From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: David Hildenbrand <david@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
Jason Wang <jasowang@redhat.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
Mike Rapoport <rppt@kernel.org>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
Oscar Salvador <osalvador@suse.de>,
Michal Hocko <mhocko@suse.com>, Roman Gushchin <guro@fb.com>,
Alex Shi <alex.shi@linux.alibaba.com>,
Steven Price <steven.price@arm.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Aili Yao <yaoaili@kingsoft.com>, Jiri Bohac <jbohac@suse.cz>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Wei Liu <wei.liu@kernel.org>,
Naoya Horiguchi <naoya.horiguchi@nec.com>,
linux-hyperv@vger.kernel.org,
virtualization@lists.linux-foundation.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH v1 0/7] fs/proc/kcore: don't read offline sections, logically offline pages and hwpoisoned pages
Date: Thu, 29 Apr 2021 14:25:12 +0200 [thread overview]
Message-ID: <20210429122519.15183-1-david@redhat.com> (raw)
This is (obviously) for v5.13++; no need to rush with review, but I decided
to send it around right away.
Looking for places where the kernel might unconditionally read
PageOffline() pages, I stumbled over /proc/kcore; turns out /proc/kcore
needs some more love to not touch some other pages we really don't want to
read -- i.e., hwpoisoned.
Examples for PageOffline() pages are pages inflated in a balloon,
memory unplugged via virtio-mem, and partially-present sections in
memory added by the Hyper-V balloon.
When reading pages inflated in a balloon, we essentially produce
unnecessary load in the hypervisor; holes in partially present sections in
case of Hyper-V are not accessible and already were a problem for
/proc/vmcore, fixed in makedumpfile by detecting PageOffline() pages. In
the future, virtio-mem might disallow reading unplugged memory -- marked
as PageOffline() -- in some environments, resulting in undefined behavior
when accessed; therefore, I'm trying to identify and rework all these
(corner) cases.
With this series, there is really only access via /dev/mem, /proc/vmcore
and kdb left after I ripped out /dev/kmem. kdb is an advanced corner-case
use case -- we won't care for now if someone explicitly tries to do nasty
things by reading from/writing to physical addresses we better not touch.
/dev/mem is a use case we won't support for virtio-mem, at least for now,
so we'll simply disallow mapping any virtio-mem memory via /dev/mem next.
/proc/vmcore is really only a problem when dumping the old kernel via
something that's not makedumpfile (read: basically never), however, we'll
try sanitizing that as well in the second kernel in the future.
Tested via kcore_dump:
https://github.com/schlafwandler/kcore_dump
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Steven Price <steven.price@arm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Aili Yao <yaoaili@kingsoft.com>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: linux-hyperv@vger.kernel.org
Cc: virtualization@lists.linux-foundation.org
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-mm@kvack.org
David Hildenbrand (7):
fs/proc/kcore: drop KCORE_REMAP and KCORE_OTHER
fs/proc/kcore: pfn_is_ram check only applies to KCORE_RAM
mm: rename and move page_is_poisoned()
fs/proc/kcore: don't read offline sections, logically offline pages
and hwpoisoned pages
mm: introduce page_offline_(begin|end|freeze|unfreeze) to synchronize
setting PageOffline()
virtio-mem: use page_offline_(start|end) when setting PageOffline()
fs/proc/kcore: use page_offline_(freeze|unfreeze)
drivers/virtio/virtio_mem.c | 2 ++
fs/proc/kcore.c | 69 ++++++++++++++++++++++++++++++-------
include/linux/kcore.h | 3 --
include/linux/page-flags.h | 12 +++++++
mm/gup.c | 6 +++-
mm/internal.h | 20 -----------
mm/util.c | 40 +++++++++++++++++++++
7 files changed, 115 insertions(+), 37 deletions(-)
base-commit: 9f4ad9e425a1d3b6a34617b8ea226d56a119a717
--
2.30.2
next reply other threads:[~2021-04-29 12:25 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-29 12:25 David Hildenbrand [this message]
2021-04-29 12:25 ` [PATCH v1 1/7] fs/proc/kcore: drop KCORE_REMAP and KCORE_OTHER David Hildenbrand
2021-05-02 6:31 ` Mike Rapoport
2021-04-29 12:25 ` [PATCH v1 2/7] fs/proc/kcore: pfn_is_ram check only applies to KCORE_RAM David Hildenbrand
2021-05-02 6:31 ` Mike Rapoport
2021-04-29 12:25 ` [PATCH v1 3/7] mm: rename and move page_is_poisoned() David Hildenbrand
2021-05-02 6:32 ` Mike Rapoport
2021-05-05 13:13 ` Michal Hocko
2021-05-05 13:17 ` David Hildenbrand
2021-05-05 13:27 ` Michal Hocko
2021-05-05 13:39 ` David Hildenbrand
2021-05-05 13:45 ` Michal Hocko
2021-05-06 1:08 ` Aili Yao
2021-05-06 0:56 ` Aili Yao
2021-05-06 7:06 ` Michal Hocko
2021-05-06 7:28 ` Aili Yao
2021-05-06 7:55 ` Michal Hocko
2021-05-06 8:52 ` Aili Yao
2021-04-29 12:25 ` [PATCH v1 4/7] fs/proc/kcore: don't read offline sections, logically offline pages and hwpoisoned pages David Hildenbrand
2021-05-02 6:32 ` Mike Rapoport
2021-04-29 12:25 ` [PATCH v1 5/7] mm: introduce page_offline_(begin|end|freeze|unfreeze) to synchronize setting PageOffline() David Hildenbrand
2021-05-02 6:33 ` Mike Rapoport
2021-05-03 8:11 ` David Hildenbrand
2021-05-05 13:24 ` Michal Hocko
2021-05-05 15:10 ` David Hildenbrand
2021-05-05 17:41 ` Mike Rapoport
2021-04-29 12:25 ` [PATCH v1 6/7] virtio-mem: use page_offline_(start|end) when " David Hildenbrand
2021-05-02 6:33 ` Mike Rapoport
2021-05-03 8:16 ` David Hildenbrand
2021-05-03 8:23 ` Michael S. Tsirkin
2021-04-29 12:25 ` [PATCH v1 7/7] fs/proc/kcore: use page_offline_(freeze|unfreeze) David Hildenbrand
2021-05-02 6:34 ` Mike Rapoport
2021-05-03 8:28 ` David Hildenbrand
2021-05-03 9:28 ` Mike Rapoport
2021-05-03 10:13 ` David Hildenbrand
2021-05-03 11:33 ` Mike Rapoport
2021-05-03 11:35 ` David Hildenbrand
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210429122519.15183-1-david@redhat.com \
--to=david@redhat.com \
--cc=adobriyan@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=alex.shi@linux.alibaba.com \
--cc=guro@fb.com \
--cc=haiyangz@microsoft.com \
--cc=jasowang@redhat.com \
--cc=jbohac@suse.cz \
--cc=kys@microsoft.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-hyperv@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@suse.com \
--cc=mike.kravetz@oracle.com \
--cc=mst@redhat.com \
--cc=naoya.horiguchi@nec.com \
--cc=osalvador@suse.de \
--cc=rppt@kernel.org \
--cc=steven.price@arm.com \
--cc=sthemmin@microsoft.com \
--cc=virtualization@lists.linux-foundation.org \
--cc=wei.liu@kernel.org \
--cc=willy@infradead.org \
--cc=yaoaili@kingsoft.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).