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=-4.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 07D3DC04EB8 for ; Thu, 6 Dec 2018 08:32:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BEE4720892 for ; Thu, 6 Dec 2018 08:32:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544085131; bh=dumXPcjkmErYSEQ3/xNLXSi6kM0Xw9noWYHddRVyUXo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=p/yZevfcQ1f93EILyeMz84n7JvKF6bRpmc7Wn6QOhuBy8I+KIj9xtJlUlxWTM8kv8 SOcH/34Hr1eA0PJlXj16OF2RM0jadfoQNvPk5tF/Yip4YRup9N3QiyXpkYz+sbCkqX x66UI078tkQ2nsME9vqD8u0riN+ZrLZGSUoE04BI= DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BEE4720892 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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 S1729311AbeLFIcK (ORCPT ); Thu, 6 Dec 2018 03:32:10 -0500 Received: from mx2.suse.de ([195.135.220.15]:44044 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727575AbeLFIcK (ORCPT ); Thu, 6 Dec 2018 03:32:10 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 0739AAD75; Thu, 6 Dec 2018 08:32:07 +0000 (UTC) Date: Thu, 6 Dec 2018 09:32:06 +0100 From: Michal Hocko To: Naoya Horiguchi Cc: Oscar Salvador , Andrew Morton , Dan Williams , Pavel Tatashin , "linux-mm@kvack.org" , LKML , Stable tree Subject: Re: [RFC PATCH] hwpoison, memory_hotplug: allow hwpoisoned pages to be offlined Message-ID: <20181206083206.GC1286@dhcp22.suse.cz> References: <20181203100309.14784-1-mhocko@kernel.org> <20181205122918.GL1286@dhcp22.suse.cz> <20181205165716.GS1286@dhcp22.suse.cz> <20181206052137.GA28595@hori1.linux.bs1.fc.nec.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181206052137.GA28595@hori1.linux.bs1.fc.nec.co.jp> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 06-12-18 05:21:38, Naoya Horiguchi wrote: > On Wed, Dec 05, 2018 at 05:57:16PM +0100, Michal Hocko wrote: > > On Wed 05-12-18 13:29:18, Michal Hocko wrote: > > [...] > > > After some more thinking I am not really sure the above reasoning is > > > still true with the current upstream kernel. Maybe I just managed to > > > confuse myself so please hold off on this patch for now. Testing by > > > Oscar has shown this patch is helping but the changelog might need to be > > > updated. > > > > OK, so Oscar has nailed it down and it seems that 4.4 kernel we have > > been debugging on behaves slightly different. The underlying problem is > > the same though. So I have reworded the changelog and added "just in > > case" PageLRU handling. Naoya, maybe you have an argument that would > > make this void for current upstream kernels. > > The following commit (not in 4.4.x stable tree) might explain the > difference you experienced: > > commit 286c469a988fbaf68e3a97ddf1e6c245c1446968 > Author: Naoya Horiguchi > Date: Wed May 3 14:56:22 2017 -0700 > > mm: hwpoison: call shake_page() after try_to_unmap() for mlocked page > > This commit adds shake_page() for mlocked pages to make sure that the target > page is flushed out from LRU cache. Without this shake_page(), subsequent > delete_from_lru_cache() (from me_pagecache_clean()) fails to isolate it and > the page will finally return back to LRU list. So this scenario leads to > "hwpoisoned by still linked to LRU list" page. OK, I see. So does that mean that the LRU handling is no longer needed and there is a guanratee that all kernels with the above commit cannot ever get an LRU page? -- Michal Hocko SUSE Labs