* Bharata B Rao (bharata@linux.vnet.ibm.com) wrote:

On Tue, Sep 08, 2015 at 01:46:52PM +0100, Dr. David Alan Gilbert wrote:

quoted

* Bharata B Rao (bharata@linux.vnet.ibm.com) wrote:

quoted

On Tue, Sep 08, 2015 at 09:59:47AM +0100, Dr. David Alan Gilbert wrote:

quoted

* Bharata B Rao (bharata@linux.vnet.ibm.com) wrote:

quoted

In fact I had successfully done postcopy migration of sPAPR guest with
this setup.

Interesting - I'd not got that far myself on power; I was hitting a problem
loading htab ( htab_load() bad index 2113929216 (14848+0 entries) in htab stream (htab_shift=25) )

Did you have to make any changes to the qemu code to get that happy?

I should have mentioned that I tried only QEMU driven migration within
the same host using wp3-postcopy branch of your tree. I don't see the
above issue.

(qemu) info migrate
capabilities: xbzrle: off rdma-pin-all: off auto-converge: off zero-blocks: off compress: off x-postcopy-ram: on 
Migration status: completed
total time: 39432 milliseconds
downtime: 162 milliseconds
setup: 14 milliseconds
transferred ram: 1297209 kbytes
throughput: 270.72 mbps
remaining ram: 0 kbytes
total ram: 4194560 kbytes
duplicate: 734015 pages
skipped: 0 pages
normal: 318469 pages
normal bytes: 1273876 kbytes
dirty sync count: 4

I will try migration between different hosts soon and check.

I hit that on the same host; are you sure you've switched into postcopy mode;
i.e. issued a migrate_start_postcopy before the end of migration?

Sorry I was following your discussion with Li in this thread

https://www.marc.info/?l=qemu-devel&m=143035620026744&w=4

and it wasn't obvious to me that anything apart from turning on the
x-postcopy-ram capability was required :(

OK.

So I do see the problem now.

At the source
-------------
Error reading data from KVM HTAB fd: Bad file descriptor
Segmentation fault

At the target
-------------
htab_load() bad index 2113929216 (14336+0 entries) in htab stream (htab_shift=25)
qemu-system-ppc64: error while loading state section id 56(spapr/htab)
qemu-system-ppc64: postcopy_ram_listen_thread: loadvm failed: -22
qemu-system-ppc64: VQ 0 size 0x100 Guest index 0x0 inconsistent with Host index 0x1f: delta 0xffe1
qemu-system-ppc64: error while loading state for instance 0x0 of device 'pci@800000020000000:00.0/virtio-net'
*** Error in `./ppc64-softmmu/qemu-system-ppc64': corrupted double-linked list: 0x00000100241234a0 ***
======= Backtrace: =========
/lib64/power8/libc.so.6Segmentation fault

Good - my current world has got rid of the segfaults/corruption in the cleanup on power - but those
are only after it stumbled over the htab problem.

I don't know the innards of power/htab, so if you've got any pointers on what upset it
I'd be happy for some pointers.

(We should probably trim the cc - since I don't think this is userfault related).

Dave

--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

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