selftests/damon/sysfs_memcg_path_leak.sh: use kmemleak

Patch series "selftests/damon: improve leak detection and wss estimation
reliability".

Two DAMON selftets, namely 'sysfs_memcg_leak' and
'sysfs_update_schemes_tried_regions_wss_estimation' frequently show
intermittent failures due to their unreliable leak detection and working
set size estimation.  Make those more reliable.

This patch (of 5):

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.

Link: https://lkml.kernel.org/r/20260117020731.226785-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20260117020731.226785-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/tools/testing/selftests/damon/sysfs_memcg_path_leak.sh b/tools/testing/selftests/damon/sysfs_memcg_path_leak.sh
index 64c5d8c518a427c238c15a5c432bc13e152e5b73..33a7ff43ed6cc7bfcfc433b52266260eddcdf44d 100755 (executable)
--- 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