| Problem checkpointing OpenVZ VMs under Xen [message #43039] |
Thu, 07 July 2011 18:23  |
giles
Messages: 5
Registered: July 2011
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Junior Member |
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Hi there,
First of all, thanks to OpenVZ's creators for producing such an useful-looking tool!
We're building an application that needs to run under Xen (for development) and on Amazon EC2 (live). Our users need to run multiple processes each, and be isolated from each other. So far we've been using chroot to enforce filesystem isolation, but we need to improve that so that they can't see each others' process, and we'd like to be able to checkpoint/restore their stuff so that we can migrate everything from machine to machine. OpenVZ looks like the perfect solution.
I've been experimenting with running the default Debian Squeeze amd64 OpenVZ package, linux-image-openvz-amd64, which supplies an OpenVZ-enabled kernel version 2.6.32-5. The package maintainer says (correctly) that it works as a Xen domU kernel. vzctl reports that it is version 3.0.24. I was able to boot a Xen image with this kernel running, and create and start an OpenVZ VM within it. So, for those who are keeping track, I had computer running Xen that had a domU with the OpenVZ kernel, which was itself hosting an OpenVZ virtual machine. Kind of a virtualization Inception. I'm very impressed at how easily it all worked.
Unfortunately checkpointing doesn't seem to work so well. Here's the output I got:
root@localhost:/var/lib/vz/template/cache# vzctl chkpnt 101
Setting up checkpoint...
suspend...
dump...
Can not dump container: Invalid argument
Message from syslogd@localhost at Jul 7 17:55:31 ...
kernel:[ 582.902928] general protection fault: 0000 [#1] SMP
Message from syslogd@localhost at Jul 7 17:55:31 ...
kernel:[ 582.902946] last sysfs file: /sys/devices/virtual/net/lo/operstate
Message from syslogd@localhost at Jul 7 17:55:31 ...
kernel:[ 582.903178] Stack:
Message from syslogd@localhost at Jul 7 17:55:31 ...
kernel:[ 582.903233] Call Trace:
Message from syslogd@localhost at Jul 7 17:55:31 ...
kernel:[ 582.903304] Code: 8b 4c 24 10 4c 8b 44 24 18 48 8b 44 24 20 48 8b 4c 24 28 48 8b 54 24 30 48 8b
74 24 38 48 8b 7c 24 40 48 83 c4 48 48 83 c4 30 c3 <6a> 00 48 89 f8 48 89 f7 ff d0 48 89 c7 e8 ec c2 f4 e0
00 00 48
Error: iptables-save terminated
Checkpointing failed
root@localhost:/var/lib/vz/template/cache#
/var/log/syslog has more details:
Jul 7 17:55:31 localhost kernel: [ 582.902928] general protection fault: 0000 [#1] SMP
Jul 7 17:55:31 localhost kernel: [ 582.902946] last sysfs file: /sys/devices/virtual/net/lo/operstate
Jul 7 17:55:31 localhost kernel: [ 582.902954] CPU 0
Jul 7 17:55:31 localhost kernel: [ 582.902961] Modules linked in: vzethdev vznetdev simfs vzrst vzcpt vzd
quota vzmon vzdev xt_tcpudp xt_length xt_hl xt_tcpmss xt_TCPMSS iptable_mangle iptable_filter xt_multiport
xt_limit xt_dscp ipt_REJECT ip_tables x_tables vzevent xfs exportfs evdev ext3 jbd mbcache xen_netfront xen
_blkfront
Jul 7 17:55:31 localhost kernel: [ 582.903037] Pid: 1496, comm: vzctl Not tainted 2.6.32-5-openvz-amd64 #
1 feoktistov
Jul 7 17:55:31 localhost kernel: [ 582.903046] RIP: 0010:[<ffffffffa0105744>] [<ffffffffa0105744>] child
_rip+0x0/0x14 [vzcpt]
