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=-9.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 A48A5C433E0 for ; Thu, 6 Aug 2020 18:53:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D98AD20855 for ; Thu, 6 Aug 2020 18:53:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596740020; bh=w//eizxwsAVrv+YPmS3JX4NMqcajxqnj5JXlDU41V9Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=HiAFLCFvuk2xiwJ4KClojxCI/vQ99WRXT4H/F/oaRdPcNnajNQPGBV4cXDMnM7ZFe IR02dDqBlc0/Im+6Se3POmcyGlF5QIbhewJfdNHiGDHoJsdQwhslhU56rEcWlAU0FV F6mvqb3NOcHBDzGn7coWtlDYO4Kh+O286MYTFsMc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728303AbgHFSxj (ORCPT ); Thu, 6 Aug 2020 14:53:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:40226 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725272AbgHFSxj (ORCPT ); Thu, 6 Aug 2020 14:53:39 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 7197B206A2; Thu, 6 Aug 2020 18:53:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596740019; bh=w//eizxwsAVrv+YPmS3JX4NMqcajxqnj5JXlDU41V9Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Qmg8P7JiHebGl+XnPaxN10Hvl7XUXGsKieVGY6wx5pNCJU+TL9eSSZLg14F1BMhzS 9IIlLt0mBO+mNtjhJmQcaCT/TwDyaHy55xIKOUqjg59mz9C5HlUGlEFkfYxQS8ImI0 lILF5Q/NmyZtnDqz12wG8Y1zccsQ3dy651vOsQAw= Date: Thu, 6 Aug 2020 20:53:53 +0200 From: Greg KH To: Robin Murphy Cc: "stable@vger.kernel.org" , linux-kernel@vger.kernel.org, Andi Kleen , Kan Liang , "Peter Zijlstra (Intel)" , x86 Subject: Re: [tip: perf/core] perf/core: Fix endless multiplex timer Message-ID: <20200806185353.GA2942033@kroah.com> References: <20200305123851.GX2596@hirez.programming.kicks-ass.net> <158470908175.28353.4859180707604949658.tip-bot2@tip-bot2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 06, 2020 at 07:11:24PM +0100, Robin Murphy wrote: > On 2020-03-20 12:58, tip-bot2 for Peter Zijlstra wrote: > > The following commit has been merged into the perf/core branch of tip: > > > > Commit-ID: 90c91dfb86d0ff545bd329d3ddd72c147e2ae198 > > Gitweb: https://git.kernel.org/tip/90c91dfb86d0ff545bd329d3ddd72c147e2ae198 > > Author: Peter Zijlstra > > AuthorDate: Thu, 05 Mar 2020 13:38:51 +01:00 > > Committer: Peter Zijlstra > > CommitterDate: Fri, 20 Mar 2020 13:06:22 +01:00 > > > > perf/core: Fix endless multiplex timer > > > > Kan and Andi reported that we fail to kill rotation when the flexible > > events go empty, but the context does not. XXX moar > > > > Fixes: fd7d55172d1e ("perf/cgroups: Don't rotate events for cgroups unnecessarily") > > Can this patch (commit 90c91dfb86d0 ("perf/core: Fix endless multiplex > timer") upstream) be applied to stable please? For PMU drivers built as > modules, the bug can actually kill the system, since the runaway hrtimer > loop keeps calling pmu->{enable,disable} after all the events have been > closed and dropped their references to pmu->module. Thus legitimately > unloading the module once things have got into this state quickly results in > a crash when those callbacks disappear. > > (FWIW I spent about two days fighting with this while testing a new driver > as a module against the 5.3 kernel installed on someone else's machine, > assuming it was a bug in my code...) What exactly kernel(s) do you wish for it to be applied to? It's already in the latest stable releases of 5.7.y. thanks, greg k-h