From: John Hubbard <jhubbard@nvidia.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Al Viro" <viro@zeniv.linux.org.uk>,
"Christoph Hellwig" <hch@infradead.org>,
"Dan Williams" <dan.j.williams@intel.com>,
"Dave Chinner" <david@fromorbit.com>,
"Ira Weiny" <ira.weiny@intel.com>, "Jan Kara" <jack@suse.cz>,
"Jason Gunthorpe" <jgg@ziepe.ca>,
"Jonathan Corbet" <corbet@lwn.net>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
"Michal Hocko" <mhocko@suse.com>,
"Mike Kravetz" <mike.kravetz@oracle.com>,
"Shuah Khan" <shuah@kernel.org>,
"Vlastimil Babka" <vbabka@suse.cz>,
"Matthew Wilcox" <willy@infradead.org>,
linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kselftest@vger.kernel.org, linux-rdma@vger.kernel.org,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
"John Hubbard" <jhubbard@nvidia.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Subject: [PATCH v5 09/12] mm: dump_page(): better diagnostics for huge pinned pages
Date: Thu, 6 Feb 2020 19:37:32 -0800 [thread overview]
Message-ID: <20200207033735.308000-10-jhubbard@nvidia.com> (raw)
In-Reply-To: <20200207033735.308000-1-jhubbard@nvidia.com>
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.
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
Documentation/core-api/pin_user_pages.rst | 7 +++++
mm/debug.c | 34 +++++++++++++++++------
2 files changed, 33 insertions(+), 8 deletions(-)
diff --git a/Documentation/core-api/pin_user_pages.rst b/Documentation/core-api/pin_user_pages.rst
index 7e5dd8b1b3f2..24641f1a1eba 100644
--- a/Documentation/core-api/pin_user_pages.rst
+++ b/Documentation/core-api/pin_user_pages.rst
@@ -215,6 +215,13 @@ Those are both going to show zero, unless CONFIG_DEBUG_VM is set. This is
because there is a noticeable performance drop in unpin_user_page(), when they
are activated.
+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
==========
diff --git a/mm/debug.c b/mm/debug.c
index f074077eee11..e82c878c27df 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -57,10 +57,20 @@ static void __dump_tail_page(struct page *page, int mapcount)
page, page_ref_count(page), mapcount, page->mapping,
page_to_pgoff(page));
} else {
- pr_warn("page:%px compound refcount:%d mapcount:%d mapping:%px "
- "index:%#lx compound_mapcount:%d\n",
- page, page_ref_count(head), mapcount, head->mapping,
- page_to_pgoff(head), compound_mapcount(page));
+ if (hpage_pincount_available(page))
+ pr_warn("page:%px compound refcount:%d mapcount:%d "
+ "mapping:%px index:%#lx compound_mapcount:%d "
+ "compound_pincount:%d\n",
+ page, page_ref_count(head), mapcount,
+ head->mapping, page_to_pgoff(head),
+ compound_mapcount(page),
+ compound_pincount(page));
+ else
+ pr_warn("page:%px compound refcount:%d mapcount:%d "
+ "mapping:%px index:%#lx compound_mapcount:%d\n",
+ page, page_ref_count(head), mapcount,
+ head->mapping, page_to_pgoff(head),
+ compound_mapcount(page));
}
if (page_ref_count(page) != 0) {
@@ -104,10 +114,18 @@ void __dump_page(struct page *page, const char *reason)
if (PageTail(page))
__dump_tail_page(page, mapcount);
- else
- pr_warn("page:%px refcount:%d mapcount:%d mapping:%px index:%#lx\n",
- page, page_ref_count(page), mapcount,
- page->mapping, page_to_pgoff(page));
+ else {
+ if (hpage_pincount_available(page))
+ pr_warn("page:%px refcount:%d mapcount:%d mapping:%px "
+ "index:%#lx compound pincount: %d\n",
+ page, page_ref_count(page), mapcount,
+ page->mapping, page_to_pgoff(page),
+ compound_pincount(page));
+ else
+ pr_warn("page:%px refcount:%d mapcount:%d mapping:%px "
+ "index:%#lx\n", page, page_ref_count(page),
+ mapcount, page->mapping, page_to_pgoff(page));
+ }
if (PageKsm(page))
type = "ksm ";
else if (PageAnon(page))
--
2.25.0
next prev parent reply other threads:[~2020-02-07 3:38 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-07 3:37 [PATCH v5 00/12] mm/gup: track FOLL_PIN pages John Hubbard
2020-02-07 3:37 ` [PATCH v5 01/12] mm: dump_page(): better diagnostics for compound pages John Hubbard
2020-02-07 17:27 ` Matthew Wilcox
2020-02-07 21:05 ` John Hubbard
2020-02-07 21:14 ` John Hubbard
2020-02-07 3:37 ` [PATCH v5 02/12] mm/gup: split get_user_pages_remote() into two routines John Hubbard
2020-02-07 3:37 ` [PATCH v5 03/12] mm/gup: pass a flags arg to __gup_device_* functions John Hubbard
2020-02-07 3:37 ` [PATCH v5 04/12] mm: introduce page_ref_sub_return() John Hubbard
2020-02-07 13:18 ` Kirill A. Shutemov
2020-02-07 3:37 ` [PATCH v5 05/12] mm/gup: pass gup flags to two more routines John Hubbard
2020-02-07 3:37 ` [PATCH v5 06/12] mm/gup: require FOLL_GET for get_user_pages_fast() John Hubbard
2020-02-07 3:37 ` [PATCH v5 07/12] mm/gup: track FOLL_PIN pages John Hubbard
2020-02-07 3:37 ` [PATCH v5 08/12] mm/gup: page->hpage_pinned_refcount: exact pin counts for huge pages John Hubbard
2020-02-07 3:37 ` John Hubbard [this message]
2020-02-07 3:37 ` [PATCH v5 10/12] mm/gup: /proc/vmstat: pin_user_pages (FOLL_PIN) reporting John Hubbard
2020-02-07 13:19 ` Kirill A. Shutemov
2020-02-10 10:16 ` Jan Kara
2020-02-10 17:07 ` John Hubbard
2020-02-07 3:37 ` [PATCH v5 11/12] mm/gup_benchmark: support pin_user_pages() and related calls John Hubbard
2020-02-07 3:37 ` [PATCH v5 12/12] selftests/vm: run_vmtests: invoke gup_benchmark with basic FOLL_PIN coverage John Hubbard
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