Re: [LTP] [PATCH 6/6] memcontrol03: Copy from kselftest

[Cyril Hrubis <chrubis@suse.cz>]

Hi!
> +// SPDX-License-Identifier: GPL-2.0
> +/*\
> + *
> + * [Description]
> + *
> + * Conversion of the third kself test in cgroup/test_memcontrol.c.
> + *
> + * Original description:
> + * "First, this test creates the following hierarchy:
> + * A       memory.min = 50M,  memory.max = 200M
> + * A/B     memory.min = 50M,  memory.current = 50M
> + * A/B/C   memory.min = 75M,  memory.current = 50M
> + * A/B/D   memory.min = 25M,  memory.current = 50M
> + * A/B/E   memory.min = 500M, memory.current = 0
> + * A/B/F   memory.min = 0,    memory.current = 50M
> + *
> + * Usages are pagecache, but the test keeps a running
> + * process in every leaf cgroup.
> + * Then it creates A/G and creates a significant
> + * memory pressure in it.
> + *
> + * A/B    memory.current ~= 50M
> + * A/B/C  memory.current ~= 33M
> + * A/B/D  memory.current ~= 17M
> + * A/B/E  memory.current ~= 0
> + *
> + * After that it tries to allocate more than there is unprotected
> + * memory in A available, and checks that memory.min protects
> + * pagecache even in this case."
> + *
> + * memory.min doesn't appear to exist on V1 so we only test on V2 like
> + * the selftest. We do test on more file systems, but not tempfs
> + * becaue it can't evict the page cache without swap. Also we avoid
> + * filesystems which allocate extra memory for buffer heads.
> + *
> + * The tolerances have been increased from the self tests.
> + *
> + */
> +
> +#define _GNU_SOURCE
> +
> +#include <inttypes.h>
> +
> +#include "memcontrol_common.h"
> +
> +#define TMPDIR "mntdir"
> +
> +static const struct tst_cgroup_group *cg_test;
> +static struct tst_cgroup_group *parent[3];
> +static struct tst_cgroup_group *children[4];
> +static int fd;
> +
> +enum checkpoints {
> +	CHILD_IDLE,
> +	TEST_DONE,
> +};
> +
> +static void cleanup_sub_groups(void)
> +{
> +	size_t i;
> +
> +	for (i = ARRAY_SIZE(children); i > 0; i--) {
> +		if (!children[i - 1])
> +			continue;
> +
> +		TST_CHECKPOINT_WAKE2(TEST_DONE,
> +				     ARRAY_SIZE(children) - 1);
> +		tst_reap_children();
> +		break;
> +	}
> +
> +	for (i = ARRAY_SIZE(children); i > 0; i--) {
> +		if (!children[i - 1])
> +			continue;
> +
> +		children[i - 1] = tst_cgroup_group_rm(children[i - 1]);
> +	}
> +
> +	for (i = ARRAY_SIZE(parent); i > 0; i--) {
> +		if (!parent[i - 1])
> +			continue;
> +
> +		parent[i - 1] = tst_cgroup_group_rm(parent[i - 1]);
> +	}
> +}
> +
> +static void alloc_anon_in_child(const struct tst_cgroup_group *const cg,
> +				const size_t size, const int expect_oom)
> +{
> +	int status;
> +	const pid_t pid = SAFE_FORK();
> +
> +	if (!pid) {
> +		SAFE_CGROUP_PRINTF(cg, "cgroup.procs", "%d", getpid());
> +
> +		tst_res(TINFO, "%d in %s: Allocating anon: %"PRIdPTR,
> +		getpid(), tst_cgroup_group_name(cg), size);
> +		alloc_anon(size);
> +		exit(0);
> +	}
> +
> +	if (expect_oom)
> +		SAFE_WAITPID(pid, &status, 0);
> +	else
> +		tst_reap_child(pid);

I guess that we can do the SAFE_WAITPID() here in both cases but just
adjust expectations:

	SAFE_WAITPID(pid, &status, 0);

	if (WIFEXITTED(status) && WEXITSTATUS(status) == 0)
		return;

	if (expect_oom && WIFSIGNALED(status) && WTERMSIG(status) == SIGKILL)
		return;

	tst_res(TFAIL, "Child %s", tst_strstatus(status);

> +}
> +
> +static void alloc_pagecache_in_child(const struct tst_cgroup_group *const cg,
> +				     const size_t size)
> +{
> +	const pid_t pid = SAFE_FORK();
> +
> +	if (pid) {
> +		TST_CHECKPOINT_WAIT(CHILD_IDLE);
> +		return;
> +	}
> +
> +	SAFE_CGROUP_PRINTF(cg, "cgroup.procs", "%d", getpid());
> +
> +	tst_res(TINFO, "%d in %s: Allocating pagecache: %"PRIdPTR,
> +		getpid(), tst_cgroup_group_name(cg), size);
> +	alloc_pagecache(fd, size);
> +
> +	TST_CHECKPOINT_WAKE(CHILD_IDLE);
> +	TST_CHECKPOINT_WAIT(TEST_DONE);
> +	exit(0);
> +}
> +
> +/*
> + */

Empty comment.

