From: "Serge E. Hallyn" <serue@us.ibm.com>
To: Cedric Le Goater <legoater@free.fr>
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
linux-api@vger.kernel.org, containers@lists.linux-foundation.org,
hpa@zytor.com, linux-kernel@vger.kernel.org,
Dave Hansen <dave@linux.vnet.ibm.com>,
linux-mm@kvack.org, viro@zeniv.linux.org.uk, mingo@elte.hu,
mpm@selenic.com, tglx@linutronix.de,
torvalds@linux-foundation.org,
Andrew Morton <akpm@linux-foundation.org>,
xemul@openvz.org
Subject: Re: How much of a mess does OpenVZ make? ;) Was: What can OpenVZ do?
Date: Fri, 13 Mar 2009 11:35:31 -0500 [thread overview]
Message-ID: <20090313163531.GA10685@us.ibm.com> (raw)
In-Reply-To: <49BA8013.3030103@free.fr>
Quoting Cedric Le Goater (legoater@free.fr):
>
> > No, what you're suggesting does not suffice.
>
> probably. I'm still trying to understand what you mean below :)
>
> Man, I hate these hierarchicals pid_ns. one level would have been enough,
> just one vpid attribute in 'struct pid*'
Well I don't mind - temporarily - saying that nested pid namespaces
are not checkpointable. It's just that if we're going to need a new
syscall anyway, then why not go ahead and address the whole problem?
It's not hugely more complicated, and seems worth it.
> > Call
> > (5591,3,1) the task knows as 5591 in the init_pid_ns, 3 in a child pid
> > ns, and 1 in grandchild pid_ns created from there. Now assume we are
> > checkpointing tasks T1=(5592,1), and T2=(5594,3,1).
> >
> > We don't care about the first number in the tuples, so they will be
> > random numbers after the recreate.
>
> yes.
>
> > But we do care about the second numbers.
>
> yes very much and we need a way set these numbers in alloc_pid()
>
> > But specifying CLONE_NEWPID while recreating the process tree
> > in userspace does not allow you to specify the 3 in (5594,3,1).
>
> I haven't looked closely at hierarchical pid namespaces but as we're
> using a an array of pid indexed but the pidns level, i don't see why
> it shouldn't be possible. you might be right.
>
> anyway, I think that some CLONE_NEW* should be forbidden. Daniel should
> send soon a little patch for the ns_cgroup restricting the clone flags
> being used in a container.
Uh, that feels a bit over the top. We want to make this
uncheckpointable (if it remains so), not prevent the whole action.
After all I may be running a container which I don't plan on ever
checkpointing, and inside that container running a job which i do
want to migrate.
So depending on if we're doing the Dave or the rest-of-the-world
way :), we either clear_bit(pidns->may_checkpoint) on the parent
pid_ns when a child is created, or we walk every task being
checkpointed and make sure they each are in the same pid_ns. Doesn't
that suffice?
-serge
next prev parent reply other threads:[~2009-03-13 16:36 UTC|newest]
Thread overview: 120+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-27 17:07 [RFC v13][PATCH 00/14] Kernel based checkpoint/restart Oren Laadan
2009-01-27 17:07 ` [RFC v13][PATCH 01/14] Create syscalls: sys_checkpoint, sys_restart Oren Laadan
2009-01-27 17:20 ` Randy Dunlap
2009-01-27 17:08 ` [RFC v13][PATCH 02/14] Checkpoint/restart: initial documentation Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 03/14] Make file_pos_read/write() public Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 04/14] General infrastructure for checkpoint restart Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 05/14] x86 support for checkpoint/restart Oren Laadan
2009-02-24 7:47 ` Nathan Lynch
2009-02-24 16:06 ` Dave Hansen
2009-03-18 7:21 ` Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 06/14] Dump memory address space Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 07/14] Restore " Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 08/14] Infrastructure for shared objects Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 09/14] Dump open file descriptors Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 10/14] Restore open file descriprtors Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 11/14] External checkpoint of a task other than ourself Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 12/14] Track in-kernel when we expect checkpoint/restart to work Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 13/14] Checkpoint multiple processes Oren Laadan
