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From: Tejun Heo <tj@kernel.org>
To: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: linux-kernel@vger.kernel.org, Andrew Vagin <avagin@parallels.com>,
	Pavel Emelyanov <xemul@parallels.com>,
	James Bottomley <jbottomley@parallels.com>,
	Glauber Costa <glommer@parallels.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@elte.hu>,
	Dave Hansen <dave@linux.vnet.ibm.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Daniel Lezcano <dlezcano@fr.ibm.com>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Oleg Nesterov <oleg@redhat.com>
Subject: Re: [patch 5/5] elf: Add support for loading ET_CKPT files
Date: Fri, 14 Oct 2011 10:33:04 -0700	[thread overview]
Message-ID: <20111014173304.GD4294@google.com> (raw)
In-Reply-To: <20111014171033.GC4294@google.com>

Hello, again.

On Fri, Oct 14, 2011 at 10:10:33AM -0700, Tejun Heo wrote:
> I see that you removed zapping to allow restoring multi-threaded
> process, which seems quite scary to me.  It might be okay, I don't
> know, but IMHO it just isn't a very good idea to introduce such
> variation to basic exec behavior for this rather narrow use case.

* It's still calling exec_mmap(), so the exec'ing thread will be on
  the new mm while other threads would still be on the old one.

* There are operations which assume that the calling task is
  de-threaded and thus has exclusive access to data structures which
  can be shared among the thread group (e.g. signal struct).  How are
  accesses to them synchronized?

* What about properties which should be reset and then shared by
  threads by inheriting (credentials, comm, self_exec_id and so on)?
  e.g. new thread follows exec-time imposed rules but old ones keep
  their original credentials.

So, no, it really doesn't look good.

Thanks.

-- 
tejun

  reply	other threads:[~2011-10-14 17:33 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-10-14 11:04 [patch 0/5] [RFC] Checkpoint/restore and Elf extension Cyrill Gorcunov
2011-10-14 11:04 ` [patch 1/5] proc: Introduce the Children: line in /proc/<pid>/status Cyrill Gorcunov
2011-10-14 16:36   ` Tejun Heo
2011-10-14 11:04 ` [patch 2/5] fs: Add do_close helper Cyrill Gorcunov
2011-10-14 11:04 ` [patch 3/5] fs, proc: Add /proc/$pid/tls entry Cyrill Gorcunov
2011-10-14 16:40   ` Tejun Heo
2011-10-14 16:43     ` Cyrill Gorcunov
2011-10-14 11:04 ` [patch 4/5] fs, proc: Add start_data, end_data, start_brk members to /proc/$pid/stat Cyrill Gorcunov
2011-10-14 11:04 ` [patch 5/5] elf: Add support for loading ET_CKPT files Cyrill Gorcunov
2011-10-14 17:10   ` Tejun Heo
2011-10-14 17:33     ` Tejun Heo [this message]
2011-10-19  9:03       ` Pavel Emelyanov
2011-10-19 18:22         ` Tejun Heo
2011-10-19 18:49           ` Cyrill Gorcunov
2011-10-19 18:52             ` Cyrill Gorcunov
2011-10-19 18:53               ` Tejun Heo
2011-10-19 19:56           ` Cyrill Gorcunov
2011-10-21 18:26             ` Tejun Heo
2011-10-21 18:36               ` Cyrill Gorcunov
2011-10-21 18:42                 ` Cyrill Gorcunov
2011-10-21 18:48                   ` Tejun Heo
2011-10-21 18:53                     ` Cyrill Gorcunov
2011-10-22  6:34                     ` Pavel Emelyanov
2011-10-20  8:33           ` Pavel Emelyanov
2011-10-20 15:56             ` Tejun Heo
2011-10-20 16:04               ` Cyrill Gorcunov
2011-10-20 17:30               ` Pavel Emelyanov
2011-10-15 18:59     ` Cyrill Gorcunov
2011-10-21 11:06     ` Glauber Costa
2011-10-21 11:20       ` Cyrill Gorcunov
2011-10-21 11:21         ` Glauber Costa
2011-10-21 11:35           ` Cyrill Gorcunov
2011-10-22 16:49     ` Dan Merillat

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