diff --git a/go.mod b/go.mod
index 479c91d9c..05a75eb59 100644
--- a/go.mod
+++ b/go.mod
@@ -19,10 +19,10 @@ require (
 	k8s.io/cli-runtime v0.21.4
 	k8s.io/client-go v0.22.5
 	k8s.io/code-generator v0.22.5
-	knative.dev/eventing v0.28.1-0.20220118233852-e0e3f446c2d8
+	knative.dev/eventing v0.28.1-0.20220119171353-ad895de5fdd8
 	knative.dev/hack v0.0.0-20220118141833-9b2ed8471e30
-	knative.dev/networking v0.0.0-20220118173833-c7164d4dd845
+	knative.dev/networking v0.0.0-20220120043934-ec785540a732
 	knative.dev/pkg v0.0.0-20220118160532-77555ea48cd4
-	knative.dev/serving v0.28.1-0.20220118185833-a3216ca8e4a4
+	knative.dev/serving v0.28.1-0.20220121012810-a4f8b72183c4
 	sigs.k8s.io/yaml v1.3.0
 )
diff --git a/go.sum b/go.sum
index dc3724ca1..df186da91 100644
--- a/go.sum
+++ b/go.sum
@@ -1850,22 +1850,22 @@ k8s.io/utils v0.0.0-20210930125809-cb0fa318a74b/go.mod h1:jPW/WVKK9YHAvNhRxK0md/
 k8s.io/utils v0.0.0-20211208161948-7d6a63dca704 h1:ZKMMxTvduyf5WUtREOqg5LiXaN1KO/+0oOQPRFrClpo=
 k8s.io/utils v0.0.0-20211208161948-7d6a63dca704/go.mod h1:jPW/WVKK9YHAvNhRxK0md/EJ228hCsBRufyofKtW8HA=
 knative.dev/caching v0.0.0-20220113145613-9df2c0c8a931/go.mod h1:kHPJyq2W2ADNAwB6lmmJcleEZfNWioIL5yEs/p5WHU0=
-knative.dev/eventing v0.28.1-0.20220118233852-e0e3f446c2d8 h1:MmqEwo3+dw2JJ3KfOyq+FnMhaA+ztcuDvMiLLkLHM6M=
-knative.dev/eventing v0.28.1-0.20220118233852-e0e3f446c2d8/go.mod h1:9wxM6SRhgS541dVDVvwMwvSJl3B1MzV7FnxxJ8bSyNs=
+knative.dev/eventing v0.28.1-0.20220119171353-ad895de5fdd8 h1:8b3bndqQAIFdEFzNip7QJEhtp+j9xdiRuJNh0jhSDT4=
+knative.dev/eventing v0.28.1-0.20220119171353-ad895de5fdd8/go.mod h1:u5T5NZTDUsLR7yJwp5MDnBnDX5MhywD3yK3Rq+7gTtI=
 knative.dev/hack v0.0.0-20220111151514-59b0cf17578e/go.mod h1:PHt8x8yX5Z9pPquBEfIj0X66f8iWkWfR0S/sarACJrI=
 knative.dev/hack v0.0.0-20220118141833-9b2ed8471e30 h1:UkNpCWCMM5C4AeQ8aTrPTuR/6OeARiqk+LEQ6tuMP7c=
 knative.dev/hack v0.0.0-20220118141833-9b2ed8471e30/go.mod h1:PHt8x8yX5Z9pPquBEfIj0X66f8iWkWfR0S/sarACJrI=
-knative.dev/hack/schema v0.0.0-20220111151514-59b0cf17578e/go.mod h1:ffjwmdcrH5vN3mPhO8RrF2KfNnbHeCE2C60A+2cv3U0=
+knative.dev/hack/schema v0.0.0-20220118141833-9b2ed8471e30/go.mod h1:ffjwmdcrH5vN3mPhO8RrF2KfNnbHeCE2C60A+2cv3U0=
 knative.dev/networking v0.0.0-20220117015928-52fb6ee37bf9/go.mod h1:h4JrHof14QSggAnthL3DPFw1cieenumKDaT+wg0EPmE=
-knative.dev/networking v0.0.0-20220118173833-c7164d4dd845 h1:5+mqH+t0Y7M0T3izEFjQzPR2ZcPKhfV8F+bsYTsj8Jg=
-knative.dev/networking v0.0.0-20220118173833-c7164d4dd845/go.mod h1:6cKBV/h/vIQWCPOkds/RvzUmMR8Vz6Dks2NWb0+3xks=
+knative.dev/networking v0.0.0-20220120043934-ec785540a732 h1:fUUb5NWfYm8TQkhv1uFYlEn91YNKp+E4BD7ax7WYHW0=
+knative.dev/networking v0.0.0-20220120043934-ec785540a732/go.mod h1:6cKBV/h/vIQWCPOkds/RvzUmMR8Vz6Dks2NWb0+3xks=
 knative.dev/pkg v0.0.0-20220113045912-c0e1594c2fb1/go.mod h1:X5B0/SR3tzOioS2WQtS9uJTO71M52qcrDkWQ5wtyLVc=
 knative.dev/pkg v0.0.0-20220114141842-0a429cba1c73/go.mod h1:X5B0/SR3tzOioS2WQtS9uJTO71M52qcrDkWQ5wtyLVc=
 knative.dev/pkg v0.0.0-20220118160532-77555ea48cd4 h1:b9aXVrcfM/ajjHE/lGvlJOHZNAR5FF2TOTLWG7eMhzQ=
