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=-17.6 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 47899C433FE for ; Mon, 6 Sep 2021 12:08:59 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C992261057 for ; Mon, 6 Sep 2021 12:08:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org C992261057 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 6F9756B0071; Mon, 6 Sep 2021 08:08:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6829B900002; Mon, 6 Sep 2021 08:08:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5714B6B0073; Mon, 6 Sep 2021 08:08:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0128.hostedemail.com [216.40.44.128]) by kanga.kvack.org (Postfix) with ESMTP id 489456B0071 for ; Mon, 6 Sep 2021 08:08:58 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id E0D84181AF5C6 for ; Mon, 6 Sep 2021 12:08:57 +0000 (UTC) X-FDA: 78557027514.18.53F3D06 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by imf03.hostedemail.com (Postfix) with ESMTP id B9AA230000AE for ; Mon, 6 Sep 2021 12:08:56 +0000 (UTC) Received: from dggeme703-chm.china.huawei.com (unknown [172.30.72.53]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4H36cV2wQSz8ssd; Mon, 6 Sep 2021 20:08:26 +0800 (CST) Received: from [10.174.178.100] (10.174.178.100) 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, 6 Sep 2021 20:08:53 +0800 Subject: Re: [PATCH] mm/page_isolation: don't putback unisolated page To: David Hildenbrand , CC: , , , References: <20210904091839.20270-1-linmiaohe@huawei.com> <5f7c4ac9-d17a-5af3-0326-1152cca38465@redhat.com> <2b103abc-2921-9d8a-7280-1d6b451c34f4@redhat.com> From: Miaohe Lin Message-ID: <3a9921cd-1393-f67c-1002-1320b9d1668d@huawei.com> Date: Mon, 6 Sep 2021 20:08:53 +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: <2b103abc-2921-9d8a-7280-1d6b451c34f4@redhat.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US X-Originating-IP: [10.174.178.100] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggeme703-chm.china.huawei.com (10.1.199.99) X-CFilter-Loop: Reflected Authentication-Results: imf03.hostedemail.com; dkim=none; spf=pass (imf03.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.189 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com; dmarc=pass (policy=none) header.from=huawei.com X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: B9AA230000AE X-Stat-Signature: y587nnw4tk53ugjanp3oh8t56sry8eaw X-HE-Tag: 1630930136-540585 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 2021/9/6 20:01, David Hildenbrand wrote: > On 06.09.21 13:50, David Hildenbrand wrote: >> On 06.09.21 13:32, Miaohe Lin wrote: >>> On 2021/9/6 17:40, David Hildenbrand wrote: >>>> On 04.09.21 11:18, Miaohe Lin wrote: >>>>> If __isolate_free_page() failed, due to zone watermark check, the p= age is >>>>> still on the free list. But this page will be put back to free list= again >>>>> via __putback_isolated_page() now. This may trigger page->flags che= cks in >>>>> __free_one_page() if PageReported is set. Or we will corrupt the fr= ee list >>>>> because list_add() will be called for pages already on another list= . >>>>> >>>>> Fixes: 3c605096d315 ("mm/page_alloc: restrict max order of merging = on isolated pageblock") >>>>> Signed-off-by: Miaohe Lin >>>>> --- >>>>> =C2=A0 =C2=A0 mm/page_isolation.c | 6 ++---- >>>>> =C2=A0 =C2=A0 1 file changed, 2 insertions(+), 4 deletions(-) >>>>> >>>>> diff --git a/mm/page_isolation.c b/mm/page_isolation.c >>>>> index 9bb562d5d194..7d70d772525c 100644 >>>>> --- a/mm/page_isolation.c >>>>> +++ b/mm/page_isolation.c >>>>> @@ -93,10 +93,8 @@ static void unset_migratetype_isolate(struct pag= e *page, unsigned migratetype) >>>>> =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 buddy_pfn =3D __find_buddy_pfn(pfn, order); >>>>> =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 buddy =3D page + (buddy_pfn - pfn); >>>>> =C2=A0 =C2=A0 -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0 if (!is_migrate_isolate_page(buddy)) { >>>>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0 __isolate_free_page(page, order); >>>>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0 isolated_page =3D true; >>>>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= } >>>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= if (!is_migrate_isolate_page(buddy)) >>>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0 isolated_page =3D !!