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=-2.3 required=3.0 tests=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 C3A3ECA9EAE for ; Tue, 29 Oct 2019 10:45:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8A8A120874 for ; Tue, 29 Oct 2019 10:45:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8A8A120874 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 081506B0005; Tue, 29 Oct 2019 06:45:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 00B9C6B0006; Tue, 29 Oct 2019 06:45:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E3D226B0007; Tue, 29 Oct 2019 06:45:23 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0068.hostedemail.com [216.40.44.68]) by kanga.kvack.org (Postfix) with ESMTP id B91696B0005 for ; Tue, 29 Oct 2019 06:45:23 -0400 (EDT) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 66B2F181AF5C6 for ; Tue, 29 Oct 2019 10:45:23 +0000 (UTC) X-FDA: 76096490526.13.loaf41_85e8dd3e0005a X-HE-Tag: loaf41_85e8dd3e0005a X-Filterd-Recvd-Size: 2501 Received: from huawei.com (szxga05-in.huawei.com [45.249.212.191]) by imf42.hostedemail.com (Postfix) with ESMTP for ; Tue, 29 Oct 2019 10:45:20 +0000 (UTC) Received: from DGGEMS414-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id B9FDE2014F5031F08BFC; Tue, 29 Oct 2019 18:45:14 +0800 (CST) Received: from [127.0.0.1] (10.133.219.218) by DGGEMS414-HUB.china.huawei.com (10.3.19.214) with Microsoft SMTP Server id 14.3.439.0; Tue, 29 Oct 2019 18:45:13 +0800 Message-ID: <5DB81838.6020208@huawei.com> Date: Tue, 29 Oct 2019 18:45:12 +0800 From: zhong jiang User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Michal Hocko CC: , , , , Minchan Kim Subject: Re: [PATCH] mm: fix unevictable page reclaim when calling madvise_pageout References: <1572275317-63910-1-git-send-email-zhongjiang@huawei.com> <20191029081102.GB31513@dhcp22.suse.cz> <5DB806D1.8020503@huawei.com> <20191029094039.GH31513@dhcp22.suse.cz> In-Reply-To: <20191029094039.GH31513@dhcp22.suse.cz> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.133.219.218] X-CFilter-Loop: Reflected 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 2019/10/29 17:40, Michal Hocko wrote: > On Tue 29-10-19 17:30:57, zhong jiang wrote: >> On 2019/10/29 16:11, Michal Hocko wrote: >>> [Cc Minchan] > [...] >>> Removing a long existing BUG_ON begs for a much better explanation. >>> shrink_page_list is not a trivial piece of code but I _suspect_ that >>> removing it should be ok for mapped pages at least (try_to_unmap) but I >>> am not so sure how unmapped unevictable pages are handled from top of my >>> head. >> As to the unmapped unevictable pages. shrink_page_list has taken that into account. >> >> shinkr_page_list >> page_evictable --> will filter the unevictable pages to putback its lru. > Ohh, it is right there at the top. Missed it. The check has been added > by Nick along with the BUG_ON. So it is sounds more like a "this > shouldn't happen" bugon. I wouldn't mind to remove it with that > justification. As you has said, Minchan fix the same kind of bug by checking PageUnevictable (I did not notice before) Wait for Minchan to see whether he has better reason. thanks, Sincerely, zhong jiang