8 files changed, 6 insertions, 56 deletions
diff --git a/pkg/sentry/kernel/BUILD b/pkg/sentry/kernel/BUILD
index c0f13bf52..53a21e1e2 100644
--- a/pkg/sentry/kernel/BUILD
+++ b/pkg/sentry/kernel/BUILD
@@ -255,7 +255,6 @@ go_library(
         "//pkg/sentry/hostcpu",
         "//pkg/sentry/inet",
         "//pkg/sentry/kernel/auth",
-        "//pkg/sentry/kernel/epoll",
         "//pkg/sentry/kernel/futex",
         "//pkg/sentry/kernel/msgqueue",
         "//pkg/sentry/kernel/sched",
diff --git a/pkg/sentry/kernel/epoll/epoll.go b/pkg/sentry/kernel/epoll/epoll.go
index 6006c46a9..8d0a21baf 100644
--- a/pkg/sentry/kernel/epoll/epoll.go
+++ b/pkg/sentry/kernel/epoll/epoll.go
@@ -66,7 +66,7 @@ type pollEntry struct {
 	file     *refs.WeakRef  `state:"manual"`
 	id       FileIdentifier `state:"wait"`
 	userData [2]int32
-	waiter   waiter.Entry `state:"manual"`
+	waiter   waiter.Entry
 	mask     waiter.EventMask
 	flags    EntryFlags
 
@@ -102,7 +102,7 @@ type EventPoll struct {
 
 	// Wait queue is used to notify interested parties when the event poll
 	// object itself becomes readable or writable.
-	waiter.Queue `state:"zerovalue"`
+	waiter.Queue
 
 	// files is the map of all the files currently being observed, it is
 	// protected by mu.
@@ -454,14 +454,3 @@ func (e *EventPoll) RemoveEntry(ctx context.Context, id FileIdentifier) error {
 
 	return nil
 }
-
-// UnregisterEpollWaiters removes the epoll waiter objects from the waiting
-// queues. This is different from Release() as the file is not dereferenced.
-func (e *EventPoll) UnregisterEpollWaiters() {
-	e.mu.Lock()
-	defer e.mu.Unlock()
-
-	for _, entry := range e.files {
-		entry.id.File.EventUnregister(&entry.waiter)
-	}
-}
diff --git a/pkg/sentry/kernel/epoll/epoll_state.go b/pkg/sentry/kernel/epoll/epoll_state.go
index e08d6287f..135a6d72c 100644
--- a/pkg/sentry/kernel/epoll/epoll_state.go
+++ b/pkg/sentry/kernel/epoll/epoll_state.go
@@ -21,9 +21,7 @@ import (
 
 // afterLoad is invoked by stateify.
 func (p *pollEntry) afterLoad() {
-	p.waiter.Callback = p
 	p.file = refs.NewWeakRef(p.id.File, p)
-	p.id.File.EventRegister(&p.waiter, p.mask)
 }
 
 // afterLoad is invoked by stateify.
diff --git a/pkg/sentry/kernel/eventfd/eventfd.go b/pkg/sentry/kernel/eventfd/eventfd.go
index 5ea44a2c2..bf625dede 100644
--- a/pkg/sentry/kernel/eventfd/eventfd.go
+++ b/pkg/sentry/kernel/eventfd/eventfd.go
@@ -54,7 +54,7 @@ type EventOperations struct {
 
 	// Queue is used to notify interested parties when the event object
 	// becomes readable or writable.
-	wq waiter.Queue `state:"zerovalue"`
+	wq waiter.Queue
 
 	// val is the current value of the event counter.
 	val uint64
diff --git a/pkg/sentry/kernel/kernel.go b/pkg/sentry/kernel/kernel.go
index f913d25db..5dc821a48 100644
--- a/pkg/sentry/kernel/kernel.go
+++ b/pkg/sentry/kernel/kernel.go
@@ -57,7 +57,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/hostcpu"
 	"gvisor.dev/gvisor/pkg/sentry/inet"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
-	"gvisor.dev/gvisor/pkg/sentry/kernel/epoll"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/futex"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/sched"
 	ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
@@ -486,11 +485,6 @@ func (k *Kernel) SaveTo(ctx context.Context, w wire.Writer) error {
 			return err
 		}
 
