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cgroupv2: use "max" for negative values 

Cgroup v1 kernel doc [1] says:

> We can write "-1" to reset the ``*.limit_in_bytes(unlimited)``.

and cgroup v2 kernel documentation [2] says:

> - If a controller implements an absolute resource guarantee and/or
>  limit, the interface files should be named "min" and "max"
>  respectively.  If a controller implements best effort resource
>  guarantee and/or limit, the interface files should be named "low"
>  and "high" respectively.
>
>  In the above four control files, the special token "max" should be
>  used to represent upward infinity for both reading and writing.

Allow -1 value to still be used for v2, converting it to "max"
where it makes sense to do so.

This fixes the following issue:

> runc update test_update --memory-swap -1:
> error while setting cgroup v2: [write /sys/fs/cgroup/machine.slice/runc-cgroups-integration-test.scope/memory.swap.max: invalid argument
> failed to write "-1" to "/sys/fs/cgroup/machine.slice/runc-cgroups-integration-test.scope/memory.swap.max"
> github.com/opencontainers/runc/libcontainer/cgroups/fscommon.WriteFile
> 	/home/kir/go/src/github.com/opencontainers/runc/libcontainer/cgroups/fscommon/fscommon.go:21
> github.com/opencontainers/runc/libcontainer/cgroups/fs2.setMemory
> 	/home/kir/go/src/github.com/opencontainers/runc/libcontainer/cgroups/fs2/memory.go:20
> github.com/opencontainers/runc/libcontainer/cgroups/fs2.(*manager).Set
> 	/home/kir/go/src/github.com/opencontainers/runc/libcontainer/cgroups/fs2/fs2.go:175
> github.com/opencontainers/runc/libcontainer/cgroups/systemd.(*UnifiedManager).Set
> 	/home/kir/go/src/github.com/opencontainers/runc/libcontainer/cgroups/systemd/unified_hierarchy.go:290
> github.com/opencontainers/runc/libcontainer.(*linuxContainer).Set
> 	/home/kir/go/src/github.com/opencontainers/runc/libcontainer/container_linux.go:211

[1] linux/Documentation/admin-guide/cgroup-v1/memory.rst
[2] linux/Documentation/admin-guide/cgroup-v2.rst

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
This commit is contained in:
Kir Kolyshkin 2020-03-26 10:02:39 -07:00
parent 96596cbbec
commit 6905b72154
2 changed files with 24 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
libcontainer/cgroups/fs2/memory.go
View File

@ -15,22 +15,38 @@ import (
"github.com/pkg/errors" "github.com/pkg/errors"
) )
// numToStr converts an int64 value to a string for writing to a
// cgroupv2 files with .min, .max, .low, or .high suffix.
// Negative values are converted to "max" for cgroupv1 compatibility
// (which used to write -1 to remove the limit).
func numToStr(value int64) (ret string) {
if value > 0 {
ret = strconv.FormatInt(value, 10)
} else if value < 0 {
ret = "max"
} else {
ret = ""
}
return ret
}
func setMemory(dirPath string, cgroup *configs.Cgroup) error { func setMemory(dirPath string, cgroup *configs.Cgroup) error {
if cgroup.Resources.MemorySwap != 0 { if val := numToStr(cgroup.Resources.MemorySwap); val != "" {
if err := fscommon.WriteFile(dirPath, "memory.swap.max", strconv.FormatInt(cgroup.Resources.MemorySwap, 10)); err != nil { if err := fscommon.WriteFile(dirPath, "memory.swap.max", val); err != nil {
return err return err
} }
} }
if cgroup.Resources.Memory != 0 { if val := numToStr(cgroup.Resources.Memory); val != "" {
if err := fscommon.WriteFile(dirPath, "memory.max", strconv.FormatInt(cgroup.Resources.Memory, 10)); err != nil { if err := fscommon.WriteFile(dirPath, "memory.max", val); err != nil {
return err return err
} }
} }
// cgroup.Resources.KernelMemory is ignored // cgroup.Resources.KernelMemory is ignored
if cgroup.Resources.MemoryReservation != 0 { if val := numToStr(cgroup.Resources.MemoryReservation); val != "" {
if err := fscommon.WriteFile(dirPath, "memory.low", strconv.FormatInt(cgroup.Resources.MemoryReservation, 10)); err != nil { if err := fscommon.WriteFile(dirPath, "memory.low", val); err != nil {
return err return err
} }
} }

12
libcontainer/cgroups/fs2/pids.go
View File

@ -6,7 +6,6 @@ import (
"io/ioutil" "io/ioutil"
"os" "os"
"path/filepath" "path/filepath"
"strconv"
"strings" "strings"
"github.com/opencontainers/runc/libcontainer/cgroups" "github.com/opencontainers/runc/libcontainer/cgroups"
@ -17,15 +16,8 @@ import (
) )
func setPids(dirPath string, cgroup *configs.Cgroup) error { func setPids(dirPath string, cgroup *configs.Cgroup) error {
if cgroup.Resources.PidsLimit != 0 { if val := numToStr(cgroup.Resources.PidsLimit); val != "" {
// "max" is the fallback value. if err := fscommon.WriteFile(dirPath, "pids.max", val); err != nil {
limit := "max"
if cgroup.Resources.PidsLimit > 0 {
limit = strconv.FormatInt(cgroup.Resources.PidsLimit, 10)
}
if err := fscommon.WriteFile(dirPath, "pids.max", limit); err != nil {
return err return err
} }
} }