Merge pull request #1 from google/master

catch up

18 files changed, 219 insertions, 142 deletions

diff --git a/pkg/sentry/mm/BUILD b/pkg/sentry/mm/BUILD
index a804b8b5c..73591dab7 100644
--- a/pkg/sentry/mm/BUILD
+++ b/pkg/sentry/mm/BUILD
@@ -1,6 +1,5 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_test")
+load("//tools:defs.bzl", "go_library", "go_test")
 load("//tools/go_generics:defs.bzl", "go_template_instance")
-load("//tools/go_stateify:defs.bzl", "go_library")
 
 package(licenses = ["notice"])
 
@@ -28,7 +27,7 @@ go_template_instance(
         "minDegree": "8",
     },
     imports = {
-        "usermem": "gvisor.dev/gvisor/pkg/sentry/usermem",
+        "usermem": "gvisor.dev/gvisor/pkg/usermem",
     },
     package = "mm",
     prefix = "vma",
@@ -48,7 +47,7 @@ go_template_instance(
         "minDegree": "8",
     },
     imports = {
-        "usermem": "gvisor.dev/gvisor/pkg/sentry/usermem",
+        "usermem": "gvisor.dev/gvisor/pkg/usermem",
     },
     package = "mm",
     prefix = "pma",
@@ -96,17 +95,18 @@ go_library(
         "vma.go",
         "vma_set.go",
     ],
-    importpath = "gvisor.dev/gvisor/pkg/sentry/mm",
     visibility = ["//pkg/sentry:internal"],
     deps = [
         "//pkg/abi/linux",
         "//pkg/atomicbitops",
+        "//pkg/context",
         "//pkg/log",
         "//pkg/refs",
+        "//pkg/safecopy",
+        "//pkg/safemem",
         "//pkg/sentry/arch",
-        "//pkg/sentry/context",
-        "//pkg/sentry/fs",
         "//pkg/sentry/fs/proc/seqfile",
+        "//pkg/sentry/fsbridge",
         "//pkg/sentry/kernel/auth",
         "//pkg/sentry/kernel/futex",
         "//pkg/sentry/kernel/shm",
@@ -114,13 +114,11 @@ go_library(
         "//pkg/sentry/memmap",
         "//pkg/sentry/pgalloc",
         "//pkg/sentry/platform",
-        "//pkg/sentry/platform/safecopy",
-        "//pkg/sentry/safemem",
         "//pkg/sentry/usage",
-        "//pkg/sentry/usermem",
+        "//pkg/sync",
         "//pkg/syserror",
         "//pkg/tcpip/buffer",
-        "//third_party/gvsync",
+        "//pkg/usermem",
     ],
 )
 
@@ -128,16 +126,16 @@ go_test(
     name = "mm_test",
     size = "small",
     srcs = ["mm_test.go"],
-    embed = [":mm"],
+    library = ":mm",
     deps = [
+        "//pkg/context",
         "//pkg/sentry/arch",
-        "//pkg/sentry/context",
-        "//pkg/sentry/context/contexttest",
+        "//pkg/sentry/contexttest",
         "//pkg/sentry/limits",
         "//pkg/sentry/memmap",
         "//pkg/sentry/pgalloc",
         "//pkg/sentry/platform",
-        "//pkg/sentry/usermem",
         "//pkg/syserror",
+        "//pkg/usermem",
     ],
 )
diff --git a/pkg/sentry/mm/README.md b/pkg/sentry/mm/README.md
index e1322e373..f4d43d927 100644
--- a/pkg/sentry/mm/README.md
+++ b/pkg/sentry/mm/README.md
@@ -274,7 +274,7 @@ In the sentry:
     methods
     [`platform.AddressSpace.MapFile` and `platform.AddressSpace.Unmap`][platform].
 
-[memmap]: https://github.com/google/gvisor/blob/master/+/master/pkg/sentry/memmap/memmap.go
-[mm]: https://github.com/google/gvisor/blob/master/+/master/pkg/sentry/mm/mm.go
-[pgalloc]: https://github.com/google/gvisor/blob/master/+/master/pkg/sentry/pgalloc/pgalloc.go
-[platform]: https://github.com/google/gvisor/blob/master/+/master/pkg/sentry/platform/platform.go
+[memmap]: https://github.com/google/gvisor/blob/master/pkg/sentry/memmap/memmap.go
+[mm]: https://github.com/google/gvisor/blob/master/pkg/sentry/mm/mm.go
+[pgalloc]: https://github.com/google/gvisor/blob/master/pkg/sentry/pgalloc/pgalloc.go
+[platform]: https://github.com/google/gvisor/blob/master/pkg/sentry/platform/platform.go
diff --git a/pkg/sentry/mm/address_space.go b/pkg/sentry/mm/address_space.go
index cfebcfd42..5c667117c 100644
--- a/pkg/sentry/mm/address_space.go
+++ b/pkg/sentry/mm/address_space.go
@@ -18,9 +18,9 @@ import (
 	"fmt"
 	"sync/atomic"
 
