Re: [Qemu-devel] migration: qemu-coroutine-lock.c:141: qemu_co_mutex_unlock: Assertion `mutex->locked == 1' failed

[Kevin Wolf]

Am 16.09.2014 um 14:59 hat Paolo Bonzini geschrieben:
> Il 16/09/2014 14:52, Kevin Wolf ha scritto:
> > Yes, that's true. We can't fix this problem in qcow2, though, because
> > it's a more general one.  I think we must make sure that
> > bdrv_invalidate_cache() doesn't yield.
> > 
> > Either by forbidding to run bdrv_invalidate_cache() in a coroutine and
> > moving the problem to the caller (where and why is it even called from a
> > coroutine?), or possibly by creating a new coroutine for the driver
> > callback and running that in a nested event loop that only handles
> > bdrv_invalidate_cache() callbacks, so that the NBD server doesn't get a
> > chance to process new requests in this thread.
> 
> Incoming migration runs in a coroutine (the coroutine entry point is
> process_incoming_migration_co).  But everything after qemu_fclose() can
> probably be moved into a separate bottom half, so that it gets out of
> coroutine context.

Alexey, you should probably rather try this (and add a bdrv_drain_all()
in bdrv_invalidate_cache) than messing around with qcow2 locks. This
isn't a problem that can be completely fixed in qcow2.

Kevin