kselftests: cgroup: update kmem test for new vmstat implementation

With memcg having switched to rstat, memory.stat output is precise.
Update the cgroup selftest to reflect the expectations and error
tolerances of the new implementation.

Also add newly tracked types of memory to the memory.stat side of the
equation, since they're included in memory.current and could throw false
positives.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Johannes Weiner <[e-mail]>
Reviewed-by: Shakeel Butt <[e-mail]>
Reviewed-by: Michal Koutný <[e-mail]>
Acked-by: Roman Gushchin <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Tejun Heo <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

tools/testing/selftests/cgroup/test_kmem.c

···
 
 
 /*
- * Memory cgroup charging and vmstat data aggregation is performed using
- * percpu batches 32 pages big (look at MEMCG_CHARGE_BATCH). So the maximum
- * discrepancy between charge and vmstat entries is number of cpus multiplied
- * by 32 pages multiplied by 2.
+ * Memory cgroup charging is performed using percpu batches 32 pages
+ * big (look at MEMCG_CHARGE_BATCH), whereas memory.stat is exact. So
+ * the maximum discrepancy between charge and vmstat entries is number
+ * of cpus multiplied by 32 pages.
  */
-#define MAX_VMSTAT_ERROR (4096 * 32 * 2 * get_nprocs())
+#define MAX_VMSTAT_ERROR (4096 * 32 * get_nprocs())
 
 
 static int alloc_dcache(const char *cgroup, void *arg)
···
  */
 static int test_kmem_memcg_deletion(const char *root)
 {
-	long current, slab, anon, file, kernel_stack, sum;
+	long current, slab, anon, file, kernel_stack, pagetables, percpu, sock, sum;
 	int ret = KSFT_FAIL;
 	char *parent;
 
···
 	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)
+	    kernel_stack < 0 || pagetables < 0 || percpu < 0 || sock < 0)
 		goto cleanup;
 
-	sum = slab + anon + file + kernel_stack;
+	sum = slab + anon + file + kernel_stack + pagetables + percpu + sock;
 	if (abs(sum - current) < MAX_VMSTAT_ERROR) {
 		ret = KSFT_PASS;
 	} else {
···
 		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);
 	}
 
 cleanup: