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

1 files changed, 25 insertions, 1 deletions

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()