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Ensure pgalloc.MemoryFile.fileSize is always chunk-aligned.

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findAvailableLocked() may return a non-aligned FileRange.End after expansion
since it may round FileRange.Start down to a hugepage boundary.

PiperOrigin-RevId: 315520321
This commit is contained in:
Jamie Liu
2020-06-09 11:16:05 -07:00
committed by gVisor bot
parent 20afd66e01
commit ecff24930c
1 changed files with 6 additions and 5 deletions
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pkg/sentry/pgalloc/pgalloc.go
+6 -5
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@@ -393,16 +393,17 @@ func (f *MemoryFile) Allocate(length uint64, kind usage.MemoryKind) (platform.Fi
return platform.FileRange{}, syserror.ENOMEM
}
// Expand the file if needed. Note that findAvailableRange will
// appropriately double the fileSize when required.
// Expand the file if needed.
if int64(fr.End) > f.fileSize {
if err := f.file.Truncate(int64(fr.End)); err != nil {
// Round the new file size up to be chunk-aligned.
newFileSize := (int64(fr.End) + chunkMask) &^ chunkMask
if err := f.file.Truncate(newFileSize); err != nil {
return platform.FileRange{}, err
}
f.fileSize = int64(fr.End)
f.fileSize = newFileSize
f.mappingsMu.Lock()
oldMappings := f.mappings.Load().([]uintptr)
newMappings := make([]uintptr, f.fileSize>>chunkShift)
newMappings := make([]uintptr, newFileSize>>chunkShift)
copy(newMappings, oldMappings)
f.mappings.Store(newMappings)
f.mappingsMu.Unlock()