Re: [PATCH 2/2] Add tests for memory.oom.group

[Shuah Khan <shuah@kernel.org>]

Hi Jay,

Thanks for the patch. Comments below:

On 09/04/2018 07:08 PM, jgkamat@fb.com wrote:
> From: Jay Kamat <jgkamat@fb.com>
> 
> 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>
> ---
>  tools/testing/selftests/cgroup/cgroup_util.c  |  21 ++
>  tools/testing/selftests/cgroup/cgroup_util.h  |   1 +
>  .../selftests/cgroup/test_memcontrol.c        | 205 ++++++++++++++++++
>  3 files changed, 227 insertions(+)
> 
> diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c
> index 4aadf38bcd5d..6799c69d7f03 100644
> --- a/tools/testing/selftests/cgroup/cgroup_util.c
> +++ b/tools/testing/selftests/cgroup/cgroup_util.c
> @@ -338,3 +338,24 @@ 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 fe82a297d4e0..cabd43fd137a 100644
> --- a/tools/testing/selftests/cgroup/cgroup_util.h
> +++ b/tools/testing/selftests/cgroup/cgroup_util.h
> @@ -39,3 +39,4 @@ 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..017c15a7a935 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 @@ static int test_memcg_sock(const char *root)
>  	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))
> +		return -1;

Missing cleanup? Should the return be just ret which is KSFT_FAIL
> +
> +	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
>  
> 

thanks,
-- Shuah