Automated rollback of changelist 633961720

PiperOrigin-RevId: 636602151

pkg/sentry/pgalloc/pgalloc.go

@@ -222,11 +222,6 @@ type MemoryFileOpts struct {
 	// RestoreID is an opaque string used to reassociate the MemoryFile with its
 	// replacement during restore.
 	RestoreID string
-
-	// EnforceMaximumAllocatable is a flag that governs whether the MemoryFile
-	// will be limited in size of total allocations by
-	// usage.MaximumAllocatableBytes.
-	EnforceMaximumAllocatable bool
 }
 
 // DelayedEvictionType is the type of MemoryFileOpts.DelayedEviction.
@@ -544,11 +539,6 @@ func (f *MemoryFile) allocate(length uint64, opts *AllocOpts) (memmap.FileRange,
 	f.mu.Lock()
 	defer f.mu.Unlock()
 
-	if !f.hasSpaceToAllocate(length) {
-		log.Debugf("Enforcing memory limit on allocation of size %d, max is %d, already have %d", length, usage.MaximumAllocatableBytes, f.usageExpected)
-		return memmap.FileRange{}, linuxerr.ENOMEM
-	}
-
 	// Align hugepage-and-larger allocations on hugepage boundaries to try
 	// to take advantage of hugetmpfs.
 	alignment := uint64(hostarch.PageSize)
@@ -593,25 +583,6 @@ func (f *MemoryFile) allocate(length uint64, opts *AllocOpts) (memmap.FileRange,
 	return fr, nil
 }
 
-func (f *MemoryFile) hasSpaceToAllocate(length uint64) bool {
-	if f.opts.EnforceMaximumAllocatable && usage.MaximumAllocatableBytes != 0 && ((f.usageExpected+length) > usage.MaximumAllocatableBytes || (f.usageExpected+length) < f.usageExpected) {
-		// f.usageExpected is not guaranteed to be correct because it is
-		// updated only when f.UpdateUsage is called periodically.
-		// To eliminate false-positives double check against the exact
-		// measure; we don't care as much about false-negatives, which
-		// helps avoid a host-syscall via f.TotalUsage in the happy-path.
-		exactUsage, err := f.TotalUsage()
-		if err != nil {
-			log.Warningf("Failed to fetch total usage for memory file: %v", err)
-			return false
-		}
-		if (exactUsage+length) > usage.MaximumAllocatableBytes || (exactUsage+length) < exactUsage {
-			return false
-		}
-	}
-	return true
-}
-
 // findAvailableRange returns an available range in the usageSet.
 //
 // Note that scanning for available slots takes place from end first backwards,

pkg/sentry/platform/systrap/systrap.go

@@ -427,9 +427,7 @@ func createMemoryFile() (*pgalloc.MemoryFile, error) {
 		return nil, fmt.Errorf("error creating memfd: %v", err)
 	}
 	memfile := os.NewFile(uintptr(fd), memfileName)
-	mf, err := pgalloc.NewMemoryFile(memfile, pgalloc.MemoryFileOpts{
-		EnforceMaximumAllocatable: true,
-	})
+	mf, err := pgalloc.NewMemoryFile(memfile, pgalloc.MemoryFileOpts{})
 	if err != nil {
 		memfile.Close()
 		return nil, fmt.Errorf("error creating pgalloc.MemoryFile: %v", err)

pkg/sentry/usage/memory.go

@@ -374,11 +374,6 @@ var (
 	// MaximumTotalMemoryBytes is the maximum reported total system memory.
 	// The 0 value indicates no maximum.
 	MaximumTotalMemoryBytes uint64
-
-	// MaximumAllocatableBytes is the maximum allowed to be allocated from a
-	// single memory file. Usually this is the same as
-	// MaximumTotalMemoryBytes.
-	MaximumAllocatableBytes uint64
 )
 
 // TotalMemory returns the "total usable memory" available.

runsc/boot/loader.go

@@ -513,9 +513,6 @@ func New(args Args) (*Loader, error) {
 		// As per tmpfs(5), the default size limit is 50% of total physical RAM.
 		// See mm/shmem.c:shmem_default_max_blocks().
 		tmpfs.SetDefaultSizeLimit(args.TotalHostMem / 2)
-		// Set a generous but sane on maximum allowable size for memory
-		// file allocates.
-		usage.MaximumAllocatableBytes = args.TotalHostMem
 	}
 
 	if args.TotalMem > 0 {
@@ -523,8 +520,6 @@ func New(args Args) (*Loader, error) {
 		// use /proc/meminfo can make allocations based on this limit.
 		usage.MinimumTotalMemoryBytes = args.TotalMem
 		usage.MaximumTotalMemoryBytes = args.TotalMem
-		// Reset max allocatable to TotalMem because it's smaller than TotalHostMem.
-		usage.MaximumAllocatableBytes = args.TotalMem
 		log.Infof("Setting total memory to %.2f GB", float64(args.TotalMem)/(1<<30))
 	}
 
@@ -738,9 +733,7 @@ func createMemoryFile() (*pgalloc.MemoryFile, error) {
 	// We can't enable pgalloc.MemoryFileOpts.UseHostMemcgPressure even if
 	// there are memory cgroups specified, because at this point we're already
 	// in a mount namespace in which the relevant cgroupfs is not visible.
-	mf, err := pgalloc.NewMemoryFile(memfile, pgalloc.MemoryFileOpts{
-		EnforceMaximumAllocatable: true,
-	})
+	mf, err := pgalloc.NewMemoryFile(memfile, pgalloc.MemoryFileOpts{})
 	if err != nil {
 		_ = memfile.Close()
 		return nil, fmt.Errorf("error creating pgalloc.MemoryFile: %w", err)