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=-5.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,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 649E7C352AA for ; Tue, 1 Oct 2019 20:39:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3790D20842 for ; Tue, 1 Oct 2019 20:39:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="uuREGNPf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727296AbfJAUj0 (ORCPT ); Tue, 1 Oct 2019 16:39:26 -0400 Received: from mail-pg1-f194.google.com ([209.85.215.194]:36481 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726703AbfJAUj0 (ORCPT ); Tue, 1 Oct 2019 16:39:26 -0400 Received: by mail-pg1-f194.google.com with SMTP id 23so1987921pgk.3 for ; Tue, 01 Oct 2019 13:39:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=ViiaaE4a8Q+hVhCBRqc18xl1Y3nut+5NVwTRaFqcP9g=; b=uuREGNPfzv4asyA+Z0PZxvx180n4lZwtC8NsKSH5G8me6FyOhde0ZH3f02DFgoLeaU gc8c0SB4FTSOSEfD/Blj3oYg1A9UECj2idyAi/N8W2S3LklqbVZ7eD4TLSBzjcXgmrpo UI2VG402Vpbg6zoTxAQo+cBr9PlEa6dT9tNzM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=ViiaaE4a8Q+hVhCBRqc18xl1Y3nut+5NVwTRaFqcP9g=; b=dnqTd3ZM1G2ZlCWQJDCpovmsPmjC/z2ZGqo127wlWXI5/6vUSwGdsa/J/aT6B+HruS V//HrT6a7sgj9nmHFwMn0wpYu+PqtjIB3aC7Rsd/WhvOndX/7oXj762I3FZq9utyyD/6 QyxYiSDOSsc/FWTLJ9hZuy3KMzK1ac4UH7YIW6xqQ6TlK5hpiH1FOLFWPu/a63ZhidbQ RgaVsYPOGouIfnmAerlzkiwBtL+lbI/5FySK/Yz8wtqZFuoNIZhUkvcZ6OirutGIlx6G BE4aqF/AkOnAgEioHiUT8CphHY++RZdRKVmOrCRe/LMVgXx3N/XbMe/KTSTBxCrezb9L IkfA== X-Gm-Message-State: APjAAAX43wQHGrw1RdoxQml6sG6hpTRNwqKXSLCfqdtCR6hCPiHGBZYB sxUcsI/vwJBdqQ/TPGG3kM6LLQ== X-Google-Smtp-Source: APXvYqyNocYdkY90GUy/OUwen6Lg6tDZndvES8R7ndPcCMoxA2F/oJqgIQ/0HkQ+lBBDc7dzg7DLhQ== X-Received: by 2002:aa7:870a:: with SMTP id b10mr218519pfo.5.1569962363777; Tue, 01 Oct 2019 13:39:23 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id g4sm17142639pfo.33.2019.10.01.13.39.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Oct 2019 13:39:23 -0700 (PDT) Date: Tue, 1 Oct 2019 16:39:22 -0400 From: Joel Fernandes To: John Stultz Cc: Peter Zijlstra , Ingo Molnar , Linus Torvalds , Linux Kernel Mailing List , Thomas Gleixner , Andrew Morton , Mathieu Desnoyers , "Eric W. Biederman" , Alistair Delva Subject: Re: [GIT PULL] scheduler fixes Message-ID: <20191001203922.GA35550@google.com> References: <20190928123905.GA97048@gmail.com> <20191001071921.GJ4519@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 01, 2019 at 11:15:01AM -0700, John Stultz wrote: > On Tue, Oct 1, 2019 at 12:19 AM Peter Zijlstra wrote: > > > > On Mon, Sep 30, 2019 at 04:45:49PM -0700, John Stultz wrote: > > > Reverting the following patches: > > > > > "sched/membarrier: Fix p->mm->membarrier_state racy load" > > > > ARGH, I fudged it... please try: > > > > > > diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c > > index a39bed2c784f..168479a7d61b 100644 > > --- a/kernel/sched/membarrier.c > > +++ b/kernel/sched/membarrier.c > > @@ -174,7 +174,6 @@ static int membarrier_private_expedited(int flags) > > */ > > if (cpu == raw_smp_processor_id()) > > continue; > > - rcu_read_lock(); > > p = rcu_dereference(cpu_rq(cpu)->curr); > > if (p && p->mm == mm) > > __cpumask_set_cpu(cpu, tmpmask); > > > Yep. Looks like that solves it! > Tested-by: John Stultz Makes sense. And here I was wondering yesterday why I was seeing bug reports with t->read_lock_nesting as non-zero when the task was interrupted in user mode ;-) Reviewed-by: Joel Fernandes (Google) thanks, - Joel