Messages in this thread |  | | Date | Tue, 9 Feb 2021 09:39:32 -0400 | From | Jason Gunthorpe <> | Subject | Re: [PATCH 1/9] mm/migrate.c: Always allow device private pages to migrate |
| |
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
|  |