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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 3EE98C282CB for ; Tue, 5 Feb 2019 13:06:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 00CAE20844 for ; Tue, 5 Feb 2019 13:06:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=tomli.me header.i=@tomli.me header.b="dq0ZedvD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728033AbfBENGM (ORCPT ); Tue, 5 Feb 2019 08:06:12 -0500 Received: from tomli.me ([153.92.126.73]:48658 "EHLO tomli.me" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726558AbfBENGM (ORCPT ); Tue, 5 Feb 2019 08:06:12 -0500 Received: from tomli.me (localhost [127.0.0.1]) by tomli.me (OpenSMTPD) with ESMTP id 04feca8d; Tue, 5 Feb 2019 13:06:09 +0000 (UTC) X-HELO: localhost.localdomain Authentication-Results: tomli.me; auth=pass (login) smtp.auth=tomli Received: from Unknown (HELO localhost.localdomain) (2402:f000:1:1501:200:5efe:7b75:4650) by tomli.me (qpsmtpd/0.95) with ESMTPSA (DHE-RSA-CHACHA20-POLY1305 encrypted); Tue, 05 Feb 2019 13:06:09 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed; d=tomli.me; h=date:from:to:cc:subject:message-id:references:mime-version:content-type:in-reply-to; s=1490979754; bh=5lcRfBFPtcEwjLQR+HPEzHjnwv8/n0ocD1kO1pC/il0=; b=dq0ZedvDWvFVfzUacS+bVObpL3/z9e99Y1xvnX6n/P427QG/f9aRZOk1JsbydjO1p8inVlo6kTD0m8uG/Ahcph5QTMIWfS5LkUDVg/z0usAN8IMNSn9Rfv+7vVPdwHjE0EESX3/xIm/DTEa486l5lc17HGmdnO/Srh6gtnnrNR7RDAm9134++1BEtZkBvtN8hMDqN9XUPTCiw4aSPJj2bNw8B/GKL/AP2bRQLr8mh5zb5xUX0RMw42evn6JWeVWpoMYgLfwfKmStKG6MpE18R6NqVn/hoHas18uQPPixCFwjwMQRYJUaWOK2PFPtoH3mBs+iH7tgjht1tADyVGTlIg== Date: Tue, 5 Feb 2019 21:05:59 +0800 From: Tom Li To: Aaro Koskinen Cc: paulmck@linux.ibm.com, ak@linux.intel.com, bp@alien8.de, hpa@zytor.com, linux-kernel@vger.kernel.org, mingo@redhat.com, rjw@rjwysocki.net, ville.syrjala@linux.intel.com, viresh.kumar@linaro.org, linux-mips@vger.kernel.org Subject: Re: [REGRESSION 4.20-rc1] 45975c7d21a1 ("rcu: Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds") Message-ID: <20190205130559.GA12858@localhost.localdomain> References: <20181113135453.GW9144@intel.com> <20181113151037.GG4170@linux.ibm.com> <20181114202013.GA27603@linux.ibm.com> <20181126220122.GA6345@linux.ibm.com> <20190205050700.GA31571@localhost.localdomain> <20190205095809.GA16356@darkstar.musicnaut.iki.fi> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190205095809.GA16356@darkstar.musicnaut.iki.fi> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Tue, Feb 05, 2019 at 11:58:09AM +0200, Aaro Koskinen wrote: > Can you try below fix? It works on my Loongson. Hello Aaro, thanks for your response. But in case you've missed the original thread, please check it at: https://lkml.org/lkml/2018/11/13/857 My problem is NOT about how to fix the problem on Loongson (or x86): the patch in the original thread (only has one-line-of-code, simply changes timing of cpufreq_core_init), or your patch, is indeed working. But they are workarounds, the real issue is the race condition in cpufreq. My question is 1. What's the progress and current consensus about how the underlying problem can be fixed. 2. If there's no consensus since November, is it possible that we land a hotfix patch to linux-stable as a temporary workaround? Cheers, Tom Li.