On Tue, Feb 09, 2021 at 12:07:14PM +1100, Alistair Popple wrote: > Device private pages are used to represent device memory that is not > directly accessible from the CPU. Extra references to a device private > page are only used to ensure the struct page itself remains valid whilst > waiting for migration entries. Therefore extra references should not > prevent device private page migration as this can lead to failures to > migrate pages back to the CPU which are fatal to the user process. This should identify the extra references in expected_count, just disabling this protection seems unsafe, ZONE_DEVICE is not so special that the refcount means nothing Is this a side effect of the extra refcounts that Ralph was trying to get rid of? I'd rather see that work finished :) Jason
