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,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 E2210C64E7B for ; Tue, 17 Nov 2020 13:40:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 759E22467D for ; Tue, 17 Nov 2020 13:40:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="hpTZM7UH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732296AbgKQNkV (ORCPT ); Tue, 17 Nov 2020 08:40:21 -0500 Received: from mail.kernel.org ([198.145.29.99]:52024 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732826AbgKQNkM (ORCPT ); Tue, 17 Nov 2020 08:40:12 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0A7B020870; Tue, 17 Nov 2020 13:40:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1605620411; bh=E9Io8XLxHspcMQcCzOCAH/XkfAhwNHImE3ViluL+oiM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hpTZM7UHNLSu19VGR4+DsiMtCkF2He6KDcKivOKCysyi7SSp+1u6N8LRgtMSoKoyi OU6e8F+xl1zkBpJrJ+Eyck5CQTSULQoAshkjDc0I9yNrxoamBVnRRBG4ktrzVwOQJr NqmvPYDj4tI6Tbs4wSRLitgysaowvd4eIrzWpL7s= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zi Yan , Andrew Morton , Yang Shi , Vlastimil Babka , Rik van Riel , Michal Hocko , Mel Gorman , Linus Torvalds Subject: [PATCH 5.9 209/255] mm/compaction: count pages and stop correctly during page isolation Date: Tue, 17 Nov 2020 14:05:49 +0100 Message-Id: <20201117122149.104711341@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201117122138.925150709@linuxfoundation.org> References: <20201117122138.925150709@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Zi Yan commit 38935861d85a4d9a353d1dd5a156c97700e2765d upstream. In isolate_migratepages_block, when cc->alloc_contig is true, we are able to isolate compound pages. But nr_migratepages and nr_isolated did not count compound pages correctly, causing us to isolate more pages than we thought. So count compound pages as the number of base pages they contain. 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 '>='. The issue can be triggered as follows: In a system with 16GB memory and an 8GB CMA region reserved by hugetlb_cma, if we first allocate 10GB THPs and mlock them (so some THPs are allocated in the CMA region and mlocked), reserving 6 1GB hugetlb pages via /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages will get stuck (looping in too_many_isolated function) until we kill either task. With the patch applied, oom will kill the application with 10GB THPs and let hugetlb page reservation finish. [ziy@nvidia.com: v3] Link: https://lkml.kernel.org/r/20201030183809.3616803-1-zi.yan@sent.com Fixes: 1da2f328fa64 ("cmm,thp,compaction,cma: allow THP migration for CMA allocations") Signed-off-by: Zi Yan Signed-off-by: Andrew Morton Reviewed-by: Yang Shi Acked-by: Vlastimil Babka Cc: Rik van Riel Cc: Michal Hocko Cc: Mel Gorman Cc: Link: https://lkml.kernel.org/r/20201029200435.3386066-1-zi.yan@sent.com Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/compaction.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1013,8 +1013,8 @@ isolate_migratepages_block(struct compac isolate_success: list_add(&page->lru, &cc->migratepages); - cc->nr_migratepages++; - nr_isolated++; + cc->nr_migratepages += compound_nr(page); + nr_isolated += compound_nr(page); /* * Avoid isolating too much unless this block is being @@ -1022,7 +1022,7 @@ isolate_success: * or a lock is contended. For contention, isolate quickly to * potentially remove one source of contention. */ - if (cc->nr_migratepages == COMPACT_CLUSTER_MAX && + if (cc->nr_migratepages >= COMPACT_CLUSTER_MAX && !cc->rescan && !cc->contended) { ++low_pfn; break; @@ -1133,7 +1133,7 @@ isolate_migratepages_range(struct compac if (!pfn) break; - if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) + if (cc->nr_migratepages >= COMPACT_CLUSTER_MAX) break; }