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Subject[PATCH] selftests: cgroup/memcontrol: add basic test for swap controls
Date
The new test verifies that memory.swap.max and memory.swap.current behave
as expected for simple allocation scenarios

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
---

The patch is against kselftest/next branch

tools/testing/selftests/cgroup/cgroup_util.c | 16 +++++
tools/testing/selftests/cgroup/cgroup_util.h | 1 +
tools/testing/selftests/cgroup/test_memcontrol.c | 91 ++++++++++++++++++++++++
3 files changed, 108 insertions(+)

diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c
index a938b6c8b55a..41cc3b5e5be1 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.c
+++ b/tools/testing/selftests/cgroup/cgroup_util.c
@@ -315,3 +315,19 @@ int alloc_anon(const char *cgroup, void *arg)
free(buf);
return 0;
}
+
+int is_swap_enabled(void)
+{
+ char buf[PAGE_SIZE];
+ const char delim[] = "\n";
+ int cnt = 0;
+ char *line;
+
+ if (read_text("/proc/swaps", buf, sizeof(buf)) <= 0)
+ return -1;
+
+ for (line = strtok(buf, delim); line; line = strtok(NULL, delim))
+ cnt++;
+
+ return cnt > 1;
+}
diff --git a/tools/testing/selftests/cgroup/cgroup_util.h b/tools/testing/selftests/cgroup/cgroup_util.h
index 000de075d3d8..fe82a297d4e0 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.h
+++ b/tools/testing/selftests/cgroup/cgroup_util.h
@@ -38,3 +38,4 @@ extern int cg_run_nowait(const char *cgroup,
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);
diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
index c92a21f3c806..beae06c9c899 100644
--- a/tools/testing/selftests/cgroup/test_memcontrol.c
+++ b/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -638,6 +638,96 @@ static int test_memcg_max(const char *root)
return ret;
}

+static int alloc_anon_50M_check_swap(const char *cgroup, void *arg)
+{
+ long mem_max = (long)arg;
+ size_t size = MB(50);
+ char *buf, *ptr;
+ long mem_current, swap_current;
+ int ret = -1;
+
+ buf = malloc(size);
+ for (ptr = buf; ptr < buf + size; ptr += PAGE_SIZE)
+ *ptr = 0;
+
+ mem_current = cg_read_long(cgroup, "memory.current");
+ if (!mem_current || !values_close(mem_current, mem_max, 3))
+ goto cleanup;
+
+ swap_current = cg_read_long(cgroup, "memory.swap.current");
+ if (!swap_current ||
+ !values_close(mem_current + swap_current, size, 3))
+ goto cleanup;
+
+ ret = 0;
+cleanup:
+ free(buf);
+ return ret;
+}
+
+/*
+ * This test checks that memory.swap.max limits the amount of
+ * anonymous memory which can be swapped out.
+ */
+static int test_memcg_swap_max(const char *root)
+{
+ int ret = KSFT_FAIL;
+ char *memcg;
+ long max;
+
+ if (!is_swap_enabled())
+ return KSFT_SKIP;
+
+ memcg = cg_name(root, "memcg_test");
+ if (!memcg)
+ goto cleanup;
+
+ if (cg_create(memcg))
+ goto cleanup;
+
+ if (cg_read_long(memcg, "memory.swap.current")) {
+ ret = KSFT_SKIP;
+ goto cleanup;
+ }
+
+ if (cg_read_strcmp(memcg, "memory.max", "max\n"))
+ goto cleanup;
+
+ if (cg_read_strcmp(memcg, "memory.swap.max", "max\n"))
+ goto cleanup;
+
+ if (cg_write(memcg, "memory.swap.max", "30M"))
+ goto cleanup;
+
+ if (cg_write(memcg, "memory.max", "30M"))
+ goto cleanup;
+
+ /* Should be killed by OOM killer */
+ if (!cg_run(memcg, alloc_anon, (void *)MB(100)))
+ goto cleanup;
+
+ if (cg_read_key_long(memcg, "memory.events", "oom ") != 1)
+ goto cleanup;
+
+ if (cg_read_key_long(memcg, "memory.events", "oom_kill ") != 1)
+ goto cleanup;
+
+ if (cg_run(memcg, alloc_anon_50M_check_swap, (void *)MB(30)))
+ goto cleanup;
+
+ max = cg_read_key_long(memcg, "memory.events", "max ");
+ if (max <= 0)
+ goto cleanup;
+
+ ret = KSFT_PASS;
+
+cleanup:
+ cg_destroy(memcg);
+ free(memcg);
+
+ return ret;
+}
+
/*
* This test disables swapping and tries to allocate anonymous memory
* up to OOM. Then it checks for oom and oom_kill events in
@@ -694,6 +784,7 @@ struct memcg_test {
T(test_memcg_high),
T(test_memcg_max),
T(test_memcg_oom_events),
+ T(test_memcg_swap_max),
};
#undef T

--
2.7.4
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