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=-18.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 6429BC4361A for ; Thu, 3 Dec 2020 16:28:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0C25A207A5 for ; Thu, 3 Dec 2020 16:28:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731271AbgLCQ2i (ORCPT ); Thu, 3 Dec 2020 11:28:38 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:29201 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726508AbgLCQ2i (ORCPT ); Thu, 3 Dec 2020 11:28:38 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607012832; 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=AKLnCPWi5C0uhOXWYAhcEf6SIUd8pMCmc8cjsrwC2Vw=; b=KWMt9Y4zkjqe+04aFI9oUv+AHfUZQimWGAHPkc5+oMYK8soOyzIVTq6yPfIUdej2E7io9i qt62NT/yDGtxBP1+znW+xRUa8V7CtdN4rs/4ibm3xZ1i4hH1jFI0jMddQjd47L+/rYN6zf x+InUhR1v53JYnaoYG+iryWiE2Ynz/Q= 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-131-cTAmb5S7OcWbeNkMp5F9Fg-1; Thu, 03 Dec 2020 11:27:10 -0500 X-MC-Unique: cTAmb5S7OcWbeNkMp5F9Fg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 06961425F7; Thu, 3 Dec 2020 16:27:09 +0000 (UTC) Received: from [10.36.113.250] (ovpn-113-250.ams2.redhat.com [10.36.113.250]) by smtp.corp.redhat.com (Postfix) with ESMTP id 214585D730; Thu, 3 Dec 2020 16:27:07 +0000 (UTC) Subject: Re: [PATCH] mm/page_isolation: do not isolate the max order page To: Muchun Song , akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20201202122114.75316-1-songmuchun@bytedance.com> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: Date: Thu, 3 Dec 2020 17:27:07 +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: <20201202122114.75316-1-songmuchun@bytedance.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02.12.20 13:21, 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. > > Signed-off-by: Muchun Song > --- > mm/page_isolation.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/page_isolation.c b/mm/page_isolation.c > index a254e1f370a3..bddf788f45bf 100644 > --- a/mm/page_isolation.c > +++ b/mm/page_isolation.c > @@ -88,7 +88,7 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype) > */ > if (PageBuddy(page)) { > order = buddy_order(page); > - if (order >= pageblock_order) { > + if (order >= pageblock_order && order < MAX_ORDER - 1) { > pfn = page_to_pfn(page); > buddy_pfn = __find_buddy_pfn(pfn, order); > buddy = page + (buddy_pfn - pfn); > Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb