From 9f33fe64f221de0eb2a290fd54357c954d9f38f8 Mon Sep 17 00:00:00 2001 From: Fabricio Voznika <fvoznika@google.com> Date: Wed, 5 May 2021 17:36:58 -0700 Subject: Fixes to runsc cgroups When loading cgroups for another process, `/proc/self` was used in a few places, causing the end state to be a mix of the process and self. This is now fixes to always use the proper `/proc/[pid]` path. Added net_prio and net_cls to the list of optional controllers. This is to allow runsc to execute then these cgroups are disabled as long as there are no net_prio and net_cls limits that need to be applied. Deflake TestMultiContainerEvent. Closes #5875 Closes #5887 PiperOrigin-RevId: 372242687 --- runsc/cgroup/cgroup.go | 254 ++++++++++++++++++++++++++++++++++--------------- 1 file changed, 175 insertions(+), 79 deletions(-) (limited to 'runsc/cgroup/cgroup.go') diff --git a/runsc/cgroup/cgroup.go b/runsc/cgroup/cgroup.go index 438b7ef3e..335e46499 100644 --- a/runsc/cgroup/cgroup.go +++ b/runsc/cgroup/cgroup.go @@ -40,23 +40,24 @@ const ( cgroupRoot = "/sys/fs/cgroup" ) -var controllers = map[string]config{ - "blkio": {ctrlr: &blockIO{}}, - "cpu": {ctrlr: &cpu{}}, - "cpuset": {ctrlr: &cpuSet{}}, - "hugetlb": {ctrlr: &hugeTLB{}, optional: true}, - "memory": {ctrlr: &memory{}}, - "net_cls": {ctrlr: &networkClass{}}, - "net_prio": {ctrlr: &networkPrio{}}, - "pids": {ctrlr: &pids{}}, +var controllers = map[string]controller{ + "blkio": &blockIO{}, + "cpu": &cpu{}, + "cpuset": &cpuSet{}, + "hugetlb": &hugeTLB{}, + "memory": &memory{}, + "net_cls": &networkClass{}, + "net_prio": &networkPrio{}, + "pids": &pids{}, // These controllers either don't have anything in the OCI spec or is // irrelevant for a sandbox. - "devices": {ctrlr: &noop{}}, - "freezer": {ctrlr: &noop{}}, - "perf_event": {ctrlr: &noop{}}, - "rdma": {ctrlr: &noop{}, optional: true}, - "systemd": {ctrlr: &noop{}}, + "cpuacct": &noop{}, + "devices": &noop{}, + "freezer": &noop{}, + "perf_event": &noop{}, + "rdma": &noop{isOptional: true}, + "systemd": &noop{}, } // IsOnlyV2 checks whether cgroups V2 is enabled and V1 is not. @@ -201,31 +202,26 @@ func countCpuset(cpuset string) (int, error) { return count, nil } -// LoadPaths loads cgroup paths for given 'pid', may be set to 'self'. -func LoadPaths(pid string) (map[string]string, error) { - f, err := os.Open(filepath.Join("/proc", pid, "cgroup")) +// loadPaths loads cgroup paths for given 'pid', may be set to 'self'. +func loadPaths(pid string) (map[string]string, error) { + procCgroup, err := os.Open(filepath.Join("/proc", pid, "cgroup")) if err != nil { return nil, err } - defer f.Close() + defer procCgroup.Close() - return loadPathsHelper(f) -} - -func loadPathsHelper(cgroup io.Reader) (map[string]string, error) { - // For nested containers, in /proc/self/cgroup we see paths from host, - // which don't exist in container, so recover the container paths here by - // double-checking with /proc/pid/mountinfo - mountinfo, err := os.Open("/proc/self/mountinfo") + // Load mountinfo for the current process, because it's where cgroups is + // being accessed from. + mountinfo, err := os.Open(filepath.Join("/proc/self/mountinfo")) if err != nil { return nil, err } defer mountinfo.Close() - return loadPathsHelperWithMountinfo(cgroup, mountinfo) + return loadPathsHelper(procCgroup, mountinfo) } -func loadPathsHelperWithMountinfo(cgroup, mountinfo io.Reader) (map[string]string, error) { +func loadPathsHelper(cgroup, mountinfo io.Reader) (map[string]string, error) { paths := make(map[string]string) scanner := bufio.NewScanner(cgroup) @@ -242,34 +238,51 @@ func loadPathsHelperWithMountinfo(cgroup, mountinfo io.Reader) (map[string]strin for _, ctrlr := range strings.Split(tokens[1], ",") { // Remove prefix for cgroups with no controller, eg. systemd. ctrlr = strings.TrimPrefix(ctrlr, "name=") - paths[ctrlr] = tokens[2] + // Discard unknown controllers. + if _, ok := controllers[ctrlr]; ok { + paths[ctrlr] = tokens[2] + } } } if err := scanner.Err(); err != nil { return nil, err } - mfScanner := bufio.NewScanner(mountinfo) - for mfScanner.Scan() { - txt := mfScanner.Text() - fields := strings.Fields(txt) + // For nested containers, in /proc/[pid]/cgroup we see paths from host, + // which don't exist in container, so recover the container paths here by + // double-checking with /proc/[pid]/mountinfo + mountScanner := bufio.NewScanner(mountinfo) + for mountScanner.Scan() { + // Format: ID parent major:minor root mount-point options opt-fields - fs-type source super-options + // Example: 39 32 0:34 / /sys/fs/cgroup/devices rw,noexec shared:18 - cgroup cgroup rw,devices + fields := strings.Fields(mountScanner.Text()) if len(fields) < 9 || fields[len(fields)-3] != "cgroup" { + // Skip mounts that are not cgroup mounts. continue } - for _, opt := range strings.Split(fields[len(fields)-1], ",") { + // Cgroup controller type is in the super-options field. + superOptions := strings.Split(fields[len(fields)-1], ",") + for _, opt := range superOptions { // Remove prefix for cgroups with no controller, eg. systemd. opt = strings.TrimPrefix(opt, "name=") + + // Only considers cgroup controllers that are registered, and skip other + // irrelevant options, e.g. rw. if cgroupPath, ok := paths[opt]; ok { - root := fields[3] - relCgroupPath, err := filepath.Rel(root, cgroupPath) - if err != nil { - return nil, err + rootDir := fields[3] + if rootDir != "/" { + // When cgroup is in submount, remove repeated path components from + // cgroup path to avoid duplicating them. + relCgroupPath, err := filepath.Rel(rootDir, cgroupPath) + if err != nil { + return nil, err + } + paths[opt] = relCgroupPath } - paths[opt] = relCgroupPath } } } - if err := mfScanner.Err(); err != nil { + if err := mountScanner.Err(); err != nil { return nil, err } @@ -279,37 +292,50 @@ func loadPathsHelperWithMountinfo(cgroup, mountinfo io.Reader) (map[string]strin // Cgroup represents a group inside all controllers. For example: // Name='/foo/bar' maps to /sys/fs/cgroup/<controller>/foo/bar on // all controllers. +// +// If Name is relative, it uses the parent cgroup path to determine the +// location. For example: +// Name='foo/bar' and Parent[ctrl]="/user.slice", then it will map to +// /sys/fs/cgroup/<ctrl>/user.slice/foo/bar type Cgroup struct { Name string `json:"name"` Parents map[string]string `json:"parents"` Own map[string]bool `json:"own"` } -// New creates a new Cgroup instance if the spec includes a cgroup path. -// Returns nil otherwise. -func New(spec *specs.Spec) (*Cgroup, error) { +// NewFromSpec creates a new Cgroup instance if the spec includes a cgroup path. +// Returns nil otherwise. Cgroup paths are loaded based on the current process. +func NewFromSpec(spec *specs.Spec) (*Cgroup, error) { if spec.Linux == nil || spec.Linux.CgroupsPath == "" { return nil, nil } - return NewFromPath(spec.Linux.CgroupsPath) + return new("self", spec.Linux.CgroupsPath) } -// NewFromPath creates a new Cgroup instance. -func NewFromPath(cgroupsPath string) (*Cgroup, error) { +// NewFromPid loads cgroup for the given process. +func NewFromPid(pid int) (*Cgroup, error) { + return new(strconv.Itoa(pid), "") +} + +func new(pid, cgroupsPath string) (*Cgroup, error) { var parents map[string]string + + // If path is relative, load cgroup paths for the process to build the + // relative paths. if !filepath.IsAbs(cgroupsPath) { var err error - parents, err = LoadPaths("self") + parents, err = loadPaths(pid) if err != nil { return nil, fmt.Errorf("finding current cgroups: %w", err) } } - own := make(map[string]bool) - return &Cgroup{ + cg := &Cgroup{ Name: cgroupsPath, Parents: parents, - Own: own, - }, nil + Own: make(map[string]bool), + } + log.Debugf("New cgroup for pid: %s, %+v", pid, cg) + return cg, nil } // Install creates and configures cgroups according to 'res'. If cgroup path @@ -323,8 +349,8 @@ func (c *Cgroup) Install(res *specs.LinuxResources) error { clean := cleanup.Make(func() { _ = c.Uninstall() }) defer clean.Clean() - for key, cfg := range controllers { - path := c.makePath(key) + for key, ctrlr := range controllers { + path := c.MakePath(key) if _, err := os.Stat(path); err == nil { // If cgroup has already been created; it has been setup by caller. Don't // make any changes to configuration, just join when sandbox/gofer starts. @@ -336,13 +362,16 @@ func (c *Cgroup) Install(res *specs.LinuxResources) error { c.Own[key] = true if err := os.MkdirAll(path, 0755); err != nil { - if cfg.optional && errors.Is(err, unix.EROFS) { + if ctrlr.optional() && errors.Is(err, unix.EROFS) { + if err := ctrlr.skip(res); err != nil { + return err + } log.Infof("Skipping cgroup %q", key) continue } return err } - if err := cfg.ctrlr.set(res, path); err != nil { + if err := ctrlr.set(res, path); err != nil { return err } } @@ -359,7 +388,7 @@ func (c *Cgroup) Uninstall() error { // cgroup is managed by caller, don't touch it. continue } - path := c.makePath(key) + path := c.MakePath(key) log.Debugf("Removing cgroup controller for key=%q path=%q", key, path) // If we try to remove the cgroup too soon after killing the @@ -387,7 +416,7 @@ func (c *Cgroup) Uninstall() error { func (c *Cgroup) Join() (func(), error) { // First save the current state so it can be restored. undo := func() {} - paths, err := LoadPaths("self") + paths, err := loadPaths("self") if err != nil { return undo, err } @@ -414,14 +443,13 @@ func (c *Cgroup) Join() (func(), error) { } // Now join the cgroups. - for key, cfg := range controllers { - path := c.makePath(key) + for key, ctrlr := range controllers { + path := c.MakePath(key) log.Debugf("Joining cgroup %q", path) - // Writing the value 0 to a cgroup.procs file causes the - // writing process to be moved to the corresponding cgroup. - // - cgroups(7). + // Writing the value 0 to a cgroup.procs file causes the writing process to + // be moved to the corresponding cgroup - cgroups(7). if err := setValue(path, "cgroup.procs", "0"); err != nil { - if cfg.optional && os.IsNotExist(err) { + if ctrlr.optional() && os.IsNotExist(err) { continue } return undo, err @@ -432,7 +460,7 @@ func (c *Cgroup) Join() (func(), error) { // CPUQuota returns the CFS CPU quota. func (c *Cgroup) CPUQuota() (float64, error) { - path := c.makePath("cpu") + path := c.MakePath("cpu") quota, err := getInt(path, "cpu.cfs_quota_us") if err != nil { return -1, err @@ -449,7 +477,7 @@ func (c *Cgroup) CPUQuota() (float64, error) { // CPUUsage returns the total CPU usage of the cgroup. func (c *Cgroup) CPUUsage() (uint64, error) { - path := c.makePath("cpuacct") + path := c.MakePath("cpuacct") usage, err := getValue(path, "cpuacct.usage") if err != nil { return 0, err @@ -459,7 +487,7 @@ func (c *Cgroup) CPUUsage() (uint64, error) { // NumCPU returns the number of CPUs configured in 'cpuset/cpuset.cpus'. func (c *Cgroup) NumCPU() (int, error) { - path := c.makePath("cpuset") + path := c.MakePath("cpuset") cpuset, err := getValue(path, "cpuset.cpus") if err != nil { return 0, err @@ -469,7 +497,7 @@ func (c *Cgroup) NumCPU() (int, error) { // MemoryLimit returns the memory limit. func (c *Cgroup) MemoryLimit() (uint64, error) { - path := c.makePath("memory") + path := c.MakePath("memory") limStr, err := getValue(path, "memory.limit_in_bytes") if err != nil { return 0, err @@ -477,7 +505,8 @@ func (c *Cgroup) MemoryLimit() (uint64, error) { return strconv.ParseUint(strings.TrimSpace(limStr), 10, 64) } -func (c *Cgroup) makePath(controllerName string) string { +// MakePath builds a path to the given controller. +func (c *Cgroup) MakePath(controllerName string) string { path := c.Name if parent, ok := c.Parents[controllerName]; ok { path = filepath.Join(parent, c.Name) @@ -485,22 +514,48 @@ func (c *Cgroup) makePath(controllerName string) string { return filepath.Join(cgroupRoot, controllerName, path) } -type config struct { - ctrlr