Add tests for memory.oom.group

Add tests for memory.oom.group for the following cases:
- Killing all processes in a leaf cgroup, but leaving the
parent untouched
- Killing all processes in a parent and leaf cgroup
- Keeping processes marked by OOM_SCORE_ADJ_MIN alive when considered
for being killed by the group oom killer.

Signed-off-by: Jay Kamat <[e-mail]>
Acked-by: Roman Gushchin <[e-mail]>
Signed-off-by: Shuah Khan (Samsung OSG) <[e-mail]>

tools/testing/selftests/cgroup/cgroup_util.c

···
 
 	return cnt > 1;
 }
+
+int set_oom_adj_score(int pid, int score)
+{
+	char path[PATH_MAX];
+	int fd, len;
+
+	sprintf(path, "/proc/%d/oom_score_adj", pid);
+
+	fd = open(path, O_WRONLY | O_APPEND);
+	if (fd < 0)
+		return fd;
+
+	len = dprintf(fd, "%d", score);
+	if (len < 0) {
+		close(fd);
+		return len;
+	}
+
+	close(fd);
+	return 0;
+}

tools/testing/selftests/cgroup/cgroup_util.h

···
 extern int alloc_pagecache(int fd, size_t size);
 extern int alloc_anon(const char *cgroup, void *arg);
 extern int is_swap_enabled(void);
+extern int set_oom_adj_score(int pid, int score);

tools/testing/selftests/cgroup/test_memcontrol.c

···
 #define _GNU_SOURCE
 
 #include <linux/limits.h>
+#include <linux/oom.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
···
 		sleep(1);
 
 	return 0;
+}
+
+static int alloc_anon_noexit(const char *cgroup, void *arg)
+{
+	int ppid = getppid();
+
+	if (alloc_anon(cgroup, arg))
+		return -1;
+
+	while (getppid() == ppid)
+		sleep(1);
+
+	return 0;
+}
+
+/*
+ * Wait until processes are killed asynchronously by the OOM killer
+ * If we exceed a timeout, fail.
+ */
+static int cg_test_proc_killed(const char *cgroup)
+{
+	int limit;
+
+	for (limit = 10; limit > 0; limit--) {
+		if (cg_read_strcmp(cgroup, "cgroup.procs", "") == 0)
+			return 0;
+
+		usleep(100000);
+	}
+	return -1;
 }
 
