From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751080AbdAWMkh (ORCPT ); Mon, 23 Jan 2017 07:40:37 -0500 Received: from szxga01-in.huawei.com ([58.251.152.64]:16683 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750718AbdAWMkg (ORCPT ); Mon, 23 Jan 2017 07:40:36 -0500 Subject: Re: [RFC v2] HWPOISON: soft offlining for non-lru movable page To: Minchan Kim , References: <1484837943-21745-1-git-send-email-ysxie@foxmail.com> <20170123051459.GB11763@bbox> CC: , , , , , , , From: Yisheng Xie Message-ID: Date: Mon, 23 Jan 2017 20:39:59 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.1.0 MIME-Version: 1.0 In-Reply-To: <20170123051459.GB11763@bbox> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.29.40] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020203.5885F9B6.00BD,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-06-18 04:22:30, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 7e48368918c0568849f77bd0f4a416ec Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Minchan, Thanks for reviewing. On 2017/1/23 13:14, Minchan Kim wrote: > Hello, > > On Thu, Jan 19, 2017 at 10:59:03PM +0800, ysxie@foxmail.com wrote: >> From: Yisheng Xie >> >> @@ -1527,7 +1527,8 @@ static int get_any_page(struct page *page, unsigned long pfn, int flags) >> { >> int ret = __get_any_page(page, pfn, flags); >> >> - if (ret == 1 && !PageHuge(page) && !PageLRU(page)) { >> + if (ret == 1 && !PageHuge(page) && >> + !PageLRU(page) && !__PageMovable(page)) { > > __PageMovable without holding page_lock could be raced so need to check > if it's okay to miss some of pages offlining by the race. > When I read description of soft_offline_page, it seems to be okay. > Just wanted double check. :) Yes, I have thought about whether should add page_lock to avoid race. For it is ok to miss some of pages caused by race, I do not add page_lock. > >> /* >> * Try to free it. >> */ >> @@ -1609,7 +1610,7 @@ static int soft_offline_huge_page(struct page *page, int flags) >> >> static int __soft_offline_page(struct page *page, int flags) >> { >> - int ret; >> + int ret = -1; >> unsigned long pfn = page_to_pfn(page); >> >> /* >> @@ -1619,7 +1620,8 @@ static int __soft_offline_page(struct page *page, int flags) >> * so there's no race between soft_offline_page() and memory_failure(). >> */ >> lock_page(page); >> - wait_on_page_writeback(page); >> + if (PageLRU(page)) >> + wait_on_page_writeback(page); > > I doubt we need to add such limitation(i.e., Only LRU pages could be write-backed). > Do you have some reason to add that code? I add this check for not quite sure about whether non-lru page will as marked as PageWriteBack(page). I will delete no need limitation in next version. > >> if (PageHWPoison(page)) { >> unlock_page(page); >> put_hwpoison_page(page); >> @@ -1630,7 +1632,8 @@ static int __soft_offline_page(struct page *page, int flags) >> * Try to invalidate first. This should work for >> * non dirty unmapped page cache pages. >> */ >> - ret = invalidate_inode_page(page); >> + if (PageLRU(page)) >> + ret = invalidate_inode_page(page); > > Ditto. > >> unlock_page(page); >> /* >> * RED-PEN would be better to keep it isolated here, but we >> @@ -1649,7 +1652,10 @@ static int __soft_offline_page(struct page *page, int flags) >> * Try to migrate to a new page instead. migrate.c >> * handles a large number of cases for us. >> */ >> - ret = isolate_lru_page(page); >> + if (PageLRU(page)) >> + ret = isolate_lru_page(page); >> + else >> + ret = !isolate_movable_page(page, ISOLATE_UNEVICTABLE); >> /* >> * Drop page reference which is came from get_any_page() >> * successful isolate_lru_page() already took another one. >> @@ -1657,18 +1663,15 @@ static int __soft_offline_page(struct page *page, int flags) >> put_hwpoison_page(page); >> if (!ret) { >> LIST_HEAD(pagelist); >> - inc_node_page_state(page, NR_ISOLATED_ANON + >> + if (PageLRU(page)) > > isolate_lru_page removes PG_lru so this check will be false. Namely, happens > isolated count mismatch happens. > Really sorry about that. That's my mistake. I will use !__PageMovable(page) instead in v3. Thanks Yisheng Xie.