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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 1242DC433E0 for ; Wed, 24 Feb 2021 20:12:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CED1B64E20 for ; Wed, 24 Feb 2021 20:12:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235543AbhBXULl (ORCPT ); Wed, 24 Feb 2021 15:11:41 -0500 Received: from mail.kernel.org ([198.145.29.99]:33776 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235427AbhBXUKV (ORCPT ); Wed, 24 Feb 2021 15:10:21 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3626E64F08; Wed, 24 Feb 2021 20:09:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1614197380; bh=VV6ZulOy2kH1v4Md6bTtg1bw8UcpYGu+3f/5IWxm+AE=; h=Date:From:To:Subject:In-Reply-To:From; b=vP6hVi4+mA48JEBv/XbAVy3giNWWIgob9CiX0fd69Xjersrv61MOqia/yl3pJuNIL ov0ujnwWJevafn16RetSlB83DYQ9WUQDUDoEhFyp5bG5e/svxnI5FFqrPSqaBdhVkV IjUbInV6VzzHt2CJwuS0LuiFORhbebSny6ud0Z6o= Date: Wed, 24 Feb 2021 12:09:39 -0800 From: Andrew Morton To: aarcange@redhat.com, akpm@linux-foundation.org, david@redhat.com, linux-mm@kvack.org, mgorman@techsingularity.net, mhocko@kernel.org, mm-commits@vger.kernel.org, rientjes@google.com, rppt@kernel.org, stable@vger.kernel.org, torvalds@linux-foundation.org, vbabka@suse.cz Subject: [patch 159/173] mm, compaction: make fast_isolate_freepages() stay within zone Message-ID: <20210224200939.yLPGAqLE6%akpm@linux-foundation.org> In-Reply-To: <20210224115824.1e289a6895087f10c41dd8d6@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Vlastimil Babka Subject: mm, compaction: make fast_isolate_freepages() stay within zone Compaction always operates on pages from a single given zone when isolating both pages to migrate and freepages. Pageblock boundaries are intersected with zone boundaries to be safe in case zone starts or ends in the middle of pageblock. The use of pageblock_pfn_to_page() protects against non-contiguous pageblocks. The functions fast_isolate_freepages() and fast_isolate_around() don't currently protect the fast freepage isolation thoroughly enough against these corner cases, and can result in freepage isolation operate outside of zone boundaries: - in fast_isolate_freepages() if we get a pfn from the first pageblock of a zone that starts in the middle of that pageblock, 'highest' can be a pfn outside of the zone. If we fail to isolate anything in this function, we may then call fast_isolate_around() on a pfn outside of the zone and there effectively do a set_pageblock_skip(page_to_pfn(highest)) which may currently hit a VM_BUG_ON() in some configurations - fast_isolate_around() checks only the zone end boundary and not beginning, nor that the pageblock is contiguous (with pageblock_pfn_to_page()) so it's possible that we end up calling isolate_freepages_block() on a range of pfn's from two different zones and end up e.g. isolating freepages under the wrong zone's lock. This patch should fix the above issues. Link: https://lkml.kernel.org/r/20210217173300.6394-1-vbabka@suse.cz Fixes: 5a811889de10 ("mm, compaction: use free lists to quickly locate a migration target") Signed-off-by: Vlastimil Babka Acked-by: David Rientjes Acked-by: Mel Gorman Cc: Andrea Arcangeli Cc: David Hildenbrand Cc: Michal Hocko Cc: Mike Rapoport Cc: Signed-off-by: Andrew Morton --- mm/compaction.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) --- a/mm/compaction.c~mm-compaction-make-fast_isolate_freepages-stay-within-zone +++ a/mm/compaction.c @@ -1284,7 +1284,7 @@ static void fast_isolate_around(struct compact_control *cc, unsigned long pfn, unsigned long nr_isolated) { unsigned long start_pfn, end_pfn; - struct page *page = pfn_to_page(pfn); + struct page *page; /* Do not search around if there are enough pages already */ if (cc->nr_freepages >= cc->nr_migratepages) @@ -1295,8 +1295,12 @@ fast_isolate_around(struct compact_contr return; /* Pageblock boundaries */ - start_pfn = pageblock_start_pfn(pfn); - end_pfn = min(pageblock_end_pfn(pfn), zone_end_pfn(cc->zone)) - 1; + start_pfn = max(pageblock_start_pfn(pfn), cc->zone->zone_start_pfn); + end_pfn = min(pageblock_end_pfn(pfn), zone_end_pfn(cc->zone)); + + page = pageblock_pfn_to_page(start_pfn, end_pfn, cc->zone); + if (!page) + return; /* Scan before */ if (start_pfn != pfn) { @@ -1398,7 +1402,8 @@ fast_isolate_freepages(struct compact_co pfn = page_to_pfn(freepage); if (pfn >= highest) - highest = pageblock_start_pfn(pfn); + highest = max(pageblock_start_pfn(pfn), + cc->zone->zone_start_pfn); if (pfn >= low_pfn) { cc->fast_search_fail = 0; @@ -1468,7 +1473,8 @@ fast_isolate_freepages(struct compact_co } else { if (cc->direct_compaction && pfn_valid(min_pfn)) { page = pageblock_pfn_to_page(min_pfn, - pageblock_end_pfn(min_pfn), + min(pageblock_end_pfn(min_pfn), + zone_end_pfn(cc->zone)), cc->zone); cc->free_pfn = min_pfn; } _