| Message ID | 20200201034029.4063170-10-jhubbard@nvidia.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/gup: track FOLL_PIN pages | expand |
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>
On Fri 31-01-20 19:40:26, 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> Looks good to me. You can add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > 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 3f72b1ea1104..dd21ea140ef4 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 beb1c59d784b..db81b11345be 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) > @@ -103,10 +113,18 @@ 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 >
diff --git a/Documentation/core-api/pin_user_pages.rst b/Documentation/core-api/pin_user_pages.rst index 3f72b1ea1104..dd21ea140ef4 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 beb1c59d784b..db81b11345be 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) @@ -103,10 +113,18 @@ 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))
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> --- Documentation/core-api/pin_user_pages.rst | 7 +++++ mm/debug.c | 34 +++++++++++++++++------ 2 files changed, 33 insertions(+), 8 deletions(-)