[PATCH 6/8] selftests/vm: gup_test: introduce the dump_pages() sub-test

John Hubbard
2020-09-28T06:22:04Z

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

Also, invoke the new test from run_vmtests.sh. This keeps it in use, and
also provides a good example of how to invoke it.

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
mm/Kconfig | 6 +++
mm/gup_test.c | 54 ++++++++++++++++++++++++++-
mm/gup_test.h | 10 +++++
tools/testing/selftests/vm/gup_test.c | 47 +++++++++++++++++++++--
4 files changed, 112 insertions(+), 5 deletions(-)

diff --git a/mm/Kconfig b/mm/Kconfig
index 588984ee5fb4..f7c4c21e5cb1 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -845,6 +845,12 @@ config GUP_TEST
get_user_pages*() and pin_user_pages*(), as well as smoke tests of
the non-_fast variants.

+ There is also a sub-test that allows running dump_page() on any
+ of up to eight pages (selected by command line args) within the
+ range of user-space addresses. These pages are either pinned via
+ pin_user_pages*(), or pinned via get_user_pages*(), as specified
+ by other command line arguments.
+
See tools/testing/selftests/vm/gup_test.c

config GUP_GET_PTE_LOW_HIGH
diff --git a/mm/gup_test.c b/mm/gup_test.c
index a980c4a194f0..e79dc364eafb 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)
{
@@ -104,6 +144,14 @@ 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:
kvfree(pages);
ret = -EINVAL;
@@ -127,10 +175,11 @@ static int __gup_test_ioctl(unsigned int cmd,
* state: print a warning if any non-dma-pinned pages are found:
*/
verify_dma_pinned(cmd, pages, nr_pages);
+ 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);
@@ -152,6 +201,7 @@ 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;
diff --git a/mm/gup_test.h b/mm/gup_test.h
index 921b4caad8ef..90a6713d50eb 100644
--- a/mm/gup_test.h
+++ b/mm/gup_test.h
@@ -9,6 +9,11 @@
#define PIN_LONGTERM_BENCHMARK _IOWR('g', 3, struct gup_test)
#define GUP_BASIC_TEST _IOWR('g', 4, struct gup_test)
#define PIN_BASIC_TEST _IOWR('g', 5, struct gup_test)
+#define DUMP_USER_PAGES_TEST _IOWR('g', 6, struct gup_test)
+
+#define GUP_TEST_MAX_PAGES_TO_DUMP 8
+
+#define GUP_TEST_FLAG_DUMP_PAGES_USE_PIN 0x1

struct gup_test {
__u64 get_delta_usec;
@@ -17,6 +22,11 @@ struct gup_test {
__u64 size;
__u32 nr_pages_per_call;
__u32 flags;
+ /*
+ * Each non-zero entry is the number of the page (1-based: first page is
+ * page 1, so that zero entries mean "do nothing") from the .addr base.
+ */
+ __u32 which_pages[GUP_TEST_MAX_PAGES_TO_DUMP];
};

#endif /* __GUP_TEST_H */
diff --git a/tools/testing/selftests/vm/gup_test.c b/tools/testing/selftests/vm/gup_test.c
index 67d57a1cc8b6..68137b337114 100644
--- a/tools/testing/selftests/vm/gup_test.c
+++ b/tools/testing/selftests/vm/gup_test.c
@@ -27,21 +27,23 @@ static char *cmd_to_str(unsigned long cmd)
return "GUP_BASIC_TEST";
case PIN_BASIC_TEST:
return "PIN_BASIC_TEST";
+ case DUMP_USER_PAGES_TEST:
+ return "DUMP_USER_PAGES_TEST";
}
return "Unknown command";
}

int main(int argc, char **argv)
{
- struct gup_test gup;
+ struct gup_test gup = { 0 };
unsigned long size = 128 * MB;
int i, fd, filed, opt, nr_pages = 1, thp = -1, repeats = 1, write = 0;
- int cmd = GUP_FAST_BENCHMARK;
+ unsigned long cmd = GUP_FAST_BENCHMARK;
int flags = MAP_PRIVATE;
char *file = "/dev/zero";
char *p;

- while ((opt = getopt(argc, argv, "m:r:n:f:abtTLUuwSH")) != -1) {
+ while ((opt = getopt(argc, argv, "m:r:n:F:f:abctTLUuwSH")) != -1) {
switch (opt) {
case 'a':
cmd = PIN_FAST_BENCHMARK;
@@ -52,6 +54,21 @@ int main(int argc, char **argv)
case 'L':
cmd = PIN_LONGTERM_BENCHMARK;
break;
+ case 'c':
+ cmd = DUMP_USER_PAGES_TEST;
+ /*
+ * Dump page 0 (index 1). May be overridden later, by
+ * user's non-option arguments.
+ *
+ * .which_pages is zero-based, so that zero can mean "do
+ * nothing".
+ */
+ gup.which_pages[0] = 1;
+ break;
+ case 'F':
+ /* strtol, so you can pass flags in hex form */
+ gup.flags = strtol(optarg, 0, 0);
+ break;
case 'm':
size = atoi(optarg) * MB;
break;
@@ -91,6 +108,30 @@ int main(int argc, char **argv)
}
}

+ if (optind < argc) {
+ int extra_arg_count = 0;
+ /*
+ * For example:
+ *
+ * ./gup_test -c 0 1 0x1001
+ *
+ * ...to dump pages 0, 1, and 4097
+ */
+
+ while ((optind < argc) &&
+ (extra_arg_count < GUP_TEST_MAX_PAGES_TO_DUMP)) {
+ /*
+ * Do the 1-based indexing here, so that the user can
+ * use normal 0-based indexing on the command line.
+ */
+ long page_index = strtol(argv[optind], 0, 0) + 1;
+
+ gup.which_pages[extra_arg_count] = page_index;
+ extra_arg_count++;
+ optind++;
+ }
+ }
+
filed = open(file, O_RDWR|O_CREAT);
if (filed < 0) {
perror("open");
--
2.28.0