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Merge pull request #1939 from cyphar/nokmem-error

cgroups: nokmem: error out on explicitly-set kmemcg limits
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crosbymichael committed Dec 4, 2018
2 parents 96ec217 + 8a4629f commit 25f3f893c86d07426df93b7aa172f33fdf093fbd
Showing with 15 additions and 4 deletions.
  1. +10 −3 libcontainer/cgroups/fs/kmem.go
  2. +5 −1 libcontainer/cgroups/fs/kmem_disabled.go
@@ -3,6 +3,7 @@
package fs
import (
"errors"
"fmt"
"io/ioutil"
"os"
@@ -17,7 +18,12 @@ import (
const cgroupKernelMemoryLimit = "memory.kmem.limit_in_bytes"
func EnableKernelMemoryAccounting(path string) error {
// Check if kernel memory is enabled
// Ensure that kernel memory is available in this kernel build. If it
// isn't, we just ignore it because EnableKernelMemoryAccounting is
// automatically called for all memory limits.
if !cgroups.PathExists(filepath.Join(path, cgroupKernelMemoryLimit)) {
return nil
}
// We have to limit the kernel memory here as it won't be accounted at all
// until a limit is set on the cgroup and limit cannot be set once the
// cgroup has children, or if there are already tasks in the cgroup.
@@ -34,8 +40,9 @@ func setKernelMemory(path string, kernelMemoryLimit int64) error {
return fmt.Errorf("no such directory for %s", cgroupKernelMemoryLimit)
}
if !cgroups.PathExists(filepath.Join(path, cgroupKernelMemoryLimit)) {
// kernel memory is not enabled on the system so we should do nothing
return nil
// We have specifically been asked to set a kmem limit. If the kernel
// doesn't support it we *must* error out.
return errors.New("kernel memory accounting not supported by this kernel")
}
if err := ioutil.WriteFile(filepath.Join(path, cgroupKernelMemoryLimit), []byte(strconv.FormatInt(kernelMemoryLimit, 10)), 0700); err != nil {
// Check if the error number returned by the syscall is "EBUSY"
@@ -2,10 +2,14 @@
package fs
import (
"errors"
)
func EnableKernelMemoryAccounting(path string) error {
return nil
}
func setKernelMemory(path string, kernelMemoryLimit int64) error {
return nil
return errors.New("kernel memory accounting disabled in this runc build")
}

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