From da2fde982a9fdc7cbda7be4f02da7f3e555f95d4 Mon Sep 17 00:00:00 2001 From: David Vernet Date: Thu, 12 May 2022 20:22:57 -0700 Subject: [PATCH] cgroup: account for memory_recursiveprot in test_memcg_low() The test_memcg_low() testcase in test_memcontrol.c verifies the expected behavior of groups using the memory.low knob. Part of the testcase verifies that a group with memory.low that experiences reclaim due to memory pressure elsewhere in the system, observes memory.events.low events as a result of that reclaim. In commit e592ca4e1552 ("mm: memcontrol: recursive memory.low protection"), the memory controller was updated to propagate memory.low and memory.min protection from a parent group to its children via a configurable memory_recursiveprot mount option. This unfortunately broke the memcg tests, which asserts that a sibling that experienced reclaim but had a memory.low value of 0, would not observe any memory.low events. This patch updates test_memcg_low() to account for the new behavior introduced by memory_recursiveprot. So as to make the test resilient to multiple configurations, the patch also adds a new proc_mount_contains() helper that checks for a string in /proc/mounts, and is used to toggle behavior based on whether the default memory_recursiveprot was present. Link: https://lkml.kernel.org/r/20220423155619.3669555-3-void@manifault.com Signed-off-by: David Vernet Acked-by: Roman Gushchin Cc: Johannes Weiner Cc: Michal Hocko Cc: Shakeel Butt Cc: Tejun Heo Signed-off-by: Andrew Morton --- tools/testing/selftests/cgroup/cgroup_util.c | 12 ++++++++++++ tools/testing/selftests/cgroup/cgroup_util.h | 1 + tools/testing/selftests/cgroup/test_memcontrol.c | 16 +++++++++++++--- 3 files changed, 26 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c index e6f3679cdcc08..b4d7027a44c3e 100644 --- a/tools/testing/selftests/cgroup/cgroup_util.c +++ b/tools/testing/selftests/cgroup/cgroup_util.c @@ -528,6 +528,18 @@ int set_oom_adj_score(int pid, int score) return 0; } +int proc_mount_contains(const char *option) +{ + char buf[4 * PAGE_SIZE]; + ssize_t read; + + read = read_text("/proc/mounts", buf, sizeof(buf)); + if (read < 0) + return read; + + return strstr(buf, option) != NULL; +} + ssize_t proc_read_text(int pid, bool thread, const char *item, char *buf, size_t size) { char path[PATH_MAX]; diff --git a/tools/testing/selftests/cgroup/cgroup_util.h b/tools/testing/selftests/cgroup/cgroup_util.h index 628738532ac9b..756f76052b443 100644 --- a/tools/testing/selftests/cgroup/cgroup_util.h +++ b/tools/testing/selftests/cgroup/cgroup_util.h @@ -48,6 +48,7 @@ extern int is_swap_enabled(void); extern int set_oom_adj_score(int pid, int score); extern int cg_wait_for_proc_count(const char *cgroup, int count); extern int cg_killall(const char *cgroup); +int proc_mount_contains(const char *option); extern ssize_t proc_read_text(int pid, bool thread, const char *item, char *buf, size_t size); extern int proc_read_strstr(int pid, bool thread, const char *item, const char *needle); extern pid_t clone_into_cgroup(int cgroup_fd); diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c index d240a391f99e1..4da138d05acb1 100644 --- a/tools/testing/selftests/cgroup/test_memcontrol.c +++ b/tools/testing/selftests/cgroup/test_memcontrol.c @@ -21,6 +21,8 @@ #include "../kselftest.h" #include "cgroup_util.h" +static bool has_recursiveprot; + /* * This test creates two nested cgroups with and without enabling * the memory controller. @@ -525,15 +527,18 @@ static int test_memcg_low(const char *root) } for (i = 0; i < ARRAY_SIZE(children); i++) { + int no_low_events_index = has_recursiveprot ? 2 : 1; + oom = cg_read_key_long(children[i], "memory.events", "oom "); low = cg_read_key_long(children[i], "memory.events", "low "); if (oom) goto cleanup; - if (i < 2 && low <= 0) + if (i <= no_low_events_index && low <= 0) goto cleanup; - if (i >= 2 && low) + if (i > no_low_events_index && low) goto cleanup; + } ret = KSFT_PASS; @@ -1382,7 +1387,7 @@ struct memcg_test { int main(int argc, char **argv) { char root[PATH_MAX]; - int i, ret = EXIT_SUCCESS; + int i, proc_status, ret = EXIT_SUCCESS; if (cg_find_unified_root(root, sizeof(root))) ksft_exit_skip("cgroup v2 isn't mounted\n"); @@ -1398,6 +1403,11 @@ int main(int argc, char **argv) if (cg_write(root, "cgroup.subtree_control", "+memory")) ksft_exit_skip("Failed to set memory controller\n"); + proc_status = proc_mount_contains("memory_recursiveprot"); + if (proc_status < 0) + ksft_exit_skip("Failed to query cgroup mount option\n"); + has_recursiveprot = proc_status; + for (i = 0; i < ARRAY_SIZE(tests); i++) { switch (tests[i].fn(root)) { case KSFT_PASS: -- 2.39.5