Re: Endless loop in qcow2_alloc_cluster_offset

Jan Kiszka
2009-12-07T14:50:15Z

Jan Kiszka wrote:
> And now it happened again (qemu-kvm head, during kernel installation
> from network onto local qcow2-disk). Any clever idea how to proceed with
> this?
>
> I could try to run the step in a loop, hopefully retriggering it once in
> a (likely longer) while. But then we need some good instrumentation first.
>

Maybe I'm seeing ghosts, and I don't even have a minimal clue about what
goes on in the code, but this looks fishy:

preallocate() invokes qcow2_alloc_cluster_offset() passing &meta, a
stack variable. It seems that qcow2_alloc_cluster_offset() may insert
this structure into cluster_allocs and leave it there. So we corrupt the
queue as soon as preallocate() returns, no?

Jan

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