From: Andrea Arcangeli <aarcange@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org, Yu Zhao <yuzhao@google.com>,
Andy Lutomirski <luto@kernel.org>, Peter Xu <peterx@redhat.com>,
Pavel Emelyanov <xemul@openvz.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Minchan Kim <minchan@kernel.org>, Will Deacon <will@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Matthew Wilcox <willy@infradead.org>,
Oleg Nesterov <oleg@redhat.com>, Jann Horn <jannh@google.com>,
Kees Cook <keescook@chromium.org>,
John Hubbard <jhubbard@nvidia.com>,
Leon Romanovsky <leonro@nvidia.com>,
Jason Gunthorpe <jgg@ziepe.ca>, Jan Kara <jack@suse.cz>,
Kirill Tkhai <ktkhai@virtuozzo.com>,
Nadav Amit <nadav.amit@gmail.com>, Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH 1/1] mm: restore full accuracy in COW page reuse
Date: Sat, 9 Jan 2021 21:54:05 -0500 [thread overview]
Message-ID: <X/psTXZp9xNgX3gE@redhat.com> (raw)
In-Reply-To: <20210110004435.26382-2-aarcange@redhat.com>
Hello,
On Sat, Jan 09, 2021 at 07:44:35PM -0500, Andrea Arcangeli wrote:
> allowing a child to corrupt memory in the parent. That's a problem
> that could happen not-maliciously too. So the scenario described
I updated the above partly quoted sentence since in the previous
version it didn't have full accuracy:
https://git.kernel.org/pub/scm/linux/kernel/git/andrea/aa.git/commit/?id=fc5a76b1c14e5e6cdc64ece306fc03773662d98a
"However since a single transient GUP pin on a tail page, would elevate
the page_count for all other tail pages (unlike the mapcount which is
subpage granular), the COW page reuse inaccuracy would then cross
different vmas and the effect would happen at a distance in vma of
different processes. A single GUP pin taken on a subpage mapped in a
different process could trigger 511 false positive COWs copies in the
local process, after a fork()."
This a best effort to try to document all side effects, but it'd be
great to hear from Kirill too on the above detail to have
confirmation.
Thanks and have a great weekend everyone,
Andrea
next prev parent reply other threads:[~2021-01-10 3:00 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-10 0:44 [PATCH 0/1] mm: restore full accuracy in COW page reuse Andrea Arcangeli
2021-01-10 0:44 ` [PATCH 1/1] " Andrea Arcangeli
2021-01-10 2:54 ` Andrea Arcangeli [this message]
2021-01-11 14:11 ` Kirill A. Shutemov
2021-01-10 0:55 ` [PATCH 0/1] " Linus Torvalds
2021-01-10 0:55 ` Linus Torvalds
2021-01-10 1:19 ` Linus Torvalds
2021-01-10 1:19 ` Linus Torvalds
2021-01-10 1:37 ` Linus Torvalds
2021-01-10 1:37 ` Linus Torvalds
2021-01-10 3:24 ` Andrea Arcangeli
2021-01-10 2:51 ` Andrea Arcangeli
2021-01-10 3:51 ` Linus Torvalds
2021-01-10 3:51 ` Linus Torvalds
2021-01-10 19:30 ` Linus Torvalds
2021-01-10 19:30 ` Linus Torvalds
2021-01-11 1:18 ` Jason Gunthorpe
2021-01-11 7:26 ` John Hubbard
2021-01-11 12:42 ` Matthew Wilcox
2021-01-11 16:05 ` Jason Gunthorpe
2021-01-11 16:15 ` Michal Hocko
2021-01-11 19:19 ` Linus Torvalds
2021-01-11 19:19 ` Linus Torvalds
2021-01-11 22:18 ` Linus Torvalds
2021-01-11 22:18 ` Linus Torvalds
2021-01-12 17:07 ` Andy Lutomirski
2021-01-12 17:07 ` Andy Lutomirski
2021-01-12 23:51 ` Jerome Glisse
2021-01-13 2:16 ` Matthew Wilcox
2021-01-13 2:43 ` Linus Torvalds
2021-01-13 2:43 ` Linus Torvalds
2021-01-13 3:31 ` Linus Torvalds
2021-01-13 3:31 ` Linus Torvalds
2021-01-13 8:52 ` David Hildenbrand
2021-01-13 8:57 ` David Hildenbrand
2021-01-13 12:32 ` Kirill A. Shutemov
2021-01-13 12:55 ` Matthew Wilcox
2021-01-13 19:54 ` Linus Torvalds
2021-01-13 19:54 ` Linus Torvalds
2021-01-13 23:54 ` Peter Xu
2021-01-11 15:52 ` Jason Gunthorpe
2021-01-15 8:59 ` David Hildenbrand
2021-01-15 18:37 ` Jason Gunthorpe
2021-01-15 19:46 ` David Hildenbrand
2021-01-15 19:53 ` Jason Gunthorpe
2021-01-16 3:40 ` John Hubbard
2021-01-16 11:42 ` David Hildenbrand
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