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=-9.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 DB2E1C00A89 for ; Fri, 30 Oct 2020 09:43:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7BDD720756 for ; Fri, 30 Oct 2020 09:43:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="Qk8xKAH6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726181AbgJ3JnM (ORCPT ); Fri, 30 Oct 2020 05:43:12 -0400 Received: from mx2.suse.de ([195.135.220.15]:57436 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725355AbgJ3JnM (ORCPT ); Fri, 30 Oct 2020 05:43:12 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1604050991; 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: in-reply-to:in-reply-to:references:references; bh=gW6rXL0xOJtuSZA4czIEKpIyYPqMh5pKjDm6Kj1ppXA=; b=Qk8xKAH6MT53xLObk/CIJp7ZTYxN3ioKcYbgVqYnVuXXBbfLb08DBybQKXLVHr4SH8OC2D sEenGfV+rHgM3Y8Hl4OQT2+CR8I+EBkRK6QHxidqn3fo+AH0axwrwZP/I6JKMZNTmrEJSc ahgM/spuXLIvfuk4Ddesotk9kRxl5pg= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 1FCD6AD49; Fri, 30 Oct 2020 09:43:11 +0000 (UTC) Date: Fri, 30 Oct 2020 10:43:08 +0100 From: Michal Hocko To: Zi Yan Cc: Andrew Morton , linux-mm@kvack.org, Rik van Riel , linux-kernel@vger.kernel.org, Vlastimil Babka Subject: Re: [PATCH] mm/compaction: count pages and stop correctly during page isolation. Message-ID: <20201030094308.GG1478@dhcp22.suse.cz> References: <20201029200435.3386066-1-zi.yan@sent.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201029200435.3386066-1-zi.yan@sent.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [Cc Vlastimil] On Thu 29-10-20 16:04:35, Zi Yan wrote: > From: Zi Yan > > In isolate_migratepages_block, when cc->alloc_contig is true, we are > able to isolate compound pages, nr_migratepages and nr_isolated did not > count compound pages correctly, causing us to isolate more pages than we > thought. Use thp_nr_pages to count pages. Otherwise, we might be trapped > in too_many_isolated while loop, since the actual isolated pages can go > up to COMPACT_CLUSTER_MAX*512=16384, where COMPACT_CLUSTER_MAX is 32, > since we stop isolation after cc->nr_migratepages reaches to > COMPACT_CLUSTER_MAX. > > In addition, after we fix the issue above, cc->nr_migratepages could > never be equal to COMPACT_CLUSTER_MAX if compound pages are isolated, > thus page isolation could not stop as we intended. Change the isolation > stop condition to >=. > > Signed-off-by: Zi Yan > --- > mm/compaction.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/mm/compaction.c b/mm/compaction.c > index ee1f8439369e..0683a4999581 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -1012,8 +1012,8 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, > > isolate_success: > list_add(&page->lru, &cc->migratepages); > - cc->nr_migratepages++; > - nr_isolated++; > + cc->nr_migratepages += thp_nr_pages(page); > + nr_isolated += thp_nr_pages(page); Does thp_nr_pages work for __PageMovable pages? -- Michal Hocko SUSE Labs