shim: fix "deadlock avoided" errors for unmount

Currently, the sporadic "mount_nullfs: /path/to/rootfs: resource
deadlock avoided" error occurs during containerd shim task creation.
The exact reason for this error is unknown, but a mounter that
sorts and unmounts nested mountpoints seems to fix the problem.

This change replaces the containerd's mounter with `moby/sys/mount`

Fixes #30

Signed-off-by: Samuel Karp <me@samuelkarp.com>

containerd/shim.go

@@ -8,6 +8,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"strconv"
+	"strings"
 	"sync"
 	"syscall"
 	"time"
@@ -19,7 +20,6 @@ import (
 	tasktypes "github.com/containerd/containerd/api/types/task"
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/log"
-	"github.com/containerd/containerd/mount"
 	"github.com/containerd/containerd/namespaces"
 	"github.com/containerd/containerd/pkg/process"
 	"github.com/containerd/containerd/runtime"
@@ -31,6 +31,7 @@ import (
 	"github.com/containerd/typeurl"
 	"github.com/gogo/protobuf/types"
 	ptypes "github.com/gogo/protobuf/types"
+	"github.com/moby/sys/mount"
 	specs "github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
@@ -338,7 +339,7 @@ func (s *service) delete(ctx context.Context, bundlePath string) (*task.DeleteRe
 		log.G(ctx).WithError(err).Error("failed to run runj delete")
 		return nil, err
 	}
-	if err := mount.UnmountAll(filepath.Join(bundlePath, "rootfs"), 0); err != nil {
+	if err := mount.RecursiveUnmount(filepath.Join(bundlePath, "rootfs")); err != nil {
 		log.G(ctx).WithError(err).Warn("failed to cleanup rootfs mount")
 	}
 	return &taskAPI.DeleteResponse{
@@ -405,20 +406,15 @@ func (s *service) Create(ctx context.Context, req *task.CreateTaskRequest) (*tas
 	defer func() {
 		if err != nil {
 			log.G(ctx).WithField("rootfs", rootfs).WithError(err).Error("failed to create,unmounting rootfs")
-			if err2 := mount.UnmountAll(rootfs, 0); err2 != nil {
+			if err2 := mount.RecursiveUnmount(rootfs); err2 != nil {
 				log.G(ctx).WithError(err2).Warn("failed to cleanup rootfs mount")
 			}
 		}
 	}()
 	for _, rm := range mounts {
-		m := &mount.Mount{
-			Type:    rm.Type,
-			Source:  rm.Source,
-			Options: rm.Options,
-		}
-		log.G(ctx).WithField("mount", m).WithField("rootfs", rootfs).Warn("mount")
-		if err := m.Mount(rootfs); err != nil {
-			return nil, errors.Wrapf(err, "failed to mount rootfs component %v", m)
+		log.G(ctx).WithField("mount", rm).WithField("rootfs", rootfs).Warn("mount")
+		if err := mount.Mount(rm.Source, rootfs, rm.Type, strings.Join(rm.Options, ",")); err != nil {
+			return nil, errors.Wrapf(err, "failed to mount rootfs component %v", rm)
 		}
 	}
 

go.mod

@@ -11,13 +11,14 @@ require (
 	github.com/containerd/typeurl v1.0.2
 	github.com/gogo/protobuf v1.3.2
 	github.com/hashicorp/go-multierror v1.1.0 // indirect
+	github.com/moby/sys/mount v0.3.3
 	github.com/opencontainers/go-digest v1.0.0
 	github.com/opencontainers/image-spec v1.0.2
 	github.com/opencontainers/runtime-spec v1.0.3-0.20210326190908-1c3f411f0417
 	github.com/pkg/errors v0.9.1
 	github.com/sirupsen/logrus v1.8.1
 	github.com/spf13/cobra v1.0.0
 	github.com/stretchr/testify v1.7.0
-	golang.org/x/sys v0.0.0-20220412211240-33da011f77ad
+	golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a
 	google.golang.org/grpc v1.34.0 // indirect
 )

go.sum

@@ -434,9 +434,12 @@ github.com/mitchellh/go-homedir v1.1.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrk
 github.com/mitchellh/mapstructure v1.1.2/go.mod h1:FVVH3fgwuzCH5S8UJGiWEs2h04kUh9fWfEaFds41c1Y=
 github.com/mitchellh/osext v0.0.0-20151018003038-5e2d6d41470f/go.mod h1:OkQIRizQZAeMln+1tSwduZz7+Af5oFlKirV/MSYes2A=
 github.com/moby/locker v1.0.1/go.mod h1:S7SDdo5zpBK84bzzVlKr2V0hz+7x9hWbYC/kq7oQppc=
+github.com/moby/sys/mount v0.3.3 h1:fX1SVkXFJ47XWDoeFW4Sq7PdQJnV2QIDZAqjNqgEjUs=
+github.com/moby/sys/mount v0.3.3/go.mod h1:PBaEorSNTLG5t/+4EgukEQVlAvVEc6ZjTySwKdqp5K0=
 github.com/moby/sys/mountinfo v0.4.0/go.mod h1:rEr8tzG/lsIZHBtN/JjGG+LMYx9eXgW2JI+6q0qou+A=
-github.com/moby/sys/mountinfo v0.4.1 h1:1O+1cHA1aujwEwwVMa2Xm2l+gIpUHyd3+D+d7LZh1kM=
 github.com/moby/sys/mountinfo v0.4.1/go.mod h1:rEr8tzG/lsIZHBtN/JjGG+LMYx9eXgW2JI+6q0qou+A=
+github.com/moby/sys/mountinfo v0.6.2 h1:BzJjoreD5BMFNmD9Rus6gdd1pLuecOFPt8wC+Vygl78=
+github.com/moby/sys/mountinfo v0.6.2/go.mod h1:IJb6JQeOklcdMU9F5xQ8ZALD+CUr5VlGpwtX+VE0rpI=
 github.com/moby/sys/symlink v0.1.0/go.mod h1:GGDODQmbFOjFsXvfLVn3+ZRxkch54RkSiGqsZeMYowQ=
 github.com/moby/term v0.0.0-20200312100748-672ec06f55cd/go.mod h1:DdlQx2hp0Ss5/fLikoLlEeIYiATotOjgB//nb973jeo=
 github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
@@ -784,8 +787,9 @@ golang.org/x/sys v0.0.0-20210324051608-47abb6519492/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210426230700-d19ff857e887/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20220412211240-33da011f77ad h1:ntjMns5wyP/fN65tdBD4g8J5w8n015+iIIs9rtjXkY0=
 golang.org/x/sys v0.0.0-20220412211240-33da011f77ad/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a h1:dGzPydgVsqGcTRVwiLJ1jVbufYwmzD3LfVPLKsKg+0k=
+golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=