diff options
Diffstat (limited to 'pkg/sentry/mm')
| -rw-r--r-- | pkg/sentry/mm/mm.go | 2 | ||||
| -rw-r--r-- | pkg/sentry/mm/mm_test.go | 3 | ||||
| -rw-r--r-- | pkg/sentry/mm/special_mappable.go | 9 | ||||
| -rw-r--r-- | pkg/sentry/mm/syscalls.go | 13 |
4 files changed, 9 insertions, 18 deletions
diff --git a/pkg/sentry/mm/mm.go b/pkg/sentry/mm/mm.go index 3e85964e4..8c9f11cce 100644 --- a/pkg/sentry/mm/mm.go +++ b/pkg/sentry/mm/mm.go @@ -242,7 +242,7 @@ type MemoryManager struct { // +stateify savable type vma struct { // mappable is the virtual memory object mapped by this vma. If mappable is - // nil, the vma represents a private anonymous mapping. + // nil, the vma represents an anonymous mapping. mappable memmap.Mappable // off is the offset into mappable at which this vma begins. If mappable is diff --git a/pkg/sentry/mm/mm_test.go b/pkg/sentry/mm/mm_test.go index fdc308542..acac3d357 100644 --- a/pkg/sentry/mm/mm_test.go +++ b/pkg/sentry/mm/mm_test.go @@ -51,7 +51,8 @@ func TestUsageASUpdates(t *testing.T) { defer mm.DecUsers(ctx) addr, err := mm.MMap(ctx, memmap.MMapOpts{ - Length: 2 * usermem.PageSize, + Length: 2 * usermem.PageSize, + Private: true, }) if err != nil { t.Fatalf("MMap got err %v want nil", err) diff --git a/pkg/sentry/mm/special_mappable.go b/pkg/sentry/mm/special_mappable.go index f4c93baeb..2dbe5b751 100644 --- a/pkg/sentry/mm/special_mappable.go +++ b/pkg/sentry/mm/special_mappable.go @@ -136,9 +136,12 @@ func (m *SpecialMappable) Length() uint64 { // NewSharedAnonMappable returns a SpecialMappable that implements the // semantics of mmap(MAP_SHARED|MAP_ANONYMOUS) and mappings of /dev/zero. // -// TODO(jamieliu): The use of SpecialMappable is a lazy code reuse hack. Linux -// uses an ephemeral file created by mm/shmem.c:shmem_zero_setup(); we should -// do the same to get non-zero device and inode IDs. +// TODO(gvisor.dev/issue/1624): Linux uses an ephemeral file created by +// mm/shmem.c:shmem_zero_setup(), and VFS2 does something analogous. VFS1 uses +// a SpecialMappable instead, incorrectly getting device and inode IDs of zero +// and causing memory for shared anonymous mappings to be allocated up-front +// instead of on first touch; this is to avoid exacerbating the fs.MountSource +// leak (b/143656263). Delete this function along with VFS1. func NewSharedAnonMappable(length uint64, mfp pgalloc.MemoryFileProvider) (*SpecialMappable, error) { if length == 0 { return nil, syserror.EINVAL diff --git a/pkg/sentry/mm/syscalls.go b/pkg/sentry/mm/syscalls.go index 4c9a575e7..a2555ba1a 100644 --- a/pkg/sentry/mm/syscalls.go +++ b/pkg/sentry/mm/syscalls.go @@ -24,7 +24,6 @@ import ( "gvisor.dev/gvisor/pkg/sentry/kernel/futex" "gvisor.dev/gvisor/pkg/sentry/limits" "gvisor.dev/gvisor/pkg/sentry/memmap" - "gvisor.dev/gvisor/pkg/sentry/pgalloc" "gvisor.dev/gvisor/pkg/syserror" "gvisor.dev/gvisor/pkg/usermem" ) @@ -93,18 +92,6 @@ func (mm *MemoryManager) MMap(ctx context.Context, opts memmap.MMapOpts) (userme } } else { opts.Offset = 0 - if !opts.Private { - if opts.MappingIdentity != nil { - return 0, syserror.EINVAL - } - m, err := NewSharedAnonMappable(opts.Length, pgalloc.MemoryFileProviderFromContext(ctx)) - if err != nil { - return 0, err - } - defer m.DecRef(ctx) - opts.MappingIdentity = m - opts.Mappable = m - } } if opts.Addr.RoundDown() != opts.Addr { |