 knative.dev/pkg v0.0.0-20220118160532-77555ea48cd4/go.mod h1:etVT7Tm8pSDf4RKhGk4r7j/hj3dNBpvT7bO6a6wpahs=
-knative.dev/reconciler-test v0.0.0-20220117082429-6a9b91eef10c/go.mod h1:zhcMJ0CfqI7de0Ir0yXTTB6BgShWvLEx+BqQdvg+1pU=
-knative.dev/serving v0.28.1-0.20220118185833-a3216ca8e4a4 h1:ihmnuJ2Aof2h908ZcvSksmFY4yakWc907ZpKQWIk9y8=
-knative.dev/serving v0.28.1-0.20220118185833-a3216ca8e4a4/go.mod h1:M6679d8WkZuG/NpVjPBkC9UppjOZRHNVJP0WIWqA62M=
+knative.dev/reconciler-test v0.0.0-20220118183433-c8bfbe66bada/go.mod h1:XV4cghzCtdASkfUsfMYSnGfGRyd/naDjy9h7Tnae22g=
+knative.dev/serving v0.28.1-0.20220121012810-a4f8b72183c4 h1:mUz+V30RkB+nKQs1mnePZhKl62/66FvcU2Y9PK1+8dc=
+knative.dev/serving v0.28.1-0.20220121012810-a4f8b72183c4/go.mod h1:M6679d8WkZuG/NpVjPBkC9UppjOZRHNVJP0WIWqA62M=
 pgregory.net/rapid v0.3.3/go.mod h1:UYpPVyjFHzYBGHIxLFoupi8vwk6rXNzRY9OMvVxFIOU=
 rsc.io/binaryregexp v0.2.0/go.mod h1:qTv7/COck+e2FymRvadv62gMdZztPaShugOCi3I+8D8=
 rsc.io/quote/v3 v3.1.0/go.mod h1:yEA65RcK8LyAZtP9Kv3t0HmxON59tX3rD+tICJqUlj0=
diff --git a/vendor/knative.dev/serving/pkg/apis/config/features.go b/vendor/knative.dev/serving/pkg/apis/config/features.go
index db4f212d6..0998025e3 100644
--- a/vendor/knative.dev/serving/pkg/apis/config/features.go
+++ b/vendor/knative.dev/serving/pkg/apis/config/features.go
@@ -54,6 +54,8 @@ func defaultFeaturesConfig() *Features {
 		ContainerSpecAddCapabilities: Disabled,
 		PodSpecTolerations:           Disabled,
 		PodSpecVolumesEmptyDir:       Disabled,
+		PodSpecPersistentVolumeClaim: Disabled,
+		PodSpecPersistentVolumeWrite: Disabled,
 		PodSpecInitContainers:        Disabled,
 		TagHeaderBasedRouting:        Disabled,
 		AutoDetectHTTP2:              Disabled,
@@ -79,6 +81,8 @@ func NewFeaturesConfigFromMap(data map[string]string) (*Features, error) {
 		asFlag("kubernetes.podspec-tolerations", &nc.PodSpecTolerations),
 		asFlag("kubernetes.podspec-volumes-emptydir", &nc.PodSpecVolumesEmptyDir),
 		asFlag("kubernetes.podspec-init-containers", &nc.PodSpecInitContainers),
+		asFlag("kubernetes.podspec-persistent-volume-claim", &nc.PodSpecPersistentVolumeClaim),
+		asFlag("kubernetes.podspec-persistent-volume-write", &nc.PodSpecPersistentVolumeWrite),
 		asFlag("tag-header-based-routing", &nc.TagHeaderBasedRouting),
 		asFlag("autodetect-http2", &nc.AutoDetectHTTP2)); err != nil {
 		return nil, err
@@ -107,6 +111,8 @@ type Features struct {
 	PodSpecTolerations           Flag
 	PodSpecVolumesEmptyDir       Flag
 	PodSpecInitContainers        Flag
+	PodSpecPersistentVolumeClaim Flag
+	PodSpecPersistentVolumeWrite Flag
 	TagHeaderBasedRouting        Flag
 	AutoDetectHTTP2              Flag
 }
diff --git a/vendor/knative.dev/serving/pkg/apis/serving/fieldmask.go b/vendor/knative.dev/serving/pkg/apis/serving/fieldmask.go
index 4ea939b29..32723a1f8 100644
--- a/vendor/knative.dev/serving/pkg/apis/serving/fieldmask.go
+++ b/vendor/knative.dev/serving/pkg/apis/serving/fieldmask.go
@@ -45,6 +45,10 @@ func VolumeMask(ctx context.Context, in *corev1.Volume) *corev1.Volume {
 		out.EmptyDir = in.EmptyDir
 	}
 
