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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 C6A46C43381 for ; Tue, 9 Feb 2021 10:18:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7A7E564E9D for ; Tue, 9 Feb 2021 10:18:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231657AbhBIKSR (ORCPT ); Tue, 9 Feb 2021 05:18:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40502 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231310AbhBIKDC (ORCPT ); Tue, 9 Feb 2021 05:03:02 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 64CB6C06178C; Tue, 9 Feb 2021 02:02:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=X2PQU1d5jzox0n/Xj9r6pmILEewABEB0sLzcB3dEs78=; b=wXj1WWStI2PDo6gGZKOUwwRAGM zjYH0nZlrd5tAt61XXt21vqKF2C7UNREVLl6r6dr3dXgFcYpbY82PWna0H+cBcDXek5+/3PCuLGOV MG3YPg93Y2rqo4o7yJw3cTjk3KIN7cgZiSAR1m0jHi6kZasS3XfRZ6PU8Q6bKT3GJe84AkemyCv+q faNz+AUi7sxy33XmmWYMUMHcqB5xnWahR1Q+r+eZUx4M7f2VDJ+lTMEowRvc4axvXWtmroqYFE27D htFI6Bu7j8Wtmvufjh7huqRbzb1TKKGnQMV2CFLFh5xE8HZ/HqEgvIpYv7k+nW2S8jJbgCjnDnPvm HdIbE7aQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1l9PqV-007H0M-GH; Tue, 09 Feb 2021 10:02:12 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 19DC7301324; Tue, 9 Feb 2021 11:02:11 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id E5A392C0909CA; Tue, 9 Feb 2021 11:02:10 +0100 (CET) Date: Tue, 9 Feb 2021 11:02:10 +0100 From: Peter Zijlstra To: Sebastian Andrzej Siewior Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Jens Axboe , Thomas Gleixner , Ingo Molnar Subject: Re: [PATCH 1/3] smp: Process pending softirqs in flush_smp_call_function_from_idle() Message-ID: References: <20210123201027.3262800-1-bigeasy@linutronix.de> <20210123201027.3262800-2-bigeasy@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210123201027.3262800-2-bigeasy@linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jan 23, 2021 at 09:10:25PM +0100, Sebastian Andrzej Siewior wrote: > send_call_function_single_ipi() may wake an idle CPU without sending an > IPI. The woken up CPU will process the SMP-functions in > flush_smp_call_function_from_idle(). Any raised softirq from within the > SMP-function call will not be processed. > Should the CPU have no tasks assigned, then it will go back to idle with > pending softirqs and the NOHZ will rightfully complain. > > Process pending softirqs on return from flush_smp_call_function_queue(). > > Fixes: b2a02fc43a1f4 ("smp: Optimize send_call_function_single_ipi()") > Reported-by: Jens Axboe > Signed-off-by: Sebastian Andrzej Siewior Fair enough. I'll stick this in tip/sched/smp for Jens and merge that into tip/sched/core. Thanks!