-		// Remove all epoll waiter objects from underlying wait queues.
-		// NOTE: for programs to resume execution in future snapshot scenarios,
-		// we will need to re-establish these waiter objects after saving.
-		k.tasks.unregisterEpollWaiters(ctx)
-
 		// Clear the dirent cache before saving because Dirents must be Loaded in a
 		// particular order (parents before children), and Loading dirents from a cache
 		// breaks that order.
@@ -623,32 +617,6 @@ func (k *Kernel) flushWritesToFiles(ctx context.Context) error {
 	})
 }
 
-// Preconditions: !VFS2Enabled.
-func (ts *TaskSet) unregisterEpollWaiters(ctx context.Context) {
-	ts.mu.RLock()
-	defer ts.mu.RUnlock()
-
-	// Tasks that belong to the same process could potentially point to the
-	// same FDTable. So we retain a map of processed ones to avoid
-	// processing the same FDTable multiple times.
-	processed := make(map[*FDTable]struct{})
-	for t := range ts.Root.tids {
-		// We can skip locking Task.mu here since the kernel is paused.
-		if t.fdTable == nil {
-			continue
-		}
-		if _, ok := processed[t.fdTable]; ok {
-			continue
-		}
-		t.fdTable.forEach(ctx, func(_ int32, file *fs.File, _ *vfs.FileDescription, _ FDFlags) {
-			if e, ok := file.FileOperations.(*epoll.EventPoll); ok {
-				e.UnregisterEpollWaiters()
-			}
-		})
-		processed[t.fdTable] = struct{}{}
-	}
-}
-
 // Preconditions: The kernel must be paused.
 func (k *Kernel) invalidateUnsavableMappings(ctx context.Context) error {
 	invalidated := make(map[*mm.MemoryManager]struct{})
diff --git a/pkg/sentry/kernel/pipe/pipe.go b/pkg/sentry/kernel/pipe/pipe.go
index 86beee6fe..8345473f3 100644
--- a/pkg/sentry/kernel/pipe/pipe.go
+++ b/pkg/sentry/kernel/pipe/pipe.go
@@ -55,7 +55,7 @@ const (
 //
 // +stateify savable
 type Pipe struct {
-	waiter.Queue `state:"nosave"`
+	waiter.Queue
 
 	// isNamed indicates whether this is a named pipe.
 	//
diff --git a/pkg/sentry/kernel/task.go b/pkg/sentry/kernel/task.go
index b0004482c..1ea3c1bf7 100644
--- a/pkg/sentry/kernel/task.go
+++ b/pkg/sentry/kernel/task.go
@@ -158,7 +158,7 @@ type Task struct {
 	// signalQueue is protected by the signalMutex. Note that the task does
 	// not implement all queue methods, specifically the readiness checks.
 	// The task only broadcast a notification on signal delivery.
-	signalQueue waiter.Queue `state:"zerovalue"`
+	signalQueue waiter.Queue
 
 	// If groupStopPending is true, the task should participate in a group
 	// stop in the interrupt path.
diff --git a/pkg/sentry/kernel/threads.go b/pkg/sentry/kernel/threads.go
index 77ad62445..e38b723ce 100644
--- a/pkg/sentry/kernel/threads.go
+++ b/pkg/sentry/kernel/threads.go
@@ -324,11 +324,7 @@ type threadGroupNode struct {
 	// eventQueue is notified whenever a event of interest to Task.Wait occurs
 	// in a child of this thread group, or a ptrace tracee of a task in this
 	// thread group. Events are defined in task_exit.go.
-	//
-	// Note that we cannot check and save this wait queue similarly to other
-	// wait queues, as the queue will not be empty by the time of saving, due
-	// to the wait sourced from Exec().
-	eventQueue waiter.Queue `state:"nosave"`
+	eventQueue waiter.Queue
 
 	// leader is the thread group's leader, which is the oldest task in the
 	// thread group; usually the last task in the thread group to call