Guest freezes if memory backing using memfd/shared/
Description of problem:
Guest VM freezes with the following memory backing is set. Required to for virtiofs, but just setting the following the guest will freeze in around 2hours, no logs or errors generate.

  <memoryBacking>
    <source type='memfd'/>
    <access mode='shared'/>
  </memoryBacking>
Steps to reproduce:
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Additional information: