[PATCH v2] selftests: cgroup: fix test_kmem_memcg_deletion kernel mem check

[Lucas Karpinski <lkarpins@redhat.com>]

The combination of using slab, anon, file, kernel_stack, and percpu is
not accurate for total kernel memory utilization. Checking kernel within
memory.stat provides a more accurate measurement.

Signed-off-by: Lucas Karpinski <lkarpins@redhat.com>
---
 v1: https://lore.kernel.org/all/eex2vdlg4ow2j5bybmav73nbfzuspkk4zobnk7svua4jaypqb5@7ie6e4mci43t/

 tools/testing/selftests/cgroup/test_kmem.c | 25 +++++-----------------
 1 file changed, 5 insertions(+), 20 deletions(-)

diff --git a/tools/testing/selftests/cgroup/test_kmem.c b/tools/testing/selftests/cgroup/test_kmem.c
index ed2e50bb1e76..3ef979ee0edf 100644
--- a/tools/testing/selftests/cgroup/test_kmem.c
+++ b/tools/testing/selftests/cgroup/test_kmem.c
@@ -166,7 +166,7 @@ static int cg_run_in_subcgroups(const char *parent,
  */
 static int test_kmem_memcg_deletion(const char *root)
 {
-	long current, slab, anon, file, kernel_stack, pagetables, percpu, sock, sum;
+	long current, kernel;
 	int ret = KSFT_FAIL;
 	char *parent;
 
@@ -184,30 +184,15 @@ static int test_kmem_memcg_deletion(const char *root)
 		goto cleanup;
 
 	current = cg_read_long(parent, "memory.current");
-	slab = cg_read_key_long(parent, "memory.stat", "slab ");
-	anon = cg_read_key_long(parent, "memory.stat", "anon ");
-	file = cg_read_key_long(parent, "memory.stat", "file ");
-	kernel_stack = cg_read_key_long(parent, "memory.stat", "kernel_stack ");
-	pagetables = cg_read_key_long(parent, "memory.stat", "pagetables ");
-	percpu = cg_read_key_long(parent, "memory.stat", "percpu ");
-	sock = cg_read_key_long(parent, "memory.stat", "sock ");
-	if (current < 0 || slab < 0 || anon < 0 || file < 0 ||
-	    kernel_stack < 0 || pagetables < 0 || percpu < 0 || sock < 0)
+	kernel = cg_read_key_long(parent, "memory.stat", "kernel ");
+	if (current < 0 || kernel < 0)
 		goto cleanup;
 
-	sum = slab + anon + file + kernel_stack + pagetables + percpu + sock;
-	if (abs(sum - current) < MAX_VMSTAT_ERROR) {
+	if (abs(kernel - current) < MAX_VMSTAT_ERROR) {
 		ret = KSFT_PASS;
 	} else {
 		printf("memory.current = %ld\n", current);
-		printf("slab + anon + file + kernel_stack = %ld\n", sum);
-		printf("slab = %ld\n", slab);
-		printf("anon = %ld\n", anon);
-		printf("file = %ld\n", file);
-		printf("kernel_stack = %ld\n", kernel_stack);
-		printf("pagetables = %ld\n", pagetables);
-		printf("percpu = %ld\n", percpu);
-		printf("sock = %ld\n", sock);
+		printf("kernel = %ld\n", kernel);
 	}
 
 cleanup:
-- 
2.41.0