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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_SANE_2 autolearn=unavailable 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 7CC60C4360C for ; Fri, 4 Oct 2019 07:59:44 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 48068222CA for ; Fri, 4 Oct 2019 07:59:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 48068222CA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=mediatek.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B665A8E0003; Fri, 4 Oct 2019 03:59:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B3EB76B0008; Fri, 4 Oct 2019 03:59:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A53AD8E0003; Fri, 4 Oct 2019 03:59:43 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0150.hostedemail.com [216.40.44.150]) by kanga.kvack.org (Postfix) with ESMTP id 82D346B0007 for ; Fri, 4 Oct 2019 03:59:43 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 4093E181AC9AE for ; Fri, 4 Oct 2019 07:59:43 +0000 (UTC) X-FDA: 76005353046.17.nerve79_8eebe6fda6151 X-HE-Tag: nerve79_8eebe6fda6151 X-Filterd-Recvd-Size: 3816 Received: from mailgw01.mediatek.com (unknown [210.61.82.183]) by imf01.hostedemail.com (Postfix) with ESMTP for ; Fri, 4 Oct 2019 07:59:41 +0000 (UTC) X-UUID: 144424648c3244ed8d0c6c7f5cadc265-20191004 X-UUID: 144424648c3244ed8d0c6c7f5cadc265-20191004 Received: from mtkcas09.mediatek.inc [(172.21.101.178)] by mailgw01.mediatek.com (envelope-from ) (Cellopoint E-mail Firewall v4.1.10 Build 0809 with TLS) with ESMTP id 1001643015; Fri, 04 Oct 2019 15:59:35 +0800 Received: from mtkcas08.mediatek.inc (172.21.101.126) by mtkmbs07n2.mediatek.inc (172.21.101.141) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Fri, 4 Oct 2019 15:59:33 +0800 Received: from [172.21.77.33] (172.21.77.33) by mtkcas08.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1395.4 via Frontend Transport; Fri, 4 Oct 2019 15:59:33 +0800 Message-ID: <1570175974.23700.0.camel@mtkswgap22> Subject: Re: [PATCH] mm/page_owner: fix incorrect looping in __set_page_owner_handle() From: Miles Chen To: Vlastimil Babka CC: Andrew Morton , , , , , Michal Hocko Date: Fri, 4 Oct 2019 15:59:34 +0800 In-Reply-To: References: <20191004073755.3228-1-miles.chen@mediatek.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit MIME-Version: 1.0 X-MTK: N X-Bogosity: Ham, tests=bogofilter, spamicity=0.000027, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, 2019-10-04 at 09:57 +0200, Vlastimil Babka wrote: > On 10/4/19 9:37 AM, Miles Chen wrote: > > In __set_page_owner_handle(), we should loop over page > > [0...(1 << order) - 1] and setup their page_owner structures. > > > > Currently, __set_page_owner_handle() update page_ext at the end of > > the loop, sets the page_owner of (page + 0) twice and > > misses the page_owner of (page + (1 << order) - 1). > > > > Fix it by updating the page_ext at the start of the loop. > > > > In i == 0 case: > > for (i = 0; i < (1 << order); i++) { > > page_owner = get_page_owner(page_ext); <- page_ext belongs to page + 0 > > ... > > page_ext = lookup_page_ext(page + i); <- lookup_page_ext(page + 0) > > } > > > > Cc: Andrew Morton > > Cc: Vlastimil Babka > > Cc: Michal Hocko > > Signed-off-by: Miles Chen > > Fixes: 7e2f2a0cd17c ("mm, page_owner: record page owner for each subpage") > > Thanks. Kirill spotted it earlier and there's a fix pending: > https://lore.kernel.org/linux-mm/20190930122916.14969-2-vbabka@suse.cz/ Great. thanks for the information. Miles > > > --- > > mm/page_owner.c | 3 +-- > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > diff --git a/mm/page_owner.c b/mm/page_owner.c > > index dee931184788..110c3e1987f2 100644 > > --- a/mm/page_owner.c > > +++ b/mm/page_owner.c > > @@ -178,6 +178,7 @@ static inline void __set_page_owner_handle(struct page *page, > > int i; > > > > for (i = 0; i < (1 << order); i++) { > > + page_ext = lookup_page_ext(page + i); > > page_owner = get_page_owner(page_ext); > > page_owner->handle = handle; > > page_owner->order = order; > > @@ -185,8 +186,6 @@ static inline void __set_page_owner_handle(struct page *page, > > page_owner->last_migrate_reason = -1; > > __set_bit(PAGE_EXT_OWNER, &page_ext->flags); > > __set_bit(PAGE_EXT_OWNER_ACTIVE, &page_ext->flags); > > - > > - page_ext = lookup_page_ext(page + i); > > } > > } > > > > >