mm/gup_benchmark: support pin_user_pages() and related calls

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.

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/20200211001536.1027652-10-jhubbard@nvidia.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/gup_benchmark.c b/mm/gup_benchmark.c
index 8dba38e..be690fa 100644 (file)
--- 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)
+{
+       unsigned long i;
+
+       switch (cmd) {
+       case GUP_FAST_BENCHMARK:
+       case GUP_LONGTERM_BENCHMARK:
+       case GUP_BENCHMARK:
+               for (i = 0; i < nr_pages; i++)
+                       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)
+{
+       unsigned long i;
+       struct page *page;
+
+       switch (cmd) {
+       case PIN_FAST_BENCHMARK:
+       case PIN_BENCHMARK:
+               for (i = 0; i < nr_pages; i++) {
+                       page = pages[i];
+                       if (WARN(!page_maybe_dma_pinned(page),
+                                "pages[%lu] 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)
 {
@@ -66,6 +110,14 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
                        nr = get_user_pages(addr, nr, gup->flags, pages + i,
                                            NULL);
                        break;
+               case PIN_FAST_BENCHMARK:
+                       nr = pin_user_pages_fast(addr, nr, gup->flags,
+                                                pages + i);
+                       break;
+               case PIN_BENCHMARK:
+                       nr = pin_user_pages(addr, nr, gup->flags, pages + i,
+                                           NULL);
+                       break;
                default:
                        kvfree(pages);
                        ret = -EINVAL;
@@ -78,15 +130,22 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
        }
        end_time = ktime_get();
 
+       /* Shifting the meaning of nr_pages: now it is actual number pinned: */
+       nr_pages = i;
+
        gup->get_delta_usec = ktime_us_delta(end_time, start_time);
        gup->size = addr - gup->addr;
 
+       /*
+        * Take an un-benchmark-timed moment to verify DMA pinned
+        * state: print a warning if any non-dma-pinned pages are found:
+        */
+       verify_dma_pinned(cmd, pages, nr_pages);
+
        start_time = ktime_get();
-       for (i = 0; i < nr_pages; i++) {
-               if (!pages[i])
-                       break;
-               put_page(pages[i]);
-       }
+
+       put_back_pages(cmd, pages, nr_pages);
+
        end_time = ktime_get();
        gup->put_delta_usec = ktime_us_delta(end_time, start_time);
 
@@ -105,6 +164,8 @@ static long gup_benchmark_ioctl(struct file *filep, unsigned int cmd,
        case GUP_FAST_BENCHMARK:
        case GUP_LONGTERM_BENCHMARK:
        case GUP_BENCHMARK:
+       case PIN_FAST_BENCHMARK:
+       case PIN_BENCHMARK:
                break;
        default:
                return -EINVAL;

diff --git a/tools/testing/selftests/vm/gup_benchmark.c b/tools/testing/selftests/vm/gup_benchmark.c
index 389327e..43b4dfe 100644 (file)
--- a/tools/testing/selftests/vm/gup_benchmark.c
+++ b/tools/testing/selftests/vm/gup_benchmark.c
@@ -18,6 +18,10 @@
 #define GUP_LONGTERM_BENCHMARK _IOWR('g', 2, struct gup_benchmark)
 #define GUP_BENCHMARK          _IOWR('g', 3, struct gup_benchmark)
 
+/* Similar to above, but use FOLL_PIN instead of FOLL_GET. */
+#define PIN_FAST_BENCHMARK     _IOWR('g', 4, struct gup_benchmark)
+#define PIN_BENCHMARK          _IOWR('g', 5, struct gup_benchmark)
+
 /* Just the flags we need, copied from mm.h: */
 #define FOLL_WRITE     0x01    /* check pte is writable */
 
@@ -40,8 +44,14 @@ int main(int argc, char **argv)
        char *file = "/dev/zero";
        char *p;
 
-       while ((opt = getopt(argc, argv, "m:r:n:f:tTLUwSH")) != -1) {
+       while ((opt = getopt(argc, argv, "m:r:n:f:abtTLUuwSH")) != -1) {
                switch (opt) {
+               case 'a':
+                       cmd = PIN_FAST_BENCHMARK;
+                       break;
+               case 'b':
+                       cmd = PIN_BENCHMARK;
+                       break;
                case 'm':
                        size = atoi(optarg) * MB;
                        break;
@@ -63,6 +73,9 @@ int main(int argc, char **argv)
                case 'U':
                        cmd = GUP_BENCHMARK;
                        break;
+               case 'u':
+                       cmd = GUP_FAST_BENCHMARK;
+                       break;
                case 'w':
                        write = 1;
                        break;