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=-8.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLACK,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 5B31DC433DF for ; Mon, 1 Jun 2020 11:40:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2856020820 for ; Mon, 1 Jun 2020 11:40:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591011612; bh=cwbptBQG0lst/6qxen2gXTCjoNh0Opi1g+edQ2IpEk0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=GBs/UbfWMQXOZt0yKJ8P76TYZ81bG81eSVUqiPRpKyM3xkBLyXbpJ1DzqQj11kpAX JAlej+uKXQgxVKh9sJI7Y8I5mV2aiTAPIw/TX+gXB9dRb0SLoxEMP/Q2kKMpH/gyvr VN9iW35TWn+5X5IgqeY+psNt9wRqovoXZCvdcCuc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726075AbgFALkL (ORCPT ); Mon, 1 Jun 2020 07:40:11 -0400 Received: from mail.kernel.org ([198.145.29.99]:56096 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725838AbgFALkL (ORCPT ); Mon, 1 Jun 2020 07:40:11 -0400 Received: from localhost (lfbn-ncy-1-324-171.w83-196.abo.wanadoo.fr [83.196.159.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 05254207FB; Mon, 1 Jun 2020 11:40:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591011610; bh=cwbptBQG0lst/6qxen2gXTCjoNh0Opi1g+edQ2IpEk0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Wnr+cXKEsqxQv7bmTMgkk0NyNBryNAz8+E9CW3e60LVcZ72QW13gfQVUrR19cQmm6 K7oIuxAYqgAq4JDpoITcwJPWJlUqhIHakmEIXxkvxcW/IGFNjB3+m9ar8b+PKn1KIO VfJ8W4t2ZrLHDh0ZujEsNCzHP66Qx/lJyHJJSOkc= Date: Mon, 1 Jun 2020 13:40:08 +0200 From: Frederic Weisbecker To: linux-kernel@vger.kernel.org, Ingo Molnar Cc: linux-tip-commits@vger.kernel.org, Qian Cai , "Peter Zijlstra (Intel)" , mgorman@techsingularity.net, x86 Subject: Re: [tip: sched/core] sched: Fix smp_call_function_single_async() usage for ILB Message-ID: <20200601114007.GA20995@lenoir> References: <20200526161907.778543557@infradead.org> <159100514169.17951.11938781317668210343.tip-bot2@tip-bot2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <159100514169.17951.11938781317668210343.tip-bot2@tip-bot2> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 01, 2020 at 09:52:21AM -0000, tip-bot2 for Peter Zijlstra wrote: > The following commit has been merged into the sched/core branch of tip: > > Commit-ID: 19a1f5ec699954d21be10f74ff71c2a7079e99ad > Gitweb: https://git.kernel.org/tip/19a1f5ec699954d21be10f74ff71c2a7079e99ad > Author: Peter Zijlstra > AuthorDate: Tue, 26 May 2020 18:10:58 +02:00 > Committer: Ingo Molnar > CommitterDate: Thu, 28 May 2020 10:54:15 +02:00 > > sched: Fix smp_call_function_single_async() usage for ILB > > The recent commit: 90b5363acd47 ("sched: Clean up scheduler_ipi()") > got smp_call_function_single_async() subtly wrong. Even though it will > return -EBUSY when trying to re-use a csd, that condition is not > atomic and still requires external serialization. > > The change in kick_ilb() got this wrong. > > While on first reading kick_ilb() has an atomic test-and-set that > appears to serialize the use, the matching 'release' is not in the > right place to actually guarantee this serialization. > > Rework the nohz_idle_balance() trigger so that the release is in the > IPI callback and thus guarantees the required serialization for the > CSD. > > Fixes: 90b5363acd47 ("sched: Clean up scheduler_ipi()") > Reported-by: Qian Cai > Signed-off-by: Peter Zijlstra (Intel) > Signed-off-by: Ingo Molnar > Reviewed-by: Frederic Weisbecker > Cc: mgorman@techsingularity.net > Link: https://lore.kernel.org/r/20200526161907.778543557@infradead.org Many patches in the series lack some Reviewed-by tags. Thanks.