[Libguestfs] Virt-v2v conversion issue

[VONDRA Alain]

Killall does nothing the process is still alive...
If I do kill -9, do I get a core dump ?
Each time I got this hang, I find only umount -f /tmp/xxxx to force qemu-img to stop.
Alain





-----Message d'origine-----
De : Richard W.M. Jones [mailto:rjones at redhat.com] 
Envoyé : mercredi 15 octobre 2014 14:41
À : VONDRA Alain
Cc : libguestfs at redhat.com
Objet : Re: [Libguestfs] Virt-v2v conversion issue

On Wed, Oct 15, 2014 at 12:23:17PM +0000, VONDRA Alain wrote:
> Now, the conversion hangs on the first disk at 54,03/100%, here is the gdb result :

OK I just talked to Paolo about this, and it's fairly serious.

Can you get a core dump from this?

You will need to set up the ulimit etc as outlined in the previous
email:

https://www.redhat.com/archives/libguestfs/2014-October/msg00102.html

then run the conversion until it hangs, then 'killall -BUS qemu-img'
which should cause qemu-img to drop a core dump file.

You can send me (privately) the core dump and I will open a BZ about this and ensure that the necessary people see this.

Thanks,

Rich.

> (gdb) t a a bt
> 
> Thread 2 (Thread 0x7f0f3cea9700 (LWP 9583)):
> #0  sem_timedwait () at 
> ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_timedwait.S:101
> #1  0x00007f0f45b765e7 in qemu_sem_timedwait ()
> #2  0x00007f0f45b0750c in worker_thread ()
> #3  0x00007f0f4203bdf3 in start_thread (arg=0x7f0f3cea9700) at 
> pthread_create.c:308
> #4  0x00007f0f41d6901d in clone () at 
> ../sysdeps/unix/sysv/linux/x86_64/clone.S:113
> 
> Thread 1 (Thread 0x7f0f45aa88c0 (LWP 9582)):
> #0  0x00007f0f41d5eb0f in __GI_ppoll (fds=0x7f0f470d7a00, nfds=1, 
> timeout=<optimized out>, sigmask=0x0) at 
> ../sysdeps/unix/sysv/linux/ppoll.c:56
> #1  0x00007f0f45b146db in qemu_poll_ns ()
> #2  0x00007f0f45b15430 in aio_poll ()
> #3  0x00007f0f45b0eedd in bdrv_prwv_co ()
> #4  0x00007f0f45b0efd3 in bdrv_rw_co ()
> #5  0x00007f0f45b05b35 in img_convert ()
> #6  0x00007f0f41c94af5 in __libc_start_main (main=0x7f0f45b01e80 <main>, argc=10, ubp_av=0x7fff19cb3ab8, init=<optimized out>, fini=<optimized out>,
>     rtld_fini=<optimized out>, stack_end=0x7fff19cb3aa8) at 
> libc-start.c:274
> #7  0x00007f0f45b022ed in _start ()
> 
> Alain
> 
> -----Message d'origine-----
> De : Richard W.M. Jones [mailto:rjones at redhat.com] Envoyé : mardi 14 
> octobre 2014 22:52 À : VONDRA Alain Cc : libguestfs at redhat.com Objet : 
> Re: [Libguestfs] Virt-v2v conversion issue
> 
> On Tue, Oct 14, 2014 at 03:40:22PM +0000, VONDRA Alain wrote:
> > Rich,
> > I've followed your instructions to trace, but I am not very skilful with gdb, maybe I made a mistake :
> > 
> > (1) As root do:
> > 
> >   echo core.%p > /proc/sys/kernel/core_pattern  -> OK
> > 
> > (2) Before running virt-v2v, do:
> > 
> >   ulimited -c unlimited                 -> I think it's ulimit -c unlimited     -> -> OK
> > 
> > and you should get a core.* file in the current directory when qemu-img segfaults.  Attach that file to gdb to get a stack trace:
> > 
> >   gdb /usr/bin/qemu-img core.XYZ                -> Do I need to wait the crash becase I don't have any core ???
> 
> Yes, you have to wait for qemu-img to crash before there will be a core dump.  If it's not crashing, then connect to qemu-img directly, something like this:
> 
>   gdb /usr/bin/qemu-img `pidof qemu-img`
> 
> and run this command:
> 
> >   (gdb) t a a bt
> 
> to show the stack trace in all threads.
> 
> If qemu-img is consuming CPU then it's probably not hung.
> 
> I'm still interested to find out why fstrim didn't work.  Can you run:
> 
> guestfish --ro -d unc-srv-qual03
> ><fs> run
> ><fs> part-list /dev/sda
> ><fs> part-list /dev/sdb
> ><fs> part-list /dev/sdc
> ><fs> part-list /dev/sdd
> (etc)
> 
> I'd be interested to see if the partitions are unaligned, which is the only reason why fstrim should fail on NTFS.
> 
> Rich.
> 
> --
> Richard Jones, Virtualization Group, Red Hat 
> http://people.redhat.com/~rjones Read my programming and 
> virtualization blog: http://rwmj.wordpress.com virt-builder quickly 
> builds VMs from scratch http://libguestfs.org/virt-builder.1.html

--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines.  Supports shell scripting, bindings from many languages.  http://libguestfs.org