From patchwork Fri Aug 7 06:17:13 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 266733 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=-7.0 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 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 B4FA2C433E1 for ; Fri, 7 Aug 2020 06:17:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 95B2722CAE for ; Fri, 7 Aug 2020 06:17:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596781036; bh=OVWvsSaIpqu3QJpZgPxOm+EG3djcXSl2jWK7tt7skCc=; h=Date:From:To:Subject:In-Reply-To:List-ID:From; b=v/z2+lJV+xFPINbURlh2jrwzX5vYamNwQOlMPvPWRbZcZuagW9N1ZAMbJwl6HukFN 8G4VKkEIKJEKhYFTAU5OS1tVhMTwpyJdpvHtmvZguLXNYB0MBBZHOEBhBB+IGgHMIq fS7V5uPFGxcq4rRAiBdvg8FL0r/0NFN6fonDS6X8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726094AbgHGGRP (ORCPT ); Fri, 7 Aug 2020 02:17:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:52284 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726038AbgHGGRP (ORCPT ); Fri, 7 Aug 2020 02:17:15 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (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 B2BE8221E5; Fri, 7 Aug 2020 06:17:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596781034; bh=OVWvsSaIpqu3QJpZgPxOm+EG3djcXSl2jWK7tt7skCc=; h=Date:From:To:Subject:In-Reply-To:From; b=W5XaOy7e8UMN+AXcaZp4uK7XILFl6Hz+VBo+fOn7tNQlNuOCQ6VU1o1S6uyTXVQeS wqOj/3im35gr42zzC4RZE1lDJXCdxlMSwZu8lXBQCPfrQ42RxLkGQfTqQs3evQhDuR cPYrVRd+TWFBxUXlZeyfBeeR/dBuxcllYB5fSmMo= Date: Thu, 06 Aug 2020 23:17:13 -0700 From: Andrew Morton To: akpm@linux-foundation.org, dan.j.williams@intel.com, david@redhat.com, hannes@cmpxchg.org, linux-mm@kvack.org, mgorman@techsingularity.net, mhocko@suse.com, minchan@kernel.org, mm-commits@vger.kernel.org, richard.weiyang@gmail.com, richard.weiyang@linux.alibaba.com, stable@vger.kernel.org, torvalds@linux-foundation.org, ying.huang@intel.com Subject: [patch 003/163] mm/shuffle: don't move pages between zones and don't read garbage memmaps Message-ID: <20200807061713.iMOMr3Cb5%akpm@linux-foundation.org> In-Reply-To: <20200806231643.a2711a608dd0f18bff2caf2b@linux-foundation.org> User-Agent: s-nail v14.8.16 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 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; }