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From:   Pavel Tatashin <pasha.tatashin@soleen.com>
To:     pasha.tatashin@soleen.com, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, akpm@linux-foundation.org, vbabka@suse.cz,
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        linux-kselftest@vger.kernel.org
Subject: [PATCH v4 10/10] selftests/vm: test faulting in kernel, and verify pinnable pages
Date:   Thu, 17 Dec 2020 13:52:43 -0500
Message-Id: <20201217185243.3288048-11-pasha.tatashin@soleen.com>
In-Reply-To: <20201217185243.3288048-1-pasha.tatashin@soleen.com>
References: <20201217185243.3288048-1-pasha.tatashin@soleen.com>
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When pages are pinned they can be faulted in userland and migrated, and
they can be faulted right in kernel without migration.

In either case, the pinned pages must end-up being pinnable (not movable).

Add a new test without touching pages in userland, and use FOLL_TOUCH
instead. Also, verify that pinned pages are pinnable.

Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
---
 mm/gup_test.c                         |  6 ++++++
 tools/testing/selftests/vm/gup_test.c | 17 +++++++++++++----
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/mm/gup_test.c b/mm/gup_test.c
index 24c70c5814ba..24fd542091ee 100644
--- a/mm/gup_test.c
+++ b/mm/gup_test.c
@@ -52,6 +52,12 @@ static void verify_dma_pinned(unsigned int cmd, struct page **pages,
 
 				dump_page(page, "gup_test failure");
 				break;
+			} else if (cmd == PIN_LONGTERM_BENCHMARK &&
+				WARN(!is_pinnable_page(page),
+				     "pages[%lu] is NOT pinnable but pinned\n",
+				     i)) {
+				dump_page(page, "gup_test failure");
+				break;
 			}
 		}
 		break;
diff --git a/tools/testing/selftests/vm/gup_test.c b/tools/testing/selftests/vm/gup_test.c
index 42c71483729f..f08cc97d424d 100644
--- a/tools/testing/selftests/vm/gup_test.c
+++ b/tools/testing/selftests/vm/gup_test.c
@@ -13,6 +13,7 @@
 
 /* Just the flags we need, copied from mm.h: */
 #define FOLL_WRITE	0x01	/* check pte is writable */
+#define FOLL_TOUCH	0x02	/* mark page accessed */
 
 static char *cmd_to_str(unsigned long cmd)
 {
@@ -39,11 +40,11 @@ int main(int argc, char **argv)
 	unsigned long size = 128 * MB;
 	int i, fd, filed, opt, nr_pages = 1, thp = -1, repeats = 1, write = 1;
 	unsigned long cmd = GUP_FAST_BENCHMARK;
-	int flags = MAP_PRIVATE;
+	int flags = MAP_PRIVATE, touch = 0;
 	char *file = "/dev/zero";
 	char *p;
 
-	while ((opt = getopt(argc, argv, "m:r:n:F:f:abctTLUuwWSHp")) != -1) {
+	while ((opt = getopt(argc, argv, "m:r:n:F:f:abctTLUuwWSHpz")) != -1) {
 		switch (opt) {
 		case 'a':
 			cmd = PIN_FAST_BENCHMARK;
@@ -110,6 +111,10 @@ int main(int argc, char **argv)
 		case 'H':
 			flags |= (MAP_HUGETLB | MAP_ANONYMOUS);
 			break;
+		case 'z':
+			/* fault pages in gup, do not fault in userland */
+			touch = 1;
+			break;
 		default:
 			return -1;
 		}
@@ -167,8 +172,12 @@ int main(int argc, char **argv)
 	else if (thp == 0)
 		madvise(p, size, MADV_NOHUGEPAGE);
 
-	for (; (unsigned long)p < gup.addr + size; p += PAGE_SIZE)
-		p[0] = 0;
+	if (touch) {
+		gup.flags |= FOLL_TOUCH;
+	} else {
+		for (; (unsigned long)p < gup.addr + size; p += PAGE_SIZE)
+			p[0] = 0;
+	}
 
 	/* Only report timing information on the *_BENCHMARK commands: */
 	if ((cmd == PIN_FAST_BENCHMARK) || (cmd == GUP_FAST_BENCHMARK) ||
-- 
2.25.1