> +static void test_memcg_min(void)
> +{
> +	long c[4];
> +	size_t i, attempts;
> +	char child_name[64];
> +
> +	fd = SAFE_OPEN(TMPDIR"/tmpfile", O_RDWR | O_CREAT, 0600);
> +	parent[0] = tst_cgroup_group_mk(cg_test, "memcg_test_0");
> +
> +	SAFE_CGROUP_SCANF(parent[0], "memory.min", "%ld", c);
> +	if (c[0]) {
> +		tst_brk(TCONF,
> +			"memory.min already set to %ld on parent group", c[0]);
> +	}
> +
> +	if (!TST_CGROUP_VER_IS_V1(parent[0], "memory")) {
> +		SAFE_CGROUP_PRINT(parent[0], "cgroup.subtree_control",
> +				  "+memory");
> +	}
> +	SAFE_CGROUP_PRINT(parent[0], "memory.max", "200M");
> +	SAFE_CGROUP_PRINT(parent[0], "memory.swap.max", "0");
> +
> +	parent[1] = tst_cgroup_group_mk(parent[0], "memcg_test_1");
> +	if (!TST_CGROUP_VER_IS_V1(parent[0], "memory")) {
> +		SAFE_CGROUP_PRINT(parent[1], "cgroup.subtree_control",
> +				  "+memory");

Don't we enable the memory controller automatically in the LTP library?

> +	}
> +
> +	parent[2] = tst_cgroup_group_mk(parent[0], "memcg_test_2");
> +
> +	for (i = 0; i < ARRAY_SIZE(children); i++) {
> +		sprintf(child_name, "child_memcg_%"PRIdPTR, i);
> +
> +		children[i] = tst_cgroup_group_mk(parent[1], child_name);

I guess that it would be a bit more elegant if the tst_cgroup_group_mk()
would have been printf-like function.

> +		if (i == 2)
> +			continue;
> +
> +		alloc_pagecache_in_child(children[i], MB(50));
> +	}
> +
> +	SAFE_CGROUP_PRINT(parent[0], "memory.min", "50M");
> +	SAFE_CGROUP_PRINT(parent[1], "memory.min", "50M");
> +	SAFE_CGROUP_PRINT(children[0], "memory.min", "75M");
> +	SAFE_CGROUP_PRINT(children[1], "memory.min", "25M");
> +	SAFE_CGROUP_PRINT(children[2], "memory.min", "500M");
> +	SAFE_CGROUP_PRINT(children[3], "memory.min", "0");
> +
> +	for (attempts = 0; attempts < 5; attempts++) {
> +		SAFE_CGROUP_SCANF(parent[1], "memory.current", "%ld", c);
> +		if (values_close(c[0], MB(150), 3))
> +			break;
> +
> +		sleep(1);
> +	}
> +
> +	alloc_anon_in_child(parent[2], MB(148), 0);

I find the usage of parent and child in the code a bit confusing, the
parent[2] is actually a child of parent[0].

Maybe we should call them "generation" such as gen1, gen2, etc.

So that we would have:

	gen1 = tst_cgroup_group_mk(cg_test, "memcg_test_gen1");
	gen2[0] = tst_cgroup_group_mk(gen1, "memcg_test_gen2_0");
	gen2[1] = tst_cgroup_group_mk(gen2, "memcg_test_get2_1");

	for (...)
		gen3[i] = tst_cgroup_group_mk(gen2[0], "memcg_test_gen3_%i", i);

> +	SAFE_CGROUP_SCANF(parent[1], "memory.current", "%ld", c);
> +	TST_EXP_EXPR(values_close(c[0], MB(50), 5), "(A/B memory.current=%ld) ~= %d", c[0], MB(50));
> +
> +	for (i = 0; i < ARRAY_SIZE(children); i++)
> +		SAFE_CGROUP_SCANF(children[i], "memory.current", "%ld", c + i);
> +
> +	TST_EXP_EXPR(values_close(c[0], MB(33), 20), "(A/B/C memory.current=%ld) ~= %d", c[0], MB(33));
> +	TST_EXP_EXPR(values_close(c[1], MB(17), 20), "(A/B/D memory.current=%ld) ~= %d", c[1], MB(17));
> +	TST_EXP_EXPR(values_close(c[2], 0, 1), "(A/B/E memory.current=%ld) ~= 0", c[2]);
> +
> +	alloc_anon_in_child(parent[2], MB(170), 1);
> +
> +	SAFE_CGROUP_SCANF(parent[1], "memory.current", "%ld", c);
> +	TST_EXP_EXPR(values_close(c[0], MB(50), 5), "(A/B memory.current=%ld) ~= %d", c[0], MB(50));
> +
> +	cleanup_sub_groups();
> +	SAFE_CLOSE(fd);
> +}
> +
> +static void cleanup(void)
> +{
> +	cleanup_sub_groups();
> +	if (fd > -1)
> +		SAFE_CLOSE(fd);

Technically this should either be fd > 0 or the global should be
initialized to -1.

> +}
> +
> +static struct tst_test test = {
> +	.cleanup = cleanup,
> +	.test_all = test_memcg_min,
> +	.mount_device = 1,
> +	.dev_min_size = 256,
> +	.mntpoint = TMPDIR,
> +	.all_filesystems = 1,
> +	.skip_filesystems = (const char *const[]){
> +		"exfat", "vfat", "fuse", "ntfs", "tmpfs", NULL
> +	},
> +	.forks_child = 1,
> +	.needs_root = 1,
> +	.needs_checkpoints = 1,
> +	.needs_cgroup_ver = TST_CGROUP_V2,
> +	.needs_cgroup_controllers = (const char *const[]){ "memory", NULL },
> +	.test_cgroup = &cg_test,
> +};
> -- 
> 2.34.1
> 
> 
> -- 
> Mailing list info: https://lists.linux.it/listinfo/ltp

-- 
Cyril Hrubis
chrubis@suse.cz

-- 
Mailing list info: https://lists.linux.it/listinfo/ltp