Commit fd06ce2c authored by Mike Yuan's avatar Mike Yuan Committed by Andrew Morton
Browse files

selftests: test_zswap: add test for hierarchical zswap.writeback 

Ensure that zswap.writeback check goes up the cgroup tree, i.e.  is
hierarchical.  Create a subcgroup which has zswap.writeback set to 1, and
the upper hierarchy's restrictions shall apply.

Link: https://lkml.kernel.org/r/20240823162506.12117-2-me@yhndnzj.com


Signed-off-by: default avatarMike Yuan <me@yhndnzj.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 20a5532f

tools/testing/selftests/cgroup/test_zswap.c

+54 −21
Original line number Diff line number Diff line
@@ -263,15 +263,13 @@ static int test_zswapin(const char *root) 
static int attempt_writeback(const char *cgroup, void *arg)

{

	long pagesize = sysconf(_SC_PAGESIZE);

	char *test_group = arg;

	size_t memsize = MB(4);

	char buf[pagesize];

	long zswap_usage;

	bool wb_enabled;

	bool wb_enabled = *(bool *) arg;

	int ret = -1;

	char *mem;



	wb_enabled = cg_read_long(test_group, "memory.zswap.writeback");

	mem = (char *)malloc(memsize);

	if (!mem)

		return ret;
@@ -288,12 +286,12 @@ static int attempt_writeback(const char *cgroup, void *arg) 
		memcpy(&mem[i], buf, pagesize);



	/* Try and reclaim allocated memory */

	if (cg_write_numeric(test_group, "memory.reclaim", memsize)) {

	if (cg_write_numeric(cgroup, "memory.reclaim", memsize)) {

		ksft_print_msg("Failed to reclaim all of the requested memory\n");

		goto out;

	}



	zswap_usage = cg_read_long(test_group, "memory.zswap.current");

	zswap_usage = cg_read_long(cgroup, "memory.zswap.current");



	/* zswpin */

	for (int i = 0; i < memsize; i += pagesize) {
@@ -303,7 +301,7 @@ static int attempt_writeback(const char *cgroup, void *arg) 
		}

	}



	if (cg_write_numeric(test_group, "memory.zswap.max", zswap_usage/2))

	if (cg_write_numeric(cgroup, "memory.zswap.max", zswap_usage/2))

		goto out;



	/*
@@ -312,7 +310,7 @@ static int attempt_writeback(const char *cgroup, void *arg) 
	 * If writeback is disabled, memory reclaim will fail as zswap is limited and

	 * it can't writeback to swap.

	 */

	ret = cg_write_numeric(test_group, "memory.reclaim", memsize);

	ret = cg_write_numeric(cgroup, "memory.reclaim", memsize);

	if (!wb_enabled)

		ret = (ret == -EAGAIN) ? 0 : -1;
@@ -321,12 +319,41 @@ static int attempt_writeback(const char *cgroup, void *arg) 
	return ret;

}



static int test_zswap_writeback_one(const char *cgroup, bool wb)

{

	long zswpwb_before, zswpwb_after;



	zswpwb_before = get_cg_wb_count(cgroup);

	if (zswpwb_before != 0) {

		ksft_print_msg("zswpwb_before = %ld instead of 0\n", zswpwb_before);

		return -1;

	}



	if (cg_run(cgroup, attempt_writeback, (void *) &wb))

		return -1;



	/* Verify that zswap writeback occurred only if writeback was enabled */

	zswpwb_after = get_cg_wb_count(cgroup);

	if (zswpwb_after < 0)

		return -1;



	if (wb != !!zswpwb_after) {

		ksft_print_msg("zswpwb_after is %ld while wb is %s",

				zswpwb_after, wb ? "enabled" : "disabled");

		return -1;

	}



	return 0;

}



/* Test to verify the zswap writeback path */

static int test_zswap_writeback(const char *root, bool wb)

{

	long zswpwb_before, zswpwb_after;

	int ret = KSFT_FAIL;

	char *test_group;

	char *test_group, *test_group_child = NULL;



	if (cg_read_strcmp(root, "memory.zswap.writeback", "1"))

		return KSFT_SKIP;



	test_group = cg_name(root, "zswap_writeback_test");

	if (!test_group)
@@ -336,29 +363,35 @@ static int test_zswap_writeback(const char *root, bool wb) 
	if (cg_write(test_group, "memory.zswap.writeback", wb ? "1" : "0"))

		goto out;



	zswpwb_before = get_cg_wb_count(test_group);

	if (zswpwb_before != 0) {

		ksft_print_msg("zswpwb_before = %ld instead of 0\n", zswpwb_before);

	if (test_zswap_writeback_one(test_group, wb))

		goto out;

	}



	if (cg_run(test_group, attempt_writeback, (void *) test_group))

	/* Reset memory.zswap.max to max (modified by attempt_writeback), and

	 * set up child cgroup, whose memory.zswap.writeback is hardcoded to 1.

	 * Thus, the parent's setting shall be what's in effect. */

	if (cg_write(test_group, "memory.zswap.max", "max"))

		goto out;

	if (cg_write(test_group, "cgroup.subtree_control", "+memory"))

		goto out;



	/* Verify that zswap writeback occurred only if writeback was enabled */

	zswpwb_after = get_cg_wb_count(test_group);

	if (zswpwb_after < 0)

	test_group_child = cg_name(test_group, "zswap_writeback_test_child");

	if (!test_group_child)

		goto out;

	if (cg_create(test_group_child))

		goto out;

	if (cg_write(test_group_child, "memory.zswap.writeback", "1"))

		goto out;



	if (wb != !!zswpwb_after) {

		ksft_print_msg("zswpwb_after is %ld while wb is %s",

				zswpwb_after, wb ? "enabled" : "disabled");

	if (test_zswap_writeback_one(test_group_child, wb))

		goto out;

	}



	ret = KSFT_PASS;



out:

	if (test_group_child) {

		cg_destroy(test_group_child);

		free(test_group_child);

	}

	cg_destroy(test_group);

	free(test_group);

	return ret;