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=-0.8 required=3.0 tests=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 3F443C2BA2B for ; Thu, 16 Apr 2020 21:04:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 19F7520786 for ; Thu, 16 Apr 2020 21:04:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="YhLp6OX5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728367AbgDPVE2 (ORCPT ); Thu, 16 Apr 2020 17:04:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42264 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726320AbgDPVE2 (ORCPT ); Thu, 16 Apr 2020 17:04:28 -0400 Received: from mail-qk1-x742.google.com (mail-qk1-x742.google.com [IPv6:2607:f8b0:4864:20::742]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E92C4C061A0C for ; Thu, 16 Apr 2020 14:04:26 -0700 (PDT) Received: by mail-qk1-x742.google.com with SMTP id o19so175914qkk.5 for ; Thu, 16 Apr 2020 14:04:26 -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; bh=zTjxp7v3io4d+TAB+jWmWDKQTEGkFrtPZXBYASTPzY0=; b=YhLp6OX5Zt3iqmVfy0c56DphC12rm977+V9+qvgsAN3mBPGE8WiEETVrjs//aKQP9P Fu2U3iy2kK1MmmtAaROyitaHjX1MYnGXVj1R1mdi9Cw5bMoty3vOgcdTmxu9fyI/f9wb Gd8JI0NPin4rrkDkSkxe9AggJC5WJ1Rd7TvwU= 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=zTjxp7v3io4d+TAB+jWmWDKQTEGkFrtPZXBYASTPzY0=; b=n2GT4YCNNtAxnxnezUqjIbqMe2gz/yZfq0Z9sNqm2hY0q7GT15OS1YXNIhR4fUh/uL thex/+f8qEVnBDsuxmwr6Z72FdU97I2XKZ8K8Q8OeKsixxSPPYN8XrvhydXt7C5DaeQk 6zIc2rzVeJ5OMUWT2JPnBpqRBMHE2c8qO1bVz2pjQdouv2V1U5RuQyQn6ccVO55XkRf0 KUv42voNH8AFUxAMPOaFPNBL9FtKIdWqyb2teuBa7FHHS3gKiUIfjAw5JS3JkFTicNZQ ESs40ml+snZ5SC2aHYgjrJJPgwhd8dGiWhF57HYd7s3Q0c28/zqx0CKUeNQomZRtp5+9 7kng== X-Gm-Message-State: AGi0PuapsZd9zSrjqFwRekYCUtdhYrGoi0pgjc0ORWdgNOkovPEEAWjI UrFYR5JDqkVr+nC+1AmnRvq3+A== X-Google-Smtp-Source: APiQypKZIX0XB2zDlpJUOkY6Nyv0G2goizI6mYpaXtJPe8hXwyaq+GC5zDZXwasYrWQ49TmXm3EEQw== X-Received: by 2002:a37:a8c7:: with SMTP id r190mr34408968qke.65.1587071066047; Thu, 16 Apr 2020 14:04:26 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id w79sm4735559qkb.97.2020.04.16.14.04.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Apr 2020 14:04:25 -0700 (PDT) Date: Thu, 16 Apr 2020 17:04:24 -0400 From: Joel Fernandes To: Sebastian Andrzej Siewior Cc: "Paul E. McKenney" , Uladzislau Rezki , rcu@vger.kernel.org, Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Thomas Gleixner , Mike Galbraith Subject: Re: [PATCH 1/3] rcu: Use static initializer for krc.lock Message-ID: <20200416210424.GD176663@google.com> References: <20200416154647.ceotefna34pdxpfi@linutronix.de> <20200416160129.GA8337@pc636> <20200416161149.lkvkfwevanff36kb@linutronix.de> <20200416161819.GA8551@pc636> <20200416163302.3fsroillwk2om5dh@linutronix.de> <20200416172953.GR17661@paulmck-ThinkPad-P72> <20200416182309.zytrgowlngpewxbt@linutronix.de> <20200416182948.GV17661@paulmck-ThinkPad-P72> <20200416184348.GB149999@google.com> <20200416205636.fdljtricn6i3a2ub@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200416205636.fdljtricn6i3a2ub@linutronix.de> Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org On Thu, Apr 16, 2020 at 10:56:36PM +0200, Sebastian Andrzej Siewior wrote: > On 2020-04-16 14:43:48 [-0400], Joel Fernandes wrote: > > > Fair enough! IIRC, get_page() uses non-raw spinlocks, so... > > > > Oh, I see Paul made the same suggestion I did for raw spinlocks. > > > > migrate_disable() is fine, but note that in the later code we will not be > > sleeping even during the get_page(), so I don't see a problem with raw > > spinlock... did I miss something? > > The buddy allocator, which get_page() is using, is using spinlock_t > which is a sleeping lock. You can't have memory allocations within a > raw_spinlock_t section even with GFP_ATOMIC on PREEMPT_RT. Oh, ok! Thanks for the clarification and sorry about the noise. Now I get your motivation with the patch. thanks, - Joel