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Merge pull request #1939 from cyphar/nokmem-error 

cgroups: nokmem: error out on explicitly-set kmemcg limits
This commit is contained in:
Michael Crosby 2018-12-04 11:14:56 -05:00 committed by GitHub
parent 96ec2177ae 8a4629f7b5
commit 25f3f893c8
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 15 additions and 4 deletions
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13
libcontainer/cgroups/fs/kmem.go
View File

@ -3,6 +3,7 @@
package fs package fs
import ( import (
"errors"
"fmt" "fmt"
"io/ioutil" "io/ioutil"
"os" "os"
@ -17,7 +18,12 @@ import (
const cgroupKernelMemoryLimit = "memory.kmem.limit_in_bytes" const cgroupKernelMemoryLimit = "memory.kmem.limit_in_bytes"
func EnableKernelMemoryAccounting(path string) error { 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 // 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 // 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. // 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) return fmt.Errorf("no such directory for %s", cgroupKernelMemoryLimit)
} }
if !cgroups.PathExists(filepath.Join(path, cgroupKernelMemoryLimit)) { if !cgroups.PathExists(filepath.Join(path, cgroupKernelMemoryLimit)) {
// kernel memory is not enabled on the system so we should do nothing // We have specifically been asked to set a kmem limit. If the kernel
return nil // 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 { 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" // Check if the error number returned by the syscall is "EBUSY"

6
libcontainer/cgroups/fs/kmem_disabled.go
View File

@ -2,10 +2,14 @@
package fs package fs
import (
"errors"
)
func EnableKernelMemoryAccounting(path string) error { func EnableKernelMemoryAccounting(path string) error {
return nil return nil
} }
func setKernelMemory(path string, kernelMemoryLimit int64) error { func setKernelMemory(path string, kernelMemoryLimit int64) error {
return nil return errors.New("kernel memory accounting disabled in this runc build")
} }