+	if cfg.Features.PodSpecPersistentVolumeClaim != config.Disabled {
+		out.PersistentVolumeClaim = in.PersistentVolumeClaim
+	}
+
 	return out
 }
 
@@ -67,6 +71,10 @@ func VolumeSourceMask(ctx context.Context, in *corev1.VolumeSource) *corev1.Volu
 		out.EmptyDir = in.EmptyDir
 	}
 
+	if cfg.Features.PodSpecPersistentVolumeClaim != config.Disabled {
+		out.PersistentVolumeClaim = in.PersistentVolumeClaim
+	}
+
 	// Too many disallowed fields to list
 
 	return out
diff --git a/vendor/knative.dev/serving/pkg/apis/serving/k8s_validation.go b/vendor/knative.dev/serving/pkg/apis/serving/k8s_validation.go
index 2d03ecbdb..eeed43fc8 100644
--- a/vendor/knative.dev/serving/pkg/apis/serving/k8s_validation.go
+++ b/vendor/knative.dev/serving/pkg/apis/serving/k8s_validation.go
@@ -85,12 +85,7 @@ var (
 func ValidateVolumes(ctx context.Context, vs []corev1.Volume, mountedVolumes sets.String) (map[string]corev1.Volume, *apis.FieldError) {
 	volumes := make(map[string]corev1.Volume, len(vs))
 	var errs *apis.FieldError
-	features := config.FromContextOrDefaults(ctx).Features
 	for i, volume := range vs {
-		if volume.EmptyDir != nil && features.PodSpecVolumesEmptyDir != config.Enabled {
-			errs = errs.Also((&apis.FieldError{Message: fmt.Sprintf("EmptyDir volume support is off, "+
-				"but found EmptyDir volume %s", volume.Name)}).ViaIndex(i))
-		}
 		if _, ok := volumes[volume.Name]; ok {
 			errs = errs.Also((&apis.FieldError{
 				Message: fmt.Sprintf("duplicate volume name %q", volume.Name),
@@ -109,14 +104,36 @@ func ValidateVolumes(ctx context.Context, vs []corev1.Volume, mountedVolumes set
 	return volumes, errs
 }
 
