@@ -283,6 +283,11 @@ func (container *Container) UpdateContainer(hostConfig *containertypes.HostConfi

 		cResources.CpusetMems = resources.CpusetMems

 	}

 	if resources.Memory != 0 {

+		// if memory limit smaller than already set memoryswap limit and doesn't

+		// update the memoryswap limit, then error out.

+		if resources.Memory > cResources.MemorySwap && resources.MemorySwap == 0 {

+			return fmt.Errorf("Memory limit should be smaller than already set memoryswap limit, update the memoryswap at the same time")

+		}

 		cResources.Memory = resources.Memory

 	}

 	if resources.MemorySwap != 0 {

@@ -236,3 +236,17 @@ func (s *DockerSuite) TestUpdateStats(c *check.C) {

 	c.Assert(preMemLimit, checker.Equals, curMemLimit)

 }

+

+func (s *DockerSuite) TestUpdateMemoryWithSwapMemory(c *check.C) {

+	testRequires(c, DaemonIsLinux)

+	testRequires(c, memoryLimitSupport)

+	testRequires(c, swapMemorySupport)

+

+	name := "test-update-container"

+	dockerCmd(c, "run", "-d", "--name", name, "--memory", "300M", "busybox", "top")

+	out, _, err := dockerCmdWithError("update", "--memory", "800M", name)

+	c.Assert(err, checker.NotNil)

+	c.Assert(out, checker.Contains, "Memory limit should be smaller than already set memoryswap limit")

+

+	dockerCmd(c, "update", "--memory", "800M", "--memory-swap", "1000M", name)

+}

@@ -67,6 +67,12 @@ a running container with kernel memory initialized.

 **-m**, **--memory**=""

    Memory limit (format: <number><optional unit>, where unit = b, k, m or g)

+   Note that the memory should be smaller than the already set swap memory limit.

+   If you want update a memory limit bigger than the already set swap memory limit,

+   you should update swap memory limit at the same time. If you don't set swap memory 

+   limit on docker create/run but only memory limit, the swap memory is double

+   the memory limit.

+

 **--memory-reservation**=""

    Memory soft limit (format: <number>[<unit>], where unit = b, k, m or g)