The patch titled
Subject: mm: dump_page(): additional diagnostics for huge pinned pages
has been added to the -mm tree. Its filename is
mm-dump_page-additional-diagnostics-for-huge-pinned-pages.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-dump_page-additional-diagnostics-for-huge-pinned-pages.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-dump_page-additional-diagnostics-for-huge-pinned-pages.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: John Hubbard <jhubbard@xxxxxxxxxx>
Subject: mm: dump_page(): additional diagnostics for huge pinned pages
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.
Link: http://lkml.kernel.org/r/20200211001536.1027652-13-jhubbard@xxxxxxxxxx
Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/core-api/pin_user_pages.rst | 7 ++++++
mm/debug.c | 21 +++++++++++++++-----
2 files changed, 23 insertions(+), 5 deletions(-)
--- a/Documentation/core-api/pin_user_pages.rst~mm-dump_page-additional-diagnostics-for-huge-pinned-pages
+++ a/Documentation/core-api/pin_user_pages.rst
@@ -238,6 +238,13 @@ long-term [R]DMA pins in place, or durin
(...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
==========
--- a/mm/debug.c~mm-dump_page-additional-diagnostics-for-huge-pinned-pages
+++ a/mm/debug.c
@@ -85,11 +85,22 @@ void __dump_page(struct page *page, cons
mapcount = PageSlab(head) ? 0 : page_mapcount(page);
if (compound)
- pr_warn("page:%px refcount:%d mapcount:%d mapping:%p "
- "index:%#lx head:%px order:%u compound_mapcount:%d\n",
- page, page_ref_count(head), mapcount,
- mapping, page_to_pgoff(page), head,
- compound_order(head), compound_mapcount(page));
+ if (hpage_pincount_available(page)) {
+ pr_warn("page:%px refcount:%d mapcount:%d mapping:%p "
+ "index:%#lx head:%px order:%u "
+ "compound_mapcount:%d compound_pincount:%d\n",
+ page, page_ref_count(head), mapcount,
+ mapping, page_to_pgoff(page), head,
+ compound_order(head), compound_mapcount(page),
+ compound_pincount(page));
+ } else {
+ pr_warn("page:%px refcount:%d mapcount:%d mapping:%p "
+ "index:%#lx head:%px order:%u "
+ "compound_mapcount:%d\n",
+ page, page_ref_count(head), mapcount,
+ mapping, page_to_pgoff(page), head,
+ compound_order(head), compound_mapcount(page));
+ }
else
pr_warn("page:%px refcount:%d mapcount:%d mapping:%p index:%#lx\n",
page, page_ref_count(page), mapcount,
_
Patches currently in -mm which might be from jhubbard@xxxxxxxxxx are
mm-gup-split-get_user_pages_remote-into-two-routines.patch
mm-gup-pass-a-flags-arg-to-__gup_device_-functions.patch
mm-introduce-page_ref_sub_return.patch
mm-gup-pass-gup-flags-to-two-more-routines.patch
mm-gup-require-foll_get-for-get_user_pages_fast.patch
mm-gup-track-foll_pin-pages.patch
mm-gup-page-hpage_pinned_refcount-exact-pin-counts-for-huge-pages.patch
mm-gup-proc-vmstat-pin_user_pages-foll_pin-reporting.patch
mm-gup_benchmark-support-pin_user_pages-and-related-calls.patch
selftests-vm-run_vmtests-invoke-gup_benchmark-with-basic-foll_pin-coverage.patch
mm-dump_page-additional-diagnostics-for-huge-pinned-pages.patch
