Re: [RFC PATCH v3 2/2] mm: remove extra ZONE_DEVICE struct page refcount

[Ram Pai]

On Thu, Oct 01, 2020 at 11:17:15AM -0700, Ralph Campbell wrote:
> ZONE_DEVICE struct pages have an extra reference count that complicates the
> code for put_page() and several places in the kernel that need to check the
> reference count to see that a page is not being used (gup, compaction,
> migration, etc.). Clean up the code so the reference count doesn't need to
> be treated specially for ZONE_DEVICE.


I was hoping this patch would resolve a page-reference issue that we run
into at random times while migrating a page to a device page backed by
secure-memory.

Unfortunately I continue to see the problem. There is a reference
held on that page, which fails the migration.

FYI
RP