From patchwork Wed Jun 24 19:31:01 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 223017 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=-4.0 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED autolearn=no 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 1990EC433DF for ; Wed, 24 Jun 2020 19:31:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F07BC2082F for ; Wed, 24 Jun 2020 19:31:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593027064; bh=EHLVJjQ/NQbGgVQHEb/j6qonSN01PUPy8HJy2PPqtLM=; h=Date:From:To:Subject:List-ID:From; b=J1xHIdLJiuXczAPpvPyqBi4sGZTtUCEer+j3Gh7IIp1cxGXbjtcIFuDom1FOz2ouf c1ruuER5MU2YXBlQkZrrD14tCmdaPX5PQt9JnytPx+1t5wrbML0Cf/b0wMFDaJ7bIK Fgt93qYrZtjlamQmq2wSbADyvjSSBOgiFTo8Qpy0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391297AbgFXTbD (ORCPT ); Wed, 24 Jun 2020 15:31:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:35138 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391239AbgFXTbD (ORCPT ); Wed, 24 Jun 2020 15:31:03 -0400 Received: from X1 (nat-ab2241.sltdut.senawave.net [162.218.216.4]) (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 A469420823; Wed, 24 Jun 2020 19:31:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593027062; bh=EHLVJjQ/NQbGgVQHEb/j6qonSN01PUPy8HJy2PPqtLM=; h=Date:From:To:Subject:From; b=gZtSe4VIqfGW67mq1Z3qyQ8zD21sX67cjzXQxxDBmtF0oEOSH1pW1/Zn1nkrunXP6 N7MxtTsfNDQ5tBRIGr6dUI20TyhHFy6w6mPqMJscwg5MauVnAU/zXUZATdPW4TwoMi j6Wk929Ei/8CcsW3BOYcpKlqN+EOgWH2eGhFzi50= Date: Wed, 24 Jun 2020 12:31:01 -0700 From: akpm@linux-foundation.org To: mm-commits@vger.kernel.org, ying.huang@intel.com, stable@vger.kernel.org, richard.weiyang@linux.alibaba.com, richard.weiyang@gmail.com, minchan@kernel.org, mhocko@suse.com, mgorman@techsingularity.net, hannes@cmpxchg.org, dan.j.williams@intel.com, akpm@linux-foundation.org, david@redhat.com Subject: + mm-shuffle-dont-move-pages-between-zones-and-dont-read-garbage-memmaps.patch added to -mm tree Message-ID: <20200624193101.HqEvE%akpm@linux-foundation.org> User-Agent: s-nail v14.9.10 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch titled Subject: mm/shuffle: don't move pages between zones and don't read garbage memmaps has been added to the -mm tree. Its filename is mm-shuffle-dont-move-pages-between-zones-and-dont-read-garbage-memmaps.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-shuffle-dont-move-pages-between-zones-and-dont-read-garbage-memmaps.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-shuffle-dont-move-pages-between-zones-and-dont-read-garbage-memmaps.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: David Hildenbrand Subject: mm/shuffle: don't move pages between zones and don't read garbage memmaps Especially with memory hotplug, we can have offline sections (with a garbage memmap) and overlapping zones. We have to make sure to only touch initialized memmaps (online sections managed by the buddy) and that the zone matches, to not move pages between zones. To test if this can actually happen, I added a simple BUG_ON(page_zone(page_i) != page_zone(page_j)); right before the swap. When hotplugging a 256M DIMM to a 4G x86-64 VM and onlining the first memory block "online_movable" and the second memory block "online_kernel", it will trigger the BUG, as both zones (NORMAL and MOVABLE) overlap. This might result in all kinds of weird situations (e.g., double allocations, list corruptions, unmovable allocations ending up in the movable zone). Link: http://lkml.kernel.org/r/20200624094741.9918-2-david@redhat.com Fixes: e900a918b098 ("mm: shuffle initial free memory to improve memory-side-cache utilization") Signed-off-by: David Hildenbrand Reviewed-by: Wei Yang Acked-by: Michal Hocko Acked-by: Dan Williams Cc: Andrew Morton Cc: Johannes Weiner Cc: Michal Hocko Cc: Minchan Kim Cc: Huang Ying Cc: Wei Yang Cc: Mel Gorman Cc: [5.2+] Signed-off-by: Andrew Morton --- mm/shuffle.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) --- a/mm/shuffle.c~mm-shuffle-dont-move-pages-between-zones-and-dont-read-garbage-memmaps +++ a/mm/shuffle.c @@ -58,25 +58,25 @@ module_param_call(shuffle, shuffle_store * For two pages to be swapped in the shuffle, they must be free (on a * 'free_area' lru), have the same order, and have the same migratetype. */ -static struct page * __meminit shuffle_valid_page(unsigned long pfn, int order) +static struct page * __meminit shuffle_valid_page(struct zone *zone, + unsigned long pfn, int order) { - struct page *page; + struct page *page = pfn_to_online_page(pfn); /* * Given we're dealing with randomly selected pfns in a zone we * need to ask questions like... */ - /* ...is the pfn even in the memmap? */ - if (!pfn_valid_within(pfn)) + /* ... is the page managed by the buddy? */ + if (!page) return NULL; - /* ...is the pfn in a present section or a hole? */ - if (!pfn_in_present_section(pfn)) + /* ... is the page assigned to the same zone? */ + if (page_zone(page) != zone) return NULL; /* ...is the page free and currently on a free_area list? */ - page = pfn_to_page(pfn); if (!PageBuddy(page)) return NULL; @@ -123,7 +123,7 @@ void __meminit __shuffle_zone(struct zon * page_j randomly selected in the span @zone_start_pfn to * @spanned_pages. */ - page_i = shuffle_valid_page(i, order); + page_i = shuffle_valid_page(z, i, order); if (!page_i) continue; @@ -137,7 +137,7 @@ void __meminit __shuffle_zone(struct zon j = z->zone_start_pfn + ALIGN_DOWN(get_random_long() % z->spanned_pages, order_pages); - page_j = shuffle_valid_page(j, order); + page_j = shuffle_valid_page(z, j, order); if (page_j && page_j != page_i) break; }