Add a new test for memory.reclaim that verifies that the interface correctly reclaims memory as intended, from both anon and file pages.
Signed-off-by: Yosry Ahmed yosryahmed@google.com Acked-by: Roman Gushchin roman.gushchin@linux.dev --- .../selftests/cgroup/test_memcontrol.c | 106 ++++++++++++++++++ 1 file changed, 106 insertions(+)
diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c index f2ffb3a30194..a9c691fb94c0 100644 --- a/tools/testing/selftests/cgroup/test_memcontrol.c +++ b/tools/testing/selftests/cgroup/test_memcontrol.c @@ -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; @@ -1263,6 +1368,7 @@ 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),