memory: update: Update state using the memory removed.

If the memory is reduced , its cgroup in the VM was updated properly. But the
runtime assumed that the memory was also removed from the VM.

Then when it is added more memory again, more is added (but not needed).

Fixes: #801

Signed-off-by: Jose Carlos Venegas Munoz <jose.carlos.venegas.munoz@intel.com>

virtcontainers/container.go

@@ -1301,9 +1301,13 @@ func (c *Container) memHotplugValid(mem uint32) (uint32, error) {
 	return uint32(math.Ceil(float64(mem)/float64(memorySectionSizeMB))) * memorySectionSizeMB, nil
 }
 
-func (c *Container) updateMemoryResources(oldResources, newResources ContainerResources) error {
+func (c *Container) updateMemoryResources(oldResources ContainerResources, newResources *ContainerResources) error {
 	oldMemMB := oldResources.MemMB
 	newMemMB := newResources.MemMB
+	c.Logger().WithFields(logrus.Fields{
+		"old-mem": fmt.Sprintf("%dMB", oldMemMB),
+		"new-mem": fmt.Sprintf("%dMB", newMemMB),
+	}).Debug("Request update memory")
 
 	if oldMemMB == newMemMB {
 		c.Logger().WithFields(logrus.Fields{
@@ -1325,16 +1329,37 @@ func (c *Container) updateMemoryResources(oldResources, newResources ContainerRe
 		addMemDevice := &memoryDevice{
 			sizeMB: int(memHotplugMB),
 		}
-		_, err = c.sandbox.hypervisor.hotplugAddDevice(addMemDevice, memoryDev)
+		data, err := c.sandbox.hypervisor.hotplugAddDevice(addMemDevice, memoryDev)
 		if err != nil {
 			return err
 		}
-		newResources.MemMB = newMemMB
+		memoryAdded, ok := data.(int)
+		if !ok {
+			return fmt.Errorf("Could not get the memory added, got %+v", data)
+		}
+		newResources.MemMB = oldMemMB + uint32(memoryAdded)
 		if err := c.sandbox.agent.onlineCPUMem(0, false); err != nil {
 			return err
 		}
 	}
-	// hot remove memory unsupported
+	if oldMemMB > newMemMB {
+		// Try to remove a memory device with the difference
+		// from new memory and old memory
+		removeMem := &memoryDevice{
+			sizeMB: int(oldMemMB - newMemMB),
+		}
+
+		data, err := c.sandbox.hypervisor.hotplugRemoveDevice(removeMem, memoryDev)
+		if err != nil {
+			return err
+		}
+		memoryRemoved, ok := data.(int)
+		if !ok {
+			return fmt.Errorf("Could not get the memory added, got %+v", data)
+		}
+		newResources.MemMB = oldMemMB - uint32(memoryRemoved)
+		newResources.MemMB = oldResources.MemMB
+	}
 	return nil
 }
 
@@ -1358,7 +1383,7 @@ func (c *Container) updateResources(oldResources, newResources ContainerResource
 
 	// Memory is not updated if memory limit not set
 	if newResources.MemMB != 0 {
-		if err := c.updateMemoryResources(oldResources, newResources); err != nil {
+		if err := c.updateMemoryResources(oldResources, &newResources); err != nil {
 			return err
 		}
 

virtcontainers/qemu.go

@@ -7,7 +7,6 @@ package virtcontainers
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -913,7 +912,7 @@ func (q *qemu) hotplugDevice(devInfo interface{}, devType deviceType, op operati
 		return nil, q.hotplugVFIODevice(device, op)
 	case memoryDev:
 		memdev := devInfo.(*memoryDevice)
-		return nil, q.hotplugMemory(memdev, op)
+		return q.hotplugMemory(memdev, op)
 	case netDev:
 		device := devInfo.(*VirtualEndpoint)
 		return nil, q.hotplugNetDevice(device, op)
@@ -1047,24 +1046,27 @@ func (q *qemu) hotplugRemoveCPUs(amount uint32) (uint32, error) {
 	return amount, q.storage.storeHypervisorState(q.id, q.state)
 }
 
-func (q *qemu) hotplugMemory(memDev *memoryDevice, op operation) error {
+func (q *qemu) hotplugMemory(memDev *memoryDevice, op operation) (int, error) {
 	if memDev.sizeMB < 0 {
-		return fmt.Errorf("cannot hotplug negative size (%d) memory", memDev.sizeMB)
+		return 0, fmt.Errorf("cannot hotplug negative size (%d) memory", memDev.sizeMB)
 	}
 
 	// We do not support memory hot unplug.
 	if op == removeDevice {
-		return errors.New("cannot hot unplug memory device")
+		// Dont fail for now, until we fix it.
+		// We return that we only unplugged 0
+		q.Logger().Warn("hot-remove VM memory not supported")
+		return 0, nil
 	}
 
 	err := q.qmpSetup()
 	if err != nil {
-		return err
+		return 0, err
 	}
 
 	maxMem, err := q.hostMemMB()
 	if err != nil {
-		return err
+		return 0, err
 	}
 
 	// calculate current memory
@@ -1072,13 +1074,13 @@ func (q *qemu) hotplugMemory(memDev *memoryDevice, op operation) error {
 
 	// Don't exceed the maximum amount of memory
 	if currentMemory+memDev.sizeMB > int(maxMem) {
-		return fmt.Errorf("Unable to hotplug %d MiB memory, the SB has %d MiB and the maximum amount is %d MiB",
+		return 0, fmt.Errorf("Unable to hotplug %d MiB memory, the SB has %d MiB and the maximum amount is %d MiB",
 			memDev.sizeMB, currentMemory, q.config.MemorySize)
 	}
 
 	memoryDevices, err := q.qmpMonitorCh.qmp.ExecQueryMemoryDevices(q.qmpMonitorCh.ctx)
 	if err != nil {
-		return fmt.Errorf("failed to query memory devices: %v", err)
+		return 0, fmt.Errorf("failed to query memory devices: %v", err)
 	}
 
 	if len(memoryDevices) != 0 {
@@ -1088,15 +1090,15 @@ func (q *qemu) hotplugMemory(memDev *memoryDevice, op operation) error {
 	return q.hotplugAddMemory(memDev)
 }
 
-func (q *qemu) hotplugAddMemory(memDev *memoryDevice) error {
+func (q *qemu) hotplugAddMemory(memDev *memoryDevice) (int, error) {
 	err := q.qmpMonitorCh.qmp.ExecHotplugMemory(q.qmpMonitorCh.ctx, "memory-backend-ram", "mem"+strconv.Itoa(memDev.slot), "", memDev.sizeMB)
 	if err != nil {
 		q.Logger().WithError(err).Error("hotplug memory")
-		return err
+		return 0, err
 	}
 
 	q.state.HotpluggedMemory += memDev.sizeMB
-	return q.storage.storeHypervisorState(q.id, q.state)
+	return memDev.sizeMB, q.storage.storeHypervisorState(q.id, q.state)
 }
 
 func (q *qemu) pauseSandbox() error {