-	"gvisor.dev/gvisor/pkg/atomicbitops"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/platform"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // AddressSpace returns the platform.AddressSpace bound to mm.
@@ -39,11 +39,18 @@ func (mm *MemoryManager) AddressSpace() platform.AddressSpace {
 //
 // When this MemoryManager is no longer needed by a task, it should call
 // Deactivate to release the reference.
-func (mm *MemoryManager) Activate() error {
+func (mm *MemoryManager) Activate(ctx context.Context) error {
 	// Fast path: the MemoryManager already has an active
 	// platform.AddressSpace, and we just need to indicate that we need it too.
-	if atomicbitops.IncUnlessZeroInt32(&mm.active) {
-		return nil
+	for {
+		active := atomic.LoadInt32(&mm.active)
+		if active == 0 {
+			// Fall back to the slow path.
+			break
+		}
+		if atomic.CompareAndSwapInt32(&mm.active, active, active+1) {
+			return nil
+		}
 	}
 
 	for {
@@ -85,16 +92,20 @@ func (mm *MemoryManager) Activate() error {
 		if as == nil {
 			// AddressSpace is unavailable, we must wait.
 			//
-			// activeMu must not be held while waiting, as the user
-			// of the address space we are waiting on may attempt
-			// to take activeMu.
-			//
-			// Don't call UninterruptibleSleepStart to register the
-			// wait to allow the watchdog stuck task to trigger in
-			// case a process is starved waiting for the address
-			// space.
+			// activeMu must not be held while waiting, as the user of the address
+			// space we are waiting on may attempt to take activeMu.
 			mm.activeMu.Unlock()
+
+			sleep := mm.p.CooperativelySchedulesAddressSpace() && mm.sleepForActivation
+			if sleep {
+				// Mark this task sleeping while waiting for the address space to
+				// prevent the watchdog from reporting it as a stuck task.
+				ctx.UninterruptibleSleepStart(false)
+			}
 			<-c
+			if sleep {
+				ctx.UninterruptibleSleepFinish(false)
+			}
 			continue
 		}
 
@@ -118,8 +129,15 @@ func (mm *MemoryManager) Activate() error {
 func (mm *MemoryManager) Deactivate() {
 	// Fast path: this is not the last goroutine to deactivate the
 	// MemoryManager.
-	if atomicbitops.DecUnlessOneInt32(&mm.active) {
-		return
+	for {
+		active := atomic.LoadInt32(&mm.active)
+		if active == 1 {
+			// Fall back to the slow path.
+			break
+		}
+		if atomic.CompareAndSwapInt32(&mm.active, active, active-1) {
+			return
+		}
 	}
 
 	mm.activeMu.Lock()
@@ -183,8 +201,10 @@ func (mm *MemoryManager) mapASLocked(pseg pmaIterator, ar usermem.AddrRange, pre
 		if pma.needCOW {
 			perms.Write = false
 		}
-		if err := mm.as.MapFile(pmaMapAR.Start, pma.file, pseg.fileRangeOf(pmaMapAR), perms, precommit); err != nil {
-			return err
+		if perms.Any() { // MapFile precondition
+			if err := mm.as.MapFile(pmaMapAR.Start, pma.file, pseg.fileRangeOf(pmaMapAR), perms, precommit); err != nil {
+				return err
+			}
 		}
 		pseg = pseg.NextSegment()
 	}
diff --git a/pkg/sentry/mm/aio_context.go b/pkg/sentry/mm/aio_context.go
index 1b746d030..379148903 100644
--- a/pkg/sentry/mm/aio_context.go
+++ b/pkg/sentry/mm/aio_context.go
@@ -15,17 +15,16 @@
 package mm
 
 import (
-	"sync"
-
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/refs"
-	"gvisor.dev/gvisor/pkg/sentry/context"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
 	"gvisor.dev/gvisor/pkg/sentry/platform"
 	"gvisor.dev/gvisor/pkg/sentry/usage"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // aioManager creates and manages asynchronous I/O contexts.
@@ -60,25 +59,27 @@ func (a *aioManager) newAIOContext(events uint32, id uint64) bool {
 	}
 
 	a.contexts[id] = &AIOContext{
-		done:           make(chan struct{}, 1),
+		requestReady:   make(chan struct{}, 1),
 		maxOutstanding: events,
 	}
 	return true
 }
 
