1 /*
2 * Copyright (C) 2025 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <cerrno>
18 #include <cstdio>
19 #include <filesystem>
20 #include <iostream>
21 #include <optional>
22 #include <random>
23 #include <string>
24 #include <vector>
25
26 #include <android-base/file.h>
27 #include <android-base/strings.h>
28 using android::base::ReadFileToString;
29 using android::base::Split;
30 using android::base::WriteStringToFile;
31
32 #include <gmock/gmock.h>
33 #include <gtest/gtest.h>
34
35 namespace {
36
37 const std::string CGROUP_V2_ROOT_PATH = "/sys/fs/cgroup";
38
isMemcgV2Enabled()39 std::optional<bool> isMemcgV2Enabled() {
40 if (std::string proc_cgroups; ReadFileToString("/proc/cgroups", &proc_cgroups)) {
41 const std::vector<std::string> lines = Split(proc_cgroups, "\n");
42 for (const std::string& line : lines) {
43 if (line.starts_with("memory")) {
44 const bool enabled = line.back() == '1';
45 if (!enabled) return false;
46
47 const std::vector<std::string> memcg_tokens = Split(line, "\t");
48 return memcg_tokens[1] == "0"; // 0 == default hierarchy == v2
49 }
50 }
51 // We know for sure it's not enabled, either because it is mounted as v1 (cgroups.json
52 // override) which would be detected above, or because it was intentionally disabled via
53 // kernel command line (cgroup_disable=memory), or because it's not built in to the kernel
54 // (CONFIG_MEMCG is not set).
55 return false;
56 }
57
58 // Problems accessing /proc/cgroups (sepolicy?) Try checking the root cgroup.controllers file.
59 perror("Warning: Could not read /proc/cgroups");
60 if (std::string controllers;
61 ReadFileToString(CGROUP_V2_ROOT_PATH + "/cgroup.controllers", &controllers)) {
62 return controllers.find("memory") != std::string::npos;
63 }
64
65 std::cerr << "Error: Could not read " << CGROUP_V2_ROOT_PATH
66 << "/cgroup.controllers: " << std::strerror(errno) << std::endl;
67 return std::nullopt;
68 }
69
checkRootSubtreeState()70 std::optional<bool> checkRootSubtreeState() {
71 if (std::string controllers;
72 ReadFileToString(CGROUP_V2_ROOT_PATH + "/cgroup.subtree_control", &controllers)) {
73 return controllers.find("memory") != std::string::npos;
74 }
75 std::cerr << "Error: Could not read " << CGROUP_V2_ROOT_PATH
76 << "/cgroup.subtree_control: " << std::strerror(errno) << std::endl;
77 return std::nullopt;
78 }
79
80 } // anonymous namespace
81
82 class MemcgV2SubdirTest : public testing::Test {
83 protected:
84 std::optional<std::string> mRandDir;
85
SetUp()86 void SetUp() override {
87 std::optional<bool> memcgV2Enabled = isMemcgV2Enabled();
88 ASSERT_NE(memcgV2Enabled, std::nullopt);
89 if (!*memcgV2Enabled) GTEST_SKIP() << "Memcg v2 not enabled";
90
91 mRootSubtreeState = checkRootSubtreeState();
92 ASSERT_NE(mRootSubtreeState, std::nullopt);
93
94 if (!*mRootSubtreeState) {
95 ASSERT_TRUE(
96 WriteStringToFile("+memory", CGROUP_V2_ROOT_PATH + "/cgroup.subtree_control"))
97 << "Could not enable memcg under root: " << std::strerror(errno);
98 }
99
100 // Make a new, temporary, randomly-named v2 cgroup in which we will attempt to activate
101 // memcg
102 std::random_device rd;
103 std::uniform_int_distribution dist(static_cast<int>('A'), static_cast<int>('Z'));
104 std::string randName = CGROUP_V2_ROOT_PATH + "/vts_libprocessgroup.";
105 for (int i = 0; i < 10; ++i) randName.append(1, static_cast<char>(dist(rd)));
106 ASSERT_TRUE(std::filesystem::create_directory(randName));
107 mRandDir = randName; // For cleanup in TearDown
108
109 std::string subtree_controllers;
110 ASSERT_TRUE(ReadFileToString(*mRandDir + "/cgroup.controllers", &subtree_controllers));
111 ASSERT_NE(subtree_controllers.find("memory"), std::string::npos)
112 << "Memcg was not activated in child cgroup";
113 }
114
TearDown()115 void TearDown() override {
116 if (mRandDir) {
117 if (!std::filesystem::remove(*mRandDir)) {
118 std::cerr << "Could not remove temporary memcg v2 test directory" << std::endl;
119 }
120 }
121
122 if (!*mRootSubtreeState) {
123 if (!WriteStringToFile("-memory", CGROUP_V2_ROOT_PATH + "/cgroup.subtree_control")) {
124 std::cerr << "Could not disable memcg under root: " << std::strerror(errno)
125 << std::endl;
126 }
127 }
128 }
129
130 private:
131 std::optional<bool> mRootSubtreeState;
132 };
133
134
TEST_F(MemcgV2SubdirTest,CanActivateMemcgV2Subtree)135 TEST_F(MemcgV2SubdirTest, CanActivateMemcgV2Subtree) {
136 ASSERT_TRUE(WriteStringToFile("+memory", *mRandDir + "/cgroup.subtree_control"))
137 << "Could not enable memcg under child cgroup subtree";
138 }
139