+func validatePersistentVolumeClaims(volume corev1.VolumeSource, features *config.Features) *apis.FieldError {
+	var errs *apis.FieldError
+	if volume.PersistentVolumeClaim == nil {
+		return nil
+	}
+	if features.PodSpecPersistentVolumeClaim != config.Enabled {
+		errs = errs.Also(&apis.FieldError{Message: fmt.Sprintf("Persistent volume claim support is disabled, "+
+			"but found persistent volume claim %s", volume.PersistentVolumeClaim.ClaimName)})
+	}
+	isWriteEnabled := features.PodSpecPersistentVolumeWrite == config.Enabled
+	if !volume.PersistentVolumeClaim.ReadOnly && !isWriteEnabled {
+		errs = errs.Also(&apis.FieldError{Message: fmt.Sprintf("Persistent volume write support is disabled, "+
+			"but found persistent volume claim %s that is not read-only", volume.PersistentVolumeClaim.ClaimName)})
+	}
+	return errs
+}
+
 func validateVolume(ctx context.Context, volume corev1.Volume) *apis.FieldError {
-	errs := apis.CheckDisallowedFields(volume, *VolumeMask(ctx, &volume))
+	features := config.FromContextOrDefaults(ctx).Features
+	errs := validatePersistentVolumeClaims(volume.VolumeSource, features)
+	if volume.EmptyDir != nil && features.PodSpecVolumesEmptyDir != config.Enabled {
+		errs = errs.Also(&apis.FieldError{Message: fmt.Sprintf("EmptyDir volume support is disabled, "+
+			"but found EmptyDir volume %s", volume.Name)})
+	}
+	errs = errs.Also(apis.CheckDisallowedFields(volume, *VolumeMask(ctx, &volume)))
 	if volume.Name == "" {
 		errs = apis.ErrMissingField("name")
 	} else if len(validation.IsDNS1123Label(volume.Name)) != 0 {
 		errs = apis.ErrInvalidValue(volume.Name, "name")
 	}
-
 	vs := volume.VolumeSource
 	errs = errs.Also(apis.CheckDisallowedFields(vs, *VolumeSourceMask(ctx, &vs)))
 	var specified []string
@@ -142,12 +159,20 @@ func validateVolume(ctx context.Context, volume corev1.Volume) *apis.FieldError
 		specified = append(specified, "emptyDir")
 		errs = errs.Also(validateEmptyDirFields(vs.EmptyDir).ViaField("emptyDir"))
 	}
+
+	if vs.PersistentVolumeClaim != nil {
+		specified = append(specified, "persistentVolumeClaim")
+	}
+
 	if len(specified) == 0 {
 		fieldPaths := []string{"secret", "configMap", "projected"}
 		cfg := config.FromContextOrDefaults(ctx)
 		if cfg.Features.PodSpecVolumesEmptyDir == config.Enabled {
 			fieldPaths = append(fieldPaths, "emptyDir")
 		}
+		if cfg.Features.PodSpecPersistentVolumeClaim == config.Enabled {
+			fieldPaths = append(fieldPaths, "persistentVolumeClaim")
+		}
 		errs = errs.Also(apis.ErrMissingOneOf(fieldPaths...))
 	} else if len(specified) > 1 {
 		errs = errs.Also(apis.ErrMultipleOneOf(specified...))
@@ -616,8 +641,21 @@ func validateVolumeMounts(mounts []corev1.VolumeMount, volumes map[string]corev1
 		}
 		seenMountPath.Insert(filepath.Clean(vm.MountPath))
 
