From: Andrew Morton <akpm@linux-foundation.org>
To: Peter Xu <peterx@redhat.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
James Houghton <jthoughton@google.com>,
Jann Horn <jannh@google.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Rik van Riel <riel@surriel.com>,
Nadav Amit <nadav.amit@gmail.com>,
Miaohe Lin <linmiaohe@huawei.com>,
Muchun Song <songmuchun@bytedance.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
David Hildenbrand <david@redhat.com>
Subject: Re: [PATCH 00/10] mm/hugetlb: Make huge_pte_offset() thread-safe for pmd unshare
Date: Tue, 29 Nov 2022 12:49:44 -0800 [thread overview]
Message-ID: <20221129124944.8eff54cda65d0f5a8a089e22@linux-foundation.org> (raw)
In-Reply-To: <20221129193526.3588187-1-peterx@redhat.com>
On Tue, 29 Nov 2022 14:35:16 -0500 Peter Xu <peterx@redhat.com> wrote:
> Based on latest mm-unstable (9ed079378408).
>
> This can be seen as a follow-up series to Mike's recent hugetlb vma lock
> series for pmd unsharing, but majorly covering safe use of huge_pte_offset.
We're at -rc7 (a -rc8 appears probable this time) and I'm looking to
settle down and stabilize things...
>
> ...
>
> huge_pte_offset() is always called with mmap lock held with either read or
> write. It was assumed to be safe but it's actually not. One race
> condition can easily trigger by: (1) firstly trigger pmd share on a memory
> range, (2) do huge_pte_offset() on the range, then at the meantime, (3)
> another thread unshare the pmd range, and the pgtable page is prone to lost
> if the other shared process wants to free it completely (by either munmap
> or exit mm).
That sounds like a hard-to-hit memory leak, but what we have here is a
user-triggerable use-after-free and an oops. Ugh.
Could people please prioritize the review and testing of this patchset?
next prev parent reply other threads:[~2022-11-29 20:49 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-29 19:35 [PATCH 00/10] mm/hugetlb: Make huge_pte_offset() thread-safe for pmd unshare Peter Xu
2022-11-29 19:35 ` [PATCH 01/10] mm/hugetlb: Let vma_offset_start() to return start Peter Xu
2022-11-30 10:11 ` David Hildenbrand
2022-11-29 19:35 ` [PATCH 02/10] mm/hugetlb: Don't wait for migration entry during follow page Peter Xu
2022-11-30 4:37 ` Mike Kravetz
2022-11-30 10:15 ` David Hildenbrand
2022-11-29 19:35 ` [PATCH 03/10] mm/hugetlb: Document huge_pte_offset usage Peter Xu
2022-11-30 4:55 ` Mike Kravetz
2022-11-30 15:58 ` Peter Xu
2022-12-05 21:47 ` Mike Kravetz
2022-11-30 10:21 ` David Hildenbrand
2022-11-30 10:24 ` David Hildenbrand
2022-11-30 16:09 ` Peter Xu
2022-11-30 16:11 ` David Hildenbrand
2022-11-30 16:25 ` Peter Xu
2022-11-30 16:31 ` David Hildenbrand
2022-11-29 19:35 ` [PATCH 04/10] mm/hugetlb: Move swap entry handling into vma lock when faulted Peter Xu
2022-12-05 22:14 ` Mike Kravetz
2022-12-05 23:36 ` Peter Xu
2022-11-29 19:35 ` [PATCH 05/10] mm/hugetlb: Make userfaultfd_huge_must_wait() safe to pmd unshare Peter Xu
2022-11-30 16:08 ` David Hildenbrand
2022-12-05 22:23 ` Mike Kravetz
2022-11-29 19:35 ` [PATCH 06/10] mm/hugetlb: Make hugetlb_follow_page_mask() " Peter Xu
2022-11-30 16:09 ` David Hildenbrand
2022-12-05 22:29 ` Mike Kravetz
2022-11-29 19:35 ` [PATCH 07/10] mm/hugetlb: Make follow_hugetlb_page() " Peter Xu
2022-11-30 16:09 ` David Hildenbrand
2022-12-05 22:45 ` Mike Kravetz
2022-11-29 19:35 ` [PATCH 08/10] mm/hugetlb: Make walk_hugetlb_range() " Peter Xu
2022-11-30 16:11 ` David Hildenbrand
2022-12-05 23:33 ` Mike Kravetz
2022-12-05 23:52 ` John Hubbard
2022-12-06 16:45 ` Peter Xu
2022-12-06 18:50 ` Mike Kravetz
2022-12-06 21:03 ` John Hubbard
2022-12-06 21:51 ` Peter Xu
2022-12-06 22:31 ` John Hubbard
2022-12-07 0:07 ` Peter Xu
2022-12-07 2:38 ` John Hubbard
2022-12-07 14:58 ` Peter Xu
2022-11-29 19:35 ` [PATCH 09/10] mm/hugetlb: Make page_vma_mapped_walk() " Peter Xu
2022-11-30 16:18 ` David Hildenbrand
2022-11-30 16:32 ` Peter Xu
2022-11-30 16:39 ` David Hildenbrand
2022-12-05 23:52 ` Mike Kravetz
2022-12-06 17:10 ` Mike Kravetz
2022-12-06 17:39 ` Peter Xu
2022-12-06 17:43 ` Peter Xu
2022-12-06 19:58 ` Mike Kravetz
2022-11-29 19:35 ` [PATCH 10/10] mm/hugetlb: Introduce hugetlb_walk() Peter Xu
2022-11-30 5:18 ` Eric Biggers
2022-11-30 15:37 ` Peter Xu
2022-12-06 0:21 ` Mike Kravetz
2022-11-29 20:49 ` Andrew Morton [this message]
2022-11-29 21:19 ` [PATCH 00/10] mm/hugetlb: Make huge_pte_offset() thread-safe for pmd unshare Peter Xu
2022-11-29 21:26 ` Andrew Morton
2022-11-29 20:51 ` Andrew Morton
2022-11-29 21:36 ` Peter Xu
2022-11-30 9:46 ` David Hildenbrand
2022-11-30 16:23 ` Peter Xu
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