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=-17.3 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=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 BFCE3C5519F for ; Fri, 27 Nov 2020 16:54:55 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5548620795 for ; Fri, 27 Nov 2020 16:54:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="beCOG855" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5548620795 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 869276B006E; Fri, 27 Nov 2020 11:54:53 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 818896B0070; Fri, 27 Nov 2020 11:54:53 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 706316B0071; Fri, 27 Nov 2020 11:54:53 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0125.hostedemail.com [216.40.44.125]) by kanga.kvack.org (Postfix) with ESMTP id 588FA6B006E for ; Fri, 27 Nov 2020 11:54:53 -0500 (EST) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 20A88181AEF23 for ; Fri, 27 Nov 2020 16:54:53 +0000 (UTC) X-FDA: 77530797666.25.girls19_4008dc727389 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin25.hostedemail.com (Postfix) with ESMTP id EBDD61804E51E for ; Fri, 27 Nov 2020 16:54:52 +0000 (UTC) X-HE-Tag: girls19_4008dc727389 X-Filterd-Recvd-Size: 5755 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by imf28.hostedemail.com (Postfix) with ESMTP for ; Fri, 27 Nov 2020 16:54:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606496091; 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=Tx+GfsVOFcrsJYDT8eLtFbbzr7c2bwydoMQi58xzc1A=; b=beCOG855UMCrTcCNOMVxUPj/QLNglIhqqf8U91KNlm/j5viezOWM836/ij69fCKFywPLZi 3D1SciggkAwLuVy05hb2OWEZCvNXBdzNRFtOfoYe11lhqwfabTf2BgR8thqVRIKc8pwf2/ 9vC9/zmhcJiYG12qXuk4BK54NYje2lI= 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-439-jx1GPTbXM8GvE0Ry2_Qj7w-1; Fri, 27 Nov 2020 11:54:49 -0500 X-MC-Unique: jx1GPTbXM8GvE0Ry2_Qj7w-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B25591005D5F; Fri, 27 Nov 2020 16:54:48 +0000 (UTC) Received: from [10.36.114.118] (ovpn-114-118.ams2.redhat.com [10.36.114.118]) by smtp.corp.redhat.com (Postfix) with ESMTP id CF8E26085D; Fri, 27 Nov 2020 16:54:46 +0000 (UTC) Subject: Re: [PATCH] mm/page_alloc: Do not isolate redundant pageblock To: Muchun Song , akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20201127141900.43348-1-songmuchun@bytedance.com> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <54061152-2a1b-694f-8d45-d1333bc4a3fb@redhat.com> Date: Fri, 27 Nov 2020 17:54:45 +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: <20201127141900.43348-1-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 10.5.11.13 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 27.11.20 15:19, Muchun Song wrote: > Current pageblock isolation logic could isolate each pageblock individually > since commit d9dddbf55667 ("mm/page_alloc: prevent merging between isolated > and other pageblocks"). So we not need to concern about page allocator > merges buddies from different pageblocks and changes MIGRATE_ISOLATE to > some other migration type. > > Signed-off-by: Muchun Song > --- > mm/page_alloc.c | 26 ++++++++------------------ > 1 file changed, 8 insertions(+), 18 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index cefbef32bf4a..608a2c2b8ab7 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -8313,16 +8313,14 @@ struct page *has_unmovable_pages(struct zone *zone, struct page *page, > } > > #ifdef CONFIG_CONTIG_ALLOC > -static unsigned long pfn_max_align_down(unsigned long pfn) > +static unsigned long pfn_align_down(unsigned long pfn) > { > - return pfn & ~(max_t(unsigned long, MAX_ORDER_NR_PAGES, > - pageblock_nr_pages) - 1); > + return pfn & ~(pageblock_nr_pages - 1); > } > > -static unsigned long pfn_max_align_up(unsigned long pfn) > +static unsigned long pfn_align_up(unsigned long pfn) > { > - return ALIGN(pfn, max_t(unsigned long, MAX_ORDER_NR_PAGES, > - pageblock_nr_pages)); > + return ALIGN(pfn, pageblock_nr_pages); > } > > /* [start, end) must belong to a single zone. */ > @@ -8415,14 +8413,6 @@ int alloc_contig_range(unsigned long start, unsigned long end, > INIT_LIST_HEAD(&cc.migratepages); > > /* > - * What we do here is we mark all pageblocks in range as > - * MIGRATE_ISOLATE. Because pageblock and max order pages may > - * have different sizes, and due to the way page allocator > - * work, we align the range to biggest of the two pages so > - * that page allocator won't try to merge buddies from > - * different pageblocks and change MIGRATE_ISOLATE to some > - * other migration type. > - * > * Once the pageblocks are marked as MIGRATE_ISOLATE, we > * migrate the pages from an unaligned range (ie. pages that > * we are interested in). This will put all the pages in > @@ -8438,8 +8428,8 @@ int alloc_contig_range(unsigned long start, unsigned long end, > * put back to page allocator so that buddy can use them. > */ > > - ret = start_isolate_page_range(pfn_max_align_down(start), > - pfn_max_align_up(end), migratetype, 0); > + ret = start_isolate_page_range(pfn_align_down(start), pfn_align_up(end), > + migratetype, 0); > if (ret) > return ret; > > @@ -8522,8 +8512,8 @@ int alloc_contig_range(unsigned long start, unsigned long end, > free_contig_range(end, outer_end - end); > > done: > - undo_isolate_page_range(pfn_max_align_down(start), > - pfn_max_align_up(end), migratetype); > + undo_isolate_page_range(pfn_align_down(start), pfn_align_up(end), > + migratetype); > return ret; > } > EXPORT_SYMBOL(alloc_contig_range); > Last time I checked, set_migratetype_isolate()->has_unmovable_pages() was not prepared for that in case of !CMA and !ZONE_MOVABLE. Assume you have an unmovable MAX_ORDER - 1 page that spans two pageblocks (e.g., x86-64). Assume you try to isolate the second pageblock. IIRC, you would answer "yes", as the refcount of all involved pages is 0. How did you test this works as expected? -- Thanks, David / dhildenb