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 5D88AC433E1 for ; Thu, 20 Aug 2020 09:38:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3020B22B3F for ; Thu, 20 Aug 2020 09:38:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597916288; bh=4fUQNNlmCRsuUQDDHxUNiUzha6ciUZBaVWDskHewTUI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=qDvGS5OmXX9oUnkWuUB1aL8u0no2XOry9CY93V/r6tBS6j5yDL9VI54WGxA9WKEkh mi2P+riVxhW2Hzyog7VkF8FNgFRe0B3CkAow68P5YDIC3XHvOt5CRNZ2Abpyal6+Zp xW0DnDbJKZWXxpfr+9cw0Ueoy5JiGwMSgTw+ctJU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728697AbgHTJiG (ORCPT ); Thu, 20 Aug 2020 05:38:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:54690 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728857AbgHTJhx (ORCPT ); Thu, 20 Aug 2020 05:37:53 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 BCE6A20724; Thu, 20 Aug 2020 09:37:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597916272; bh=4fUQNNlmCRsuUQDDHxUNiUzha6ciUZBaVWDskHewTUI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=A+Aj/bxExLUiaEmWq6rTFxcIenFpDGYDntgg3meDTJSdQZRO9VzpHVfOKPKNiFCC5 MbckfebTZBP9gpJ1BILOjiqIxlaQh/5Wpp2oaAFjB31BkS9xr15xued32ZFC/I9bAi BJzoEd3CyAO/B/Lbb4IMbWE4jW4pgKRgA7TtzeUI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, David Hildenbrand , Andrew Morton , Wei Yang , Michal Hocko , Dan Williams , Johannes Weiner , Minchan Kim , Huang Ying , Wei Yang , Mel Gorman , Linus Torvalds Subject: [PATCH 5.7 071/204] mm/shuffle: dont move pages between zones and dont read garbage memmaps Date: Thu, 20 Aug 2020 11:19:28 +0200 Message-Id: <20200820091609.893192254@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200820091606.194320503@linuxfoundation.org> References: <20200820091606.194320503@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: David Hildenbrand commit 4a93025cbe4a0b19d1a25a2d763a3d2018bad0d9 upstream. 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). Fixes: e900a918b098 ("mm: shuffle initial free memory to improve memory-side-cache utilization") Signed-off-by: David Hildenbrand Signed-off-by: Andrew Morton 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+] Link: http://lkml.kernel.org/r/20200624094741.9918-2-david@redhat.com Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/shuffle.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) --- a/mm/shuffle.c +++ b/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; }