diff --git a/libcontainer/cgroups/utils.go b/libcontainer/cgroups/utils.go index 67341e690d2..ec3e0e71e09 100644 --- a/libcontainer/cgroups/utils.go +++ b/libcontainer/cgroups/utils.go @@ -415,26 +415,26 @@ func ConvertCPUSharesToCgroupV2Value(cpuShares uint64) uint64 { // ConvertMemorySwapToCgroupV2Value converts MemorySwap value from OCI spec // for use by cgroup v2 drivers. A conversion is needed since Resources.MemorySwap -// is defined as memory+swap combined, while in cgroup v2 swap is a separate value. +// is defined as memory+swap combined, while in cgroup v2 swap is a separate value, +// so we need to subtract memory from it where it makes sense. func ConvertMemorySwapToCgroupV2Value(memorySwap, memory int64) (int64, error) { - // for compatibility with cgroup1 controller, set swap to unlimited in - // case the memory is set to unlimited, and swap is not explicitly set, - // treating the request as "set both memory and swap to unlimited". - if memory == -1 && memorySwap == 0 { + switch { + case memory == -1 && memorySwap == 0: + // For compatibility with cgroup1 controller, set swap to unlimited in + // case the memory is set to unlimited and the swap is not explicitly set, + // treating the request as "set both memory and swap to unlimited". return -1, nil - } - if memorySwap == -1 || memorySwap == 0 { - // -1 is "max", 0 is "unset", so treat as is + case memorySwap == -1, memorySwap == 0: + // Treat -1 ("max") and 0 ("unset") swap as is. return memorySwap, nil - } - // sanity checks - if memory == 0 || memory == -1 { + case memory == 0, memory == -1: + // Unset or unlimited memory, can't calculate swap. return 0, errors.New("unable to set swap limit without memory limit") - } - if memory < 0 { + case memory < 0: + // Does not make sense to subtract a negative value. return 0, fmt.Errorf("invalid memory value: %d", memory) - } - if memorySwap < memory { + case memorySwap < memory: + // Sanity check. return 0, errors.New("memory+swap limit should be >= memory limit") }