On Dec 19, 2023, at 15:55, peterx@redhat.com wrote:

From: Peter Xu <peterx@redhat.com>

Introduce per-vma begin()/end() helpers for pgtable walks.  This is a
preparation work to merge hugetlb pgtable walkers with generic mm.

The helpers need to be called before and after a pgtable walk, will start
to be needed if the pgtable walker code supports hugetlb pages.  It's a
hook point for any type of VMA, but for now only hugetlb uses it to
stablize the pgtable pages from getting away (due to possible pmd
unsharing).

Reviewed-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Peter Xu <peterx@redhat.com>

Reviewed-by: Muchun Song <redacted>

Thanks.