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From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>,
	Steven Sistare <steven.sistare@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>,
	Anthony Yznaga <anthony.yznaga@oracle.com>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, linux-arch@vger.kernel.org,
	mhocko@kernel.org, tglx@linutronix.de, mingo@redhat.com,
	bp@alien8.de, x86@kernel.org, hpa@zytor.com,
	viro@zeniv.linux.org.uk, akpm@linux-foundation.org,
	arnd@arndb.de, keescook@chromium.org, gerg@linux-m68k.org,
	ktkhai@virtuozzo.com, christian.brauner@ubuntu.com,
	peterz@infradead.org, esyr@redhat.com, jgg@ziepe.ca,
	christian@kellner.me, areber@redhat.com, cyphar@cyphar.com
Subject: Re: [RFC PATCH 0/5] madvise MADV_DOEXEC
Date: Mon, 03 Aug 2020 08:42:50 -0700	[thread overview]
Message-ID: <1596469370.29091.13.camel@HansenPartnership.com> (raw)
In-Reply-To: <877dufvje9.fsf@x220.int.ebiederm.org>

On Mon, 2020-08-03 at 10:28 -0500, Eric W. Biederman wrote:
[...]
> What is wrong with live migration between one qemu process and
> another qemu process on the same machine not work for this use case?
> 
> Just reusing live migration would seem to be the simplest path of
> all, as the code is already implemented.  Further if something goes
> wrong with the live migration you can fallback to the existing
> process.  With exec there is no fallback if the new version does not
> properly support the handoff protocol of the old version.

Actually, could I ask this another way: the other patch set you sent to
the KVM list was to snapshot the VM to a PKRAM capsule preserved across
kexec using zero copy for extremely fast save/restore.  The original
idea was to use this as part of a CRIU based snapshot, kexec to new
system, restore.  However, why can't you do a local snapshot, restart
qemu, restore using the PKRAM capsule to achieve exactly the same as
MADV_DOEXEC does but using a system that's easy to reason about?  It
may be slightly slower, but I think we're still talking milliseconds.

James


  reply	other threads:[~2020-08-03 15:42 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-27 17:11 Anthony Yznaga
2020-07-27 17:07 ` Eric W. Biederman
2020-07-27 18:00   ` Steven Sistare
2020-07-28 13:40     ` Christian Brauner
2020-07-27 17:11 ` [RFC PATCH 1/5] elf: reintroduce using MAP_FIXED_NOREPLACE for elf executable mappings Anthony Yznaga
2020-07-27 17:11 ` [RFC PATCH 2/5] mm: do not assume only the stack vma exists in setup_arg_pages() Anthony Yznaga
2020-07-27 17:11 ` [RFC PATCH 3/5] mm: introduce VM_EXEC_KEEP Anthony Yznaga
2020-07-28 13:38   ` Eric W. Biederman
2020-07-28 17:44     ` Anthony Yznaga
2020-07-29 13:52   ` Kirill A. Shutemov
2020-07-29 23:20     ` Anthony Yznaga
2020-07-27 17:11 ` [RFC PATCH 4/5] exec, elf: require opt-in for accepting preserved mem Anthony Yznaga
2020-07-27 17:11 ` [RFC PATCH 5/5] mm: introduce MADV_DOEXEC Anthony Yznaga
2020-07-28 13:22   ` Kirill Tkhai
2020-07-28 14:06     ` Steven Sistare
2020-07-28 11:34 ` [RFC PATCH 0/5] madvise MADV_DOEXEC Kirill Tkhai
2020-07-28 17:28   ` Anthony Yznaga
2020-07-28 14:23 ` Andy Lutomirski
2020-07-28 14:30   ` Steven Sistare
2020-07-30 15:22 ` Matthew Wilcox
2020-07-30 15:27   ` Christian Brauner
2020-07-30 15:34     ` Matthew Wilcox
2020-07-30 15:54       ` Christian Brauner
2020-07-31  9:12     ` Stefan Hajnoczi
2020-07-30 15:59   ` Steven Sistare
2020-07-30 17:12     ` Matthew Wilcox
2020-07-30 17:35       ` Steven Sistare
2020-07-30 17:49         ` Matthew Wilcox
2020-07-30 18:27           ` Steven Sistare
2020-07-30 21:58             ` Eric W. Biederman
2020-07-31 14:57               ` Steven Sistare
2020-07-31 15:27                 ` Matthew Wilcox
2020-07-31 16:11                   ` Steven Sistare
2020-07-31 16:56                     ` Jason Gunthorpe
2020-07-31 17:15                       ` Steven Sistare
2020-07-31 17:48                         ` Jason Gunthorpe
2020-07-31 17:55                           ` Steven Sistare
2020-08-03  8:32                             ` David Laight
2020-07-31 17:23                     ` Matthew Wilcox
2020-08-03 15:28                 ` Eric W. Biederman
2020-08-03 15:42                   ` James Bottomley [this message]
2020-08-03 20:03                     ` Steven Sistare
2020-08-04  8:44                     ` David Laight
2020-08-04 11:13                       ` Matthew Wilcox
2020-08-03 19:29                   ` Steven Sistare
2020-07-31 19:41 ` Steven Sistare
2021-07-08  9:52 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-07-08 12:48   ` Steven Sistare

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