The patch titled Subject: cgroup: account for memory_recursiveprot in test_memcg_low() has been added to the -mm tree. Its filename is cgroup-account-for-memory_recursiveprot-in-test_memcg_low.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/cgroup-account-for-memory_recursiveprot-in-test_memcg_low.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/cgroup-account-for-memory_recursiveprot-in-test_memcg_low.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: David Vernet <void@xxxxxxxxxxxxx> Subject: 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 8a931f801340 ("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/20220422155728.3055914-3-void@xxxxxxxxxxxxx Signed-off-by: David Vernet <void@xxxxxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx> Cc: Shakeel Butt <shakeelb@xxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- 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(-) --- a/tools/testing/selftests/cgroup/cgroup_util.c~cgroup-account-for-memory_recursiveprot-in-test_memcg_low +++ a/tools/testing/selftests/cgroup/cgroup_util.c @@ -535,6 +535,18 @@ 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]; --- a/tools/testing/selftests/cgroup/cgroup_util.h~cgroup-account-for-memory_recursiveprot-in-test_memcg_low +++ a/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); --- a/tools/testing/selftests/cgroup/test_memcontrol.c~cgroup-account-for-memory_recursiveprot-in-test_memcg_low +++ a/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. @@ -521,15 +523,18 @@ static int test_memcg_low(const char *ro } 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; @@ -1272,7 +1277,7 @@ 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"); @@ -1288,6 +1293,11 @@ 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: _ Patches currently in -mm which might be from void@xxxxxxxxxxxxx are cgroups-refactor-children-cgroups-in-memcg-tests.patch cgroup-account-for-memory_recursiveprot-in-test_memcg_low.patch cgroup-account-for-memory_localevents-in-test_memcg_oom_group_leaf_events.patch cgroup-removing-racy-check-in-test_memcg_sock.patch cgroup-fix-racy-check-in-alloc_pagecache_max_30m-helper-function.patch