 /*
···
 	return ret;
 }
 
+/*
+ * This test disables swapping and tries to allocate anonymous memory
+ * up to OOM with memory.group.oom set. Then it checks that all
+ * processes in the leaf (but not the parent) were killed.
+ */
+static int test_memcg_oom_group_leaf_events(const char *root)
+{
+	int ret = KSFT_FAIL;
+	char *parent, *child;
+
+	parent = cg_name(root, "memcg_test_0");
+	child = cg_name(root, "memcg_test_0/memcg_test_1");
+
+	if (!parent || !child)
+		goto cleanup;
+
+	if (cg_create(parent))
+		goto cleanup;
+
+	if (cg_create(child))
+		goto cleanup;
+
+	if (cg_write(parent, "cgroup.subtree_control", "+memory"))
+		goto cleanup;
+
+	if (cg_write(child, "memory.max", "50M"))
+		goto cleanup;
+
+	if (cg_write(child, "memory.swap.max", "0"))
+		goto cleanup;
+
+	if (cg_write(child, "memory.oom.group", "1"))
+		goto cleanup;
+
+	cg_run_nowait(parent, alloc_anon_noexit, (void *) MB(60));
+	cg_run_nowait(child, alloc_anon_noexit, (void *) MB(1));
+	cg_run_nowait(child, alloc_anon_noexit, (void *) MB(1));
+	if (!cg_run(child, alloc_anon, (void *)MB(100)))
+		goto cleanup;
+
+	if (cg_test_proc_killed(child))
+		goto cleanup;
+
+	if (cg_read_key_long(child, "memory.events", "oom_kill ") <= 0)
+		goto cleanup;
+
+	if (cg_read_key_long(parent, "memory.events", "oom_kill ") != 0)
+		goto cleanup;
+
+	ret = KSFT_PASS;
+
+cleanup:
+	if (child)
+		cg_destroy(child);
+	if (parent)
+		cg_destroy(parent);
+	free(child);
+	free(parent);
+
+	return ret;
+}
+
+/*
+ * This test disables swapping and tries to allocate anonymous memory
+ * up to OOM with memory.group.oom set. Then it checks that all
+ * processes in the parent and leaf were killed.
+ */
+static int test_memcg_oom_group_parent_events(const char *root)
+{
+	int ret = KSFT_FAIL;
+	char *parent, *child;
+
+	parent = cg_name(root, "memcg_test_0");
+	child = cg_name(root, "memcg_test_0/memcg_test_1");
+
+	if (!parent || !child)
+		goto cleanup;
+
+	if (cg_create(parent))
+		goto cleanup;
+
+	if (cg_create(child))
+		goto cleanup;
+
+	if (cg_write(parent, "memory.max", "80M"))
+		goto cleanup;
+
+	if (cg_write(parent, "memory.swap.max", "0"))
+		goto cleanup;
+
+	if (cg_write(parent, "memory.oom.group", "1"))
+		goto cleanup;
+
+	cg_run_nowait(parent, alloc_anon_noexit, (void *) MB(60));
+	cg_run_nowait(child, alloc_anon_noexit, (void *) MB(1));
+	cg_run_nowait(child, alloc_anon_noexit, (void *) MB(1));
+
+	if (!cg_run(child, alloc_anon, (void *)MB(100)))
+		goto cleanup;
+
+	if (cg_test_proc_killed(child))
+		goto cleanup;
+	if (cg_test_proc_killed(parent))
+		goto cleanup;
+
+	ret = KSFT_PASS;
+
+cleanup:
+	if (child)
+		cg_destroy(child);
+	if (parent)
+		cg_destroy(parent);
+	free(child);
+	free(parent);
+
+	return ret;
+}
+
+/*
+ * This test disables swapping and tries to allocate anonymous memory
+ * up to OOM with memory.group.oom set. Then it checks that all
+ * processes were killed except those set with OOM_SCORE_ADJ_MIN
+ */
+static int test_memcg_oom_group_score_events(const char *root)
+{
+	int ret = KSFT_FAIL;
+	char *memcg;
+	int safe_pid;
+
+	memcg = cg_name(root, "memcg_test_0");
+
+	if (!memcg)
+		goto cleanup;
+
+	if (cg_create(memcg))
+		goto cleanup;
+
+	if (cg_write(memcg, "memory.max", "50M"))
+		goto cleanup;
+
+	if (cg_write(memcg, "memory.swap.max", "0"))
+		goto cleanup;
+
+	if (cg_write(memcg, "memory.oom.group", "1"))
+		goto cleanup;
+
+	safe_pid = cg_run_nowait(memcg, alloc_anon_noexit, (void *) MB(1));
+	if (set_oom_adj_score(safe_pid, OOM_SCORE_ADJ_MIN))
+		goto cleanup;
+
+	cg_run_nowait(memcg, alloc_anon_noexit, (void *) MB(1));
+	if (!cg_run(memcg, alloc_anon, (void *)MB(100)))
+		goto cleanup;
+
+	if (cg_read_key_long(memcg, "memory.events", "oom_kill ") != 3)
+		goto cleanup;
+
+	if (kill(safe_pid, SIGKILL))
+		goto cleanup;
+
+	ret = KSFT_PASS;
+
+cleanup:
+	if (memcg)
+		cg_destroy(memcg);
+	free(memcg);
+
+	return ret;
+}
+
+
 #define T(x) { x, #x }
 struct memcg_test {
 	int (*fn)(const char *root);
···
 	T(test_memcg_oom_events),
 	T(test_memcg_swap_max),
 	T(test_memcg_sock),
+	T(test_memcg_oom_group_leaf_events),
+	T(test_memcg_oom_group_parent_events),
+	T(test_memcg_oom_group_score_events),
 };
 #undef T