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=-13.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,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 82B98C433FE for ; Fri, 4 Dec 2020 17:13:03 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 039C022B30 for ; Fri, 4 Dec 2020 17:13:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 039C022B30 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 69AC26B005C; Fri, 4 Dec 2020 12:13:02 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 64B0E6B005D; Fri, 4 Dec 2020 12:13:02 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 560576B006E; Fri, 4 Dec 2020 12:13:02 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0122.hostedemail.com [216.40.44.122]) by kanga.kvack.org (Postfix) with ESMTP id 4033B6B005C for ; Fri, 4 Dec 2020 12:13:02 -0500 (EST) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 043A03620 for ; Fri, 4 Dec 2020 17:13:02 +0000 (UTC) X-FDA: 77556245004.02.watch38_300a574273c6 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin02.hostedemail.com (Postfix) with ESMTP id D872610097AA3 for ; Fri, 4 Dec 2020 17:13:01 +0000 (UTC) X-HE-Tag: watch38_300a574273c6 X-Filterd-Recvd-Size: 3622 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [63.128.21.124]) by imf19.hostedemail.com (Postfix) with ESMTP for ; Fri, 4 Dec 2020 17:13:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607101980; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=nag/x65iAPAl/1Alf3Nf9G48tZh8GI4qc8JEI5vv/wk=; b=eCRvq9VvhmKn/IDNz1UTyjX/PJQeFqPKiarAst/khoc8FW7PVF3V28VV/FRzr0ta08dOSh DkkS43cANssQVhrP5WHo1YeSa7CO4mByEkBR54blZTO4TkLIBo84OgjtOGpnRoluwfkV9d hStCmdChocSDIgQkcRh8Hvr8phF+msw= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-480-oCOkwryzMNixMwsWKjQ0Hw-1; Fri, 04 Dec 2020 12:12:58 -0500 X-MC-Unique: oCOkwryzMNixMwsWKjQ0Hw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1939AC7401; Fri, 4 Dec 2020 17:12:57 +0000 (UTC) Received: from [10.36.112.162] (ovpn-112-162.ams2.redhat.com [10.36.112.162]) by smtp.corp.redhat.com (Postfix) with ESMTP id C7CA310023AE; Fri, 4 Dec 2020 17:12:55 +0000 (UTC) Subject: Re: [External] Re: [PATCH v2] mm/page_isolation: do not isolate the max order page To: Muchun Song Cc: Andrew Morton , Linux Memory Management List , LKML , Vlastimil Babka References: <20201203162237.21885-1-songmuchun@bytedance.com> <46fcf0c1-7c38-723b-8905-953d72f1d6bc@redhat.com> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <49b09de4-4b21-e6a7-0730-e125fcb398b3@redhat.com> Date: Fri, 4 Dec 2020 18:12:55 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 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 04.12.20 17:12, Muchun Song wrote: > On Fri, Dec 4, 2020 at 12:28 AM David Hildenbrand wrote: >> >> On 03.12.20 17:22, Muchun Song wrote: >>> The max order page has no buddy page and never merge to other order. >>> So isolating and then freeing it is pointless. And if order == MAX_ORDER >>> - 1, then the buddy can actually be a !pfn_valid() in some corner case? >>> pfn_valid_within(buddy_pfn) that follows would only catch it on archs >>> with holes in zone. Then is_migrate_isolate_page(buddy) might access an >>> invalid buddy. So this is also a bug fix. >>> >>> Fixes: 3c605096d315 ("mm/page_alloc: restrict max order of merging on isolated pageblock") >> >> As just replied to v1, I don't think this is required and the patch > > You mean we should remove the Fixes tag? Thanks. As discussed in v1, I don't think we really have systems where this applies, but could be in corner cases on MIPS or with FLATMEM. Let's just leave it like that. :) Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb