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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 3F521ECE58E for ; Fri, 11 Oct 2019 14:06:49 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0F54520679 for ; Fri, 11 Oct 2019 14:06:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0F54520679 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id AD8066B0003; Fri, 11 Oct 2019 10:06:48 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A87E46B0005; Fri, 11 Oct 2019 10:06:48 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 99EFC8E0001; Fri, 11 Oct 2019 10:06:48 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 79B136B0003 for ; Fri, 11 Oct 2019 10:06:48 -0400 (EDT) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id 32E1D824CA38 for ; Fri, 11 Oct 2019 14:06:48 +0000 (UTC) X-FDA: 76031679696.04.quilt70_758c9ca8b011b X-HE-Tag: quilt70_758c9ca8b011b X-Filterd-Recvd-Size: 4753 Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by imf13.hostedemail.com (Postfix) with ESMTP for ; Fri, 11 Oct 2019 14:06:47 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4DB19307C829; Fri, 11 Oct 2019 14:06:46 +0000 (UTC) Received: from t460s.redhat.com (ovpn-117-27.ams2.redhat.com [10.36.117.27]) by smtp.corp.redhat.com (Postfix) with ESMTP id CBF8B5D721; Fri, 11 Oct 2019 14:06:38 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Qian Cai , Andrew Morton , Vlastimil Babka , Michal Hocko , Thomas Gleixner , "Peter Zijlstra (Intel)" , Miles Chen , Mike Rapoport , Greg Kroah-Hartman , David Hildenbrand Subject: [PATCH v2] mm/page_owner: Don't access uninitialized memmaps when reading /proc/pagetypeinfo Date: Fri, 11 Oct 2019 16:06:38 +0200 Message-Id: <20191011140638.8160-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.40]); Fri, 11 Oct 2019 14:06:46 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Qian Cai Uninitialized memmaps contain garbage and in the worst case trigger kernel BUGs, especially with CONFIG_PAGE_POISONING. They should not get touched. For example, when not onlining a memory block that is spanned by a zone and reading /proc/pagetypeinfo with CONFIG_DEBUG_VM_PGFLAGS and CONFIG_PAGE_POISONING, we can trigger a kernel BUG: :/# echo 1 > /sys/devices/system/memory/memory40/online :/# echo 1 > /sys/devices/system/memory/memory42/online :/# cat /proc/pagetypeinfo > test.file [ 42.489856] page:fffff2c585200000 is uninitialized and poisoned [ 42.489861] raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff = ffffffffffffffff [ 42.492235] raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff = ffffffffffffffff [ 42.493501] page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) [ 42.494533] There is not page extension available. [ 42.495358] ------------[ cut here ]------------ [ 42.496163] kernel BUG at include/linux/mm.h:1107! [ 42.497069] invalid opcode: 0000 [#1] SMP NOPTI Please not that this change does not affect ZONE_DEVICE, because pagetypeinfo_showmixedcount_print() is called from mm/vmstat.c:pagetypeinfo_showmixedcount() only for populated zones, and ZONE_DEVICE is never populated (zone->present_pages always 0). Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memor= y to zones until online") # visible after d0dc12e86b319 Signed-off-by: Qian Cai Cc: Andrew Morton Cc: Vlastimil Babka Cc: Michal Hocko Cc: Thomas Gleixner Cc: "Peter Zijlstra (Intel)" Cc: Miles Chen Cc: Mike Rapoport Cc: Qian Cai Cc: Greg Kroah-Hartman [ move check to outer loop, add comment, rephrase description ] Signed-off-by: David Hildenbrand --- Cai asked me to follow up on: [PATCH] mm/page_owner: fix a crash after memory offline --- mm/page_owner.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/page_owner.c b/mm/page_owner.c index dee931184788..7d149211f6be 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -284,7 +284,8 @@ void pagetypeinfo_showmixedcount_print(struct seq_fil= e *m, * not matter as the mixed block count will still be correct */ for (; pfn < end_pfn; ) { - if (!pfn_valid(pfn)) { + page =3D pfn_to_online_page(pfn); + if (!page) { pfn =3D ALIGN(pfn + 1, MAX_ORDER_NR_PAGES); continue; } @@ -292,13 +293,13 @@ void pagetypeinfo_showmixedcount_print(struct seq_f= ile *m, block_end_pfn =3D ALIGN(pfn + 1, pageblock_nr_pages); block_end_pfn =3D min(block_end_pfn, end_pfn); =20 - page =3D pfn_to_page(pfn); pageblock_mt =3D get_pageblock_migratetype(page); =20 for (; pfn < block_end_pfn; pfn++) { if (!pfn_valid_within(pfn)) continue; =20 + /* The pageblock is online, no need to recheck. */ page =3D pfn_to_page(pfn); =20 if (page_zone(page) !=3D zone) --=20 2.21.0