__isolate_free_page(page, or= der); >>>>> =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } >>>>> =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } >>>>> =C2=A0=C2=A0=20 >>>> >>>> Shouldn't we much rather force to ignore watermarks here and make su= re __isolate_free_page() never fails? >>> >>> It seems it is not easy to force to ignore watermarks here. And it's = not a problem >>> if __isolate_free_page() fails because we can do move_freepages_block= () anyway. >>> What do you think? Many thanks. >> >> I'm wondering if all this complexity in this function is even required= . What about something like this: (completely untested) >> >> diff --git a/mm/page_isolation.c b/mm/page_isolation.c >> index bddf788f45bf..29ff2fcb339c 100644 >> --- a/mm/page_isolation.c >> +++ b/mm/page_isolation.c >> @@ -66,12 +66,10 @@ static int set_migratetype_isolate(struct page *pa= ge, int migratetype, int isol_ >> =C2=A0=C2=A0 =C2=A0=C2=A0 static void unset_migratetype_isolate(struct= page *page, unsigned migratetype) >> =C2=A0=C2=A0 { >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 bool buddy_merge_possible =3D fa= lse; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct zone *zo= ne; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long f= lags, nr_pages; >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 bool isolated_page =3D false; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned int or= der; >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long pfn, buddy_pfn; >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct page *buddy; >> =C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 zo= ne =3D page_zone(page); >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 spin_lock_irqsa= ve(&zone->lock, flags); >> @@ -79,26 +77,15 @@ static void unset_migratetype_isolate(struct page = *page, unsigned migratetype) >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 goto out; >> =C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * Because freepage with mo= re than pageblock_order on isolated >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * pageblock is restricted = to merge due to freepage counting problem, >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * it is possible that ther= e is free buddy page. >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * move_freepages_block() d= oesn't care of merge so we need other >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * approach in order to mer= ge them. Isolation and free will make >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * these pages to be merged= . >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * If our free page spans a= t least this whole pageblock and could >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * eventually get merged in= to an even bigger page, go via >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * __putback_isolated_page(= ), because move_freepages_block() won't >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * trigger merging of free = pages. >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 */ >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (PageBuddy(p= age)) { >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 order =3D buddy_order(page); >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0 if (order >=3D pageblock_order && order < MAX_ORDER - 1) = { >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pfn =3D p= age_to_pfn(page); >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 buddy_pfn= =3D __find_buddy_pfn(pfn, order); >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 buddy =3D= page + (buddy_pfn - pfn); >> - >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (pfn_v= alid_within(buddy_pfn) && >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0 !is_migrate_isolate_page(buddy)) { >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 __isolate_free_page(page, order); >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 isolated_page =3D true; >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0 } >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0 if (order >=3D pageblock_order && order < MAX_ORDER - 1) >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 buddy_mer= ge_possible =3D true; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } >> =C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* >> @@ -111,12 +98,12 @@ static void unset_migratetype_isolate(struct page= *page, unsigned migratetype) >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * onlinin= g - just onlined memory won't immediately be considered for >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * allocat= ion. >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 */ >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (!isolated_page) { >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (!buddy_merge_possible) { >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 nr_pages =3D move_freepages_block(zone, pa= ge, migratetype, NULL); >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 __mod_zone_freepage_state(zone, nr_pages, = migratetype); >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 set_pageblock_m= igratetype(page, migratetype); >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (isolated_page) >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (buddy_merge_possible) >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 __putback_isolated_page(page, order, migra= tetype); >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 zone->nr_isolat= e_pageblock--; >> =C2=A0=C2=A0 out: >=20 > Okay, I just had another look -- that won't work because as you correct= ly said, it still is on the freelist ... >=20 > So your fix is certainly correct :) Many thanks for your effort and suggestion. :) >