Re: [PATCH v1 02/14] mm: remove extra ZONE_DEVICE struct page refcount

On 8/25/21 05:48, Alex Sierra wrote:

From: Ralph Campbell <redacted>

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.

That's certainly welcome. I just wonder what was the reason to use 1 in the
first place and why it's no longer necessary?