[PATCH 0/2] mm/damon/sysfs: fix unexpected targets adding bug

[PATCH 0/2] mm/damon/sysfs: fix unexpected targets adding bug

[SeongJae Park]

The sysfs code for online targets updating can result in adding more than
expected monigoring targets to the context.  It can result in unexpected amount
of memory consumption and monitoring overhead.  This patchset fixes the issue
(patch 1), and add a kunit test for avoiding similar bug of future (patch 2).

SeongJae Park (2):
  mm/damon/sysfs: remove requested targets when online-commit inputs
  mm/damon/sysfs-test: add a unit test for damon_sysfs_set_targets()

 mm/damon/Kconfig      | 12 ++++++
 mm/damon/sysfs-test.h | 86 +++++++++++++++++++++++++++++++++++++++++++
 mm/damon/sysfs.c      | 52 ++++++--------------------
 3 files changed, 109 insertions(+), 41 deletions(-)
 create mode 100644 mm/damon/sysfs-test.h


base-commit: 9a969da6ffb9609f5fa8d0b7fdc6859c37a10335
-- 
2.34.1

[PATCH 2/2] mm/damon/sysfs-test: add a unit test for damon_sysfs_set_targets()

[SeongJae Park]

damon_sysfs_set_targets() had a bug that can result in unexpected memory
usage and monitoring overhead increase.  The bug has fixed by a previous
commit.  Add a unit test for avoiding a similar bug of future.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/Kconfig      | 12 ++++++
 mm/damon/sysfs-test.h | 86 +++++++++++++++++++++++++++++++++++++++++++
 mm/damon/sysfs.c      |  2 +
 3 files changed, 100 insertions(+)
 create mode 100644 mm/damon/sysfs-test.h

diff --git a/mm/damon/Kconfig b/mm/damon/Kconfig
index 436c6b4cb5ec..29f43fbc2eff 100644
--- a/mm/damon/Kconfig
+++ b/mm/damon/Kconfig
@@ -59,6 +59,18 @@ config DAMON_SYSFS
 	  This builds the sysfs interface for DAMON.  The user space can use
 	  the interface for arbitrary data access monitoring.
 
+config DAMON_SYSFS_KUNIT_TEST
+	bool "Test for damon debugfs interface" if !KUNIT_ALL_TESTS
+	depends on DAMON_SYSFS && KUNIT=y
+	default KUNIT_ALL_TESTS
+	help
+	  This builds the DAMON sysfs interface Kunit test suite.
+
+	  For more information on KUnit and unit tests in general, please refer
+	  to the KUnit documentation.
+
+	  If unsure, say N.
+
 config DAMON_DBGFS
 	bool "DAMON debugfs interface (DEPRECATED!)"
 	depends on DAMON_VADDR && DAMON_PADDR && DEBUG_FS
diff --git a/mm/damon/sysfs-test.h b/mm/damon/sysfs-test.h
new file mode 100644
index 000000000000..73bdce2452c1
--- /dev/null
+++ b/mm/damon/sysfs-test.h
@@ -0,0 +1,86 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Data Access Monitor Unit Tests
+ *
+ * Author: SeongJae Park <sj@kernel.org>
+ */
+
+#ifdef CONFIG_DAMON_SYSFS_KUNIT_TEST
+
+#ifndef _DAMON_SYSFS_TEST_H
+#define _DAMON_SYSFS_TEST_H
+
+#include <kunit/test.h>
+
+static unsigned int nr_damon_targets(struct damon_ctx *ctx)
+{
+	struct damon_target *t;
+	unsigned int nr_targets = 0;
+
+	damon_for_each_target(t, ctx)
+		nr_targets++;
+
+	return nr_targets;
+}
+
+static int __damon_sysfs_test_get_any_pid(int min, int max)
+{
+	struct pid *pid;
+	int i;
+
+	for (i = min; i <= max; i++) {
+		pid = find_get_pid(i);
+		if (pid) {
+			put_pid(pid);
+			return i;
+		}
+	}
+	return -1;
+}
+
+static void damon_sysfs_test_set_targets(struct kunit *test)
+{
+	struct damon_sysfs_targets *sysfs_targets;
+	struct damon_sysfs_target *sysfs_target;
+	struct damon_ctx *ctx;
+
+	sysfs_targets = damon_sysfs_targets_alloc();
+	sysfs_targets->nr = 1;
+	sysfs_targets->targets_arr = kmalloc_array(1,
+			sizeof(*sysfs_targets->targets_arr), GFP_KERNEL);
+
+	sysfs_target = damon_sysfs_target_alloc();
+	sysfs_target->pid = __damon_sysfs_test_get_any_pid(12, 100);
+	sysfs_target->regions = damon_sysfs_regions_alloc();
+	sysfs_targets->targets_arr[0] = sysfs_target;
+
+	ctx = damon_new_ctx();
+
+	damon_sysfs_set_targets(ctx, sysfs_targets);
+	KUNIT_EXPECT_EQ(test, 1u, nr_damon_targets(ctx));
+
+	sysfs_target->pid = __damon_sysfs_test_get_any_pid(
+			sysfs_target->pid + 1, 200);
+	damon_sysfs_set_targets(ctx, sysfs_targets);
+	KUNIT_EXPECT_EQ(test, 1u, nr_damon_targets(ctx));
+
+	damon_destroy_ctx(ctx);
+	kfree(sysfs_targets->targets_arr);
+	kfree(sysfs_targets);
+	kfree(sysfs_target);
+}
+
+static struct kunit_case damon_sysfs_test_cases[] = {
+	KUNIT_CASE(damon_sysfs_test_set_targets),
+	{},
+};
+
+static struct kunit_suite damon_sysfs_test_suite = {
+	.name = "damon-sysfs",
+	.test_cases = damon_sysfs_test_cases,
+};
+kunit_test_suite(damon_sysfs_test_suite);
+
+#endif /* _DAMON_SYSFS_TEST_H */
+
+#endif /* CONFIG_DAMON_SYSFS_KUNIT_TEST */
diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 5268e8503722..d13e353bee52 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1804,3 +1804,5 @@ static int __init damon_sysfs_init(void)
 	return err;
 }
 subsys_initcall(damon_sysfs_init);
+
+#include "sysfs-test.h"
-- 
2.34.1