-		if volumes[vm.Name].EmptyDir == nil && !vm.ReadOnly {
-			errs = errs.Also(apis.ErrMissingField("readOnly").ViaIndex(i))
+		shouldCheckReadOnlyVolume := volumes[vm.Name].EmptyDir == nil && volumes[vm.Name].PersistentVolumeClaim == nil
+		if shouldCheckReadOnlyVolume && !vm.ReadOnly {
+			errs = errs.Also((&apis.FieldError{
+				Message: "volume mount should be readOnly for this type of volume",
+				Paths:   []string{"readOnly"},
+			}).ViaIndex(i))
+		}
+
+		if volumes[vm.Name].PersistentVolumeClaim != nil {
+			if volumes[vm.Name].PersistentVolumeClaim.ReadOnly && !vm.ReadOnly {
+				errs = errs.Also((&apis.FieldError{
+					Message: "volume is readOnly but volume mount is not",
+					Paths:   []string{"readOnly"},
+				}).ViaIndex(i))
+			}
 		}
 	}
 	return errs
diff --git a/vendor/knative.dev/serving/pkg/apis/serving/v1/revision_defaults.go b/vendor/knative.dev/serving/pkg/apis/serving/v1/revision_defaults.go
index 88724199f..354b12d89 100644
--- a/vendor/knative.dev/serving/pkg/apis/serving/v1/revision_defaults.go
+++ b/vendor/knative.dev/serving/pkg/apis/serving/v1/revision_defaults.go
@@ -121,7 +121,7 @@ func (rs *RevisionSpec) applyDefault(ctx context.Context, container *corev1.Cont
 
 	vNames := make(sets.String)
 	for _, v := range rs.PodSpec.Volumes {
-		if v.EmptyDir != nil {
+		if v.EmptyDir != nil || v.PersistentVolumeClaim != nil {
 			vNames.Insert(v.Name)
 		}
 	}
diff --git a/vendor/knative.dev/serving/pkg/testing/v1/revision.go b/vendor/knative.dev/serving/pkg/testing/v1/revision.go
index 3445dc0ab..6a5cdfa82 100644
--- a/vendor/knative.dev/serving/pkg/testing/v1/revision.go
+++ b/vendor/knative.dev/serving/pkg/testing/v1/revision.go
@@ -232,6 +232,22 @@ func WithRevisionInitContainers() RevisionOption {
 	}
 }
 
+func WithRevisionPVC() RevisionOption {
+	return func(r *v1.Revision) {
+		r.Spec.Volumes = []corev1.Volume{{
+			Name: "claimvolume",
+			VolumeSource: corev1.VolumeSource{PersistentVolumeClaim: &corev1.PersistentVolumeClaimVolumeSource{
+				ClaimName: "myclaim",
+				ReadOnly:  false,
+			}}},
+		}
+		r.Spec.Containers[0].VolumeMounts = []corev1.VolumeMount{{
+			Name:      "claimvolume",
+			MountPath: "/data",
+		}}
+	}
+}
+
 // Revision creates a revision object with given ns/name and options.
 func Revision(namespace, name string, ro ...RevisionOption) *v1.Revision {
 	r := &v1.Revision{
diff --git a/vendor/knative.dev/serving/test/e2e-auto-tls-tests.sh b/vendor/knative.dev/serving/test/e2e-auto-tls-tests.sh
index 0b881e8f3..d893e0d4c 100644
--- a/vendor/knative.dev/serving/test/e2e-auto-tls-tests.sh
+++ b/vendor/knative.dev/serving/test/e2e-auto-tls-tests.sh
@@ -158,12 +158,7 @@ function delete_dns_record() {
 }
 
 # Script entry point.
-
-# Skip installing istio as an add-on
-# Temporarily increasing the cluster size for serving tests to rule out
-# resource/eviction as causes of flakiness.
-# Pin to 1.20 since scale test is super flakey on 1.21
-initialize "$@" --skip-istio-addon --min-nodes=4 --max-nodes=4 --enable-ha --cluster-version=1.20
+initialize "$@" --skip-istio-addon --min-nodes=4 --max-nodes=4 --enable-ha --cluster-version=1.21
 
 # Run the tests
 header "Running tests"
diff --git a/vendor/knative.dev/serving/test/e2e-tests.sh b/vendor/knative.dev/serving/test/e2e-tests.sh
index 2425a3622..4fc6f283b 100644
--- a/vendor/knative.dev/serving/test/e2e-tests.sh
+++ b/vendor/knative.dev/serving/test/e2e-tests.sh
@@ -28,12 +28,7 @@
 source $(dirname $0)/e2e-common.sh
 