controller - optional bool -} - type controller interface { + // optional controllers don't fail if not found. + optional() bool + // set applies resource limits to controller. set(*specs.LinuxResources, string) error + // skip is called when controller is not found to check if it can be safely + // skipped or not based on the spec. + skip(*specs.LinuxResources) error +} + +type noop struct { + isOptional bool } -type noop struct{} +func (n *noop) optional() bool { + return n.isOptional +} func (*noop) set(*specs.LinuxResources, string) error { return nil } -type memory struct{} +func (n *noop) skip(*specs.LinuxResources) error { + if !n.isOptional { + panic("cgroup controller is not optional") + } + return nil +} + +type mandatory struct{} + +func (*mandatory) optional() bool { + return false +} + +func (*mandatory) skip(*specs.LinuxResources) error { + panic("cgroup controller is not optional") +} + +type memory struct { + mandatory +} func (*memory) set(spec *specs.LinuxResources, path string) error { if spec == nil || spec.Memory == nil { @@ -533,7 +588,9 @@ func (*memory) set(spec *specs.LinuxResources, path string) error { return nil } -type cpu struct{} +type cpu struct { + mandatory +} func (*cpu) set(spec *specs.LinuxResources, path string) error { if spec == nil || spec.CPU == nil { @@ -554,7 +611,9 @@ func (*cpu) set(spec *specs.LinuxResources, path string) error { return setOptionalValueInt(path, "cpu.rt_runtime_us", spec.CPU.RealtimeRuntime) } -type cpuSet struct{} +type cpuSet struct { + mandatory +} func (*cpuSet) set(spec *specs.LinuxResources, path string) error { // cpuset.cpus and mems are required fields, but are not set on a new cgroup. @@ -576,7 +635,9 @@ func (*cpuSet) set(spec *specs.LinuxResources, path string) error { return setValue(path, "cpuset.mems", spec.CPU.Mems) } -type blockIO struct{} +type blockIO struct { + mandatory +} func (*blockIO) set(spec *specs.LinuxResources, path string) error { if spec == nil || spec.BlockIO == nil { @@ -628,6 +689,10 @@ func setThrottle(path, name string, devs []specs.LinuxThrottleDevice) error { type networkClass struct{} +func (*networkClass) optional() bool { + return true +} + func (*networkClass) set(spec *specs.LinuxResources, path string) error { if spec == nil || spec.Network == nil { return nil @@ -635,8 +700,19 @@ func (*networkClass) set(spec *specs.LinuxResources, path string) error { return setOptionalValueUint32(path, "net_cls.classid", spec.Network.ClassID) } +func (*networkClass) skip(spec *specs.LinuxResources) error { + if spec != nil && spec.Network != nil && spec.Network.ClassID != nil { + return fmt.Errorf("Network.ClassID set but net_cls cgroup controller not found") + } + return nil +} + type networkPrio struct{} +func (*networkPrio) optional() bool { + return true +} + func (*networkPrio) set(spec *specs.LinuxResources, path string) error { if spec == nil || spec.Network == nil { return nil @@ -650,7 +726,16 @@ func (*networkPrio) set(spec *specs.LinuxResources, path string) error { return nil } -type pids struct{} +func (*networkPrio) skip(spec *specs.LinuxResources) error { + if spec != nil && spec.Network != nil && len(spec.Network.Priorities) > 0 { + return fmt.Errorf("Network.Priorities set but net_prio cgroup controller not found") + } + return nil +} + +type pids struct { + mandatory +} func (*pids) set(spec *specs.LinuxResources, path string) error { if spec == nil || spec.Pids == nil || spec.Pids.Limit <= 0 { @@ -662,6 +747,17 @@ func (*pids) set(spec *specs.LinuxResources, path string) error { type hugeTLB struct{} +func (*hugeTLB) optional() bool { + return true +} + +func (*hugeTLB) skip(spec *specs.LinuxResources) error { + if spec != nil && len(spec.HugepageLimits) > 0 { + return fmt.Errorf("HugepageLimits set but hugetlb cgroup controller not found") + } + return nil +} + func (*hugeTLB) set(spec *specs.LinuxResources, path string) error { if spec == nil { return nil -- cgit v1.2.3