[libvirt-users] Libvirt migration issues (0.9.4 and 0.9.9)

[Daniel Espling]

Sorry for the spamming, but changing the below code:

 if (cloexec) 
        fd = fcntl(sock->fd, F_DUPFD_CLOEXEC);
    else
        fd = dup(sock->fd);

to:

fd = dup(sock->fd);
if (cloexec && fd >= 0)
        cntl(fd, F_SETFD, FD_CLOEXEC);

made it work for me.

//Daniel


On Jan 31, 2012, at 10:32 AM, Daniel Espling wrote:

> Hi again,
> 
> I spent some time trying to debug this:
> 
> added some printouts and noticed that the virNetSocketDupFD() function is called with cloexec = True, hence triggering the call:  fd = fcntl(sock->fd, F_DUPFD_CLOEXEC);
> 
> However, running on CentOS 5.5 our glibc version is glibc-2.5-49.el5_5.5, and it seems the F_DUPFD_CLOEXEC flag was not added until glibc2.7 [1]. I then tried to replace that code with:
> 
> if (cloexec) {
>        fd = fcntl(sock->fd, F_DUPFD);
>        if (fd >= 0)
>            fcntl(fd, F_SETFD, FD_CLOEXEC);
>    }
> 
> but the results are the same; Unable to copy socket file handle: Invalid argument
> 
> I also added some more printouts to find more about the fd:
> 2012-01-31 11:20:24.093+0000: 10445: error : virNetSocketDupFD:790 : sock->fd: 15, cloexec: 1: Invalid argument
> 
> and can at least see that fd 15 is the one complaining. Looking at lsof for the KVM process:
> 
> kvm        7456      root   13u     0000                0,8           0        852 anon_inode
> kvm        7456      root   14u     IPv4             167375                    TCP localhost.localdomain:5900 (LISTEN)
> kvm        7456      root   15r     FIFO                0,7                 167376 pipe
> kvm        7456      root   16w     FIFO                0,7                 167376 pipe
> kvm        7456      root   17u      CHR             10,200                   2986 /dev/net/tun
> 
> Seems like it fails duplicating a pipe leading back to the same process?
> 
> Regards,
> 
> Daniel
> 
> 1) http://stackoverflow.com/questions/1643304/how-to-set-close-on-exec-by-default
> 
> 
> On Jan 30, 2012, at 3:14 PM, Daniel Espling wrote:
> 
>> Dear all,
>> 
>> we're having two different problems with migrations in libvirt, running as root user on host machines with CentOS release 5.5 (Final), kernel: Linux 2.6.32.24 #3 SMP Fri Oct 29 16:22:02 BST 2010 x86_64 x86_64 x86_64 GNU/Linux
>> 
>> First case:
>> 
>> virsh version
>> Compiled against library: libvir 0.9.4
>> Using library: libvir 0.9.4
>> Using API: QEMU 0.9.4
>> Running hypervisor: QEMU 1.0.50
>> 
>> Migrations work well for a basic VM, but if we attach a disk to the usb bus migration is no longer possible and fails with the error message: "error: operation failed: migration job: is not active". This is regardless of if the device is mounted inside the VM or not (debian). Please find more information attached.
>> 
>> If we attach the same (.iso based) disk to the scsi bus instead, migrations work as normal.
>> 
>> ----
>> 
>> To mitigate this problem, we tried upgrading to a more recent libvirt version:
>> 
>> Compiled against library: libvir 0.9.9
>> Using library: libvir 0.9.9
>> Using API: QEMU 0.9.9
>> Running hypervisor: QEMU 1.0.50
>> 
>> When trying to migrate a normal (debian) instance from one host to another using the same domain as in the previous successful case without any devices attached, migration fails with the error message "error: Unable to copy socket file handle: Invalid argument". The libvirt.log only has a similar single-line of information:  2012-01-30 15:44:46.772+0000: 7546: error : virNetSocketDupFD:787 : Unable to copy socket file handle: Invalid argument. 
>> 
>> The network configuration used here is the same as we successfully used in the 0.9.4 test case, using static ip's.
>> 
>> Thankful for assistance, not really sure what to try next. :)
>> 
>> Regards,
>> Daniel Espling
>> 
>> 
>> <libvirt_0.9.4.txt>_______________________________________________
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> 
> 
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