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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 BDE68C43A1D for ; Thu, 12 Jul 2018 11:30:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6D22120BF2 for ; Thu, 12 Jul 2018 11:30:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6D22120BF2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726723AbeGLLjU (ORCPT ); Thu, 12 Jul 2018 07:39:20 -0400 Received: from mga05.intel.com ([192.55.52.43]:8878 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726534AbeGLLjU (ORCPT ); Thu, 12 Jul 2018 07:39:20 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Jul 2018 04:30:11 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,342,1526367600"; d="scan'208";a="72156327" Received: from unknown (HELO [10.239.13.97]) ([10.239.13.97]) by orsmga001.jf.intel.com with ESMTP; 12 Jul 2018 04:30:06 -0700 Message-ID: <5B473CB8.1050306@intel.com> Date: Thu, 12 Jul 2018 19:34:16 +0800 From: Wei Wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Michal Hocko CC: Linus Torvalds , virtio-dev@lists.oasis-open.org, Linux Kernel Mailing List , virtualization , KVM list , linux-mm , "Michael S. Tsirkin" , Andrew Morton , Paolo Bonzini , liliang.opensource@gmail.com, yang.zhang.wz@gmail.com, quan.xu0@gmail.com, nilal@redhat.com, Rik van Riel , peterx@redhat.com Subject: Re: [PATCH v35 1/5] mm: support to get hints of free page blocks References: <1531215067-35472-1-git-send-email-wei.w.wang@intel.com> <1531215067-35472-2-git-send-email-wei.w.wang@intel.com> <5B455D50.90902@intel.com> <20180711092152.GE20050@dhcp22.suse.cz> <5B46BB46.2080802@intel.com> <5B46C258.40601@intel.com> <20180712081317.GD32648@dhcp22.suse.cz> In-Reply-To: <20180712081317.GD32648@dhcp22.suse.cz> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/12/2018 04:13 PM, Michal Hocko wrote: > On Thu 12-07-18 10:52:08, Wei Wang wrote: >> On 07/12/2018 10:30 AM, Linus Torvalds wrote: >>> On Wed, Jul 11, 2018 at 7:17 PM Wei Wang wrote: >>>> Would it be better to remove __GFP_THISNODE? We actually want to get all >>>> the guest free pages (from all the nodes). >>> Maybe. Or maybe it would be better to have the memory balloon logic be >>> per-node? Maybe you don't want to remove too much memory from one >>> node? I think it's one of those "play with it" things. >>> >>> I don't think that's the big issue, actually. I think the real issue >>> is how to react quickly and gracefully to "oops, I'm trying to give >>> memory away, but now the guest wants it back" while you're in the >>> middle of trying to create that 2TB list of pages. >> OK. virtio-balloon has already registered an oom notifier >> (virtballoon_oom_notify). I plan to add some control there. If oom happens, >> - stop the page allocation; >> - immediately give back the allocated pages to mm. > Please don't. Oom notifier is an absolutely hideous interface which > should go away sooner or later (I would much rather like the former) so > do not build a new logic on top of it. I would appreciate if you > actually remove the notifier much more. > > You can give memory back from the standard shrinker interface. If we are > reaching low reclaim priorities then we are struggling to reclaim memory > and then you can start returning pages back. OK. Just curious why oom notifier is thought to be hideous, and has it been a consensus? Best, Wei