🤖 fix: lookup parent cgroupv2 memory.current and memory.stat

cgroupv2.go

@@ -179,10 +179,59 @@ func (s cgroupV2Statter) memoryMaxBytes() (*float64, error) {
 	return ptr.To(float64(maxUsageBytes)), nil
 }
 
-func (s cgroupV2Statter) memory(p Prefix) (*Result, error) {
+func (s cgroupV2Statter) memoryCurrentBytes() (int64, error) {
 	memoryUsagePath := filepath.Join(s.path, cgroupV2MemoryUsageBytes)
+
+	currUsageBytes, err := readInt64(s.fs, memoryUsagePath)
+	if err != nil {
+		if !errors.Is(err, fs.ErrNotExist) {
+			return 0, xerrors.Errorf("read memory current: %w", err)
+		}
+
+		// If the memory current file does not exist, and we have a parent,
+		// we shall call the parent to find its current memory value.
+		if s.parent != nil {
+			result, err := s.parent.memoryCurrentBytes()
+			if err != nil {
+				return 0, xerrors.Errorf("read parent memory current: %w", err)
+			}
+			return result, nil
+		}
+
+		// We have no parent, and no memory current file, so return the error.
+		return 0, xerrors.Errorf("read memory current: %w", err)
+	}
+
+	return currUsageBytes, nil
+}
+
+func (s cgroupV2Statter) memoryInactiveFileBytes() (int64, error) {
 	memoryStatPath := filepath.Join(s.path, cgroupV2MemoryStat)
 
+	inactiveFileBytes, err := readInt64Prefix(s.fs, memoryStatPath, "inactive_file")
+	if err != nil {
+		if !errors.Is(err, fs.ErrNotExist) {
+			return 0, xerrors.Errorf("read memory stat inactive_file: %w", err)
+		}
+
+		// If the memory stat file does not exist, and we have a parent,
+		// we shall call the parent to find its inactive_file value.
+		if s.parent != nil {
+			result, err := s.parent.memoryInactiveFileBytes()
+			if err != nil {
+				return 0, xerrors.Errorf("read parent memory stat inactive_file: %w", err)
+			}
+			return result, nil
+		}
+
+		// We have no parent, and no memory stat file, so return the error.
+		return 0, xerrors.Errorf("read memory stat inactive_file: %w", err)
+	}
+
+	return inactiveFileBytes, nil
+}
+
+func (s cgroupV2Statter) memory(p Prefix) (*Result, error) {
 	// https://docs.kernel.org/6.17/admin-guide/cgroup-v2.html#memory-interface-files
 	r := &Result{
 		Unit:   "B",
@@ -194,12 +243,12 @@ func (s cgroupV2Statter) memory(p Prefix) (*Result, error) {
 		r.Total = total
 	}
 
-	currUsageBytes, err := readInt64(s.fs, memoryUsagePath)
+	currUsageBytes, err := s.memoryCurrentBytes()
 	if err != nil {
 		return nil, xerrors.Errorf("read memory usage: %w", err)
 	}
 
-	inactiveFileBytes, err := readInt64Prefix(s.fs, memoryStatPath, "inactive_file")
+	inactiveFileBytes, err := s.memoryInactiveFileBytes()
 	if err != nil {
 		return nil, xerrors.Errorf("read memory stats: %w", err)
 	}

