diff --git a/pkg/agent/config/config.go b/pkg/agent/config/config.go
index f624e4da89bc..e55fb71c0677 100644
--- a/pkg/agent/config/config.go
+++ b/pkg/agent/config/config.go
@@ -569,7 +569,7 @@ func get(ctx context.Context, envInfo *cmds.Agent, proxy proxy.Proxy) (*config.N
 	nodeConfig.Containerd.Debug = envInfo.Debug
 	applyContainerdStateAndAddress(nodeConfig)
 	applyCRIDockerdAddress(nodeConfig)
-	applyContainerdQoSClassConfigFileIfPresent(envInfo, nodeConfig)
+	applyContainerdQoSClassConfigFileIfPresent(envInfo, &nodeConfig.Containerd)
 	nodeConfig.Containerd.Template = filepath.Join(envInfo.DataDir, "agent", "etc", "containerd", "config.toml.tmpl")
 	nodeConfig.Certificate = servingCert
 
diff --git a/pkg/agent/config/config_linux.go b/pkg/agent/config/config_linux.go
index c29e0a7d8b40..b668ab0a6877 100644
--- a/pkg/agent/config/config_linux.go
+++ b/pkg/agent/config/config_linux.go
@@ -22,20 +22,26 @@ func applyCRIDockerdAddress(nodeConfig *config.Node) {
 	nodeConfig.CRIDockerd.Address = "unix:///run/k3s/cri-dockerd/cri-dockerd.sock"
 }
 
-func applyContainerdQoSClassConfigFileIfPresent(envInfo *cmds.Agent, nodeConfig *config.Node) {
-	blockioPath := filepath.Join(envInfo.DataDir, "agent", "etc", "containerd", "blockio_config.yaml")
+func applyContainerdQoSClassConfigFileIfPresent(envInfo *cmds.Agent, containerdConfig *config.Containerd) {
+	containerdConfigDir := filepath.Join(envInfo.DataDir, "agent", "etc", "containerd")
+
+	blockioPath := filepath.Join(containerdConfigDir, "blockio_config.yaml")
 
 	// Set containerd config if file exists
-	if _, err := os.Stat(blockioPath); !errors.Is(err, os.ErrNotExist) {
-		logrus.Infof("BlockIO configuration file found")
-		nodeConfig.Containerd.BlockIOConfig = blockioPath
+	if fileInfo, err := os.Stat(blockioPath); !errors.Is(err, os.ErrNotExist) {
+		if fileInfo.Mode().IsRegular() {
+			logrus.Infof("BlockIO configuration file found")
+			containerdConfig.BlockIOConfig = blockioPath
+		}
 	}
 
-	rdtPath := filepath.Join(envInfo.DataDir, "agent", "etc", "containerd", "rdt_config.yaml")
+	rdtPath := filepath.Join(containerdConfigDir, "rdt_config.yaml")
 
