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Very often the owner of the aliased region is the same as the owner of the alias region itself. When this happens, the reference count can never go back to 0 and the owner is leaked. This is for example breaking hot-unplug of virtio-pci devices (the device cannot be plugged back again with the same id). Another common use for alias is to transform the system I/O address space into an MMIO regions; in this case the aliased region never dies, so there is no problem. Otherwise the owner is always the same for aliasing and aliased region. I checked all calls to memory_region_init_alias introduced after commit dfde4e6 (memory: add ref/unref calls, 2013-05-06) and they do not need the reference in order to keep the owner of the aliased region alive. Reported-by: Michael S. Tsirkin <mst@redhat.com> Tested-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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