-// destroyAIOContext destroys an asynchronous I/O context.
+// destroyAIOContext destroys an asynchronous I/O context. It doesn't wait for
+// for pending requests to complete. Returns the destroyed AIOContext so it can
+// be drained.
 //
-// False is returned if the context does not exist.
-func (a *aioManager) destroyAIOContext(id uint64) bool {
+// Nil is returned if the context does not exist.
+func (a *aioManager) destroyAIOContext(id uint64) *AIOContext {
 	a.mu.Lock()
 	defer a.mu.Unlock()
 	ctx, ok := a.contexts[id]
 	if !ok {
-		return false
+		return nil
 	}
 	delete(a.contexts, id)
 	ctx.destroy()
-	return true
+	return ctx
 }
 
 // lookupAIOContext looks up the given context.
@@ -103,8 +104,8 @@ type ioResult struct {
 //
 // +stateify savable
 type AIOContext struct {
-	// done is the notification channel used for all requests.
-	done chan struct{} `state:"nosave"`
+	// requestReady is the notification channel used for all requests.
+	requestReady chan struct{} `state:"nosave"`
 
 	// mu protects below.
 	mu sync.Mutex `state:"nosave"`
@@ -130,8 +131,14 @@ func (ctx *AIOContext) destroy() {
 	ctx.mu.Lock()
 	defer ctx.mu.Unlock()
 	ctx.dead = true
-	if ctx.outstanding == 0 {
-		close(ctx.done)
+	ctx.checkForDone()
+}
+
+// Preconditions: ctx.mu must be held by caller.
+func (ctx *AIOContext) checkForDone() {
+	if ctx.dead && ctx.outstanding == 0 {
+		close(ctx.requestReady)
+		ctx.requestReady = nil
 	}
 }
 
@@ -155,11 +162,12 @@ func (ctx *AIOContext) PopRequest() (interface{}, bool) {
 
 	// Is there anything ready?
 	if e := ctx.results.Front(); e != nil {
-		ctx.results.Remove(e)
-		ctx.outstanding--
-		if ctx.outstanding == 0 && ctx.dead {
-			close(ctx.done)
+		if ctx.outstanding == 0 {
+			panic("AIOContext outstanding is going negative")
 		}
+		ctx.outstanding--
+		ctx.results.Remove(e)
+		ctx.checkForDone()
 		return e.data, true
 	}
 	return nil, false
@@ -173,26 +181,58 @@ func (ctx *AIOContext) FinishRequest(data interface{}) {
 
 	// Push to the list and notify opportunistically. The channel notify
 	// here is guaranteed to be safe because outstanding must be non-zero.
-	// The done channel is only closed when outstanding reaches zero.
+	// The requestReady channel is only closed when outstanding reaches zero.
 	ctx.results.PushBack(&ioResult{data: data})
 
 	select {
-	case ctx.done <- struct{}{}:
+	case ctx.requestReady <- struct{}{}:
 	default:
 	}
 }
 
 // WaitChannel returns a channel that is notified when an AIO request is
-// completed.
-//
-// The boolean return value indicates whether or not the context is active.
-func (ctx *AIOContext) WaitChannel() (chan struct{}, bool) {
+// completed. Returns nil if the context is destroyed and there are no more
+// outstanding requests.
+func (ctx *AIOContext) WaitChannel() chan struct{} {
 	ctx.mu.Lock()
 	defer ctx.mu.Unlock()
-	if ctx.outstanding == 0 && ctx.dead {
-		return nil, false
+	return ctx.requestReady
+}
+
+// Dead returns true if the context has been destroyed.
+func (ctx *AIOContext) Dead() bool {
+	ctx.mu.Lock()
+	defer ctx.mu.Unlock()
+	return ctx.dead
+}
+
+// CancelPendingRequest forgets about a request that hasn't yet completed.
+func (ctx *AIOContext) CancelPendingRequest() {
+	ctx.mu.Lock()
+	defer ctx.mu.Unlock()
+
+	if ctx.outstanding == 0 {
+		panic("AIOContext outstanding is going negative")
 	}
-	return ctx.done, true
+	ctx.outstanding--
+	ctx.checkForDone()
+}
+
+// Drain drops all completed requests. Pending requests remain untouched.
+func (ctx *AIOContext) Drain() {
+	ctx.mu.Lock()
+	defer ctx.mu.Unlock()
+
+	if ctx.outstanding == 0 {
+		return
+	}
+	size := uint32(ctx.results.Len())
+	if ctx.outstanding < size {
+		panic("AIOContext outstanding is going negative")
+	}
+	ctx.outstanding -= size
+	ctx.results.Reset()
+	ctx.checkForDone()
 }
 
