From dc8fb2f282ad13e550b65958fea40c7eb766d42a Mon Sep 17 00:00:00 2001 From: John Hubbard Date: Wed, 1 Apr 2020 21:05:52 -0700 Subject: mm: dump_page(): additional diagnostics for huge pinned pages MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Andrew Morton Acked-by: Kirill A. Shutemov Cc: Jan Kara Cc: Matthew Wilcox Cc: Ira Weiny Cc: Jérôme Glisse Cc: Al Viro Cc: Christoph Hellwig Cc: Dan Williams Cc: Dave Chinner Cc: Jason Gunthorpe Cc: Jonathan Corbet Cc: Michal Hocko Cc: Mike Kravetz Cc: Shuah Khan Cc: Vlastimil Babka Link: http://lkml.kernel.org/r/20200211001536.1027652-13-jhubbard@nvidia.com Signed-off-by: Linus Torvalds --- Documentation/core-api/pin_user_pages.rst | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'Documentation/core-api') diff --git a/Documentation/core-api/pin_user_pages.rst b/Documentation/core-api/pin_user_pages.rst index 5c8a5f89756b..2e939ff10b86 100644 --- a/Documentation/core-api/pin_user_pages.rst +++ b/Documentation/core-api/pin_user_pages.rst @@ -238,6 +238,13 @@ long-term [R]DMA pins in place, or during pin/unpin transitions. (...unless it was already out of balance due to a long-term RDMA pin being in place.) +Other diagnostics +================= + +dump_page() has been enhanced slightly, to handle these new counting fields, and +to better report on compound pages in general. Specifically, for compound pages +with order > 1, the exact (hpage_pinned_refcount) pincount is reported. + References ========== -- cgit v1.2.3