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Date:   Wed, 26 Jan 2022 16:12:18 +0200
From:   Mike Rapoport <rppt@kernel.org>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     David Hildenbrand <david@redhat.com>,
        "Kirill A. Shutemov" <kirill@shutemov.name>,
        Khalid Aziz <khalid.aziz@oracle.com>,
        akpm@linux-foundation.org, longpeng2@huawei.com, arnd@arndb.de,
        dave.hansen@linux.intel.com, surenb@google.com,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Peter Xu <peterx@redhat.com>
Subject: Re: [RFC PATCH 0/6] Add support for shared PTEs across processes
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On Wed, Jan 26, 2022 at 01:38:49PM +0000, Matthew Wilcox wrote:
> On Wed, Jan 26, 2022 at 11:16:42AM +0100, David Hildenbrand wrote:
> > A while ago I talked with Peter about an extended uffd (here: WP)
> > mechanism that would work on fds instead of the process address space.
> 
> As far as I can tell, uffd is a grotesque hack that exists to work around
> the poor choice to use anonymous memory instead of file-backed memory
> in kvm.  Every time I see somebody mention it, I feel pain.

How file-backed memory would have helped for the major use-case of uffd
which is post-copy migration?

-- 
Sincerely yours,
Mike.