 // aioMappable implements memmap.MappingIdentity and memmap.Mappable for AIO
@@ -333,9 +373,9 @@ func (mm *MemoryManager) NewAIOContext(ctx context.Context, events uint32) (uint
 		Length:          aioRingBufferSize,
 		MappingIdentity: m,
 		Mappable:        m,
-		// TODO(fvoznika): Linux does "do_mmap_pgoff(..., PROT_READ |
-		// PROT_WRITE, ...)" in fs/aio.c:aio_setup_ring(); why do we make this
-		// mapping read-only?
+		// Linux uses "do_mmap_pgoff(..., PROT_READ | PROT_WRITE, ...)" in
+		// fs/aio.c:aio_setup_ring(). Since we don't implement AIO_RING_MAGIC,
+		// user mode should not write to this page.
 		Perms:    usermem.Read,
 		MaxPerms: usermem.Read,
 	})
@@ -350,11 +390,11 @@ func (mm *MemoryManager) NewAIOContext(ctx context.Context, events uint32) (uint
 	return id, nil
 }
 
-// DestroyAIOContext destroys an asynchronous I/O context. It returns false if
-// the context does not exist.
-func (mm *MemoryManager) DestroyAIOContext(ctx context.Context, id uint64) bool {
+// DestroyAIOContext destroys an asynchronous I/O context. It returns the
+// destroyed context. nil if the context does not exist.
+func (mm *MemoryManager) DestroyAIOContext(ctx context.Context, id uint64) *AIOContext {
 	if _, ok := mm.LookupAIOContext(ctx, id); !ok {
-		return false
+		return nil
 	}
 
 	// Only unmaps after it assured that the address is a valid aio context to
diff --git a/pkg/sentry/mm/aio_context_state.go b/pkg/sentry/mm/aio_context_state.go
index c37fc9f7b..3dabac1af 100644
--- a/pkg/sentry/mm/aio_context_state.go
+++ b/pkg/sentry/mm/aio_context_state.go
@@ -16,5 +16,5 @@ package mm
 
 // afterLoad is invoked by stateify.
 func (a *AIOContext) afterLoad() {
-	a.done = make(chan struct{}, 1)
+	a.requestReady = make(chan struct{}, 1)
 }
diff --git a/pkg/sentry/mm/debug.go b/pkg/sentry/mm/debug.go
index df9adf708..c273c982e 100644
--- a/pkg/sentry/mm/debug.go
+++ b/pkg/sentry/mm/debug.go
@@ -18,7 +18,7 @@ import (
 	"bytes"
 	"fmt"
 
-	"gvisor.dev/gvisor/pkg/sentry/context"
+	"gvisor.dev/gvisor/pkg/context"
 )
 
 const (
diff --git a/pkg/sentry/mm/io.go b/pkg/sentry/mm/io.go
index b03e7d020..fa776f9c6 100644
--- a/pkg/sentry/mm/io.go
+++ b/pkg/sentry/mm/io.go
@@ -15,11 +15,11 @@
 package mm
 
 import (
-	"gvisor.dev/gvisor/pkg/sentry/context"
+	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/safemem"
 	"gvisor.dev/gvisor/pkg/sentry/platform"
-	"gvisor.dev/gvisor/pkg/sentry/safemem"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // There are two supported ways to copy data to/from application virtual
diff --git a/pkg/sentry/mm/lifecycle.go b/pkg/sentry/mm/lifecycle.go
index 4e9ca1de6..aac56679b 100644
--- a/pkg/sentry/mm/lifecycle.go
+++ b/pkg/sentry/mm/lifecycle.go
@@ -18,27 +18,27 @@ import (
 	"fmt"
 	"sync/atomic"
 
-	"gvisor.dev/gvisor/pkg/atomicbitops"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/context"
 	"gvisor.dev/gvisor/pkg/sentry/limits"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
 	"gvisor.dev/gvisor/pkg/sentry/platform"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // NewMemoryManager returns a new MemoryManager with no mappings and 1 user.
-func NewMemoryManager(p platform.Platform, mfp pgalloc.MemoryFileProvider) *MemoryManager {
+func NewMemoryManager(p platform.Platform, mfp pgalloc.MemoryFileProvider, sleepForActivation bool) *MemoryManager {
 	return &MemoryManager{
-		p:           p,
-		mfp:         mfp,
-		haveASIO:    p.SupportsAddressSpaceIO(),
-		privateRefs: &privateRefs{},
-		users:       1,
-		auxv:        arch.Auxv{},
-		dumpability: UserDumpable,
-		aioManager:  aioManager{contexts: make(map[uint64]*AIOContext)},
+		p:                  p,
+		mfp:                mfp,
+		haveASIO:           p.SupportsAddressSpaceIO(),
+		privateRefs:        &privateRefs{},
+		users:              1,
+		auxv:               arch.Auxv{},
+		dumpability:        UserDumpable,
+		aioManager:         aioManager{contexts: make(map[uint64]*AIOContext)},
+		sleepForActivation: sleepForActivation,
 	}
 }
 
