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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 1D2DFC742D2 for ; Fri, 12 Jul 2019 21:21:15 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D39D52146E for ; Fri, 12 Jul 2019 21:21:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="VyTzUkFw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D39D52146E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 59D188E0169; Fri, 12 Jul 2019 17:21:14 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 54C218E0003; Fri, 12 Jul 2019 17:21:14 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 461888E0169; Fri, 12 Jul 2019 17:21:14 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-pg1-f197.google.com (mail-pg1-f197.google.com [209.85.215.197]) by kanga.kvack.org (Postfix) with ESMTP id 0F7468E0003 for ; Fri, 12 Jul 2019 17:21:14 -0400 (EDT) Received: by mail-pg1-f197.google.com with SMTP id d187so6414310pga.7 for ; Fri, 12 Jul 2019 14:21:14 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:date:from:to:cc:subject :message-id:in-reply-to:references:mime-version :content-transfer-encoding; bh=F1lNHfCed2lqUhBPAULxhJwb0vbJQ1dpTWKObGf7USA=; b=Z8j+YXlfZtF9aYcQJmZvgmP/0J4owgkXrhaKDEI+ioJRkadJ7NPajEXtfW1CatjfMa HF4XUUAgP/6eiZYsY3fA9hBhgE7KF9SddRQ0NmD+WamWs5T9oyGNKJC4/jbI1RapLz5M rRyu8Yn08wCO9Hu85JumbWxKMdu/pfMY4M52qz2JxhSpTFFDEt1gTr+93VRgxECb5IXa szghjySf8KydKe0Gr73A1JH//Yam2A0gH1yFBTkoXwSGU8Qrja4MrVnNULueH3kc3IZz lg9heZ41s0XhEQEbZofeC2GO79H1LwRatEuq7nDeCAVvxsRbsZ7VB5zOpducftJmqWti bO9w== X-Gm-Message-State: APjAAAVZskJGHeC1okIlHgWD/m8b+oKIDfv5drCQRpHxObrM8VaZVlMB 5LYifvm7rMhNHcaRz3t76vVLyXhnDHsRx92UNWWjusN5lwfrWlUETvzpZ1OHmb7hTT5zLxdTseD kJ8pXAbXJy9G6mPh4vBWs4DT4t9ES1NAmBxanMlVfQwdosbQ2EY5S64MZ5fPx7A0uww== X-Received: by 2002:a63:f150:: with SMTP id o16mr4280586pgk.105.1562966473473; Fri, 12 Jul 2019 14:21:13 -0700 (PDT) X-Google-Smtp-Source: APXvYqy1iuSG+MWrt/zATeiPNA+p/JgWymaJa2z0Ahr6mBB49jjFOlEwNeNj3ruYjhz0t7PXHiRz X-Received: by 2002:a63:f150:: with SMTP id o16mr4280528pgk.105.1562966472670; Fri, 12 Jul 2019 14:21:12 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1562966472; cv=none; d=google.com; s=arc-20160816; b=tTOX553AqTCj6sHaqGv0IZgSkNcu77DC9ZuJGZOOn2ZctU8sNtXjHwC3lcf3OItIbc hichRv2ePWFdajOOdjxCfQNdb01i2LB2FrvNG63RIGoRPc4PyVQjM9aCMI6qA5S8KXzT 3pp8TVjdvUXZqZyMrzT0BgTZ0BEhbgoZoypKNkR+owkLOrMGjsEPgZudC222JH9qlS0X EEVnRCyomnn5v9GTItaFBUbC3v1CGBcrSoudNRUiTIZ44+JPDWRLHraHJ6bY4PLgmGnS 3rNAroziVnrk/RlivO4lhti5fUmhB8yQsOrNLEB111DRfQ1/5CZxl9FFx89aF3rYuFPm yzog== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:dkim-signature; bh=F1lNHfCed2lqUhBPAULxhJwb0vbJQ1dpTWKObGf7USA=; b=vFzrum0DZKY3exkr0tCv+XMuR12sy9iuSAAEnPdrxv7AP3sVc3LouyAYsEO/MYWw3u eOCQvBWKFREfY5NRCVLEc9lHBXWXAdDzePLmaEn2KKKKwicnVevIqKpQWAKX/zt6FhuO hGGSBUybxQN7KSQRqXNFGJ6Wxo/fSGhI8rC0G2eElSPHzeyb5pZwEsuSCt2M119xe5CW geV4T/k9jOLK/f6gZwNi3fysjmsSIOmSk960GO6/KuGumJPHPNM+ML8cUBW76rO9GU++ fKoJA9M4LGj4AhdbjulkNGW1YhwrD1AOnLRJATiZG5Xz7Gm2kZxE8n4RMTUA0t/MFvKe wAqA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=VyTzUkFw; spf=pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from mail.kernel.org (mail.kernel.org. [198.145.29.99]) by mx.google.com with ESMTPS id f20si9343855pfn.166.2019.07.12.14.21.12 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 12 Jul 2019 14:21:12 -0700 (PDT) Received-SPF: pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) client-ip=198.145.29.99; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=VyTzUkFw; spf=pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from akpm3.svl.corp.google.com (unknown [104.133.8.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0D7B42146E; Fri, 12 Jul 2019 21:21:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562966472; bh=UfhH+qwZBH+tVJt9XqklnwhR+TQu6aQMk7iJb9IF0v0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=VyTzUkFwOSGD10Gtwey/oyOtWAAxst1dmhN6RE5AaeNaVvM/b/+22UD0qVzNQATrx dPHaudNa72m9jBuShTX3SO2XmSAu0YvIf20RvuUJzXu6uGLkPVhYBUxVQX+cpHRr1l o3nJ3wtiZtrUWIHvpVcShCPJAxXOCZ2SkkbIX73s= Date: Fri, 12 Jul 2019 14:21:11 -0700 From: Andrew Morton To: Mel Gorman Cc: Jan Kara , linux-mm@kvack.org, mhocko@suse.cz, stable@vger.kernel.org Subject: Re: [PATCH RFC] mm: migrate: Fix races of __find_get_block() and page migration Message-Id: <20190712142111.eac6322eea55f7e8f75b7b33@linux-foundation.org> In-Reply-To: <20190712123935.GK13484@suse.de> References: <20190711125838.32565-1-jack@suse.cz> <20190711170455.5a9ae6e659cab1a85f9aa30c@linux-foundation.org> <20190712091746.GB906@quack2.suse.cz> <20190712101042.GJ13484@suse.de> <20190712112056.GA24009@quack2.suse.cz> <20190712123935.GK13484@suse.de> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, 12 Jul 2019 13:39:35 +0100 Mel Gorman wrote: > > So although I still think that just failing the migration if we cannot > > invalidate buffer heads is a safer choice, just extending the private_lock > > protected section does not seem as bad as I was afraid. > > > > That does not seem too bad and your revised patch looks functionally > fine. I'd leave out the tracepoints though because a perf probe would have > got roughly the same data and the tracepoint may be too specific to track > another class of problem. Whether the tracepoint survives or not and > with a changelog added; > > Acked-by: Mel Gorman > > Andrew, which version do you want to go with, the original version or > this one that holds private_lock for slightly longer during migration? The revised version looks much more appealing for a -stable backport. I expect any mild performance issues can be address in the usual fashion. My main concern is not to put a large performance regression into mainline and stable kernels. How confident are we that this is (will be) sufficiently tested from that point of view?