Stub oom_score_adj and oom_score.

Adds an oom_score_adj and oom_score proc file stub. oom_score_adj accepts
writes of values -1000 to 1000 and persists the value with the task. New tasks
inherit the parent's oom_score_adj.

oom_score is a read-only stub that always returns the value '0'.

Issue #202

PiperOrigin-RevId: 299245355

3 files changed, 106 insertions, 0 deletions

diff --git a/test/syscalls/linux/BUILD b/test/syscalls/linux/BUILD
index 0fbd556de..43455f1a3 100644
--- a/test/syscalls/linux/BUILD
+++ b/test/syscalls/linux/BUILD
@@ -1632,6 +1632,19 @@ cc_binary(
 )
 
 cc_binary(
+    name = "proc_pid_oomscore_test",
+    testonly = 1,
+    srcs = ["proc_pid_oomscore.cc"],
+    linkstatic = 1,
+    deps = [
+        "//test/util:fs_util",
+        "//test/util:test_main",
+        "//test/util:test_util",
+        "@com_google_absl//absl/strings",
+    ],
+)
+
+cc_binary(
     name = "proc_pid_smaps_test",
     testonly = 1,
     srcs = ["proc_pid_smaps.cc"],
diff --git a/test/syscalls/linux/proc.cc b/test/syscalls/linux/proc.cc
index f91187e75..5a70f6c3b 100644
--- a/test/syscalls/linux/proc.cc
+++ b/test/syscalls/linux/proc.cc
@@ -1431,6 +1431,12 @@ TEST(ProcPidFile, SubprocessRunning) {
 
   EXPECT_THAT(ReadWhileRunning("uid_map", buf, sizeof(buf)),
               SyscallSucceedsWithValue(sizeof(buf)));
+
+  EXPECT_THAT(ReadWhileRunning("oom_score", buf, sizeof(buf)),
+              SyscallSucceedsWithValue(sizeof(buf)));
+
+  EXPECT_THAT(ReadWhileRunning("oom_score_adj", buf, sizeof(buf)),
+              SyscallSucceedsWithValue(sizeof(buf)));
 }
 
 // Test whether /proc/PID/ files can be read for a zombie process.
@@ -1466,6 +1472,12 @@ TEST(ProcPidFile, SubprocessZombie) {
   EXPECT_THAT(ReadWhileZombied("uid_map", buf, sizeof(buf)),
               SyscallSucceedsWithValue(sizeof(buf)));
 
+  EXPECT_THAT(ReadWhileZombied("oom_score", buf, sizeof(buf)),
+              SyscallSucceedsWithValue(sizeof(buf)));
+
+  EXPECT_THAT(ReadWhileZombied("oom_score_adj", buf, sizeof(buf)),
+              SyscallSucceedsWithValue(sizeof(buf)));
+
   // FIXME(gvisor.dev/issue/164): Inconsistent behavior between gVisor and linux
   // on proc files.
   //
@@ -1527,6 +1539,15 @@ TEST(ProcPidFile, SubprocessExited) {
 
   EXPECT_THAT(ReadWhileExited("uid_map", buf, sizeof(buf)),
               SyscallSucceedsWithValue(sizeof(buf)));
+
+  if (!IsRunningOnGvisor()) {
+    // FIXME(gvisor.dev/issue/164): Succeeds on gVisor.
+    EXPECT_THAT(ReadWhileExited("oom_score", buf, sizeof(buf)),
+                SyscallFailsWithErrno(ESRCH));
+  }
+
+  EXPECT_THAT(ReadWhileExited("oom_score_adj", buf, sizeof(buf)),
+              SyscallFailsWithErrno(ESRCH));
 }
 
 PosixError DirContainsImpl(absl::string_view path,
diff --git a/test/syscalls/linux/proc_pid_oomscore.cc b/test/syscalls/linux/proc_pid_oomscore.cc
new file mode 100644
index 000000000..707821a3f
--- /dev/null
+++ b/test/syscalls/linux/proc_pid_oomscore.cc
@@ -0,0 +1,72 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <errno.h>
+
+#include <exception>
+#include <iostream>
+#include <string>
+
+#include "test/util/fs_util.h"
+#include "test/util/test_util.h"
+
+namespace gvisor {
+namespace testing {
+
+namespace {
+
+PosixErrorOr<int> ReadProcNumber(std::string path) {
+  ASSIGN_OR_RETURN_ERRNO(std::string contents, GetContents(path));
+  EXPECT_EQ(contents[contents.length() - 1], '\n');
+
+  int num;
+  if (!absl::SimpleAtoi(contents, &num)) {
+    return PosixError(EINVAL, "invalid value: " + contents);
+  }
+
+  return num;
+}
+
+TEST(ProcPidOomscoreTest, BasicRead) {
+  auto const oom_score =
+      ASSERT_NO_ERRNO_AND_VALUE(ReadProcNumber("/proc/self/oom_score"));
+  EXPECT_LE(oom_score, 1000);
+  EXPECT_GE(oom_score, -1000);
+}
+
+TEST(ProcPidOomscoreAdjTest, BasicRead) {
+  auto const oom_score =
+      ASSERT_NO_ERRNO_AND_VALUE(ReadProcNumber("/proc/self/oom_score_adj"));
+
+  // oom_score_adj defaults to 0.
+  EXPECT_EQ(oom_score, 0);
+}
+
+TEST(ProcPidOomscoreAdjTest, BasicWrite) {
+  constexpr int test_value = 7;
+  FileDescriptor fd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open("/proc/self/oom_score_adj", O_WRONLY));
+  ASSERT_THAT(
+      RetryEINTR(write)(fd.get(), std::to_string(test_value).c_str(), 1),
+      SyscallSucceeds());
+
+  auto const oom_score =
+      ASSERT_NO_ERRNO_AND_VALUE(ReadProcNumber("/proc/self/oom_score_adj"));
+  EXPECT_EQ(oom_score, test_value);
+}
+
+}  // namespace
+
+}  // namespace testing
+}  // namespace gvisor