@@ -80,9 +80,11 @@ func (mm *MemoryManager) Fork(ctx context.Context) (*MemoryManager, error) {
 		envv:                 mm.envv,
 		auxv:                 append(arch.Auxv(nil), mm.auxv...),
 		// IncRef'd below, once we know that there isn't an error.
-		executable:  mm.executable,
-		dumpability: mm.dumpability,
-		aioManager:  aioManager{contexts: make(map[uint64]*AIOContext)},
+		executable:         mm.executable,
+		dumpability:        mm.dumpability,
+		aioManager:         aioManager{contexts: make(map[uint64]*AIOContext)},
+		sleepForActivation: mm.sleepForActivation,
+		vdsoSigReturnAddr:  mm.vdsoSigReturnAddr,
 	}
 
 	// Copy vmas.
@@ -229,7 +231,15 @@ func (mm *MemoryManager) Fork(ctx context.Context) (*MemoryManager, error) {
 // IncUsers increments mm's user count and returns true. If the user count is
 // already 0, IncUsers does nothing and returns false.
 func (mm *MemoryManager) IncUsers() bool {
-	return atomicbitops.IncUnlessZeroInt32(&mm.users)
+	for {
+		users := atomic.LoadInt32(&mm.users)
+		if users == 0 {
+			return false
+		}
+		if atomic.CompareAndSwapInt32(&mm.users, users, users+1) {
+			return true
+		}
+	}
 }
 
 // DecUsers decrements mm's user count. If the user count reaches 0, all
diff --git a/pkg/sentry/mm/metadata.go b/pkg/sentry/mm/metadata.go
index d2a01d48a..28e5057f7 100644
--- a/pkg/sentry/mm/metadata.go
+++ b/pkg/sentry/mm/metadata.go
@@ -16,8 +16,8 @@ package mm
 
 import (
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/fs"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/sentry/fsbridge"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // Dumpability describes if and how core dumps should be created.
@@ -132,7 +132,7 @@ func (mm *MemoryManager) SetAuxv(auxv arch.Auxv) {
 //
 // An additional reference will be taken in the case of a non-nil executable,
 // which must be released by the caller.
-func (mm *MemoryManager) Executable() *fs.Dirent {
+func (mm *MemoryManager) Executable() fsbridge.File {
 	mm.metadataMu.Lock()
 	defer mm.metadataMu.Unlock()
 
@@ -147,15 +147,15 @@ func (mm *MemoryManager) Executable() *fs.Dirent {
 // SetExecutable sets the executable.
 //
 // This takes a reference on d.
-func (mm *MemoryManager) SetExecutable(d *fs.Dirent) {
+func (mm *MemoryManager) SetExecutable(file fsbridge.File) {
 	mm.metadataMu.Lock()
 
 	// Grab a new reference.
-	d.IncRef()
+	file.IncRef()
 
 	// Set the executable.
 	orig := mm.executable
-	mm.executable = d
+	mm.executable = file
 
 	mm.metadataMu.Unlock()
 
@@ -167,3 +167,17 @@ func (mm *MemoryManager) SetExecutable(d *fs.Dirent) {
 		orig.DecRef()
 	}
 }
+
+// VDSOSigReturn returns the address of vdso_sigreturn.
+func (mm *MemoryManager) VDSOSigReturn() uint64 {
+	mm.metadataMu.Lock()
+	defer mm.metadataMu.Unlock()
+	return mm.vdsoSigReturnAddr
+}
+
+// SetVDSOSigReturn sets the address of vdso_sigreturn.
+func (mm *MemoryManager) SetVDSOSigReturn(addr uint64) {
+	mm.metadataMu.Lock()
+	defer mm.metadataMu.Unlock()
+	mm.vdsoSigReturnAddr = addr
+}
diff --git a/pkg/sentry/mm/mm.go b/pkg/sentry/mm/mm.go
index f350e0109..6db7c3d40 100644
--- a/pkg/sentry/mm/mm.go
+++ b/pkg/sentry/mm/mm.go
@@ -35,16 +35,15 @@
 package mm
 
 import (
-	"sync"
-
+	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/safemem"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/fs"
+	"gvisor.dev/gvisor/pkg/sentry/fsbridge"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
 	"gvisor.dev/gvisor/pkg/sentry/platform"
-	"gvisor.dev/gvisor/pkg/sentry/safemem"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
-	"gvisor.dev/gvisor/third_party/gvsync"
+	"gvisor.dev/gvisor/pkg/sync"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // MemoryManager implements a virtual address space.
@@ -82,7 +81,7 @@ type MemoryManager struct {
 	users int32
 
