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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22111C433F5 for ; Fri, 8 Oct 2021 14:03:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0885261029 for ; Fri, 8 Oct 2021 14:03:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234096AbhJHOFJ (ORCPT ); Fri, 8 Oct 2021 10:05:09 -0400 Received: from foss.arm.com ([217.140.110.172]:54092 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234083AbhJHOFI (ORCPT ); Fri, 8 Oct 2021 10:05:08 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 93B316D; Fri, 8 Oct 2021 07:03:12 -0700 (PDT) Received: from e113632-lin (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E1E253F66F; Fri, 8 Oct 2021 07:03:10 -0700 (PDT) From: Valentin Schneider To: Frederic Weisbecker , "Paul E . McKenney" Cc: LKML , Frederic Weisbecker , Sebastian Andrzej Siewior , Peter Zijlstra , Uladzislau Rezki , Thomas Gleixner , Boqun Feng , Neeraj Upadhyay , Josh Triplett , Joel Fernandes , rcu@vger.kernel.org Subject: Re: [PATCH 00/11] rcu: Make rcu_core() safe in PREEMPT_RT with NOCB + a few other fixes In-Reply-To: <87fstkmybc.mognet@arm.com> References: <20210929221012.228270-1-frederic@kernel.org> <87fstkmybc.mognet@arm.com> Date: Fri, 08 Oct 2021 15:03:02 +0100 Message-ID: <87ee8vlill.mognet@arm.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/10/21 18:47, Valentin Schneider wrote: > On 30/09/21 00:10, Frederic Weisbecker wrote: >> PREEMPT_RT has made rcu_core() preemptible, making it unsafe against >> concurrent NOCB (de-)offloading. >> >> Thomas suggested to drop the local_lock() based solution and simply >> check the offloaded state while context looks safe but that's not >> enough. Here is a bit of rework. >> >> git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git >> rcu/rt >> >> HEAD: aac1c58961446c731f2e989bd822ca1fd2659bad >> >> Thanks, >> Frederic > > FWIW I've had RCU torture with NOCB toggling running for half a day on my > Arm Juno and nothing to report. I still need to rebase this on an -rt tree > and give it a spin with CONFIG_PREEMPT_RT. Rebased on top of v5.15-rc4-rt7-rebase with Thomas' patch reverted and ran the same thing under CONFIG_PREEMPT_RT, nothing seems to catch on fire, so: Tested-by: Valentin Schneider