stat_internal_test.go

@@ -491,6 +491,36 @@ func TestStatter(t *testing.T) {
 				assert.Nil(t, mem.Total)
 				assert.Equal(t, "B", mem.Unit)
 			})
+
+			t.Run("Memory/CurrentInParent", func(t *testing.T) {
+				t.Parallel()
+
+				fs := initFS(t, fsContainerCgroupV2KubernetesMissingMemoryCurrent)
+				s, err := New(WithFS(fs), withNoWait, withIsCgroupV2(true))
+				require.NoError(t, err)
+
+				mem, err := s.ContainerMemory(PrefixDefault)
+				require.NoError(t, err)
+
+				require.NotNil(t, mem)
+				assert.Equal(t, 268435456.0, mem.Used)
+				assert.Equal(t, "B", mem.Unit)
+			})
+
+			t.Run("Memory/StatInParent", func(t *testing.T) {
+				t.Parallel()
+
+				fs := initFS(t, fsContainerCgroupV2KubernetesMissingMemoryStat)
+				s, err := New(WithFS(fs), withNoWait, withIsCgroupV2(true))
+				require.NoError(t, err)
+
+				mem, err := s.ContainerMemory(PrefixDefault)
+				require.NoError(t, err)
+
+				require.NotNil(t, mem)
+				assert.Equal(t, 268435456.0, mem.Used)
+				assert.Equal(t, "B", mem.Unit)
+			})
 		})
 	})
 }
@@ -805,6 +835,36 @@ sysboxfs /proc/sys sysboxfs rw,nosuid,nodev,noexec,relatime 0 0`,
 		filepath.Join(cgroupRootPath, "init.scope", cgroupV2MemoryStat):       "inactive_file 268435456",
 		filepath.Join(cgroupRootPath, "init.scope", cgroupV2MemoryUsageBytes): "536870912",
 	}
+	// Variant where child has memory.stat but NOT memory.current (should inherit from root)
+	fsContainerCgroupV2KubernetesMissingMemoryCurrent = map[string]string{
+		procOneCgroup:  "0::/",
+		procSelfCgroup: fmt.Sprintf("0::%s", fsContainerCgroupV2KubernetesPath),
+		procMounts: `overlay / overlay rw,relatime,lowerdir=/some/path:/some/path,upperdir=/some/path:/some/path,workdir=/some/path:/some/path 0 0
+proc /proc/sys proc ro,nosuid,nodev,noexec,relatime 0 0`,
+		sysCgroupType: "domain",
+
+		filepath.Join(cgroupRootPath, fsContainerCgroupV2KubernetesPath, cgroupV2CPUMax):         "max 100000",
+		filepath.Join(cgroupRootPath, fsContainerCgroupV2KubernetesPath, cgroupV2CPUStat):        "usage_usec 0",
+		filepath.Join(cgroupRootPath, fsContainerCgroupV2KubernetesPath, cgroupV2MemoryMaxBytes): "max",
+		filepath.Join(cgroupRootPath, fsContainerCgroupV2KubernetesPath, cgroupV2MemoryStat):     "inactive_file 268435456",
+		// memory.current purposefully missing at child - should inherit from root
+		filepath.Join(cgroupRootPath, cgroupV2MemoryUsageBytes): "536870912",
+	}
+	// Variant where child has memory.current but NOT memory.stat (should inherit from root)
+	fsContainerCgroupV2KubernetesMissingMemoryStat = map[string]string{
+		procOneCgroup:  "0::/",
+		procSelfCgroup: fmt.Sprintf("0::%s", fsContainerCgroupV2KubernetesPath),
+		procMounts: `overlay / overlay rw,relatime,lowerdir=/some/path:/some/path,upperdir=/some/path:/some/path,workdir=/some/path:/some/path 0 0
+proc /proc/sys proc ro,nosuid,nodev,noexec,relatime 0 0`,
+		sysCgroupType: "domain",
+
+		filepath.Join(cgroupRootPath, fsContainerCgroupV2KubernetesPath, cgroupV2CPUMax):           "max 100000",
+		filepath.Join(cgroupRootPath, fsContainerCgroupV2KubernetesPath, cgroupV2CPUStat):          "usage_usec 0",
+		filepath.Join(cgroupRootPath, fsContainerCgroupV2KubernetesPath, cgroupV2MemoryMaxBytes):   "max",
+		filepath.Join(cgroupRootPath, fsContainerCgroupV2KubernetesPath, cgroupV2MemoryUsageBytes): "536870912",
+		// memory.stat purposefully missing at child - should inherit from root
+		filepath.Join(cgroupRootPath, cgroupV2MemoryStat): "inactive_file 268435456",
+	}
 	fsContainerCgroupV1 = map[string]string{
 		procOneCgroup:  "0::/docker/aa86ac98959eeedeae0ecb6e0c9ddd8ae8b97a9d0fdccccf7ea7a474f4e0bb1f",
 		procSelfCgroup: "0::/docker/aa86ac98959eeedeae0ecb6e0c9ddd8ae8b97a9d0fdccccf7ea7a474f4e0bb1f",