 	// mappingMu is analogous to Linux's struct mm_struct::mmap_sem.
-	mappingMu gvsync.DowngradableRWMutex `state:"nosave"`
+	mappingMu sync.RWMutex `state:"nosave"`
 
 	// vmas stores virtual memory areas. Since vmas are stored by value,
 	// clients should usually use vmaIterator.ValuePtr() instead of
@@ -125,7 +124,7 @@ type MemoryManager struct {
 
 	// activeMu is loosely analogous to Linux's struct
 	// mm_struct::page_table_lock.
-	activeMu gvsync.DowngradableRWMutex `state:"nosave"`
+	activeMu sync.RWMutex `state:"nosave"`
 
 	// pmas stores platform mapping areas used to implement vmas. Since pmas
 	// are stored by value, clients should usually use pmaIterator.ValuePtr()
@@ -217,7 +216,7 @@ type MemoryManager struct {
 	// is not nil, it holds a reference on the Dirent.
 	//
 	// executable is protected by metadataMu.
-	executable *fs.Dirent
+	executable fsbridge.File
 
 	// dumpability describes if and how this MemoryManager may be dumped to
 	// userspace.
@@ -228,6 +227,14 @@ type MemoryManager struct {
 	// aioManager keeps track of AIOContexts used for async IOs. AIOManager
 	// must be cloned when CLONE_VM is used.
 	aioManager aioManager
+
+	// sleepForActivation indicates whether the task should report to be sleeping
+	// before trying to activate the address space. When set to true, delays in
+	// activation are not reported as stuck tasks by the watchdog.
+	sleepForActivation bool
+
+	// vdsoSigReturnAddr is the address of 'vdso_sigreturn'.
+	vdsoSigReturnAddr uint64
 }
 
 // vma represents a virtual memory area.
@@ -280,7 +287,7 @@ type vma struct {
 	mlockMode memmap.MLockMode
 
 	// numaPolicy is the NUMA policy for this vma set by mbind().
-	numaPolicy int32
+	numaPolicy linux.NumaPolicy
 
 	// numaNodemask is the NUMA nodemask for this vma set by mbind().
 	numaNodemask uint64
diff --git a/pkg/sentry/mm/mm_test.go b/pkg/sentry/mm/mm_test.go
index 4d2bfaaed..fdc308542 100644
--- a/pkg/sentry/mm/mm_test.go
+++ b/pkg/sentry/mm/mm_test.go
@@ -17,21 +17,21 @@ package mm
 import (
 	"testing"
 
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/context"
-	"gvisor.dev/gvisor/pkg/sentry/context/contexttest"
+	"gvisor.dev/gvisor/pkg/sentry/contexttest"
 	"gvisor.dev/gvisor/pkg/sentry/limits"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
 	"gvisor.dev/gvisor/pkg/sentry/platform"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 func testMemoryManager(ctx context.Context) *MemoryManager {
 	p := platform.FromContext(ctx)
 	mfp := pgalloc.MemoryFileProviderFromContext(ctx)
-	mm := NewMemoryManager(p, mfp)
+	mm := NewMemoryManager(p, mfp, false)
 	mm.layout = arch.MmapLayout{
 		MinAddr:      p.MinUserAddress(),
 		MaxAddr:      p.MaxUserAddress(),
diff --git a/pkg/sentry/mm/pma.go b/pkg/sentry/mm/pma.go
index c976c6f45..62e4c20af 100644
--- a/pkg/sentry/mm/pma.go
+++ b/pkg/sentry/mm/pma.go
@@ -17,14 +17,14 @@ package mm
 import (
 	"fmt"
 
-	"gvisor.dev/gvisor/pkg/sentry/context"
+	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/safecopy"
+	"gvisor.dev/gvisor/pkg/safemem"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/platform"
-	"gvisor.dev/gvisor/pkg/sentry/platform/safecopy"
-	"gvisor.dev/gvisor/pkg/sentry/safemem"
 	"gvisor.dev/gvisor/pkg/sentry/usage"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // existingPMAsLocked checks that pmas exist for all addresses in ar, and
diff --git a/pkg/sentry/mm/procfs.go b/pkg/sentry/mm/procfs.go
index 8c2246bb4..6efe5102b 100644
--- a/pkg/sentry/mm/procfs.go
+++ b/pkg/sentry/mm/procfs.go
@@ -19,10 +19,10 @@ import (
 	"fmt"
 	"strings"
 
