On 4/17/19 10:48 AM, Kevin Wolf wrote: > Even for block nodes with bs->drv == NULL, we can't just ignore a > bdrv_set_aio_context() call. Leaving the node in its old context can > mean that it's still in an iothread context in bdrv_close_all() during > shutdown, resulting in an attempted unlock of the AioContext lock which > we don't hold. >
Seems like an "interesting" bug to diagnose. At any rate, getting rid of the short-circuiting makes sense, and it's nice that you did manage to come up with a reliable reproducer. > The reproducer I used is a qcow2 image on gluster volume, where the > virtual disk size (4 GB) is larger than the gluster volume size (64M), > so we can easily trigger an ENOSPC. This backend is assigned to a > virtio-blk device using an iothread, and then from the guest a > 'dd if=/dev/zero of=/dev/vda bs=1G count=1' causes the VM to stop > because of an I/O error. qemu_gluster_co_flush_to_disk() sets > bs->drv = NULL on error, so when virtio-blk stops the dataplane, the > block nodes stay in the iothread AioContext. A 'quit' monitor command > issued from this paused state crashes the process. > > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1631227 > Cc: qemu-sta...@nongnu.org > Signed-off-by: Kevin Wolf <kw...@redhat.com> > --- > block.c | 12 ++---------- > 1 file changed, 2 insertions(+), 10 deletions(-) Reviewed-by: Eric Blake <ebl...@redhat.com> -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org
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