[PATCH 1/5] selftests/damon/sysfs_memcg_path_leak.sh: use kmemleak

[SeongJae Park <sj@kernel.org>]

sysfs_memcg_path_leak.sh determines if the memory leak has happened by
seeing if Slab size on /proc/meminfo increases more than expected after
an action.  Depending on the system and background workloads, the
reasonable expectation varies.  For the reason, the test frequently
shows intermittent failures.  Use kmemleak, which is much more reliable
and correct, instead.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 .../selftests/damon/sysfs_memcg_path_leak.sh  | 26 ++++++++++---------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/tools/testing/selftests/damon/sysfs_memcg_path_leak.sh b/tools/testing/selftests/damon/sysfs_memcg_path_leak.sh
index 64c5d8c518a4..33a7ff43ed6c 100755
--- a/tools/testing/selftests/damon/sysfs_memcg_path_leak.sh
+++ b/tools/testing/selftests/damon/sysfs_memcg_path_leak.sh
@@ -14,6 +14,13 @@ then
 	exit $ksft_skip
 fi
 
+kmemleak="/sys/kernel/debug/kmemleak"
+if [ ! -f "$kmemleak" ]
+then
+	echo "$kmemleak not found"
+	exit $ksft_skip
+fi
+
 # ensure filter directory
 echo 1 > "$damon_sysfs/kdamonds/nr_kdamonds"
 echo 1 > "$damon_sysfs/kdamonds/0/contexts/nr_contexts"
@@ -22,22 +29,17 @@ echo 1 > "$damon_sysfs/kdamonds/0/contexts/0/schemes/0/filters/nr_filters"
 
 filter_dir="$damon_sysfs/kdamonds/0/contexts/0/schemes/0/filters/0"
 
-before_kb=$(grep Slab /proc/meminfo | awk '{print $2}')
-
-# try to leak 3000 KiB
-for i in {1..102400};
+# try to leak 128 times
+for i in {1..128};
 do
 	echo "012345678901234567890123456789" > "$filter_dir/memcg_path"
 done
 
-after_kb=$(grep Slab /proc/meminfo | awk '{print $2}')
-# expect up to 1500 KiB free from other tasks memory
-expected_after_kb_max=$((before_kb + 1500))
-
-if [ "$after_kb" -gt "$expected_after_kb_max" ]
+echo scan > "$kmemleak"
+kmemleak_report=$(cat "$kmemleak")
+if [ "$kmemleak_report" = "" ]
 then
-	echo "maybe memcg_path are leaking: $before_kb -> $after_kb"
-	exit 1
-else
 	exit 0
 fi
+echo "$kmemleak_report"
+exit 1
-- 
2.47.3