From patchwork Wed Feb 17 19:14:36 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 384829 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 82F4BC433DB for ; Wed, 17 Feb 2021 19:15:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3D00964DE0 for ; Wed, 17 Feb 2021 19:15:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232179AbhBQTPS (ORCPT ); Wed, 17 Feb 2021 14:15:18 -0500 Received: from mail.kernel.org ([198.145.29.99]:51906 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230332AbhBQTPS (ORCPT ); Wed, 17 Feb 2021 14:15:18 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id D9ADD64DE0; Wed, 17 Feb 2021 19:14:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1613589277; bh=iU3PfsIzGA3sNcC86BCTvbXOB6J4qS6l8Qb/VUL2WvM=; h=Date:From:To:Subject:From; b=TDCLKv8MD52tX/yxslVCbLAsc9vZNLLeiO+syitIxzOfrQwYMgdMbbrvkpR4dbey+ KjJLQ85XzJu1jjhjG/8g//lhDJCOY86lU24XLOPnrYAj80GOno2tgXtZEmFom+x72x B10DCLiH/kYgF23yDkF8BSNtyEJ5RvAqq/W5HRmY= Date: Wed, 17 Feb 2021 11:14:36 -0800 From: akpm@linux-foundation.org To: mm-commits@vger.kernel.org, stable@vger.kernel.org, rppt@kernel.org, rientjes@google.com, mhocko@kernel.org, mgorman@techsingularity.net, david@redhat.com, aarcange@redhat.com, vbabka@suse.cz Subject: + mm-compaction-make-fast_isolate_freepages-stay-within-zone.patch added to -mm tree Message-ID: <20210217191436.shTJB%akpm@linux-foundation.org> User-Agent: s-nail v14.9.10 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch titled Subject: mm, compaction: make fast_isolate_freepages() stay within zone has been added to the -mm tree. Its filename is mm-compaction-make-fast_isolate_freepages-stay-within-zone.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-make-fast_isolate_freepages-stay-within-zone.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-make-fast_isolate_freepages-stay-within-zone.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ 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; }