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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1A3E5C7EE23 for ; Sun, 26 Feb 2023 14:45:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229597AbjBZOpJ (ORCPT ); Sun, 26 Feb 2023 09:45:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39906 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229741AbjBZOpB (ORCPT ); Sun, 26 Feb 2023 09:45:01 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 79BEE126E5; Sun, 26 Feb 2023 06:45:00 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id EBDA960C17; Sun, 26 Feb 2023 14:44:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8202BC4339E; Sun, 26 Feb 2023 14:44:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1677422699; bh=hidf1LCxSl9/1F8ZVMb+D+asQX2snZDriZhMM69zhno=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UDKVM/9UyUq15Qqd2TustFtF/XIeZZpXdwEIG9mjJTCFCSk+E7NT/woO8Cgb+y9WT 5bB1DDr7plQpPr9RIVPvIkjsz8ppKszlqNDR5jx7EJ93oBcGAAz2V/q3zloxLC2d6o DoFzr3frnfUDAYEMSw9ErjzoQLQICAzyUasGcb0kR+NpusN4q3G1AXfrStceQxIh9k GNQ5Jn6IqeVK/u/22xZ77VLXlV8HUC0nuivAxTaXq5O/oXCSirSFehB6phv0L56+d0 aA1bkqrE3ijawt0z7tFL3ZSjCdiA+mK4VF4OCRnvExO/11+sNk2Sgsa/9A9q2KWTJJ qbGLcGT4xFXbA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Paul E. McKenney" , Sasha Levin , frederic@kernel.org, quic_neeraju@quicinc.com, josh@joshtriplett.org, rcu@vger.kernel.org Subject: [PATCH AUTOSEL 6.2 05/53] rcu: Suppress smp_processor_id() complaint in synchronize_rcu_expedited_wait() Date: Sun, 26 Feb 2023 09:43:57 -0500 Message-Id: <20230226144446.824580-5-sashal@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230226144446.824580-1-sashal@kernel.org> References: <20230226144446.824580-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" [ Upstream commit 2d7f00b2f01301d6e41fd4a28030dab0442265be ] The normal grace period's RCU CPU stall warnings are invoked from the scheduling-clock interrupt handler, and can thus invoke smp_processor_id() with impunity, which allows them to directly invoke dump_cpu_task(). In contrast, the expedited grace period's RCU CPU stall warnings are invoked from process context, which causes the dump_cpu_task() function's calls to smp_processor_id() to complain bitterly in debug kernels. This commit therefore causes synchronize_rcu_expedited_wait() to disable preemption around its call to dump_cpu_task(). Signed-off-by: Paul E. McKenney Signed-off-by: Sasha Levin --- kernel/rcu/tree_exp.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index ed6c3cce28f23..927abaf6c822e 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -667,7 +667,9 @@ static void synchronize_rcu_expedited_wait(void) mask = leaf_node_cpu_bit(rnp, cpu); if (!(READ_ONCE(rnp->expmask) & mask)) continue; + preempt_disable(); // For smp_processor_id() in dump_cpu_task(). dump_cpu_task(cpu); + preempt_enable(); } } jiffies_stall = 3 * rcu_exp_jiffies_till_stall_check() + 3; -- 2.39.0