windows-xp/Source/XPSP1/NT/base/ntos/mm/allocvm.c

/*++

Copyright (c) 1989  Microsoft Corporation

Module Name:

   allocvm.c

Abstract:

    This module contains the routines which implement the
    NtAllocateVirtualMemory service.

Author:

    Lou Perazzoli (loup) 22-May-1989
    Landy Wang (landyw) 02-June-1997

Revision History:

--*/

#include "mi.h"

#if DBG
PEPROCESS MmWatchProcess;
VOID MmFooBar(VOID);
#endif // DBG

const ULONG MMVADKEY = ' daV'; //Vad

//
// This registry-settable variable provides a way to give all applications
// virtual address ranges from the highest address downwards.  The idea is to
// make it easy to test 3GB-aware apps on 32-bit machines and 64-bit apps on
// NT64.
//

ULONG MmAllocationPreference;

NTSTATUS
MiResetVirtualMemory (
    IN PVOID StartingAddress,
    IN PVOID EndingAddress,
    IN PMMVAD Vad,
    IN PEPROCESS Process
    );

LOGICAL
MiCreatePageTablesForPhysicalRange (
    IN PEPROCESS Process,
    IN PVOID StartingAddress,
    IN PVOID EndingAddress
    );

VOID
MiPhysicalViewInserter (
    IN PEPROCESS Process,
    IN PMI_PHYSICAL_VIEW PhysicalView
    );

VOID
MiFlushAcquire (
    IN PCONTROL_AREA ControlArea
    );

VOID
MiFlushRelease (
    IN PCONTROL_AREA ControlArea
    );

#ifdef ALLOC_PRAGMA
#pragma alloc_text(PAGE,NtAllocateVirtualMemory)
#pragma alloc_text(PAGELK,MiCreatePageTablesForPhysicalRange)
#pragma alloc_text(PAGELK,MiDeletePageTablesForPhysicalRange)
#pragma alloc_text(PAGELK,MiResetVirtualMemory)
#endif

SIZE_T MmTotalProcessCommit;        // Only used for debugging


NTSTATUS
NtAllocateVirtualMemory(
    IN HANDLE ProcessHandle,
    IN OUT PVOID *BaseAddress,
    IN ULONG_PTR ZeroBits,
    IN OUT PSIZE_T RegionSize,
    IN ULONG AllocationType,
    IN ULONG Protect
    )

/*++

Routine Description:

    This function creates a region of pages within the virtual address
    space of a subject process.

Arguments:

    ProcessHandle - Supplies an open handle to a process object.

    BaseAddress - Supplies a pointer to a variable that will receive
                  the base address of the allocated region of pages.
                  If the initial value of this argument is not null,
                  then the region will be allocated starting at the
                  specified virtual address rounded down to the next
                  host page size address boundary. If the initial
                  value of this argument is null, then the operating
                  system will determine where to allocate the region.
        
    ZeroBits - Supplies the number of high order address bits that
               must be zero in the base address of the section view. The
               value of this argument must be less than or equal to the
               maximum number of zero bits and is only used when memory
               management determines where to allocate the view (i.e. when
               BaseAddress is null).

               If ZeroBits is zero, then no zero bit constraints are applied.

               If ZeroBits is greater than 0 and less than 32, then it is
               the number of leading zero bits from bit 31.  Bits 63:32 are
               also required to be zero.  This retains compatibility
               with 32-bit systems.
                
               If ZeroBits is greater than 32, then it is considered as
               a mask and then number of leading zero are counted out
               in the mask.  This then becomes the zero bits argument.

    RegionSize - Supplies a pointer to a variable that will receive
                 the actual size in bytes of the allocated region
                 of pages. The initial value of this argument
                 specifies the size in bytes of the region and is
                 rounded up to the next host page size boundary.

    AllocationType - Supplies a set of flags that describe the type
                     of allocation that is to be performed for the
                     specified region of pages. Flags are:
            
         MEM_COMMIT - The specified region of pages is to be committed.

         MEM_RESERVE - The specified region of pages is to be reserved.

         MEM_TOP_DOWN - The specified region should be created at the
                        highest virtual address possible based on ZeroBits.

         MEM_RESET - Reset the state of the specified region so
                     that if the pages are in page paging file, they
                     are discarded and pages of zeroes are brought in.
                     If the pages are in memory and modified, they are marked
                     as not modified so they will not be written out to
                     the paging file.  The contents are NOT zeroed.

