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 <jgkamat@fb.com>
Acked-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>

3 files changed, 227 insertions, 0 deletions

diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c
index f857def9a9e6..14c9fe284806 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.c
+++ b/tools/testing/selftests/cgroup/cgroup_util.c
@@ -348,3 +348,24 @@ int is_swap_enabled(void)
 
         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;
+}
diff --git a/tools/testing/selftests/cgroup/cgroup_util.h b/tools/testing/selftests/cgroup/cgroup_util.h
index 1ff6f9f1abdc..9ac8b7958f83 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.h
+++ b/tools/testing/selftests/cgroup/cgroup_util.h
@@ -40,3 +40,4 @@ extern int get_temp_fd(void);
 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);
diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
index cf0bddc9d271..28d321ba311b 100644
--- a/tools/testing/selftests/cgroup/test_memcontrol.c
+++ b/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -2,6 +2,7 @@
 #define _GNU_SOURCE
 
 #include <linux/limits.h>
+#include <linux/oom.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -202,6 +203,36 @@ static int alloc_pagecache_50M_noexit(const char *cgroup, void *arg)
         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;
+}
+
 /*
  * First, this test creates the following hierarchy:
  * A       memory.min = 50M,  memory.max = 200M
@@ -964,6 +995,177 @@ cleanup:
         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);
@@ -978,6 +1180,9 @@ struct memcg_test {
         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