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Date:   Sun, 27 Oct 2019 13:00:13 +0200
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Subject: Re: [PATCH RFC] mm: add MAP_EXCLUSIVE to create exclusive user mappings
To:     Florian Weimer <fw@deneb.enyo.de>
CC:     linux-kernel@vger.kernel.org,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        James Bottomley <jejb@linux.ibm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, linux-api@vger.kernel.org,
        linux-mm@kvack.org, x86@kernel.org,
        Mike Rapoport <rppt@linux.ibm.com>
From:   Mike Rapoport <rppt@kernel.org>
Message-ID: <385EB6D4-A1B0-4617-B256-181AA1C3BDE3@kernel.org>
Sender: linux-kernel-owner@vger.kernel.org
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On October 27, 2019 12:30:21 PM GMT+02:00, Florian Weimer <fw@deneb=2Eenyo=
=2Ede> wrote:
>* Mike Rapoport:
>
>> The patch below aims to allow applications to create mappins that
>have
>> pages visible only to the owning process=2E Such mappings could be used
>to
>> store secrets so that these secrets are not visible neither to other
>> processes nor to the kernel=2E
>
>How is this expected to interact with CRIU?

CRIU dumps the memory contents using a parasite code from inside the dumpe=
e address space, so it would work the same way as for the other mappings=2E=
 Of course, at the restore time the exclusive mapping should be recreated w=
ith the appropriate flags=2E

>> I've only tested the basic functionality, the changes should be
>verified
>> against THP/migration/compaction=2E Yet, I'd appreciate early feedback=
=2E
>
>What are the expected semantics for VM migration?  Should it fail?

I don't quite follow=2E If qemu would use such mappings it would be able t=
o transfer them during live migration=2E

--=20
Sincerely yours,
Mike