                     The Protect argument is ignored, but a valid protection
                     must be specified.

         MEM_PHYSICAL - The specified region of pages will map physical memory
                        directly via the AWE APIs.

         MEM_WRITE_WATCH - The specified private region is to be used for
                           write-watch purposes.

    Protect - Supplies the protection desired for the committed region of pages.

         PAGE_NOACCESS - No access to the committed region
                         of pages is allowed. An attempt to read,
                         write, or execute the committed region
                         results in an access violation.

         PAGE_EXECUTE - Execute access to the committed
                        region of pages is allowed. An attempt to
                        read or write the committed region results in
                        an access violation.

         PAGE_READONLY - Read only and execute access to the
                         committed region of pages is allowed. An
                         attempt to write the committed region results
                         in an access violation.

         PAGE_READWRITE - Read, write, and execute access to
                          the committed region of pages is allowed. If
                          write access to the underlying section is
                          allowed, then a single copy of the pages are
                          shared. Otherwise the pages are shared read
                          only/copy on write.

         PAGE_NOCACHE - The region of pages should be allocated
                        as non-cachable.

Return Value:

    Various NTSTATUS codes.

--*/

{
    ULONG Locked;
    PMMVAD Vad;
    PMMVAD FoundVad;
    PMMVAD PreviousVad;
    PMMVAD NextVad;
    PEPROCESS Process;
    KPROCESSOR_MODE PreviousMode;
    PVOID StartingAddress;
    PVOID EndingAddress;
    NTSTATUS Status;
    PVOID TopAddress;
    PVOID CapturedBase;
    SIZE_T CapturedRegionSize;
    SIZE_T NumberOfPages;
    PMMPTE PointerPte;
    PMMPTE CommitLimitPte;
    ULONG ProtectionMask;
    PMMPTE LastPte;
    PMMPTE PointerPde;
    PMMPTE StartingPte;
    MMPTE TempPte;
    ULONG OldProtect;
    SIZE_T QuotaCharge;
    SIZE_T QuotaFree;
    SIZE_T CopyOnWriteCharge;
    LOGICAL Attached;
    LOGICAL ChargedExactQuota;
    MMPTE DecommittedPte;
    ULONG ChangeProtection;
    PVOID UsedPageTableHandle;
    PUCHAR Va;
    LOGICAL ChargedJobCommit;
    PMI_PHYSICAL_VIEW PhysicalView;
    PRTL_BITMAP BitMap;
    ULONG BitMapSize;
    ULONG BitMapBits;
    KAPC_STATE ApcState;
    SECTION Section;
    LARGE_INTEGER NewSize;
    PCONTROL_AREA ControlArea;
    PSEGMENT Segment;
#if defined(_MIALT4K_)
    PVOID OriginalBase;
    SIZE_T OriginalRegionSize;
    PVOID WowProcess;
    PVOID StartingAddressFor4k;
    PVOID EndingAddressFor4k;
    SIZE_T CapturedRegionSizeFor4k;
    ULONG OriginalProtectionMask;
    ULONG AltFlags;
    ULONG NativePageProtection;
#endif
    PETHREAD CurrentThread;
    PEPROCESS CurrentProcess;
    ULONG ExecutePermission;

    PAGED_CODE();

    Attached = FALSE;

    //
    // Check the zero bits argument for correctness.
    //

#if defined (_WIN64)

    if (ZeroBits >= 32) {

        //
        // ZeroBits is a mask instead of a count.  Translate it to a count now.
        //

        ZeroBits = 64 - RtlFindMostSignificantBit (ZeroBits) -1;        
    }
    else if (ZeroBits) {
        ZeroBits += 32;
    }

#endif

    if (ZeroBits > MM_MAXIMUM_ZERO_BITS) {
        return STATUS_INVALID_PARAMETER_3;
    }

    //
    // Check the AllocationType for correctness.
    //

    if ((AllocationType & ~(MEM_COMMIT | MEM_RESERVE | MEM_PHYSICAL |
                            MEM_TOP_DOWN | MEM_RESET | MEM_WRITE_WATCH)) != 0) {
        return STATUS_INVALID_PARAMETER_5;
    }