2009-01-27 17:08 ` [RFC v13][PATCH 14/14] Restart " Oren Laadan
2009-02-10 17:05 ` [RFC v13][PATCH 00/14] Kernel based checkpoint/restart Dave Hansen
2009-02-11 22:14 ` Andrew Morton
2009-02-12 9:17 ` Ingo Molnar
2009-02-12 18:11 ` Dave Hansen
2009-02-12 20:48 ` Serge E. Hallyn
2009-02-13 10:20 ` Ingo Molnar
2009-02-12 18:11 ` Dave Hansen
2009-02-12 19:30 ` Matt Mackall
2009-02-12 19:42 ` Andrew Morton
2009-02-12 21:51 ` What can OpenVZ do? Dave Hansen
2009-02-12 22:10 ` Andrew Morton
2009-02-12 23:04 ` How much of a mess does OpenVZ make? ;) Was: " Dave Hansen
2009-02-26 15:57 ` Alexey Dobriyan
2009-03-10 21:53 ` Alexey Dobriyan
2009-03-10 23:28 ` Serge E. Hallyn
2009-03-11 8:26 ` Cedric Le Goater
2009-03-12 14:53 ` Serge E. Hallyn
2009-03-12 21:01 ` Greg Kurz
2009-03-12 21:21 ` Serge E. Hallyn
2009-03-13 4:29 ` Ying Han
2009-03-13 5:34 ` Sukadev Bhattiprolu
2009-03-13 6:19 ` Ying Han
2009-03-13 17:27 ` Linus Torvalds
2009-03-13 19:02 ` Serge E. Hallyn
2009-03-13 19:35 ` Alexey Dobriyan
2009-03-13 21:01 ` Linus Torvalds
2009-03-13 21:51 ` Dave Hansen
2009-03-13 22:15 ` Oren Laadan
2009-03-14 0:27 ` Eric W. Biederman
2009-03-14 8:12 ` Ingo Molnar
2009-03-16 22:33 ` Kevin Fox
2009-03-19 21:19 ` Eric W. Biederman
2009-03-14 0:20 ` Alexey Dobriyan
2009-03-14 8:25 ` Ingo Molnar
2009-03-16 6:01 ` Oren Laadan
2009-03-13 20:48 ` Mike Waychison
2009-03-13 22:35 ` Oren Laadan
2009-03-18 18:54 ` Mike Waychison
2009-03-18 19:04 ` Oren Laadan
2009-03-13 15:27 ` Cedric Le Goater
2009-03-13 17:11 ` Greg Kurz
2009-03-13 17:37 ` Serge E. Hallyn
2009-03-13 15:47 ` Cedric Le Goater
2009-03-13 16:35 ` Serge E. Hallyn [this message]
2009-03-13 16:53 ` Cedric Le Goater
2009-02-26 16:27 ` Alexey Dobriyan
2009-02-26 17:33 ` Ingo Molnar
2009-02-26 18:30 ` Greg Kurz
2009-02-26 22:17 ` Alexey Dobriyan
2009-02-27 9:19 ` Greg Kurz
2009-02-27 10:53 ` Alexey Dobriyan
2009-02-27 14:33 ` Cedric Le Goater
2009-02-27 9:36 ` Cedric Le Goater
2009-02-26 22:31 ` Alexey Dobriyan
2009-02-27 9:03 ` Ingo Molnar
2009-02-27 9:19 ` Andrew Morton
2009-02-27 10:57 ` Alexey Dobriyan
2009-02-27 9:22 ` Andrew Morton
2009-02-27 10:59 ` Alexey Dobriyan
2009-02-27 16:14 ` Dave Hansen
2009-02-27 21:57 ` Alexey Dobriyan
2009-02-27 21:54 ` Dave Hansen
2009-03-01 1:33 ` Alexey Dobriyan
2009-03-01 20:02 ` Serge E. Hallyn
2009-03-01 20:56 ` Alexey Dobriyan
2009-03-01 22:21 ` Serge E. Hallyn
2009-03-03 16:17 ` Cedric Le Goater
2009-03-03 18:28 ` Serge E. Hallyn
2009-02-13 10:53 ` Ingo Molnar
2009-02-16 20:51 ` Dave Hansen
2009-02-17 22:23 ` Ingo Molnar
2009-02-17 22:30 ` Dave Hansen
2009-02-18 0:32 ` Ingo Molnar
2009-02-18 0:40 ` Dave Hansen
2009-02-18 5:11 ` Alexey Dobriyan
2009-02-18 18:16 ` Ingo Molnar
2009-02-18 21:27 ` Dave Hansen
2009-02-18 23:15 ` Ingo Molnar
2009-02-19 19:06 ` Banning checkpoint (was: Re: What can OpenVZ do?) Alexey Dobriyan
2009-02-19 19:11 ` Dave Hansen
2009-02-24 4:47 ` Alexey Dobriyan
2009-02-24 5:11 ` Dave Hansen
2009-02-24 15:43 ` Serge E. Hallyn
2009-02-24 20:09 ` Alexey Dobriyan
2009-02-12 22:17 ` What can OpenVZ do? Alexey Dobriyan
2009-02-13 10:27 ` Ingo Molnar
2009-02-13 11:32 ` Alexey Dobriyan
2009-02-13 11:45 ` Ingo Molnar
2009-02-13 22:28 ` Alexey Dobriyan
2009-03-14 0:04 ` Eric W. Biederman
2009-03-14 0:26 ` Serge E. Hallyn
2009-02-12 22:57 ` [RFC v13][PATCH 00/14] Kernel based checkpoint/restart Dave Hansen
2009-02-12 23:05 ` Matt Mackall
2009-02-12 23:13 ` Dave Hansen
2009-02-13 23:28 ` Andrew Morton
2009-02-14 23:08 ` Ingo Molnar
2009-02-14 23:31 ` Andrew Morton
2009-02-14 23:50 ` Ingo Molnar
2009-02-16 17:37 ` Dave Hansen
2009-03-13 2:45 ` Oren Laadan
2009-03-13 3:57 ` Oren Laadan
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