-	"gvisor.dev/gvisor/pkg/sentry/context"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/fs/proc/seqfile"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 const (
@@ -66,8 +66,6 @@ func (mm *MemoryManager) ReadMapsDataInto(ctx context.Context, buf *bytes.Buffer
 	var start usermem.Addr
 
 	for vseg := mm.vmas.LowerBoundSegment(start); vseg.Ok(); vseg = vseg.NextSegment() {
-		// FIXME(b/30793614): If we use a usermem.Addr for the handle, we get
-		// "panic: autosave error: type usermem.Addr is not registered".
 		mm.appendVMAMapsEntryLocked(ctx, vseg, buf)
 	}
 
@@ -81,7 +79,6 @@ func (mm *MemoryManager) ReadMapsDataInto(ctx context.Context, buf *bytes.Buffer
 	//
 	// Artifically adjust the seqfile handle so we only output vsyscall entry once.
 	if start != vsyscallEnd {
-		// FIXME(b/30793614): Can't get a pointer to constant vsyscallEnd.
 		buf.WriteString(vsyscallMapsEntry)
 	}
 }
@@ -97,8 +94,6 @@ func (mm *MemoryManager) ReadMapsSeqFileData(ctx context.Context, handle seqfile
 		start = *handle.(*usermem.Addr)
 	}
 	for vseg := mm.vmas.LowerBoundSegment(start); vseg.Ok(); vseg = vseg.NextSegment() {
-		// FIXME(b/30793614): If we use a usermem.Addr for the handle, we get
-		// "panic: autosave error: type usermem.Addr is not registered".
 		vmaAddr := vseg.End()
 		data = append(data, seqfile.SeqData{
 			Buf:    mm.vmaMapsEntryLocked(ctx, vseg),
@@ -116,7 +111,6 @@ func (mm *MemoryManager) ReadMapsSeqFileData(ctx context.Context, handle seqfile
 	//
 	// Artifically adjust the seqfile handle so we only output vsyscall entry once.
 	if start != vsyscallEnd {
-		// FIXME(b/30793614): Can't get a pointer to constant vsyscallEnd.
 		vmaAddr := vsyscallEnd
 		data = append(data, seqfile.SeqData{
 			Buf:    []byte(vsyscallMapsEntry),
@@ -154,7 +148,7 @@ func (mm *MemoryManager) appendVMAMapsEntryLocked(ctx context.Context, vseg vmaI
 
 	// Do not include the guard page: fs/proc/task_mmu.c:show_map_vma() =>
 	// stack_guard_page_start().
-	fmt.Fprintf(b, "%08x-%08x %s%s %08x %02x:%02x %d ",
+	lineLen, _ := fmt.Fprintf(b, "%08x-%08x %s%s %08x %02x:%02x %d ",
 		vseg.Start(), vseg.End(), vma.realPerms, private, vma.off, devMajor, devMinor, ino)
 
 	// Figure out our filename or hint.
@@ -171,7 +165,7 @@ func (mm *MemoryManager) appendVMAMapsEntryLocked(ctx context.Context, vseg vmaI
 	}
 	if s != "" {
 		// Per linux, we pad until the 74th character.
-		if pad := 73 - b.Len(); pad > 0 {
+		if pad := 73 - lineLen; pad > 0 {
 			b.WriteString(strings.Repeat(" ", pad))
 		}
 		b.WriteString(s)
@@ -187,15 +181,12 @@ func (mm *MemoryManager) ReadSmapsDataInto(ctx context.Context, buf *bytes.Buffe
 	var start usermem.Addr
 
 	for vseg := mm.vmas.LowerBoundSegment(start); vseg.Ok(); vseg = vseg.NextSegment() {
-		// FIXME(b/30793614): If we use a usermem.Addr for the handle, we get
-		// "panic: autosave error: type usermem.Addr is not registered".
 		mm.vmaSmapsEntryIntoLocked(ctx, vseg, buf)
 	}
 
