From patchwork Tue Oct 1 14:40:05 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 11168985 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9725F912 for ; Tue, 1 Oct 2019 14:41:51 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7599621906 for ; Tue, 1 Oct 2019 14:41:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="DQGJEqhr" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7599621906 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=tfQzDY5Xwd47oQaccD6iEug9zLREiBMK1JZVxGNVLQg=; b=DQGJEqhrtxKddC UR4cQX/4NNJjdEzpIbXgvRuSCZFUQs6dkV1wjWQZGv9msANSwZF1MIr2BNN8VBKM8L68UvBWGQ8g4 pdgv075bVyA4rjPk3bHXJ5NZopuK6L1hgifsrSZv9wuJ4E+wtslxU3prxpocSPi0QbuNUv/rkniTt m+ZMG+oQQxnogXBn0VxSq3u6hlOrAYWac4yZkE73DOiuffxVIaf1wKQwfBtz/D+VDgzv2dbwiltLY QEWddn7vKMiUrn8XWnrjKP9UYB2owkwNbKcPBRReaO6eYev1BUhn4LkYCW2IE9ZeM7+exw/ptsb+H wBdaBQEf7xW4istOXOSg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.2 #3 (Red Hat Linux)) id 1iFJLZ-0002vg-I6; Tue, 01 Oct 2019 14:41:49 +0000 Received: from mx1.redhat.com ([209.132.183.28]) by bombadil.infradead.org with esmtps (Exim 4.92.2 #3 (Red Hat Linux)) id 1iFJL4-0002Ny-2m for linux-arm-kernel@lists.infradead.org; Tue, 01 Oct 2019 14:41:19 +0000 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 813722EF16A; Tue, 1 Oct 2019 14:41:17 +0000 (UTC) Received: from t460s.redhat.com (ovpn-116-54.ams2.redhat.com [10.36.116.54]) by smtp.corp.redhat.com (Postfix) with ESMTP id D83F15D9C9; Tue, 1 Oct 2019 14:41:14 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Subject: [PATCH v5 04/10] mm/memory_hotplug: Don't access uninitialized memmaps in shrink_zone_span() Date: Tue, 1 Oct 2019 16:40:05 +0200 Message-Id: <20191001144011.3801-5-david@redhat.com> In-Reply-To: <20191001144011.3801-1-david@redhat.com> References: <20191001144011.3801-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Tue, 01 Oct 2019 14:41:17 +0000 (UTC) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191001_074118_172078_C12C8DB3 X-CRM114-Status: GOOD ( 17.84 ) X-Spam-Score: -5.0 (-----) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (-5.0 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at https://www.dnswl.org/, high trust [209.132.183.28 listed in list.dnswl.org] -0.0 SPF_HELO_PASS SPF: HELO matches SPF record -0.0 SPF_PASS SPF: sender matches SPF record X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-s390@vger.kernel.org, Michal Hocko , linux-ia64@vger.kernel.org, Pavel Tatashin , linux-sh@vger.kernel.org, "Aneesh Kumar K . V" , David Hildenbrand , linux-mm@kvack.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org, Dan Williams , linux-arm-kernel@lists.infradead.org, Oscar Salvador Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Let's limit shrinking to !ZONE_DEVICE so we can fix the current code. We should never try to touch the memmap of offline sections where we could have uninitialized memmaps and could trigger BUGs when calling page_to_nid() on poisoned pages. There is no reliable way to distinguish an uninitialized memmap from an initialized memmap that belongs to ZONE_DEVICE, as we don't have anything like SECTION_IS_ONLINE we can use similar to pfn_to_online_section() for !ZONE_DEVICE memory. E.g., set_zone_contiguous() similarly relies on pfn_to_online_section() and will therefore never set a ZONE_DEVICE zone consecutive. Stopping to shrink the ZONE_DEVICE therefore results in no observable changes, besides /proc/zoneinfo indicating different boundaries - something we can totally live with. Before commit d0dc12e86b31 ("mm/memory_hotplug: optimize memory hotplug"), the memmap was initialized with 0 and the node with the right value. So the zone might be wrong but not garbage. After that commit, both the zone and the node will be garbage when touching uninitialized memmaps. Cc: Andrew Morton Cc: Oscar Salvador Cc: David Hildenbrand Cc: Michal Hocko Cc: Pavel Tatashin Cc: Dan Williams Fixes: d0dc12e86b31 ("mm/memory_hotplug: optimize memory hotplug") Reported-by: Aneesh Kumar K.V Signed-off-by: David Hildenbrand --- mm/memory_hotplug.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 86b4dc18e831..afed8331332b 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -331,7 +331,7 @@ static unsigned long find_smallest_section_pfn(int nid, struct zone *zone, unsigned long end_pfn) { for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SUBSECTION) { - if (unlikely(!pfn_valid(start_pfn))) + if (unlikely(!pfn_to_online_page(start_pfn))) continue; if (unlikely(pfn_to_nid(start_pfn) != nid)) @@ -356,7 +356,7 @@ static unsigned long find_biggest_section_pfn(int nid, struct zone *zone, /* pfn is the end pfn of a memory section. */ pfn = end_pfn - 1; for (; pfn >= start_pfn; pfn -= PAGES_PER_SUBSECTION) { - if (unlikely(!pfn_valid(pfn))) + if (unlikely(!pfn_to_online_page(pfn))) continue; if (unlikely(pfn_to_nid(pfn) != nid)) @@ -415,7 +415,7 @@ static void shrink_zone_span(struct zone *zone, unsigned long start_pfn, */ pfn = zone_start_pfn; for (; pfn < zone_end_pfn; pfn += PAGES_PER_SUBSECTION) { - if (unlikely(!pfn_valid(pfn))) + if (unlikely(!pfn_to_online_page(pfn))) continue; if (page_zone(pfn_to_page(pfn)) != zone) @@ -463,6 +463,14 @@ static void __remove_zone(struct zone *zone, unsigned long start_pfn, struct pglist_data *pgdat = zone->zone_pgdat; unsigned long flags; + /* + * Zone shrinking code cannot properly deal with ZONE_DEVICE. So + * we will not try to shrink the zones - which is okay as + * set_zone_contiguous() cannot deal with ZONE_DEVICE either way. + */ + if (zone_idx(zone) == ZONE_DEVICE) + return; + pgdat_resize_lock(zone->zone_pgdat, &flags); shrink_zone_span(zone, start_pfn, start_pfn + nr_pages); update_pgdat_span(pgdat);