github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/sentry/fsimpl/cgroupfs/memory.go (about)

     1  // Copyright 2021 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package cgroupfs
    16  
    17  import (
    18  	"bytes"
    19  	"fmt"
    20  	"math"
    21  
    22  	"github.com/SagerNet/gvisor/pkg/abi/linux"
    23  	"github.com/SagerNet/gvisor/pkg/context"
    24  	"github.com/SagerNet/gvisor/pkg/sentry/fsimpl/kernfs"
    25  	"github.com/SagerNet/gvisor/pkg/sentry/kernel"
    26  	"github.com/SagerNet/gvisor/pkg/sentry/kernel/auth"
    27  	"github.com/SagerNet/gvisor/pkg/sentry/usage"
    28  )
    29  
    30  // +stateify savable
    31  type memoryController struct {
    32  	controllerCommon
    33  
    34  	limitBytes int64
    35  }
    36  
    37  var _ controller = (*memoryController)(nil)
    38  
    39  func newMemoryController(fs *filesystem, defaults map[string]int64) *memoryController {
    40  	c := &memoryController{
    41  		// Linux sets this to (PAGE_COUNTER_MAX * PAGE_SIZE) by default, which
    42  		// is ~ 2**63 on a 64-bit system. So essentially, inifinity. The exact
    43  		// value isn't very important.
    44  		limitBytes: math.MaxInt64,
    45  	}
    46  	if val, ok := defaults["memory.limit_in_bytes"]; ok {
    47  		c.limitBytes = val
    48  		delete(defaults, "memory.limit_in_bytes")
    49  	}
    50  	c.controllerCommon.init(controllerMemory, fs)
    51  	return c
    52  }
    53  
    54  // AddControlFiles implements controller.AddControlFiles.
    55  func (c *memoryController) AddControlFiles(ctx context.Context, creds *auth.Credentials, _ *cgroupInode, contents map[string]kernfs.Inode) {
    56  	contents["memory.usage_in_bytes"] = c.fs.newControllerFile(ctx, creds, &memoryUsageInBytesData{})
    57  	contents["memory.limit_in_bytes"] = c.fs.newStaticControllerFile(ctx, creds, linux.FileMode(0644), fmt.Sprintf("%d\n", c.limitBytes))
    58  }
    59  
    60  // +stateify savable
    61  type memoryUsageInBytesData struct{}
    62  
    63  // Generate implements vfs.DynamicBytesSource.Generate.
    64  func (d *memoryUsageInBytesData) Generate(ctx context.Context, buf *bytes.Buffer) error {
    65  	// TODO(b/183151557): This is a giant hack, we're using system-wide
    66  	// accounting since we know there is only one cgroup.
    67  	k := kernel.KernelFromContext(ctx)
    68  	mf := k.MemoryFile()
    69  	mf.UpdateUsage()
    70  	_, totalBytes := usage.MemoryAccounting.Copy()
    71  
    72  	fmt.Fprintf(buf, "%d\n", totalBytes)
    73  	return nil
    74  }