linux-kernel - [PATCH v1 7/9] selftests/mm: Make migration test robust to failure

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Date:   Thu, 13 Jul 2023 14:54:38 +0100
From:   Ryan Roberts <ryan.roberts@....com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Shuah Khan <shuah@...nel.org>,
        Jérôme Glisse <jglisse@...hat.com>,
        David Hildenbrand <david@...hat.com>,
        Mark Brown <broonie@...nel.org>,
        John Hubbard <jhubbard@...dia.com>,
        Florent Revest <revest@...omium.org>,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>
Cc:     Ryan Roberts <ryan.roberts@....com>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, linux-kselftest@...r.kernel.org
Subject: [PATCH v1 7/9] selftests/mm: Make migration test robust to failure

The `migration` test currently has a number of robustness problems that
cause it to hang and leak resources.

Timeout: There are 3 tests, which each previously ran for 60 seconds.
However, the timeout in mm/settings for a single test binary was set to
45 seconds. So when run using run_kselftest.sh, the top level timeout
would trigger before the test binary was finished. Solve this by meeting
in the middle; each of the 3 tests now runs for 20 seconds (for a total
of 60), and the top level timeout is set to 90 seconds.

Leaking child processes: the `shared_anon` test fork()s some children
but then an ASSERT() fires before the test kills those children. The
assert causes immediate exit of the parent and leaking of the children.
Furthermore, if run using the run_kselftest.sh wrapper, the wrapper
would get stuck waiting for those children to exit, which never happens.
Solve this by deferring any asserts until after the children are killed.
The same pattern is used for the threaded tests for uniformity.

With these changes, the test binary now runs to completion on arm64,
with 2 tests passing and the `shared_anon` test failing.

Signed-off-by: Ryan Roberts <ryan.roberts@....com>
---
 tools/testing/selftests/mm/migration.c | 14 ++++++++++----
 tools/testing/selftests/mm/settings    |  2 +-
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/mm/migration.c b/tools/testing/selftests/mm/migration.c
index 379581567f27..189d7d9070e8 100644
--- a/tools/testing/selftests/mm/migration.c
+++ b/tools/testing/selftests/mm/migration.c
@@ -15,7 +15,7 @@
 #include <time.h>
 
 #define TWOMEG (2<<20)
-#define RUNTIME (60)
+#define RUNTIME (20)
 
 #define ALIGN(x, a) (((x) + (a - 1)) & (~((a) - 1)))
 
@@ -118,6 +118,7 @@ TEST_F_TIMEOUT(migration, private_anon, 2*RUNTIME)
 {
 	uint64_t *ptr;
 	int i;
+	int ret;
 
 	if (self->nthreads < 2 || self->n1 < 0 || self->n2 < 0)
 		SKIP(return, "Not enough threads or NUMA nodes available");
@@ -131,9 +132,10 @@ TEST_F_TIMEOUT(migration, private_anon, 2*RUNTIME)
 		if (pthread_create(&self->threads[i], NULL, access_mem, ptr))
 			perror("Couldn't create thread");
 
-	ASSERT_EQ(migrate(ptr, self->n1, self->n2), 0);
+	ret = migrate(ptr, self->n1, self->n2);
 	for (i = 0; i < self->nthreads - 1; i++)
 		ASSERT_EQ(pthread_cancel(self->threads[i]), 0);
+	ASSERT_EQ(ret, 0);
 }
 
 /*
@@ -144,6 +146,7 @@ TEST_F_TIMEOUT(migration, shared_anon, 2*RUNTIME)
 	pid_t pid;
 	uint64_t *ptr;
 	int i;
+	int ret;
 
 	if (self->nthreads < 2 || self->n1 < 0 || self->n2 < 0)
 		SKIP(return, "Not enough threads or NUMA nodes available");
@@ -161,9 +164,10 @@ TEST_F_TIMEOUT(migration, shared_anon, 2*RUNTIME)
 			self->pids[i] = pid;
 	}
 
-	ASSERT_EQ(migrate(ptr, self->n1, self->n2), 0);
+	ret = migrate(ptr, self->n1, self->n2);
 	for (i = 0; i < self->nthreads - 1; i++)
 		ASSERT_EQ(kill(self->pids[i], SIGTERM), 0);
+	ASSERT_EQ(ret, 0);
 }
 
 /*
@@ -173,6 +177,7 @@ TEST_F_TIMEOUT(migration, private_anon_thp, 2*RUNTIME)
 {
 	uint64_t *ptr;
 	int i;
+	int ret;
 
 	if (self->nthreads < 2 || self->n1 < 0 || self->n2 < 0)
 		SKIP(return, "Not enough threads or NUMA nodes available");
@@ -188,9 +193,10 @@ TEST_F_TIMEOUT(migration, private_anon_thp, 2*RUNTIME)
 		if (pthread_create(&self->threads[i], NULL, access_mem, ptr))
 			perror("Couldn't create thread");
 
-	ASSERT_EQ(migrate(ptr, self->n1, self->n2), 0);
+	ret = migrate(ptr, self->n1, self->n2);
 	for (i = 0; i < self->nthreads - 1; i++)
 		ASSERT_EQ(pthread_cancel(self->threads[i]), 0);
+	ASSERT_EQ(ret, 0);
 }
 
 TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/mm/settings b/tools/testing/selftests/mm/settings
index 9abfc60e9e6f..ba4d85f74cd6 100644
--- a/tools/testing/selftests/mm/settings
+++ b/tools/testing/selftests/mm/settings
@@ -1 +1 @@
-timeout=45
+timeout=90
-- 
2.25.1