From cdc69458a5f3d4cf31372efd45fe92cec6b167e4 Mon Sep 17 00:00:00 2001 From: David Vernet Date: Thu, 12 May 2022 20:22:57 -0700 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/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 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'tools/testing/selftests/cgroup/cgroup_util.c') diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c index e6f3679cdcc0..b4d7027a44c3 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]; -- cgit v1.2.3-59-g8ed1b