Commit eae3cb2e authored by Yosry Ahmed's avatar Yosry Ahmed Committed by Andrew Morton
Browse files

selftests: cgroup: add a selftest for memory.reclaim 

Add a new test for memory.reclaim that verifies that the interface
correctly reclaims memory as intended, from both anon and file pages.

Link: https://lkml.kernel.org/r/20220425190040.2475377-5-yosryahmed@google.com


Signed-off-by: default avatarYosry Ahmed <yosryahmed@google.com>
Acked-by: default avatarRoman Gushchin <roman.gushchin@linux.dev>
Acked-by: default avatarDavid Rientjes <rientjes@google.com>
Cc: Chen Wandun <chenwandun@huawei.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Michal Koutn" <mkoutny@suse.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Vaibhav Jain <vaibhav@linux.ibm.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent a3622a53

tools/testing/selftests/cgroup/test_memcontrol.c

+106 −0
Original line number Diff line number Diff line
@@ -760,6 +760,111 @@ static int test_memcg_max(const char *root) 
	return ret;

}



/*

 * This test checks that memory.reclaim reclaims the given

 * amount of memory (from both anon and file, if possible).

 */

static int test_memcg_reclaim(const char *root)

{

	int ret = KSFT_FAIL, fd, retries;

	char *memcg;

	long current, expected_usage, to_reclaim;

	char buf[64];



	memcg = cg_name(root, "memcg_test");

	if (!memcg)

		goto cleanup;



	if (cg_create(memcg))

		goto cleanup;



	current = cg_read_long(memcg, "memory.current");

	if (current != 0)

		goto cleanup;



	fd = get_temp_fd();

	if (fd < 0)

		goto cleanup;



	cg_run_nowait(memcg, alloc_pagecache_50M_noexit, (void *)(long)fd);



	/*

	 * If swap is enabled, try to reclaim from both anon and file, else try

	 * to reclaim from file only.

	 */

	if (is_swap_enabled()) {

		cg_run_nowait(memcg, alloc_anon_noexit, (void *) MB(50));

		expected_usage = MB(100);

	} else

		expected_usage = MB(50);



	/*

	 * Wait until current usage reaches the expected usage (or we run out of

	 * retries).

	 */

	retries = 5;

	while (!values_close(cg_read_long(memcg, "memory.current"),

			    expected_usage, 10)) {

		if (retries--) {

			sleep(1);

			continue;

		} else {

			fprintf(stderr,

				"failed to allocate %ld for memcg reclaim test\n",

				expected_usage);

			goto cleanup;

		}

	}



	/*

	 * Reclaim until current reaches 30M, this makes sure we hit both anon

	 * and file if swap is enabled.

	 */

	retries = 5;

	while (true) {

		int err;



		current = cg_read_long(memcg, "memory.current");

		to_reclaim = current - MB(30);



		/*

		 * We only keep looping if we get EAGAIN, which means we could

		 * not reclaim the full amount.

		 */

		if (to_reclaim <= 0)

			goto cleanup;





		snprintf(buf, sizeof(buf), "%ld", to_reclaim);

		err = cg_write(memcg, "memory.reclaim", buf);

		if (!err) {

			/*

			 * If writing succeeds, then the written amount should have been

			 * fully reclaimed (and maybe more).

			 */

			current = cg_read_long(memcg, "memory.current");

			if (!values_close(current, MB(30), 3) && current > MB(30))

				goto cleanup;

			break;

		}



		/* The kernel could not reclaim the full amount, try again. */

		if (err == -EAGAIN && retries--)

			continue;



		/* We got an unexpected error or ran out of retries. */

		goto cleanup;

	}



	ret = KSFT_PASS;

cleanup:

	cg_destroy(memcg);

	free(memcg);

	close(fd);



	return ret;

}



static int alloc_anon_50M_check_swap(const char *cgroup, void *arg)

{

	long mem_max = (long)arg;
@@ -1264,6 +1369,7 @@ struct memcg_test { 
	T(test_memcg_high),

	T(test_memcg_high_sync),

	T(test_memcg_max),

	T(test_memcg_reclaim),

	T(test_memcg_oom_events),

	T(test_memcg_swap_max),

	T(test_memcg_sock),