From: Mike Kravetz <mike.kravetz@oracle.com>
To: Peter Xu <peterx@redhat.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Axel Rasmussen <axelrasmussen@google.com>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v3 4/4] hugetlb/userfaultfd: Unshare all pmds for hugetlbfs when register wp
Date: Thu, 18 Feb 2021 14:18:44 -0800 [thread overview]
Message-ID: <ff2fa34e-2a9b-a386-fd56-426eeac7d429@oracle.com> (raw)
In-Reply-To: <20210218215555.10710-1-peterx@redhat.com>
On 2/18/21 1:55 PM, Peter Xu wrote:
> Huge pmd sharing for hugetlbfs is racy with userfaultfd-wp because
> userfaultfd-wp is always based on pgtable entries, so they cannot be shared.
>
> Walk the hugetlb range and unshare all such mappings if there is, right before
> UFFDIO_REGISTER will succeed and return to userspace.
>
> This will pair with want_pmd_share() in hugetlb code so that huge pmd sharing
> is completely disabled for userfaultfd-wp registered range.
>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
> fs/userfaultfd.c | 4 ++++
> include/linux/hugetlb.h | 3 +++
> mm/hugetlb.c | 51 +++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 58 insertions(+)
Thanks,
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
--
Mike Kravetz
prev parent reply other threads:[~2021-02-18 22:18 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-18 21:54 [PATCH v3 0/4] hugetlb: Disable huge pmd unshare for uffd-wp Peter Xu
2021-02-18 21:54 ` [PATCH v3 1/4] hugetlb: Pass vma into huge_pte_alloc() and huge_pmd_share() Peter Xu
2021-02-18 22:13 ` Mike Kravetz
2021-02-18 22:27 ` Peter Xu
2021-02-18 22:38 ` Mike Kravetz
2021-02-18 23:02 ` Peter Xu
2021-02-18 21:55 ` [PATCH v3 2/4] hugetlb/userfaultfd: Forbid huge pmd sharing when uffd enabled Peter Xu
2021-02-18 21:55 ` [PATCH v3 3/4] mm/hugetlb: Move flush_hugetlb_tlb_range() into hugetlb.h Peter Xu
2021-02-18 21:55 ` [PATCH v3 4/4] hugetlb/userfaultfd: Unshare all pmds for hugetlbfs when register wp Peter Xu
2021-02-18 22:18 ` Mike Kravetz [this message]
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