 	// We always emulate vsyscall, so advertise it here. See
 	// ReadMapsSeqFileData for additional commentary.
 	if start != vsyscallEnd {
-		// FIXME(b/30793614): Can't get a pointer to constant vsyscallEnd.
 		buf.WriteString(vsyscallSmapsEntry)
 	}
 }
@@ -211,8 +202,6 @@ func (mm *MemoryManager) ReadSmapsSeqFileData(ctx context.Context, handle seqfil
 		start = *handle.(*usermem.Addr)
 	}
 	for vseg := mm.vmas.LowerBoundSegment(start); vseg.Ok(); vseg = vseg.NextSegment() {
-		// FIXME(b/30793614): If we use a usermem.Addr for the handle, we get
-		// "panic: autosave error: type usermem.Addr is not registered".
 		vmaAddr := vseg.End()
 		data = append(data, seqfile.SeqData{
 			Buf:    mm.vmaSmapsEntryLocked(ctx, vseg),
@@ -223,7 +212,6 @@ func (mm *MemoryManager) ReadSmapsSeqFileData(ctx context.Context, handle seqfil
 	// We always emulate vsyscall, so advertise it here. See
 	// ReadMapsSeqFileData for additional commentary.
 	if start != vsyscallEnd {
-		// FIXME(b/30793614): Can't get a pointer to constant vsyscallEnd.
 		vmaAddr := vsyscallEnd
 		data = append(data, seqfile.SeqData{
 			Buf:    []byte(vsyscallSmapsEntry),
diff --git a/pkg/sentry/mm/save_restore.go b/pkg/sentry/mm/save_restore.go
index 93259c5a3..f56215d9a 100644
--- a/pkg/sentry/mm/save_restore.go
+++ b/pkg/sentry/mm/save_restore.go
@@ -17,7 +17,7 @@ package mm
 import (
 	"fmt"
 
-	"gvisor.dev/gvisor/pkg/sentry/context"
+	"gvisor.dev/gvisor/pkg/context"
 )
 
 // InvalidateUnsavable invokes memmap.Mappable.InvalidateUnsavable on all
diff --git a/pkg/sentry/mm/shm.go b/pkg/sentry/mm/shm.go
index b9f2d23e5..6432731d4 100644
--- a/pkg/sentry/mm/shm.go
+++ b/pkg/sentry/mm/shm.go
@@ -15,10 +15,10 @@
 package mm
 
 import (
-	"gvisor.dev/gvisor/pkg/sentry/context"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/shm"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // DetachShm unmaps a sysv shared memory segment.
diff --git a/pkg/sentry/mm/special_mappable.go b/pkg/sentry/mm/special_mappable.go
index ea2d7af74..9ad52082d 100644
--- a/pkg/sentry/mm/special_mappable.go
+++ b/pkg/sentry/mm/special_mappable.go
@@ -15,14 +15,14 @@
 package mm
 
 import (
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/refs"
-	"gvisor.dev/gvisor/pkg/sentry/context"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
 	"gvisor.dev/gvisor/pkg/sentry/platform"
 	"gvisor.dev/gvisor/pkg/sentry/usage"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // SpecialMappable implements memmap.MappingIdentity and memmap.Mappable with
diff --git a/pkg/sentry/mm/syscalls.go b/pkg/sentry/mm/syscalls.go
index c2466c988..3f496aa9f 100644
--- a/pkg/sentry/mm/syscalls.go
+++ b/pkg/sentry/mm/syscalls.go
@@ -19,14 +19,14 @@ import (
 	mrand "math/rand"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
-	"gvisor.dev/gvisor/pkg/sentry/context"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/futex"
 	"gvisor.dev/gvisor/pkg/sentry/limits"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
 	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // HandleUserFault handles an application page fault. sp is the faulting
@@ -974,7 +974,7 @@ func (mm *MemoryManager) MLockAll(ctx context.Context, opts MLockAllOpts) error
 }
 
 // NumaPolicy implements the semantics of Linux's get_mempolicy(MPOL_F_ADDR).
-func (mm *MemoryManager) NumaPolicy(addr usermem.Addr) (int32, uint64, error) {
+func (mm *MemoryManager) NumaPolicy(addr usermem.Addr) (linux.NumaPolicy, uint64, error) {
 	mm.mappingMu.RLock()
 	defer mm.mappingMu.RUnlock()
 	vseg := mm.vmas.FindSegment(addr)
@@ -986,7 +986,7 @@ func (mm *MemoryManager) NumaPolicy(addr usermem.Addr) (int32, uint64, error) {
 }
 
 // SetNumaPolicy implements the semantics of Linux's mbind().
-func (mm *MemoryManager) SetNumaPolicy(addr usermem.Addr, length uint64, policy int32, nodemask uint64) error {
+func (mm *MemoryManager) SetNumaPolicy(addr usermem.Addr, length uint64, policy linux.NumaPolicy, nodemask uint64) error {
 	if !addr.IsPageAligned() {
 		return syserror.EINVAL
 	}
diff --git a/pkg/sentry/mm/vma.go b/pkg/sentry/mm/vma.go
index f2fd70799..9a14e69e6 100644
--- a/pkg/sentry/mm/vma.go
+++ b/pkg/sentry/mm/vma.go
@@ -18,13 +18,13 @@ import (
 	"fmt"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
-	"gvisor.dev/gvisor/pkg/sentry/context"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/limits"
 	"gvisor.dev/gvisor/pkg/sentry/memmap"
-	"gvisor.dev/gvisor/pkg/sentry/usermem"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // Preconditions: mm.mappingMu must be locked for writing. opts must be valid