Re: [PATCH v3 09/12] mm: dump_page(): better diagnostics for huge pinned pages

On Fri, Jan 31, 2020 at 07:40:26PM -0800, John Hubbard wrote:

As part of pin_user_pages() and related API calls, pages are "dma-pinned". For the case of compound pages of order > 1, the per-page accounting of dma pins is accomplished via the 3rd struct page in the compound page. In order to support debugging of any pin_user_pages()- related problems, enhance dump_page() so as to report the pin count in that case.

Documentation/core-api/pin_user_pages.rst is also updated accordingly.

Signed-off-by: John Hubbard jhubbard@nvidia.com

Acked-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com