Jul 7 17:55:31 localhost kernel: [ 582.903063] RSP: 0003:ffff88000249bf58 EFLAGS: 00000200
Jul 7 17:55:31 localhost kernel: [ 582.903071] RAX: 0000000000000000 RBX: 00000000fffffff0 RCX: 000000000
0000000
Jul 7 17:55:31 localhost kernel: [ 582.903081] RDX: 0000000000004011 RSI: ffff880009407ce8 RDI: ffffffffa
01035ec
Jul 7 17:55:31 localhost kernel: [ 582.903090] RBP: 0000000000000002 R08: 0000000000000040 R09: 000080d00
9407fd8
Jul 7 17:55:31 localhost kernel: [ 582.903099] R10: 0000000000000000 R11: ffffffff8122c942 R12: 000000000
0000000
Jul 7 17:55:31 localhost kernel: [ 582.903108] R13: 0000000000004011 R14: ffff880009407ce8 R15: ffffffffa
01035ec
Jul 7 17:55:31 localhost kernel: [ 582.903120] FS: 00007feadc849700(0000) GS:ffff88000311b000(0000) knlG
S:0000000000000000
Jul 7 17:55:31 localhost kernel: [ 582.903131] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b
Jul 7 17:55:31 localhost kernel: [ 582.903139] CR2: 00007feadbd43760 CR3: 0000000009ba6000 CR4: 000000000
0002660
Jul 7 17:55:31 localhost kernel: [ 582.903149] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 000000000
0000000
Jul 7 17:55:31 localhost kernel: [ 582.903158] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 000000000
0000400
Jul 7 17:55:31 localhost kernel: [ 582.903168] Process vzctl (pid: 1496, veid=0, threadinfo ffff88000249a
000, task ffff88000fe2d000)
Jul 7 17:55:31 localhost kernel: [ 582.903178] Stack:
Jul 7 17:55:31 localhost kernel: [ 582.903183] ffffffffa01035ec ffff880009407ce8 0000000000004011 000000
0000000000
Jul 7 17:55:31 localhost kernel: [ 582.903197] <0> ffffffff81010e31 ffffffff810115dd ffffffff8122c942 000
0000000000000
Jul 7 17:55:31 localhost kernel: [ 582.903214] <0> 000080d009407fd8 0000000000000040 0000000000000000 000
0000000000000
Jul 7 17:55:31 localhost kernel: [ 582.903233] Call Trace:
Jul 7 17:55:31 localhost kernel: [ 582.903242] [<ffffffffa01035ec>] ? dumpfn+0x0/0x106 [vzcpt]
Jul 7 17:55:31 localhost kernel: [ 582.903254] [<ffffffff81010e31>] ? int_ret_from_sys_call+0x7/0x1b
Jul 7 17:55:31 localhost kernel: [ 582.903264] [<ffffffff810115dd>] ? retint_restore_args+0x5/0x6
Jul 7 17:55:31 localhost kernel: [ 582.903276] [<ffffffff8122c942>] ? sock_destroy_inode+0x0/0x10
Jul 7 17:55:31 localhost kernel: [ 582.903285] [<ffffffff8122c942>] ? sock_destroy_inode+0x0/0x10
Jul 7 17:55:31 localhost kernel: [ 582.903296] [<ffffffffa0105744>] ? child_rip+0x0/0x14 [vzcpt]
Jul 7 17:55:31 localhost kernel: [ 582.903304] Code: 8b 4c 24 10 4c 8b 44 24 18 48 8b 44 24 20 48 8b 4c 2
4 28 48 8b 54 24 30 48 8b 74 24 38 48 8b 7c 24 40 48 83 c4 48 48 83 c4 30 c3 <6a> 00 48 89 f8 48 89 f7 ff d
0 48 89 c7 e8 ec c2 f4 e0 00 00 48
Jul 7 17:55:31 localhost kernel: [ 582.903418] RIP [<ffffffffa0105744>] child_rip+0x0/0x14 [vzcpt]
Jul 7 17:55:31 localhost kernel: [ 582.903429] RSP <ffff88000249bf58>
Jul 7 17:55:31 localhost kernel: [ 582.903437] ---[ end trace ff752e26828c9f92 ]---
Jul 7 17:55:31 localhost kernel: [ 582.903674] CPT ERR: ffff880001953000,101 :iptables-save terminated
Is this an unavoidable problem when running under Xen? Or perhaps a bug? Or something that I can fix with appropriate configuration? Or am I just being stupid? I really hope it's one of the latter two :-)
Thanks in advance for any help.
Giles
--
Giles Thomas
Resolver Systems Ltd
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