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 7F188C6FD1A for ; Tue, 7 Mar 2023 17:43:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231717AbjCGRn3 (ORCPT ); Tue, 7 Mar 2023 12:43:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50212 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232039AbjCGRnC (ORCPT ); Tue, 7 Mar 2023 12:43:02 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0CBAB9B980 for ; Tue, 7 Mar 2023 09:39:04 -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 D67E561520 for ; Tue, 7 Mar 2023 17:39:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CE468C433D2; Tue, 7 Mar 2023 17:39:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678210743; bh=nt8qevdm9MKP8Zuhidf146WHwAMz6rf41y0GSmmipy0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UrCbBLiD5szbFp6LzIVjkZRUF1XgYZsdSp4C3F48J2HAZfvvlFH3P5iqR9ccFSvQi JYcAsb8Ui5sI8b7nLHcOfqOru+tTRLz8TPlwdVLX3H+9dpqgIwNz1Ke93o/5xFxBwp Jcdbndu/IultEvMxurHgIMbCYMkmC+oVN/MkiUz0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Paul E. McKenney" , Sasha Levin Subject: [PATCH 6.2 0640/1001] rcu: Suppress smp_processor_id() complaint in synchronize_rcu_expedited_wait() Date: Tue, 7 Mar 2023 17:56:52 +0100 Message-Id: <20230307170049.369987155@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230307170022.094103862@linuxfoundation.org> References: <20230307170022.094103862@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@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; -- 2.39.2