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=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 ABBE5C43460 for ; Tue, 11 May 2021 22:53:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 896E061421 for ; Tue, 11 May 2021 22:53:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230334AbhEKWy6 (ORCPT ); Tue, 11 May 2021 18:54:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:33932 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230305AbhEKWyP (ORCPT ); Tue, 11 May 2021 18:54:15 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3175061946; Tue, 11 May 2021 22:53:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1620773587; bh=wUdaSFc5MlL9R/weJL4BK5WyqaGeP7pB4eQbiGMG6yE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Z/fr6QW0V/VZdgWxNBBpjHn4Lk1HYwNkpQgZK/q+Fn1A1baU3cjUDes4GebZnmDrn Mc2e0K2VIV/Lclr78u9W83aAD3GZAp2RgOK9TNqBejOaT61rRccZ8DB/whFRldmVk3 5blJOq8xvZjHcOs8fBlrgiqjBq+LKE1fWmgf9m40JF9qXf57nXsTu4kuI4kF5gk+PR i9KD6Rx10XA6OXZtPCOXCo/rZuvuPE2RAYwR/V9pcfueEKSxpKJ5V2tdAjaRQ3w7Yb jzOBPjxLm88b1yXDGuM2Aa1UplWGGgwWEGRTMqO4L3u23iJYBdD8yy0fU1sdA8xIuZ 93K99Itz0hehQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 9B26B5C0DF3; Tue, 11 May 2021 15:53:06 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 11/19] rcu: Make show_rcu_gp_kthreads() dump rcu_node structures blocking GP Date: Tue, 11 May 2021 15:52:56 -0700 Message-Id: <20210511225304.2893154-11-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20210511225241.GA2893003@paulmck-ThinkPad-P17-Gen-1> References: <20210511225241.GA2893003@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, show_rcu_gp_kthreads() only dumps rcu_node structures that have outdated ideas of the current grace-period number. This commit also dumps those that are in any way blocking the current grace period. This helps diagnose RCU priority boosting failures. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree_stall.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index c1f83864a18e..e6bd518e0bc4 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -746,8 +746,9 @@ void show_rcu_gp_kthreads(void) data_race(rcu_state.gp_max), data_race(rcu_state.gp_flags)); rcu_for_each_node_breadth_first(rnp) { - if (ULONG_CMP_GE(READ_ONCE(rcu_state.gp_seq), - READ_ONCE(rnp->gp_seq_needed))) + if (ULONG_CMP_GE(READ_ONCE(rcu_state.gp_seq), READ_ONCE(rnp->gp_seq_needed)) && + !data_race(rnp->qsmask) && !data_race(rnp->boost_tasks) && + !data_race(rnp->exp_tasks) && !data_race(rnp->gp_tasks)) continue; pr_info("\trcu_node %d:%d ->gp_seq %ld ->gp_seq_needed %ld ->qsmask %#lx %c%c%c%c ->n_boosts %ld\n", rnp->grplo, rnp->grphi, -- 2.31.1.189.g2e36527f23