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    SubjectRe: [PATCH v3 11/12] mm/gup_benchmark: support pin_user_pages() and related calls
    On Fri, Jan 31, 2020 at 07:40:28PM -0800, John Hubbard wrote:
    > Up until now, gup_benchmark supported testing of the
    > following kernel functions:
    >
    > * get_user_pages(): via the '-U' command line option
    > * get_user_pages_longterm(): via the '-L' command line option
    > * get_user_pages_fast(): as the default (no options required)
    >
    > Add test coverage for the new corresponding pin_*() functions:
    >
    > * pin_user_pages_fast(): via the '-a' command line option
    > * pin_user_pages(): via the '-b' command line option
    >
    > Also, add an option for clarity: '-u' for what is now (still) the
    > default choice: get_user_pages_fast().
    >
    > Also, for the commands that set FOLL_PIN, verify that the pages
    > really are dma-pinned, via the new is_dma_pinned() routine.
    > Those commands are:
    >
    > PIN_FAST_BENCHMARK : calls pin_user_pages_fast()
    > PIN_BENCHMARK : calls pin_user_pages()
    >
    > In between the calls to pin_*() and unpin_user_pages(),
    > check each page: if page_maybe_dma_pinned() returns false, then
    > WARN and return.
    >
    > Do this outside of the benchmark timestamps, so that it doesn't
    > affect reported times.
    >
    > Reviewed-by: Ira Weiny <ira.weiny@intel.com>
    > Signed-off-by: John Hubbard <jhubbard@nvidia.com>
    > ---
    > mm/gup_benchmark.c | 71 ++++++++++++++++++++--
    > tools/testing/selftests/vm/gup_benchmark.c | 15 ++++-
    > 2 files changed, 80 insertions(+), 6 deletions(-)
    >
    > diff --git a/mm/gup_benchmark.c b/mm/gup_benchmark.c
    > index 8dba38e79a9f..447628d0131f 100644
    > --- a/mm/gup_benchmark.c
    > +++ b/mm/gup_benchmark.c
    > @@ -8,6 +8,8 @@
    > #define GUP_FAST_BENCHMARK _IOWR('g', 1, struct gup_benchmark)
    > #define GUP_LONGTERM_BENCHMARK _IOWR('g', 2, struct gup_benchmark)
    > #define GUP_BENCHMARK _IOWR('g', 3, struct gup_benchmark)
    > +#define PIN_FAST_BENCHMARK _IOWR('g', 4, struct gup_benchmark)
    > +#define PIN_BENCHMARK _IOWR('g', 5, struct gup_benchmark)
    >
    > struct gup_benchmark {
    > __u64 get_delta_usec;
    > @@ -19,6 +21,48 @@ struct gup_benchmark {
    > __u64 expansion[10]; /* For future use */
    > };
    >
    > +static void put_back_pages(unsigned int cmd, struct page **pages,
    > + unsigned long nr_pages)
    > +{
    > + int i;
    > +
    > + switch (cmd) {
    > + case GUP_FAST_BENCHMARK:
    > + case GUP_LONGTERM_BENCHMARK:
    > + case GUP_BENCHMARK:
    > + for (i = 0; i < nr_pages; i++)

    'i' is 'int' and 'nr_pages' is 'unsigned long'.
    There's space for trouble :P

    > + put_page(pages[i]);
    > + break;
    > +
    > + case PIN_FAST_BENCHMARK:
    > + case PIN_BENCHMARK:
    > + unpin_user_pages(pages, nr_pages);
    > + break;
    > + }
    > +}
    > +
    > +static void verify_dma_pinned(unsigned int cmd, struct page **pages,
    > + unsigned long nr_pages)
    > +{
    > + int i;
    > + struct page *page;
    > +
    > + switch (cmd) {
    > + case PIN_FAST_BENCHMARK:
    > + case PIN_BENCHMARK:
    > + for (i = 0; i < nr_pages; i++) {

    Ditto.

    > + page = pages[i];
    > + if (WARN(!page_maybe_dma_pinned(page),
    > + "pages[%d] is NOT dma-pinned\n", i)) {
    > +
    > + dump_page(page, "gup_benchmark failure");
    > + break;
    > + }
    > + }
    > + break;
    > + }
    > +}
    > +
    > static int __gup_benchmark_ioctl(unsigned int cmd,
    > struct gup_benchmark *gup)
    > {

    --
    Kirill A. Shutemov

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