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 B01D7C433EF for ; Tue, 8 Feb 2022 16:16:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1382927AbiBHQQz (ORCPT ); Tue, 8 Feb 2022 11:16:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47692 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1382881AbiBHQQs (ORCPT ); Tue, 8 Feb 2022 11:16:48 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9678AC061579 for ; Tue, 8 Feb 2022 08:16:47 -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 2DC75616AD for ; Tue, 8 Feb 2022 16:16:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 32B65C340EF; Tue, 8 Feb 2022 16:16:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644337006; bh=RqIk4EnOdjCYrxJGCZyCg+wmvIsqy3TKXzcC2Wpnv+0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rLOx/H7YJ24xl8oOEqYH0a0xEAGRe469GYLbMo1UGHz8Vkqa5QhUkXk/Y321AOVmm OkoTr8rBESWWnjjicWK0As70+z6d66hPsIMgFG5uO5lxEzJDpntZgVsGia7sLSeYfP QY59mNjPG1uFO/0rmkg63cErj1u3ZHYqgjkF3jKyurRAObaFprzTA5+6dfY0aIwTLm gbukNz1jzR6Qxmp1BpPkZWPJaONKVQYgS7Qvf/6khVdm14RpbZBi22ftmPQqCwM/b4 hRZLkSBIuUamZgeGXfIoE1mfVPBNA8q/pVlmilDh5isaHD71x+l0+GftJSPT8BLfGF +Lvu989ljuGHA== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , "Paul E . McKenney" , Peter Zijlstra , Thomas Gleixner , Paul Menzel Subject: [PATCH 3/3] lib/irq_poll: Declare IRQ_POLL softirq vector as ksoftirqd-parking safe Date: Tue, 8 Feb 2022 17:16:35 +0100 Message-Id: <20220208161635.544701-4-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220208161635.544701-1-frederic@kernel.org> References: <20220208161635.544701-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following warning may appear while setting a CPU down: NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #20!!! The IRQ_POLL_SOFTIRQ vector can be raised during the hotplug cpu_down() path after ksoftirqd is parked and before the CPU actually dies. However this is handled afterward at the CPUHP_IRQ_POLL_DEAD stage where the queue gets migrated. Hence this warning can be considered spurious and the vector can join the "hotplug-safe" list. Reported-by: Paul Menzel Signed-off-by: Frederic Weisbecker Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Paul E. McKenney Cc: Paul Menzel --- include/linux/interrupt.h | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index 9613326d2f8a..f40754caaefa 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -580,12 +580,15 @@ enum }; /* - * Ignoring the RCU vector after ksoftirqd is parked is fine - * because: - * 1) rcutree_migrate_callbacks() takes care of the queue. + * The following vectors can be safely ignored after ksoftirqd is parked: + * + * _ RCU: + * 1) rcutree_migrate_callbacks() migrates the queue. * 2) rcu_report_dead() reports the final quiescent states. + * + * _ IRQ_POLL: irq_poll_cpu_dead() migrates the queue */ -#define SOFTIRQ_HOTPLUG_SAFE_MASK (BIT(RCU_SOFTIRQ)) +#define SOFTIRQ_HOTPLUG_SAFE_MASK (BIT(RCU_SOFTIRQ) | BIT(IRQ_POLL_SOFTIRQ)) /* map softirq index to softirq name. update 'softirq_to_name' in * kernel/softirq.c when adding a new softirq. -- 2.25.1