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=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 3A688C47080 for ; Mon, 24 May 2021 04:00:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0EECD6024A for ; Mon, 24 May 2021 04:00:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231328AbhEXECF (ORCPT ); Mon, 24 May 2021 00:02:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60568 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229965AbhEXECE (ORCPT ); Mon, 24 May 2021 00:02:04 -0400 Received: from mail-pg1-x52e.google.com (mail-pg1-x52e.google.com [IPv6:2607:f8b0:4864:20::52e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 93896C061756 for ; Sun, 23 May 2021 21:00:35 -0700 (PDT) Received: by mail-pg1-x52e.google.com with SMTP id m124so19104060pgm.13 for ; Sun, 23 May 2021 21:00:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=PkGL/jirzcz4Lvqb4/MaE1jMqBDDNPzHgjnDClieuEo=; b=RyMoNBJ5LXlz3lErKrV7Mx+2qO+5hLyS2t1/2Ij/ygzhBpM3lEEYRALvBPTm6/adVi i9KOdXO8aoiolkhvwTvEZ+abOqr1qHY0HBAnWR9MzpiSA9NUmaOInZywi7Yx1ssTKyDs awWKkQAVMDcb8L1v47QGpZRl2l9a4DKVwKg8M= 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; bh=PkGL/jirzcz4Lvqb4/MaE1jMqBDDNPzHgjnDClieuEo=; b=mr6GbPbMLbgs62KjL/IaObQvZDb2gVc2AD9a3MxzC4OGZkXhs7otZeTQwa6q1Pc1IT AKk7iG26kDvVAjz5iyZ6VLbXT58eGkI8TwAI9Yqsx1NasLA2+1ADSkRIBb1xEbJKk2pb 0FVUufQJyJ17uokLdFhXaz95pi0YlxKIEwSlyQGioh3RAQ4LGyZHEpzMvK3CtTYwxzDI JEGisznh8DotITZce+iEdGJNqgpmf8iJkL1xn/qbRF5vU36DgQOjKk1sABHGmQne+OuZ Y9ioB7kFMlTfRJbPiMboQZBcYXUoizIRYUMCGO9EvMn2CUXrxXGES22EwdS3qxFHdQon JL9w== X-Gm-Message-State: AOAM531bnjI7Sn2mMskTgqRWQzItkfW+tqtoAVWLsQsfdX/cTHBToS3I 6vPZQh+y/+KqBIlmMOuzSGUy6w== X-Google-Smtp-Source: ABdhPJwzqY9hiTjr90NxYZ01WoyFOoK/lrGZrXP5jkiQDmlyC/gLbRo96v9qx+cbDPzt/qZ6SeNXrg== X-Received: by 2002:a62:1d52:0:b029:2dd:ee:1439 with SMTP id d79-20020a621d520000b02902dd00ee1439mr22124945pfd.57.1621828835108; Sun, 23 May 2021 21:00:35 -0700 (PDT) Received: from google.com ([2409:10:2e40:5100:7357:1320:fdb3:1853]) by smtp.gmail.com with ESMTPSA id o17sm3991608pgj.25.2021.05.23.21.00.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 23 May 2021 21:00:34 -0700 (PDT) Date: Mon, 24 May 2021 13:00:29 +0900 From: Sergey Senozhatsky To: "Paul E. McKenney" Cc: Sergey Senozhatsky , Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , rcu@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCHv2 1/2] rcu/tree: handle VM stoppage in stall detection Message-ID: References: <20210521155624.174524-1-senozhatsky@chromium.org> <20210521180127.GD4441@paulmck-ThinkPad-P17-Gen-1> <20210521213855.GA3437356@paulmck-ThinkPad-P17-Gen-1> <20210524034645.GH4441@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210524034645.GH4441@paulmck-ThinkPad-P17-Gen-1> Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org On (21/05/23 20:46), Paul E. McKenney wrote: > > In theory, yes, sort of, anyway. In practice, highly unlikely. > The most plausible way for this to happen is for this code path to be > delayed for a long time on a 32-bit system, so that jiffies+ULONG_MAX/2 > actually arrives. But in that case, all sorts of other complaints > would happen first. I see. > But I could make this a cmpxchg(), if that is what you are getting at. No, it's good. I was just curious what scenario I was missing.