From: Alexey Dobriyan <adobriyan@gmail.com>
To: "Serge E. Hallyn" <serue@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>,
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, mpm@selenic.com,
Andrew Morton <akpm@linux-foundation.org>,
torvalds@linux-foundation.org, tglx@linutronix.de,
xemul@openvz.org
Subject: Re: How much of a mess does OpenVZ make? ;) Was: What can OpenVZ do?
Date: Sun, 1 Mar 2009 23:56:59 +0300 [thread overview]
Message-ID: <20090301205659.GA7276@x200.localdomain> (raw)
In-Reply-To: <20090301200231.GA25276@us.ibm.com>
On Sun, Mar 01, 2009 at 02:02:31PM -0600, Serge E. Hallyn wrote:
> Quoting Alexey Dobriyan (adobriyan@gmail.com):
> > On Fri, Feb 27, 2009 at 01:31:12AM +0300, Alexey Dobriyan wrote:
> > > This is collecting and start of dumping part of cleaned up OpenVZ C/R
> > > implementation, FYI.
> >
> > OK, here is second version which shows what to do with shared objects
> > (cr_dump_nsproxy(), cr_dump_task_struct()), introduced more checks
> > (still no unlinked files) and dumps some more information including
> > structures connections (cr_pos_*)
> >
> > Dumping pids in under thinking because in OpenVZ pids are saved as
> > numbers due to CLONE_NEWPID is not allowed in container. In presense
> > of multiple CLONE_NEWPID levels this must present a big problem. Looks
> > like there is now way to not dump pids as separate object.
> >
> > As result, struct cr_image_pid is variable-sized, don't know how this will
> > play later.
> >
> > Also, pid refcount check for external pointers is busted right now,
> > because /proc inode pins struct pid, so there is almost always refcount
> > vs ->o_count mismatch.
> >
> > No restore yet. ;-)
>
> Hi Alexey,
>
> thanks for posting this. Of course there are some predictable responses
> (I like the simplicity of pure in-kernel, Dave will not :) but this
> needs to be posted to make us talk about it.
>
> A few more comments that came to me while looking it over:
>
> 1. cap_sys_admin check is unfortunate. In discussions about Oren's
> patchset we've agreed that not having that check from the outset forces
> us to consider security with each new patch and feature, which is a good
> thing.
Removing CAP_SYS_ADMIN on restore?
> 2. if any tasks being checkpointed are frozen, checkpoint has the
> side effect of thawing them, right?
Haven't tried, but should be a bug, yes. It will be "thaw or kill"
depending on "flags".
> 3. wrt pids, i guess what you really want is to store the pids from
> init_tsk's level down to the task's lowest pid, right? Then you
> manually set each of those on restart? Any higher pids of course
> don't matter.
Yes, numbers are really meant to be from init_tsk level.
> 4. do you have any thoughts on what to do with the mntns info at
> restart? Will you try to detect mounts which need to be re-created?
> How?
Haven't thought, but it will be tricky for sure :^)
> 5. Since you're always setting f_pos, this won't work straight over
> a pipe? Do you figure that's just not a worthwhile feature?
So far there were no loops when dumping data structures, but I _think_
there will be some, so seeking over dumpfile would be inevitable.
> Were you saying (in response to Dave) that you're having private
> discussions about whether to pursue posting this as an alternative
> to Oren's patchset? If so, any updates on those discussions?
Right now, no.
next prev parent reply other threads:[~2009-03-01 20:50 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
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 [this message]
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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