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=-9.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 9D985C433DF for ; Mon, 19 Oct 2020 07:31:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 482A22224D for ; Mon, 19 Oct 2020 07:31:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603092709; bh=KFsyT7urKjJFB18TZy+h5omSaThGdcmVuNrOKwGa1Mc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=Jqf8g81D5nFbzqa1Mj1MUZ0b+kHaaG7iVzvCqC90GTeRVx+MC2xnYX99ykZgfaQxs 5JVeLLTDgyqA43Di7GEIiXFFeoRpL8rQhshLL7Dgd3BvltobM4tV0BgXnbQYhs89aY 12cw3xEkMRwfCjSNwhLrkpYNmFeYdMmUEkTxua1M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727612AbgJSHbs (ORCPT ); Mon, 19 Oct 2020 03:31:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60512 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727420AbgJSHbr (ORCPT ); Mon, 19 Oct 2020 03:31:47 -0400 Received: from mail-wr1-x441.google.com (mail-wr1-x441.google.com [IPv6:2a00:1450:4864:20::441]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8F689C061755 for ; Mon, 19 Oct 2020 00:31:47 -0700 (PDT) Received: by mail-wr1-x441.google.com with SMTP id i1so10181674wro.1 for ; Mon, 19 Oct 2020 00:31:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=oxyUXQ2bhTcts6eK+RKa2UHLZ9th37dz3H9VJoRJ+nw=; b=PEJ462LavaXKCSxFbYT71XlFdHxA1yHiVzsrwSxrE9pf7+4iOdMwtp1A0u/eo0JspQ f0BDcRNhAEb69/3getFrZ7XXX4bvrCyV51qe0QbllWF39hT59JfbR36JtRUwynbHbtAN jaeYXZ24EJIoiWb17KA1t73xjj9+waZWlJK3NKwpDdhShNNhdZj54rpMO/Svtazy9v9T mRuJpVR3vP/66C2BAMgAOxFF6Uw8cVwkRY9kYcwtKL44VLiF+JRCljkT/RBb86QTeFMz sbKgAOaH1LWVaAxkUZuIQd9wB3puhDulV0p/skCv0s6ToNU3isSqtco3rZWtbxEGmXO0 JOjg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=oxyUXQ2bhTcts6eK+RKa2UHLZ9th37dz3H9VJoRJ+nw=; b=khA4q1Tpwt9JQCL/EfgQoaIQvKIocW2rWry0SEyHnwhH38MyiScTcVhGT2PUqhrcrG MOLq3bhUVTPLEjBIXlguH7Dk6xgmBSFvpu3T/wojK3ckkDTmhk7yc60dGvxdRGBgndqo W9tpIqypFLOQzE/BfFAQ0j5MnSETbY6WPKvAw4gu3lGv7k/eqPTPAMAeOGlAejS7rgdg DFt5e80AiQ82DV8IB/HgyPxgAAyOBhcgeOGllk982hH4NeNb3MrSPjNzY95nM0XzN+Cr MBGxxVIK8+pE9ZviTan7ckwh0HZ9s/pfEVMMAl7G7Vl7kOMl43GG9VXg88tg2jVmifcI WpFg== X-Gm-Message-State: AOAM531pVRQ9q3OLprFKPP5+tgMSLODA3YR6m2O0qT44ZyvjLdAP1uvr e4sO3ZUhqt9NR3fE+lCNuTg= X-Google-Smtp-Source: ABdhPJyEElzs5fN5/xHdG4CD1u84HiC+mOTuOdhdqyIsgXtCQw8Ni8Lx2Y9sc788QYxY7BtegUwzTw== X-Received: by 2002:a5d:60cc:: with SMTP id x12mr18096536wrt.314.1603092706302; Mon, 19 Oct 2020 00:31:46 -0700 (PDT) Received: from gmail.com (54033286.catv.pool.telekom.hu. [84.3.50.134]) by smtp.gmail.com with ESMTPSA id x10sm119588wrp.62.2020.10.19.00.31.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Oct 2020 00:31:45 -0700 (PDT) Sender: Ingo Molnar Date: Mon, 19 Oct 2020 09:31:43 +0200 From: Ingo Molnar To: Linus Torvalds Cc: Linux Kernel Mailing List , "Paul E. McKenney" , Thomas Gleixner , Peter Zijlstra , Andrew Morton Subject: Re: [GIT PULL] RCU changes for v5.10 Message-ID: <20201019073143.GA3785787@gmail.com> References: <20201012141451.GA3425471@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Linus Torvalds wrote: > On Mon, Oct 12, 2020 at 7:14 AM Ingo Molnar wrote: > > > > Please pull the latest core/rcu git tree from: > > > > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core-rcu-2020-10-12 > > I've pulled everything but that last merge and the PREEMPT_COUNT > stuff that came with it. > > When Paul asked whether it was ok for RCU to use preempt_count() and > I answered in the affirmative, I didn't mean it in the sense of "RCU > wants to force it on everybody else too". > > I'm pretty convinced that the proper fix is to simply make sure that > rcu_free() and friends aren't run under any raw spinlocks. So even > if the cost of preempt-count isn't that noticeable, there just isn't > a reason for RCU to say "screw everybody else, I want this" when > there are other alternatives. That's certainly true - thanks for catching this & sorting it out from the bigger pull request! Thanks, Ingo