selftests/vm: gup_test: introduce the dump_pages() sub-test
For quite a while, I was doing a quick hack to gup_test.c (previously,
gup_benchmark.c) whenever I wanted to try out my changes to dump_page().
This makes that hack unnecessary, and instead allows anyone to easily get
the same coverage from a user space program. That saves a lot of time
because you don't have to change the kernel, in order to test different
pages and options.
The new sub-test takes advantage of the existing gup_test infrastructure,
which already provides a simple user space program, some allocated user
space pages, an ioctl call, pinning of those pages (via either
get_user_pages or pin_user_pages) and a corresponding kernel-side test
invocation. There's not much more required, mainly just a couple of
inputs from the user.
In fact, the new test re-uses the existing command line options in order
to get various helpful combinations (THP or normal, _fast or slow gup, gup
vs. pup, and more).
New command line options are: which pages to dump, and what type of
"get/pin" to use.
In order to figure out which pages to dump, the logic is:
* If the user doesn't specify anything, the page 0 (the first page in
the address range that the program sets up for testing) is dumped.
* Or, the user can type up to 8 page indices anywhere on the command
line. If you type more than 8, then it uses the first 8 and ignores the
remaining items.
For example:
./gup_test -ct -F 1 0 19 0x1000
Meaning:
-c: dump pages sub-test
-t: use THP pages
-F 1: use pin_user_pages() instead of get_user_pages()
0 19 0x1000: dump pages 0, 19, and 4096
Link: https://lkml.kernel.org/r/20201026064021.3545418-7-jhubbard@nvidia.com
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/gup_test.c b/mm/gup_test.c
index 173bb38..087ddaf 100644
--- a/mm/gup_test.c
+++ b/mm/gup_test.c
@@ -7,7 +7,7 @@
#include "gup_test.h"
static void put_back_pages(unsigned int cmd, struct page **pages,
- unsigned long nr_pages)
+ unsigned long nr_pages, unsigned int gup_test_flags)
{
unsigned long i;
@@ -23,6 +23,15 @@ static void put_back_pages(unsigned int cmd, struct page **pages,
case PIN_LONGTERM_BENCHMARK:
unpin_user_pages(pages, nr_pages);
break;
+ case DUMP_USER_PAGES_TEST:
+ if (gup_test_flags & GUP_TEST_FLAG_DUMP_PAGES_USE_PIN) {
+ unpin_user_pages(pages, nr_pages);
+ } else {
+ for (i = 0; i < nr_pages; i++)
+ put_page(pages[i]);
+
+ }
+ break;
}
}
@@ -49,6 +58,37 @@ static void verify_dma_pinned(unsigned int cmd, struct page **pages,
}
}
+static void dump_pages_test(struct gup_test *gup, struct page **pages,
+ unsigned long nr_pages)
+{
+ unsigned int index_to_dump;
+ unsigned int i;
+
+ /*
+ * Zero out any user-supplied page index that is out of range. Remember:
+ * .which_pages[] contains a 1-based set of page indices.
+ */
+ for (i = 0; i < GUP_TEST_MAX_PAGES_TO_DUMP; i++) {
+ if (gup->which_pages[i] > nr_pages) {
+ pr_warn("ZEROING due to out of range: .which_pages[%u]: %u\n",
+ i, gup->which_pages[i]);
+ gup->which_pages[i] = 0;
+ }
+ }
+
+ for (i = 0; i < GUP_TEST_MAX_PAGES_TO_DUMP; i++) {
+ index_to_dump = gup->which_pages[i];
+
+ if (index_to_dump) {
+ index_to_dump--; // Decode from 1-based, to 0-based
+ pr_info("---- page #%u, starting from user virt addr: 0x%llx\n",
+ index_to_dump, gup->addr);
+ dump_page(pages[index_to_dump],
+ "gup_test: dump_pages() test");
+ }
+ }
+}
+
static int __gup_test_ioctl(unsigned int cmd,
struct gup_test *gup)
{
@@ -111,6 +151,14 @@ static int __gup_test_ioctl(unsigned int cmd,
gup->flags | FOLL_LONGTERM,
pages + i, NULL);
break;
+ case DUMP_USER_PAGES_TEST:
+ if (gup->flags & GUP_TEST_FLAG_DUMP_PAGES_USE_PIN)
+ nr = pin_user_pages(addr, nr, gup->flags,
+ pages + i, NULL);
+ else
+ nr = get_user_pages(addr, nr, gup->flags,
+ pages + i, NULL);
+ break;
default:
ret = -EINVAL;
goto unlock;
@@ -134,9 +182,12 @@ static int __gup_test_ioctl(unsigned int cmd,
*/
verify_dma_pinned(cmd, pages, nr_pages);
+ if (cmd == DUMP_USER_PAGES_TEST)
+ dump_pages_test(gup, pages, nr_pages);
+
start_time = ktime_get();
- put_back_pages(cmd, pages, nr_pages);
+ put_back_pages(cmd, pages, nr_pages, gup->flags);
end_time = ktime_get();
gup->put_delta_usec = ktime_us_delta(end_time, start_time);
@@ -161,6 +212,7 @@ static long gup_test_ioctl(struct file *filep, unsigned int cmd,
case PIN_LONGTERM_BENCHMARK:
case GUP_BASIC_TEST:
case PIN_BASIC_TEST:
+ case DUMP_USER_PAGES_TEST:
break;
default:
return -EINVAL;