 # Script entry point.
-
-# Skip installing istio as an add-on.
-# Temporarily increasing the cluster size for serving tests to rule out
-# resource/eviction as causes of flakiness.
-# Pin to 1.20 since scale test is super flakey on 1.21
-initialize --skip-istio-addon --min-nodes=4 --max-nodes=4 --enable-ha --cluster-version=1.20 "$@"
+initialize --skip-istio-addon --min-nodes=4 --max-nodes=4 --enable-ha --cluster-version=1.21 "$@"
 
 # Run the tests
 header "Running tests"
@@ -112,7 +107,8 @@ kubectl replace cm "config-gc" -n ${SYSTEM_NAMESPACE} -f ${TMP_DIR}/config-gc.ya
 # Note that we use a very high -parallel because each ksvc is run as its own
 # sub-test. If this is not larger than the maximum scale tested then the test
 # simply cannot pass.
-go_test_e2e -timeout=20m -parallel=300 ./test/scale ${TEST_OPTIONS} || failed=1
+# TODO - Renable once we get this reliably passing on GKE 1.21
+# go_test_e2e -timeout=20m -parallel=300 ./test/scale ${TEST_OPTIONS} || failed=1
 
 # Run HPA tests
 go_test_e2e -timeout=30m -tags=hpa ./test/e2e ${TEST_OPTIONS} || failed=1
diff --git a/vendor/knative.dev/serving/test/e2e-upgrade-tests.sh b/vendor/knative.dev/serving/test/e2e-upgrade-tests.sh
index b1f08d2d4..396c821f9 100644
--- a/vendor/knative.dev/serving/test/e2e-upgrade-tests.sh
+++ b/vendor/knative.dev/serving/test/e2e-upgrade-tests.sh
@@ -40,10 +40,7 @@ function stage_test_resources() {
 # Script entry point.
 
 # Skip installing istio as an add-on.
-# Temporarily increasing the cluster size for serving tests to rule out
-# resource/eviction as causes of flakiness.
-# Pin to 1.20 since scale test is super flakey on 1.21
-initialize "$@" --skip-istio-addon  --min-nodes=4 --max-nodes=4 --cluster-version=1.20 \
+initialize "$@" --skip-istio-addon  --min-nodes=4 --max-nodes=4 --cluster-version=1.21 \
   --install-latest-release
 
 # TODO(#2656): Reduce the timeout after we get this test to consistently passing.
diff --git a/vendor/modules.txt b/vendor/modules.txt
index 2da336071..82fa73b55 100644
--- a/vendor/modules.txt
+++ b/vendor/modules.txt
@@ -748,7 +748,7 @@ k8s.io/utils/buffer
 k8s.io/utils/integer
 k8s.io/utils/pointer
 k8s.io/utils/trace
-# knative.dev/eventing v0.28.1-0.20220118233852-e0e3f446c2d8
+# knative.dev/eventing v0.28.1-0.20220119171353-ad895de5fdd8
 ## explicit
 knative.dev/eventing/pkg/apis/config
 knative.dev/eventing/pkg/apis/duck
@@ -777,7 +777,7 @@ knative.dev/eventing/pkg/client/clientset/versioned/typed/sources/v1beta2/fake
 # knative.dev/hack v0.0.0-20220118141833-9b2ed8471e30
 ## explicit
 knative.dev/hack
-# knative.dev/networking v0.0.0-20220118173833-c7164d4dd845
+# knative.dev/networking v0.0.0-20220120043934-ec785540a732
 ## explicit
 knative.dev/networking/pkg
 knative.dev/networking/pkg/apis/networking
@@ -835,7 +835,7 @@ knative.dev/pkg/tracing/config
 knative.dev/pkg/tracing/propagation
 knative.dev/pkg/tracing/propagation/tracecontextb3
 knative.dev/pkg/tracker
-# knative.dev/serving v0.28.1-0.20220118185833-a3216ca8e4a4
+# knative.dev/serving v0.28.1-0.20220121012810-a4f8b72183c4
 ## explicit
 knative.dev/serving/pkg/apis/autoscaling
 knative.dev/serving/pkg/apis/autoscaling/v1alpha1