 	// Set containerd config if file exists
-	if _, err := os.Stat(rdtPath); !errors.Is(err, os.ErrNotExist) {
-		logrus.Infof("RDT configuration file found")
-		nodeConfig.Containerd.RDTConfig = rdtPath
+	if fileInfo, err := os.Stat(rdtPath); !errors.Is(err, os.ErrNotExist) {
+		if fileInfo.Mode().IsRegular() {
+			logrus.Infof("RDT configuration file found")
+			containerdConfig.RDTConfig = rdtPath
+		}
 	}
 }
diff --git a/pkg/agent/config/config_linux_test.go b/pkg/agent/config/config_linux_test.go
new file mode 100644
index 000000000000..868304fcb86c
--- /dev/null
+++ b/pkg/agent/config/config_linux_test.go
@@ -0,0 +1,165 @@
+//go:build linux
+// +build linux
+
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"reflect"
+	"testing"
+
+	"github.com/k3s-io/k3s/pkg/cli/cmds"
+	"github.com/k3s-io/k3s/pkg/daemons/config"
+	"github.com/k3s-io/k3s/tests"
+)
+
+func Test_UnitApplyContainerdQoSClassConfigFileIfPresent(t *testing.T) {
+	configControl := config.Control{
+		DataDir: "/tmp/k3s/",
+	}
+
+	if err := tests.GenerateDataDir(&configControl); err != nil {
+		t.Errorf("Test_UnitApplyContainerdQoSClassConfigFileIfPresent() setup failed = %v", err)
+	}
+	defer tests.CleanupDataDir(&configControl)
+
+	containerdConfigDir := filepath.Join(configControl.DataDir, "agent", "etc", "containerd")
+	os.MkdirAll(containerdConfigDir, 0700)
+
+	type args struct {
+		envInfo          *cmds.Agent
+		containerdConfig *config.Containerd
+	}
+	tests := []struct {
+		name     string
+		args     args
+		setup    func() error
+		teardown func()
+		want     *config.Containerd
+	}{
+		{
+			name: "No config file",
+			args: args{
+				envInfo: &cmds.Agent{
+					DataDir: configControl.DataDir,
+				},
+				containerdConfig: &config.Containerd{},
+			},
+			setup: func() error {
+				return nil
+			},
+			teardown: func() {},
+			want:     &config.Containerd{},
+		},
+		{
+			name: "BlockIO config file",
+			args: args{
+				envInfo: &cmds.Agent{
+					DataDir: configControl.DataDir,
+				},
+				containerdConfig: &config.Containerd{},
+			},
+			setup: func() error {
+				_, err := os.Create(filepath.Join(containerdConfigDir, "blockio_config.yaml"))
+				return err
+			},
+			teardown: func() {
+				os.Remove(filepath.Join(containerdConfigDir, "blockio_config.yaml"))
+			},
+			want: &config.Containerd{
+				BlockIOConfig: filepath.Join(containerdConfigDir, "blockio_config.yaml"),
+			},
+		},
+		{
+			name: "RDT config file",
+			args: args{
+				envInfo: &cmds.Agent{
+					DataDir: configControl.DataDir,
+				},
+				containerdConfig: &config.Containerd{},
+			},
+			setup: func() error {
+				_, err := os.Create(filepath.Join(containerdConfigDir, "rdt_config.yaml"))
+				return err
+			},
+			teardown: func() {
+				os.Remove(filepath.Join(containerdConfigDir, "rdt_config.yaml"))
+			},
+			want: &config.Containerd{
+				RDTConfig: filepath.Join(containerdConfigDir, "rdt_config.yaml"),
+			},
+		},
+		{
+			name: "Both config files",
+			args: args{
+				envInfo: &cmds.Agent{
+					DataDir: configControl.DataDir,
+				},
+				containerdConfig: &config.Containerd{},
+			},
+			setup: func() error {
+				_, err := os.Create(filepath.Join(containerdConfigDir, "blockio_config.yaml"))
+				if err != nil {
+					return err
+				}
+				_, err = os.Create(filepath.Join(containerdConfigDir, "rdt_config.yaml"))
+				return err
+			},
+			teardown: func() {
+				os.Remove(filepath.Join(containerdConfigDir, "blockio_config.yaml"))
+				os.Remove(filepath.Join(containerdConfigDir, "rdt_config.yaml"))
+			},
+			want: &config.Containerd{
+				BlockIOConfig: filepath.Join(containerdConfigDir, "blockio_config.yaml"),
+				RDTConfig:     filepath.Join(containerdConfigDir, "rdt_config.yaml"),
+			},
+		},
+		{
+			name: "BlockIO path is a directory",
+			args: args{
+				envInfo: &cmds.Agent{
+					DataDir: configControl.DataDir,
+				},
+				containerdConfig: &config.Containerd{},
+			},
+			setup: func() error {
+				return os.Mkdir(filepath.Join(containerdConfigDir, "blockio_config.yaml"), 0700)
+			},
+			teardown: func() {
+				os.Remove(filepath.Join(containerdConfigDir, "blockio_config.yaml"))
+			},
+			want: &config.Containerd{},
+		},
+		{
+			name: "RDT path is a directory",
+			args: args{
+				envInfo: &cmds.Agent{
+					DataDir: configControl.DataDir,
+				},
+				containerdConfig: &config.Containerd{},
+			},
+			setup: func() error {
+				return os.Mkdir(filepath.Join(containerdConfigDir, "rdt_config.yaml"), 0700)
+			},
+			teardown: func() {
+				os.Remove(filepath.Join(containerdConfigDir, "rdt_config.yaml"))
+			},
+			want: &config.Containerd{},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tt.setup()
+			defer tt.teardown()
+
+			envInfo := tt.args.envInfo
+			containerdConfig := tt.args.containerdConfig
+			applyContainerdQoSClassConfigFileIfPresent(envInfo, containerdConfig)
+			if !reflect.DeepEqual(containerdConfig, tt.want) {
+				t.Errorf("applyContainerdQoSClassConfigFileIfPresent() = %+v\nWant %+v", containerdConfig, tt.want)
+			}
+		})
+	}
+}
diff --git a/pkg/agent/config/config_windows.go b/pkg/agent/config/config_windows.go
index 351d624efbaf..226ea7a01388 100644
--- a/pkg/agent/config/config_windows.go
+++ b/pkg/agent/config/config_windows.go
@@ -19,6 +19,6 @@ func applyCRIDockerdAddress(nodeConfig *config.Node) {
 	nodeConfig.CRIDockerd.Address = "npipe:////.pipe/cri-dockerd"
 }
 
-func applyContainerdQoSClassConfigFileIfPresent(envInfo *cmds.Agent, nodeConfig *config.Node) {
+func applyContainerdQoSClassConfigFileIfPresent(envInfo *cmds.Agent, containerdConfig *config.Containerd) {
 	// QoS-class resource management not supported on windows.
 }