU-Tasks work well with CPU hotplug Date: Fri, 25 Nov 2022 23:54:27 +0800 Message-Id: <20221125155427.1381933-1-qiang1.zhang@intel.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org Currently, for the case of num_online_cpus() <= 1, return directly, indicates the end of current grace period and then release old data. it's not accurate, for SMP system, when num_online_cpus() is equal one, maybe another cpu that in offline process(after invoke __cpu_disable()) is still in the rude RCU-Tasks critical section holding the old data, this lead to memory corruption. Therefore, this commit add cpus_read_lock/unlock() before executing num_online_cpus(). Signed-off-by: Zqiang --- kernel/rcu/tasks.h | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index 4a991311be9b..08e72c6462d8 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -1033,14 +1033,30 @@ static void rcu_tasks_be_rude(struct work_struct *work) { } +static DEFINE_PER_CPU(struct work_struct, rude_work); + // Wait for one rude RCU-tasks grace period. static void rcu_tasks_rude_wait_gp(struct rcu_tasks *rtp) { + int cpu; + struct work_struct *work; + + cpus_read_lock(); if (num_online_cpus() <= 1) - return; // Fastpath for only one CPU. + goto end;// Fastpath for only one CPU. rtp->n_ipis += cpumask_weight(cpu_online_mask); - schedule_on_each_cpu(rcu_tasks_be_rude); + for_each_online_cpu(cpu) { + work = per_cpu_ptr(&rude_work, cpu); + INIT_WORK(work, rcu_tasks_be_rude); + schedule_work_on(cpu, work); + } + + for_each_online_cpu(cpu) + flush_work(per_cpu_ptr(&rude_work, cpu)); + +end: + cpus_read_unlock(); } void call_rcu_tasks_rude(struct rcu_head *rhp, rcu_callback_t func);