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=-5.6 required=3.0 tests=BAYES_00,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 9089DC433E3 for ; Wed, 15 Jul 2020 19:02:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 67D8820657 for ; Wed, 15 Jul 2020 19:02:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="AJrZs7DM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726634AbgGOTCz (ORCPT ); Wed, 15 Jul 2020 15:02:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37290 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726761AbgGOTCw (ORCPT ); Wed, 15 Jul 2020 15:02:52 -0400 Received: from mail-lj1-x243.google.com (mail-lj1-x243.google.com [IPv6:2a00:1450:4864:20::243]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8C2E3C08C5CE; Wed, 15 Jul 2020 12:02:52 -0700 (PDT) Received: by mail-lj1-x243.google.com with SMTP id z24so3813946ljn.8; Wed, 15 Jul 2020 12:02:52 -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=24j8BD/rk1NCezefIEXui0kY0H9CcCq5N57TnMuH0Cs=; b=AJrZs7DMub0Mmpklzzn+wMRqarleeITlOdNdHKFOGnsjGhIvg4RadvozaRFCXFQaJf X77nBWccXJek+u3muNeIFHurc3tLJTbykuiahETAXS+gBNBxh/1qZIvzu0n/yLjWbTFd gTqke7t3gVWxGkDBg1n59jGgmPKYfm3waBnYTyT/+d9CybsSSF7jH1WAnT1VsYCrMq7+ 37ewHdUaA8AAUWwJxjG+kVaQCxiyDm1c6CeIxVRz02hYonygKPpWGfOZRVqYFdEp95Ct PF1kNoHJn7JwFn/IXryaMa9RbAlLyZNvqdqsuHP8Q/5m1GS5nDS19yKIXHt8E5N+4vgX GJMg== 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=24j8BD/rk1NCezefIEXui0kY0H9CcCq5N57TnMuH0Cs=; b=C3/NeDUJyUfUY86XotiYggGLKChXyDpi76Esn3K4JL+PuPwBptWYUtSZnd5amEIYC2 mcHlIcLtveAgAaSCjVKG9aLSgzTSxiNfVVkwtezniRFV+CLSq0c7kVacPjIw06c8j7Mr HbSHY7HYugZ0pTnVTRDnl6L2M+K9K2D+vdM4vLq6vRuhwSLtWfp/bfM7jqQQkyDn3qgc onPtoKcv0hyd8bgQ0K/Us6U1awjrBRvC0rgGpf6UUTLsGoAZFEZHQ9mosbEEtAzKgu4E sVjeSNftZRtM3yxbTh9MydaP8JWOfxjmyz48obxXhx2/j8TDBWO2X+JQMqL/wSj3JCt/ 36sw== X-Gm-Message-State: AOAM533rEdHqpmA2SYU7Jq9EuMB2L3Qv7KfDmMMHuam2npv/sgwpDHlQ PJNaAlZixjGitxyr3tLDl4mu3WilfHQ= X-Google-Smtp-Source: ABdhPJyeS11MWJWIPMBKnsprqezqgfZ2gTNo4TwAAgBZVHDbSLb9SAwVA3YDJDjCwnF9BB4jYImGIA== X-Received: by 2002:a2e:780b:: with SMTP id t11mr234821ljc.271.1594839770991; Wed, 15 Jul 2020 12:02:50 -0700 (PDT) Received: from pc636 (h5ef52e31.seluork.dyn.perspektivbredband.net. [94.245.46.49]) by smtp.gmail.com with ESMTPSA id g24sm594774ljl.139.2020.07.15.12.02.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jul 2020 12:02:45 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Wed, 15 Jul 2020 21:02:43 +0200 To: Sebastian Andrzej Siewior Cc: "Uladzislau Rezki (Sony)" , LKML , RCU , linux-mm@kvack.org, "Paul E . McKenney" , Andrew Morton , "Theodore Y . Ts'o" , Matthew Wilcox , Joel Fernandes , Oleksiy Avramchenko Subject: Re: [PATCH 1/1] rcu/tree: Drop the lock before entering to page allocator Message-ID: <20200715190243.GA26735@pc636> References: <20200715183537.4010-1-urezki@gmail.com> <20200715185628.7b4k3o5efp4gnbla@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200715185628.7b4k3o5efp4gnbla@linutronix.de> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org On Wed, Jul 15, 2020 at 08:56:28PM +0200, Sebastian Andrzej Siewior wrote: > On 2020-07-15 20:35:37 [+0200], Uladzislau Rezki (Sony) wrote: > > @@ -3306,6 +3307,9 @@ kvfree_call_rcu_add_ptr_to_bulk(struct kfree_rcu_cpu *krcp, void *ptr) > > if (IS_ENABLED(CONFIG_PREEMPT_RT)) > > return false; > > > > + preempt_disable(); > > + krc_this_cpu_unlock(*krcp, *flags); > > Now you enter memory allocator with disabled preemption. This isn't any > better but we don't have a warning for this yet. > Please elaborate why it is not allowed? Consider the code: spin_lock(); __get_free_page(GFP_NOWAIT | __GFP_NOWARN); spin_unlock(); Also, please note we do it for regular kernel. > > What happened to the part where I asked for a spinlock_t? > What do you mean? -- Vlad Rezki