    //
    // One of MEM_COMMIT, MEM_RESET or MEM_RESERVE must be set.
    //

    if ((AllocationType & (MEM_COMMIT | MEM_RESERVE | MEM_RESET)) == 0) {
        return STATUS_INVALID_PARAMETER_5;
    }

    if ((AllocationType & MEM_RESET) && (AllocationType != MEM_RESET)) {

        //
        // MEM_RESET may not be used with any other flag.
        //

        return STATUS_INVALID_PARAMETER_5;
    }

    if (AllocationType & MEM_WRITE_WATCH) {

        //
        // Write watch address spaces can only be created with MEM_RESERVE.
        //

        if ((AllocationType & MEM_RESERVE) == 0) {
            return STATUS_INVALID_PARAMETER_5;
        }
    }

    if (AllocationType & MEM_PHYSICAL) {

        //
        // MEM_PHYSICAL must be used with MEM_RESERVE and no other flags.
        // This memory is always read-write when allocated.
        //

        if (AllocationType != (MEM_RESERVE | MEM_PHYSICAL)) {
            return STATUS_INVALID_PARAMETER_5;
        }

        if (Protect != PAGE_READWRITE) {
            return STATUS_INVALID_PARAMETER_6;
        }
    }

    //
    // Check the protection field.
    //

    ProtectionMask = MiMakeProtectionMask (Protect);
    if (ProtectionMask == MM_INVALID_PROTECTION) {
        return STATUS_INVALID_PAGE_PROTECTION;
    }

    ChangeProtection = FALSE;

    CurrentThread = PsGetCurrentThread ();

    CurrentProcess = PsGetCurrentProcessByThread (CurrentThread);

    PreviousMode = KeGetPreviousModeByThread(&CurrentThread->Tcb);

    //
    // Establish an exception handler, probe the specified addresses
    // for write access and capture the initial values.
    //

    try {

        if (PreviousMode != KernelMode) {

            ProbeForWritePointer (BaseAddress);
            ProbeForWriteUlong_ptr (RegionSize);
        }

        //
        // Capture the base address.
        //

        CapturedBase = *BaseAddress;

        //
        // Capture the region size.
        //

        CapturedRegionSize = *RegionSize;

    } except (ExSystemExceptionFilter()) {

        //
        // If an exception occurs during the probe or capture
        // of the initial values, then handle the exception and
        // return the exception code as the status value.
        //

        return GetExceptionCode();
    }

#if defined(_MIALT4K_)

    OriginalBase = CapturedBase;
    OriginalRegionSize = CapturedRegionSize;

#endif

    //
    // Make sure the specified starting and ending addresses are
    // within the user part of the virtual address space.
    //

    if (CapturedBase > MM_HIGHEST_VAD_ADDRESS) {

        //
        // Invalid base address.
        //

        return STATUS_INVALID_PARAMETER_2;
    }

    if ((((ULONG_PTR)MM_HIGHEST_VAD_ADDRESS + 1) - (ULONG_PTR)CapturedBase) <
            CapturedRegionSize) {

        //
        // Invalid region size;
        //

        return STATUS_INVALID_PARAMETER_4;
    }

    if (CapturedRegionSize == 0) {

        //
        // Region size cannot be 0.
        //

        return STATUS_INVALID_PARAMETER_4;
    }

    //
    // Reference the specified process handle for VM_OPERATION access.
    //

    if (ProcessHandle == NtCurrentProcess()) {
        Process = CurrentProcess;
    }
    else {
        Status = ObReferenceObjectByHandle ( ProcessHandle,
                                             PROCESS_VM_OPERATION,
                                             PsProcessType,
                                             PreviousMode,
                                             (PVOID *)&Process,
                                             NULL );

        if (!NT_SUCCESS(Status)) {
            return Status;
        }

        //
        // If the specified process is not the current process, attach
        // to the specified process.
        //

        if (CurrentProcess != Process) {
            KeStackAttachProcess (&Process->Pcb, &ApcState);
            Attached = TRUE;
        }
    }

    //
    // Add execute permission if necessary.
    //

#if defined (_WIN64)
    if (Process->Wow64Process == NULL && AllocationType & MEM_COMMIT)
#elif defined (_X86PAE_)
    if (AllocationType & MEM_COMMIT)
#else
    if (FALSE)
#endif
    {

        if (Process->Peb != NULL) {

            ExecutePermission = 0;

            try {
                ExecutePermission = Process->Peb->ExecuteOptions & MEM_EXECUTE_OPTION_DATA;
            } except (EXCEPTION_EXECUTE_HANDLER) {
                Status = GetExceptionCode();
                goto ErrorReturn1;
            }

            if (ExecutePermission != 0) {

                switch (Protect & 0xF) {
                    case PAGE_READONLY:
                        Protect &= ~PAGE_READONLY;
                        Protect |= PAGE_EXECUTE_READ;
                        break;
                    case PAGE_READWRITE:
                        Protect &= ~PAGE_READWRITE;
                        Protect |= PAGE_EXECUTE_READWRITE;
                        break;
                    case PAGE_WRITECOPY:
                        Protect &= ~PAGE_WRITECOPY;
                        Protect |= PAGE_EXECUTE_WRITECOPY;
                        break;
                    default:
                        break;
                }

