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=-2.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, 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 7972CC3A5A6 for ; Tue, 27 Aug 2019 12:17:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 427112184D for ; Tue, 27 Aug 2019 12:17:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="imq0LcQt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728694AbfH0MRk (ORCPT ); Tue, 27 Aug 2019 08:17:40 -0400 Received: from mail-ed1-f68.google.com ([209.85.208.68]:37160 "EHLO mail-ed1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726170AbfH0MRj (ORCPT ); Tue, 27 Aug 2019 08:17:39 -0400 Received: by mail-ed1-f68.google.com with SMTP id f22so31078241edt.4 for ; Tue, 27 Aug 2019 05:17:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=FbGzDuD3RIJ23CO8zb5ApvjBQtLaEmsyKeBOr5aEVwk=; b=imq0LcQtyoCAq4I0t8Dbrpw8qW3p9yhMU1fK7FXpWEAkChTCA/eOGL+sCo2A/5Vdhy icR35TMDiD2XozCvk28c+t3qkmvleFbwayAzGcVkDjd8cEbvOQXsizvKLd3TJpRsc7cJ g5CFwSbwijT5W50v67l+4k/pNFjK7gLJ4RLSEBNztBjjYSpe8HMYBbm3H88kvoD9nY1Y DQc9iQ1MKP6lUqS7opFfw8u2BmSaWPVzNTQ0W0Ppb1AuiGo5HqYTjOkiRWttGHfU9D/3 5mtZSEGkk24Uu5ynKhR99hKzMK74T9FENLeMmtxBOXPfgmLGdEy40KiYF4IlHYPj7cs8 tKKQ== 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:user-agent; bh=FbGzDuD3RIJ23CO8zb5ApvjBQtLaEmsyKeBOr5aEVwk=; b=L759wncuU7OFvMezszudJkAdyptP7giEA8peh6bnRencPbr6yl07412AMssI3pPm9K ZCdRNv2L9PmStjwFJmLTNSzJ0WLE8kl0TMSb/MTNnrTD8x1oVGPN+Cb2JzYecmUCG1l6 g9CCwyI2HgXXd0BV7nT36ole6YnB89Q3yyYtQxTdKG27gHknq0gyY0uYjTyBQn5nNa0I oJN08rOmex7kyLSssHThaI37mZNFjtnHZgeTgk3Rn9bMWFRQoZxlD+20lP+VLsNvmm/q bumhIkD2nxLzz9XRRzzR8O1URxR31zQUC595xMY5o4ByIJyian8y7OH5thvJf0UGTHDv 65pg== X-Gm-Message-State: APjAAAXU/VmRXLlbu159sp/FpFhFLH0FzDehYcElU94Eblx7It2KnP+D C9GpFaGrOjaT7YivTl42KfgA3Q== X-Google-Smtp-Source: APXvYqzX5zFQNMBVLvorfdtCo4ceiZTMT5GoTFrvYFVZ1XxJOiQHwWwe82lNcIwbXgct8DP82OccIg== X-Received: by 2002:a17:906:a3c4:: with SMTP id ca4mr20907390ejb.5.1566908258127; Tue, 27 Aug 2019 05:17:38 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id v20sm1927306edl.35.2019.08.27.05.17.37 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 27 Aug 2019 05:17:37 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id C36CA100746; Tue, 27 Aug 2019 15:17:39 +0300 (+03) Date: Tue, 27 Aug 2019 15:17:39 +0300 From: "Kirill A. Shutemov" To: Michal Hocko Cc: Vlastimil Babka , kirill.shutemov@linux.intel.com, Yang Shi , hannes@cmpxchg.org, rientjes@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [v2 PATCH -mm] mm: account deferred split THPs into MemAvailable Message-ID: <20190827121739.bzbxjloq7bhmroeq@box> References: <1566410125-66011-1-git-send-email-yang.shi@linux.alibaba.com> <20190822080434.GF12785@dhcp22.suse.cz> <20190822152934.w6ztolutdix6kbvc@box> <20190826074035.GD7538@dhcp22.suse.cz> <20190826131538.64twqx3yexmhp6nf@box> <20190827060139.GM7538@dhcp22.suse.cz> <20190827110210.lpe36umisqvvesoa@box> <20190827120923.GB7538@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190827120923.GB7538@dhcp22.suse.cz> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 27, 2019 at 02:09:23PM +0200, Michal Hocko wrote: > On Tue 27-08-19 14:01:56, Vlastimil Babka wrote: > > On 8/27/19 1:02 PM, Kirill A. Shutemov wrote: > > > On Tue, Aug 27, 2019 at 08:01:39AM +0200, Michal Hocko wrote: > > >> On Mon 26-08-19 16:15:38, Kirill A. Shutemov wrote: > > >>> > > >>> Unmapped completely pages will be freed with current code. Deferred split > > >>> only applies to partly mapped THPs: at least on 4k of the THP is still > > >>> mapped somewhere. > > >> > > >> Hmm, I am probably misreading the code but at least current Linus' tree > > >> reads page_remove_rmap -> [page_remove_anon_compound_rmap ->\ deferred_split_huge_page even > > >> for fully mapped THP. > > > > > > Well, you read correctly, but it was not intended. I screwed it up at some > > > point. > > > > > > See the patch below. It should make it work as intened. > > > > > > It's not bug as such, but inefficientcy. We add page to the queue where > > > it's not needed. > > > > But that adding to queue doesn't affect whether the page will be freed > > immediately if there are no more partial mappings, right? I don't see > > deferred_split_huge_page() pinning the page. > > So your patch wouldn't make THPs freed immediately in cases where they > > haven't been freed before immediately, it just fixes a minor > > inefficiency with queue manipulation? > > Ohh, right. I can see that in free_transhuge_page now. So fully mapped > THPs really do not matter and what I have considered an odd case is > really happening more often. > > That being said this will not help at all for what Yang Shi is seeing > and we need a more proactive deferred splitting as I've mentioned > earlier. It was not intended to fix the issue. It's fix for current logic. I'm playing with the work approach now. -- Kirill A. Shutemov