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=-17.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 1BDAAC4320A for ; Mon, 23 Aug 2021 09:14:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A3D2561357 for ; Mon, 23 Aug 2021 09:14:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org A3D2561357 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 3DD2B8D0001; Mon, 23 Aug 2021 05:14:37 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 38CE96B0074; Mon, 23 Aug 2021 05:14:37 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 27B548D0001; Mon, 23 Aug 2021 05:14:37 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0020.hostedemail.com [216.40.44.20]) by kanga.kvack.org (Postfix) with ESMTP id 0AC9C6B0073 for ; Mon, 23 Aug 2021 05:14:37 -0400 (EDT) Received: from smtpin12.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 8D5A7267E0 for ; Mon, 23 Aug 2021 09:14:36 +0000 (UTC) X-FDA: 78505784952.12.C41EB77 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by imf28.hostedemail.com (Postfix) with ESMTP id ACA2E90000AC for ; Mon, 23 Aug 2021 09:14:34 +0000 (UTC) Received: from dggeme703-chm.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4GtRKt1P9bzbdRw; Mon, 23 Aug 2021 17:10:42 +0800 (CST) Received: from [10.174.177.35] (10.174.177.35) by dggeme703-chm.china.huawei.com (10.1.199.99) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.8; Mon, 23 Aug 2021 17:14:30 +0800 Subject: Re: [PATCH 3/3] mm/memory_hotplug: make HWPoisoned dirty swapcache pages unmovable To: =?UTF-8?B?SE9SSUdVQ0hJIE5BT1lBKOWggOWPoyDnm7TkuZ8p?= CC: "akpm@linux-foundation.org" , "mhocko@suse.com" , "minchan@kernel.org" , "cgoldswo@codeaurora.org" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" References: <20210821094246.10149-1-linmiaohe@huawei.com> <20210821094246.10149-4-linmiaohe@huawei.com> <20210823082646.GB1452382@hori.linux.bs1.fc.nec.co.jp> From: Miaohe Lin Message-ID: Date: Mon, 23 Aug 2021 17:14:29 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210823082646.GB1452382@hori.linux.bs1.fc.nec.co.jp> Content-Type: text/plain; charset="utf-8" Content-Language: en-US X-Originating-IP: [10.174.177.35] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggeme703-chm.china.huawei.com (10.1.199.99) X-CFilter-Loop: Reflected X-Rspamd-Queue-Id: ACA2E90000AC Authentication-Results: imf28.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=huawei.com; spf=pass (imf28.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.188 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com X-Rspamd-Server: rspam01 X-Stat-Signature: ige8nngtayata1afnha3w4rwe56nt6oz X-HE-Tag: 1629710074-730277 Content-Transfer-Encoding: quoted-printable 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 2021/8/23 16:26, HORIGUCHI NAOYA(=E5=A0=80=E5=8F=A3 =E7=9B=B4=E4=B9=9F= ) wrote: > On Sat, Aug 21, 2021 at 05:42:46PM +0800, Miaohe Lin wrote: >> HWPoisoned dirty swapcache pages are kept for killing owner processes. >> We should not offline these pages or do_swap_page() would access the >> offline pages and lead to bad ending. >> >=20 > Thank you for the report. I'm not yet sure of the whole picture of thi= s > issue. do_swap_page() is expected to return with fault VM_FAULT_HWPOIS= ON > when called via the access to the error page, so I wonder why this does= n't > work for your situation. And what is the "bad ending" in the descripti= on? >=20 IMO we might hotremove the page while SwapCache still have ref to it. Thu= s the page struct would be accessed after offlined. The page struct should be invali= d in this case and this would make do_swap_page fragile. Or am I miss something? > I feel that aborting memory hotremove due to a hwpoisoned dirty swapcac= he > might be too hard, so I'd like to find another solution if we have. If there is a better way, we can just drop this one. Many thanks for your review and reply! :) > # You may separate this patch from former two to make them merged to > # mainline soon. >=20 > Thanks, > Naoya Horiguchi >=20 >> Signed-off-by: Miaohe Lin >> --- >> mm/memory_hotplug.c | 6 ++++++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >> index 9fd0be32a281..0488eed3327c 100644 >> --- a/mm/memory_hotplug.c >> +++ b/mm/memory_hotplug.c >> @@ -1664,6 +1664,12 @@ static int scan_movable_pages(unsigned long sta= rt, unsigned long end, >> */ >> if (PageOffline(page) && page_count(page)) >> return -EBUSY; >> + /* >> + * HWPoisoned dirty swapcache pages are definitely unmovable >> + * because they are kept for killing owner processes. >> + */ >> + if (PageHWPoison(page) && PageSwapCache(page)) >> + return -EBUSY;