Decouple filemem from platform and move it to pgalloc.MemoryFile.

This is in preparation for improved page cache reclaim, which requires
greater integration between the page cache and page allocator.

PiperOrigin-RevId: 238444706
Change-Id: Id24141b3678d96c7d7dc24baddd9be555bffafe4

4 files changed, 35 insertions, 4 deletions

diff --git a/runsc/boot/BUILD b/runsc/boot/BUILD
index daa197437..df9907e52 100644
--- a/runsc/boot/BUILD
+++ b/runsc/boot/BUILD
@@ -51,6 +51,8 @@ go_library(
         "//pkg/sentry/kernel/kdefs",
         "//pkg/sentry/limits",
         "//pkg/sentry/loader",
+        "//pkg/sentry/memutil",
+        "//pkg/sentry/pgalloc",
         "//pkg/sentry/platform",
         "//pkg/sentry/platform/kvm",
         "//pkg/sentry/platform/ptrace",
diff --git a/runsc/boot/controller.go b/runsc/boot/controller.go
index a864be720..14e1eba5b 100644
--- a/runsc/boot/controller.go
+++ b/runsc/boot/controller.go
@@ -332,6 +332,11 @@ func (cm *containerManager) Restore(o *RestoreOpts, _ *struct{}) error {
 	k := &kernel.Kernel{
 		Platform: p,
 	}
+	mf, err := createMemoryFile()
+	if err != nil {
+		return fmt.Errorf("creating memory file: %v", err)
+	}
+	k.SetMemoryFile(mf)
 	cm.l.k = k
 
 	// Set up the restore environment.
@@ -362,7 +367,7 @@ func (cm *containerManager) Restore(o *RestoreOpts, _ *struct{}) error {
 	loadOpts := state.LoadOpts{
 		Source: o.FilePayload.Files[0],
 	}
-	if err := loadOpts.Load(k, p, networkStack); err != nil {
+	if err := loadOpts.Load(k, networkStack); err != nil {
 		return err
 	}
 
@@ -384,7 +389,7 @@ func (cm *containerManager) Restore(o *RestoreOpts, _ *struct{}) error {
 	cm.l.mu.Lock()
 	eid := execID{cid: o.SandboxID}
 	cm.l.processes = map[execID]*execProcess{
-		eid: &execProcess{
+		eid: {
 			tg: cm.l.k.GlobalInit(),
 		},
 	}
diff --git a/runsc/boot/events.go b/runsc/boot/events.go
index f954b8c0b..717adfedd 100644
--- a/runsc/boot/events.go
+++ b/runsc/boot/events.go
@@ -68,7 +68,7 @@ func (cm *containerManager) Event(_ *struct{}, out *Event) error {
 }
 
 func (s *Stats) populateMemory(k *kernel.Kernel) {
-	mem := k.Platform.Memory()
+	mem := k.MemoryFile()
 	mem.UpdateUsage()
 	_, totalUsage := usage.MemoryAccounting.Copy()
 	s.Memory.Usage = MemoryEntry{
diff --git a/runsc/boot/loader.go b/runsc/boot/loader.go
index 9ebe64dce..56cb137f0 100644
--- a/runsc/boot/loader.go
+++ b/runsc/boot/loader.go
@@ -37,6 +37,8 @@ import (
 	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/loader"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/memutil"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/pgalloc"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/platform"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/platform/kvm"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/platform/ptrace"
@@ -189,6 +191,13 @@ func New(args Args) (*Loader, error) {
 		Platform: p,
 	}
 
+	// Create memory file.
+	mf, err := createMemoryFile()
+	if err != nil {
+		return nil, fmt.Errorf("creating memory file: %v", err)
+	}
+	k.SetMemoryFile(mf)
+
 	// Create VDSO.
 	//
 	// Pass k as the platform since it is savable, unlike the actual platform.
@@ -297,7 +306,7 @@ func New(args Args) (*Loader, error) {
 		stdioFDs:     args.StdioFDs,
 		rootProcArgs: procArgs,
 		sandboxID:    args.ID,
-		processes:    map[execID]*execProcess{eid: &execProcess{}},
+		processes:    map[execID]*execProcess{eid: {}},
 	}
 
 	// We don't care about child signals; some platforms can generate a
@@ -404,6 +413,21 @@ func createPlatform(conf *Config, deviceFD int) (platform.Platform, error) {
 	}
 }
 
+func createMemoryFile() (*pgalloc.MemoryFile, error) {
+	const memfileName = "runsc-memory"
+	memfd, err := memutil.CreateMemFD(memfileName, 0)
+	if err != nil {
+		return nil, fmt.Errorf("error creating memfd: %v", err)
+	}
+	memfile := os.NewFile(uintptr(memfd), memfileName)
+	mf, err := pgalloc.NewMemoryFile(memfile)
+	if err != nil {
+		memfile.Close()
+		return nil, fmt.Errorf("error creating pgalloc.MemoryFile: %v", err)
+	}
+	return mf, nil
+}
+
 // Run runs the root container..
 func (l *Loader) Run() error {
 	err := l.run()