Report total memory based on limit or host

gVisor was previously reporting the lower of cgroup limit or 2GB as total
memory. This may cause applications to make bad decisions based on amount
of memory available to them when more than 2GB is required.

This change makes the lower of cgroup limit or the host total memory to be
reported inside the sandbox. This also is more inline with docker which always
reports host total memory. Note that reporting cgroup limit is strictly better
than host total memory when there is a limit set.

Fixes #5608

PiperOrigin-RevId: 403241608

1 files changed, 40 insertions, 4 deletions

diff --git a/test/e2e/integration_test.go b/test/e2e/integration_test.go
index d41139944..c5aa35623 100644
--- a/test/e2e/integration_test.go
+++ b/test/e2e/integration_test.go
@@ -29,6 +29,7 @@ import (
 	"net"
 	"net/http"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"regexp"
 	"strconv"
@@ -41,8 +42,12 @@ import (
 	"gvisor.dev/gvisor/pkg/test/testutil"
 )
 
-// defaultWait is the default wait time used for tests.
-const defaultWait = time.Minute
+const (
+	// defaultWait is the default wait time used for tests.
+	defaultWait = time.Minute
+
+	memInfoCmd = "cat /proc/meminfo | grep MemTotal: | awk '{print $2}'"
+)
 
 func TestMain(m *testing.M) {
 	dockerutil.EnsureSupportedDockerVersion()
@@ -255,16 +260,47 @@ func TestConnectToSelf(t *testing.T) {
 	}
 }
 
+func TestMemory(t *testing.T) {
+	// Find total amount of memory in the host.
+	host, err := exec.Command("sh", "-c", memInfoCmd).CombinedOutput()
+	if err != nil {
+		t.Fatal(err)
+	}
+	want, err := strconv.ParseUint(strings.TrimSpace(string(host)), 10, 64)
+	if err != nil {
+		t.Fatalf("failed to parse %q: %v", host, err)
+	}
+
+	ctx := context.Background()
+	d := dockerutil.MakeContainer(ctx, t)
+	defer d.CleanUp(ctx)
+
+	out, err := d.Run(ctx, dockerutil.RunOpts{Image: "basic/alpine"}, "sh", "-c", memInfoCmd)
+	if err != nil {
+		t.Fatalf("docker run failed: %v", err)
+	}
+
+	// Get memory from inside the container and ensure it matches the host.
+	got, err := strconv.ParseUint(strings.TrimSpace(out), 10, 64)
+	if err != nil {
+		t.Fatalf("failed to parse %q: %v", out, err)
+	}
+	if got != want {
+		t.Errorf("MemTotal got: %d, want: %d", got, want)
+	}
+}
+
 func TestMemLimit(t *testing.T) {
 	ctx := context.Background()
 	d := dockerutil.MakeContainer(ctx, t)
 	defer d.CleanUp(ctx)
 
 	allocMemoryKb := 50 * 1024
-	out, err := d.Run(ctx, dockerutil.RunOpts{
+	opts := dockerutil.RunOpts{
 		Image:  "basic/alpine",
 		Memory: allocMemoryKb * 1024, // In bytes.
-	}, "sh", "-c", "cat /proc/meminfo | grep MemTotal: | awk '{print $2}'")
+	}
+	out, err := d.Run(ctx, opts, "sh", "-c", memInfoCmd)
 	if err != nil {
 		t.Fatalf("docker run failed: %v", err)
 	}