From patchwork Tue Sep 1 15:09:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 264564 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=-13.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 E7CC8C433E6 for ; Tue, 1 Sep 2020 16:35:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C44BD2065F for ; Tue, 1 Sep 2020 16:35:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598978151; bh=vmVs7s+zVn4sfC9M7I4r7u/oNgRtmgIaQa3zAc5OEXQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=zFykfFyDs6NHMw5T+5IlSciu+zAz4LTryyHOL7nLZ7ku0Bd/EHIAI79RXusH03Mnk mrgyuCiQ1pGiOfDjss4bKV0ofL3MI7mFD9gIylRcz1a2Ac3tPp07PAXuwIAJ6f4PEg 56jMX6eNOjzCnS0dqTDBX23AjiZw36ynwF3gGW8Q= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730742AbgIAQfu (ORCPT ); Tue, 1 Sep 2020 12:35:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:59640 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730566AbgIAP3x (ORCPT ); Tue, 1 Sep 2020 11:29:53 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 C760120BED; Tue, 1 Sep 2020 15:29:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598974192; bh=vmVs7s+zVn4sfC9M7I4r7u/oNgRtmgIaQa3zAc5OEXQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xqZm86lQxX/fI4uO8VV2WsdFy7w/X0tAcfFN/KyPzUX6a5UHvjg8Aa3HBxVxCFKJK lvXn//dZNVHbSHL80KG/OSrpLGYuzoALerqM+khbE2ISzWCUVX6lhtYhu3Bf31ZD6U Z7JG3K9465b9rgjUjNAMMoYsBVq0Y4tfFGi1k/aE= 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 , Sasha Levin Subject: [PATCH 5.4 080/214] mm/shuffle: dont move pages between zones and dont read garbage memmaps Date: Tue, 1 Sep 2020 17:09:20 +0200 Message-Id: <20200901150956.820425188@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200901150952.963606936@linuxfoundation.org> References: <20200901150952.963606936@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: David Hildenbrand [ Upstream commit 4a93025cbe4a0b19d1a25a2d763a3d2018bad0d9 ] 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: Sasha Levin --- mm/shuffle.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/mm/shuffle.c b/mm/shuffle.c index b3fe97fd66541..56958ffa5a3a9 100644 --- a/mm/shuffle.c +++ b/mm/shuffle.c @@ -58,25 +58,25 @@ module_param_call(shuffle, shuffle_store, shuffle_show, &shuffle_param, 0400); * 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_present(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 zone *z) * 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 zone *z) 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; }