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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 DE86AC3A5A9 for ; Mon, 4 May 2020 16:56:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AEA742073E for ; Mon, 4 May 2020 16:56:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="WB7fNAz7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729860AbgEDQ4f (ORCPT ); Mon, 4 May 2020 12:56:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46926 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729816AbgEDQ4e (ORCPT ); Mon, 4 May 2020 12:56:34 -0400 Received: from mail-lf1-x142.google.com (mail-lf1-x142.google.com [IPv6:2a00:1450:4864:20::142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6E238C061A0E; Mon, 4 May 2020 09:56:34 -0700 (PDT) Received: by mail-lf1-x142.google.com with SMTP id a9so4994212lfb.8; Mon, 04 May 2020 09:56:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=uq7Cp9sRzO17hCXg+U38cDHiVk9tcoMKEdlR/VPmBCA=; b=WB7fNAz7ezTp/EIxVo9weanA4wgM5W+Ik6gzOwV1XRS6yZuIjkezO6aJeK7bxe22Fk rjL49+fRdQZv0itvLwP+/nUzdiwrdtUV6PTc70cyu0avMZO36CZPeIBVIqf0gZe5laIv xDH9JMsspY1KpfqgDGbosG6TIjW5TMb1HqyTiuB4bIMPv0nsjyOxFCIh3PeTHF/73NtJ mq7Ay5vCk9uiOyJpDPe/71Yqmgr1eAMjQHHjDJ/OAaIF4jVDDjVWNSkjQpAmDpyquedd XQIOwu+Nfm3SVDbWZ2dXPAYdJ4CRx5BZH3ie8uGHfYh6/MA/IHTkESuSaloDqAaciVws nlsA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=uq7Cp9sRzO17hCXg+U38cDHiVk9tcoMKEdlR/VPmBCA=; b=DSK68eUE4pYBYmNYGghmxLTy2MUTw4CyiKOY4Vpa0eTuotCAOiLZnQPoeehIuovyw4 Jh2gQkR8jpakyKP1CqBo1YZi/qfqoi4h29nqCBfo7Rn1gjRqOtiAzcxnlv+UGVHqdMyJ SeLwdoSZcAAYEC4z+w62eyTF5oVPx5xG0Gw6uT1+1DF+p4mFJNrB+wFgcal1RA28Jds4 +66hsFTBtw1EncwvEi4KfnnNk7uJ+ohmbvpwCHjwMocjUzMLnZtGF0p0pvGD4ifazEm2 pNlgiwUbRBRo+eQr9puVw7U3rrixHkkmEEdnQPU8vwIMw67N1fn9HvkBdLW6u48Mp3Qt cJWg== X-Gm-Message-State: AGi0PuYuiDDNSHoYAD0SG7OAOkHhWnilonSn4fCNVeyfgE7Q4AjN1pUm niP85OTnHxTD7BScqPSO/JRP4/dciEvK/Q== X-Google-Smtp-Source: APiQypJIYOGRdt0a6sPjl66fJSqZJTkezZ3Epnp3pIhYCU2UkMwickRewOFI8jnorrTODAWiTk7xuQ== X-Received: by 2002:a19:7418:: with SMTP id v24mr5524146lfe.15.1588611392880; Mon, 04 May 2020 09:56:32 -0700 (PDT) Received: from pc636 (h5ef52e31.seluork.dyn.perspektivbredband.net. [94.245.46.49]) by smtp.gmail.com with ESMTPSA id h22sm8680500ljb.65.2020.05.04.09.56.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 May 2020 09:56:32 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Mon, 4 May 2020 18:56:29 +0200 To: "Paul E. McKenney" Cc: Uladzislau Rezki , Joel Fernandes , LKML , linux-mm@kvack.org, Andrew Morton , "Theodore Y . Ts'o" , Matthew Wilcox , RCU , Oleksiy Avramchenko Subject: Re: [PATCH 19/24] rcu/tree: Support reclaim for head-less object Message-ID: <20200504165629.GA20257@pc636> References: <20200428205903.61704-1-urezki@gmail.com> <20200428205903.61704-20-urezki@gmail.com> <20200501223909.GF7560@paulmck-ThinkPad-P72> <20200504001258.GD197097@google.com> <20200504002855.GF2869@paulmck-ThinkPad-P72> <20200504003237.GD212435@google.com> <20200504142153.GG17577@pc636> <20200504153147.GL2869@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200504153147.GL2869@paulmck-ThinkPad-P72> 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 > > > > For single argument we can drop the lock before the entry to the page > > allocator. Because it follows might_sleep() anotation we avoid of having > > a situation when spinlock(rt mutex) is taken from any atomic context. > > > > Since the lock is dropped the current context can be interrupted by > > an IRQ which in its turn can also call kvfree_rcu() on current CPU. > > In that case it must be double argument(single is not allowed) kvfree_rcu() > > call. For PREEMPT_RT if no cache everything is reverted to rcu_head usage, > > i.e. the entry to page allocator is bypassed. > > > > It can be addressed as a separate patch and send out later on if we > > are on the same page. > > > > Paul, Joel what are your opinions? > > I strongly prefer that it be removed from the series. I do understand > that this is a bit more hassle right now, but this does help avoid > confusion in the future, plus perhaps also avoiding issues with future > bisections. > We have already decided to get rid of it, i mean small allocations(dynamic rcu_head attaching). I will exclude it from next patch-set version. -- Vlad Rezki