                //
                // Recheck protection.
                //

                ProtectionMask = MiMakeProtectionMask (Protect);

                if (ProtectionMask == MM_INVALID_PROTECTION) {
                    Status = STATUS_INVALID_PAGE_PROTECTION;
                    goto ErrorReturn1;
                }
            }
        }
    }
              
    //
    // Get the address creation mutex to block multiple threads from
    // creating or deleting address space at the same time and
    // get the working set mutex so virtual address descriptors can
    // be inserted and walked.  Block APCs so an APC which takes a page
    // fault does not corrupt various structures.
    //

    QuotaCharge = 0;

    if ((CapturedBase == NULL) || (AllocationType & MEM_RESERVE)) {

        //
        // PAGE_WRITECOPY is not valid for private pages.
        //

        if ((Protect & PAGE_WRITECOPY) ||
            (Protect & PAGE_EXECUTE_WRITECOPY)) {
            Status = STATUS_INVALID_PAGE_PROTECTION;
            goto ErrorReturn1;
        }

        //
        // Reserve the address space.
        //

        if (CapturedBase == NULL) {

            //
            // No base address was specified.  This MUST be a reserve or
            // reserve and commit.
            //

            CapturedRegionSize = ROUND_TO_PAGES (CapturedRegionSize);

            //
            // If the number of zero bits is greater than zero, then calculate
            // the highest address.
            //

            if (ZeroBits != 0) {
                TopAddress = (PVOID)(((ULONG_PTR)MM_USER_ADDRESS_RANGE_LIMIT) >> ZeroBits);

                //
                // Keep the top address below the highest user vad address
                // regardless.
                //

                if (TopAddress > MM_HIGHEST_VAD_ADDRESS) {
                    Status = STATUS_INVALID_PARAMETER_3;
                    goto ErrorReturn1;
                }

            }
            else {
                TopAddress = (PVOID)MM_HIGHEST_VAD_ADDRESS;
            }

            //
            // Check whether the registry indicates that all applications
            // should be given virtual address ranges from the highest
            // address downwards in order to test 3GB-aware apps on 32-bit
            // machines and 64-bit apps on NT64.
            //

            ASSERT ((MmAllocationPreference == 0) ||
                    (MmAllocationPreference == MEM_TOP_DOWN));

#if defined (_WIN64)
            if (Process->Wow64Process == NULL)
#endif
            AllocationType |= MmAllocationPreference;

            //
            // Note this calculation assumes the starting address will be
            // allocated on at least a page boundary.
            //

            NumberOfPages = BYTES_TO_PAGES (CapturedRegionSize);

            //
            // Initializing StartingAddress and EndingAddress is not needed for
            // correctness but without it the compiler cannot compile this code
            // W4 to check for use of uninitialized variables.
            //

            StartingAddress = NULL;
            EndingAddress = NULL;
        }
        else {

            //
            // A non-NULL base address was specified.  Check to make sure
            // the specified base address to ending address is currently
            // unused.
            //

            EndingAddress = (PVOID)(((ULONG_PTR)CapturedBase +
                                  CapturedRegionSize - 1L) | (PAGE_SIZE - 1L));

            //
            // Align the starting address on a 64k boundary.
            //

            StartingAddress = (PVOID)MI_64K_ALIGN(CapturedBase);

            NumberOfPages = BYTES_TO_PAGES ((PCHAR)EndingAddress -
                                            (PCHAR)StartingAddress);

            //
            // Initializing TopAddress is not needed for
            // correctness but without it the compiler cannot compile this code
            // W4 to check for use of uninitialized variables.
            //

            TopAddress = NULL;
        }

        BitMapSize = 0;

        //
        // Allocate resources up front before acquiring mutexes to reduce
        // contention.
        //

