Merge pull request #3141 from kinvolk/schu/workaround-ubuntu-kernel-oops

Workaround Ubuntu kernel oops

Fixes #3131

probe/endpoint/ebpf.go

@@ -53,16 +53,28 @@ type EbpfTracker struct {
 	closedDuringInit  map[fourTuple]struct{}
 }
 
-var releaseRegex = regexp.MustCompile(`^(\d+)\.(\d+).*$`)
+// releaseRegex should match all possible variations of a common Linux
+// version string:
+//   - 4.1
+//   - 4.22-foo
+//   - 4.1.2-foo
+//   - 4.1.2-33.44+bar
+//   - etc.
+// For example, on a Ubuntu system the vendor specific release part
+// (after the first `-`) could look like:
+// '<ABI number>.<upload number>-<flavour>' or
+// '<ABI number>-<flavour>'
+// See https://wiki.ubuntu.com/Kernel/FAQ
+var releaseRegex = regexp.MustCompile(`^(\d+)\.(\d+)\.?(\d*)-?(\d*)(.*)$`)
 
 func isKernelSupported() error {
-	release, _, err := host.GetKernelReleaseAndVersion()
+	release, version, err := host.GetKernelReleaseAndVersion()
 	if err != nil {
 		return err
 	}
 
 	releaseParts := releaseRegex.FindStringSubmatch(release)
-	if len(releaseParts) != 3 {
+	if len(releaseParts) != 6 {
 		return fmt.Errorf("got invalid release version %q (expected format '4.4[.2-1]')", release)
 	}
 
@@ -84,6 +96,24 @@ func isKernelSupported() error {
 		return fmt.Errorf("got kernel %s but need kernel >=4.4", release)
 	}
 
+	if strings.Contains(version, "Ubuntu") {
+		// Check for specific Ubuntu kernel versions with
+		// known issues.
+
+		abiNumber, err := strconv.Atoi(releaseParts[4])
+		if err != nil {
+			// By now we know it's at least kernel 4.4 and
+			// not "119-ish", so allow it.
+			return nil
+		}
+		// TODO: give the check an upper limit once the bug is fixed
+		if major == 4 && minor == 4 && abiNumber >= 119 {
+			// https://github.com/weaveworks/scope/issues/3131
+			// https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1763454
+			return fmt.Errorf("got Ubuntu kernel %s with known bug", release)
+		}
+	}
+
 	return nil
 }
 

probe/endpoint/ebpf_test.go

@@ -8,6 +8,8 @@ import (
 	"time"
 
 	"github.com/weaveworks/tcptracer-bpf/pkg/tracer"
+
+	"github.com/weaveworks/scope/probe/host"
 )
 
 func newMockEbpfTracker() *EbpfTracker {
@@ -233,3 +235,74 @@ func TestInvalidTimeStampDead(t *testing.T) {
 		t.Errorf("expected ebpfTracker to be set to dead after events with wrong order")
 	}
 }
+
+func TestIsKernelSupported(t *testing.T) {
+	var release, version string
+	oldGetKernelReleaseAndVersion := host.GetKernelReleaseAndVersion
+	defer func() {
+		host.GetKernelReleaseAndVersion = oldGetKernelReleaseAndVersion
+	}()
+	host.GetKernelReleaseAndVersion = func() (string, string, error) { return release, version, nil }
+	testVersions := []struct {
+		release   string
+		version   string
+		supported bool
+	}{
+		{
+			"4.1",
+			"",
+			false,
+		},
+		{
+			"4.4",
+			"",
+			true,
+		},
+		{
+			"4.4-custom",
+			"",
+			true,
+		},
+		{
+			"4.4.127",
+			"",
+			true,
+		},
+		{
+			"4.4.0-119-generic",
+			"#143-Ubuntu SMP Mon Apr 2 16:08:24 UTC 2018",
+			false,
+		},
+		{
+			"4.4.0-116-generic",
+			"#140-Ubuntu SMP Mon Feb 12 21:23:04 UTC 2018",
+			true,
+		},
+		{
+			"4.13.0-38-generic",
+			"#43-Ubuntu SMP Wed Mar 14 15:20:44 UTC 2018",
+			true,
+		},
+		{
+			"4.13.0-119-generic",
+			"#43-Ubuntu SMP Wed Apr 1 00:00:00 UTC 2018",
+			true,
+		},
+		{
+			"4.9.0-6-amd64",
+			"#1 SMP Debian 4.9.82-1+deb9u3 (2018-03-02)",
+			true,
+		},
+	}
+	for _, tv := range testVersions {
+		release = tv.release
+		version = tv.version
+		err := isKernelSupported()
+		if tv.supported && err != nil {
+			t.Errorf("expected kernel release %q version %q to be supported but got error: %v", release, version, err)
+		}
+		if !tv.supported && err == nil {
+			t.Errorf("expected kernel release %q version %q to not be supported", release, version)
+		}
+	}
+}