        Vad = ExAllocatePoolWithTag (NonPagedPool, sizeof(MMVAD_SHORT), 'SdaV');

        if (Vad == NULL) {
            Status = STATUS_INSUFFICIENT_RESOURCES;
            goto ErrorReturn1;
        }

        Vad->u.LongFlags = 0;

        //
        // Calculate the page file quota for this address range.
        //

        if (AllocationType & MEM_COMMIT) {
            QuotaCharge = NumberOfPages;
            Vad->u.VadFlags.MemCommit = 1;
        }

        if (AllocationType & MEM_PHYSICAL) {
            Vad->u.VadFlags.UserPhysicalPages = 1;
        }

        Vad->u.VadFlags.Protection = ProtectionMask;
        Vad->u.VadFlags.PrivateMemory = 1;

        Vad->u.VadFlags.CommitCharge = QuotaCharge;

        //
        // Initializing BitMap & PhysicalView is not needed for
        // correctness but without it the compiler cannot compile this code
        // W4 to check for use of uninitialized variables.
        //

        BitMap = NULL;
        PhysicalView = NULL;

        if (AllocationType & MEM_PHYSICAL) {

            if (AllocationType & MEM_WRITE_WATCH) {
                ExFreePool (Vad);
                Status = STATUS_INVALID_PARAMETER_5;
                goto ErrorReturn1;
            }

            if ((Process->AweInfo == NULL) && (MiAllocateAweInfo () == NULL)) {
                ExFreePool (Vad);
                Status = STATUS_INSUFFICIENT_RESOURCES;
                goto ErrorReturn1;
            }

            PhysicalView = (PMI_PHYSICAL_VIEW) ExAllocatePoolWithTag (
                                                   NonPagedPool,
                                                   sizeof(MI_PHYSICAL_VIEW),
                                                   MI_PHYSICAL_VIEW_KEY);

            if (PhysicalView == NULL) {
                ExFreePool (Vad);
                Status = STATUS_INSUFFICIENT_RESOURCES;
                goto ErrorReturn1;
            }

            PhysicalView->Vad = Vad;
            PhysicalView->u.LongFlags = MI_PHYSICAL_VIEW_AWE;
        }
        else if (AllocationType & MEM_WRITE_WATCH) {

            ASSERT (AllocationType & MEM_RESERVE);

#if defined (_WIN64)
            if (NumberOfPages >= _4gb) {

                //
                // The bitmap package only handles 32 bits.
                //

                ExFreePool (Vad);
                Status = STATUS_INSUFFICIENT_RESOURCES;
                goto ErrorReturn1;
            }
#endif

            BitMapBits = (ULONG)NumberOfPages;

            BitMapSize = sizeof(RTL_BITMAP) + (ULONG)(((BitMapBits + 31) / 32) * 4);
            BitMap = ExAllocatePoolWithTag (NonPagedPool, BitMapSize, 'wwmM');

            if (BitMap == NULL) {
                ExFreePool (Vad);
                Status = STATUS_INSUFFICIENT_RESOURCES;
                goto ErrorReturn1;
            }

            //
            // Charge quota for the nonpaged pool for the bitmap.  This is
            // done here rather than by using ExAllocatePoolWithQuota
            // so the process object is not referenced by the quota charge.
            //
    
            Status = PsChargeProcessNonPagedPoolQuota (Process,
                                                       BitMapSize);
    
            if (!NT_SUCCESS(Status)) {
                ExFreePool (Vad);
                ExFreePool (BitMap);
                goto ErrorReturn1;
            }

            PhysicalView = (PMI_PHYSICAL_VIEW) ExAllocatePoolWithTag (
                                                   NonPagedPool,
                                                   sizeof(MI_PHYSICAL_VIEW),
                                                   MI_WRITEWATCH_VIEW_KEY);

            if (PhysicalView == NULL) {
                ExFreePool (Vad);
                ExFreePool (BitMap);
                PsReturnProcessNonPagedPoolQuota (Process, BitMapSize);
                Status = STATUS_INSUFFICIENT_RESOURCES;
                goto ErrorReturn1;
            }

            RtlInitializeBitMap (BitMap, (PULONG)(BitMap + 1), BitMapBits);
    
            RtlClearAllBits (BitMap);

            PhysicalView->Vad = Vad;
            PhysicalView->u.BitMap = BitMap;

            Vad->u.VadFlags.WriteWatch = 1;
        }

        //
        // Now acquire mutexes, check ranges and insert.
        //

        LOCK_ADDRESS_SPACE (Process);

        //
        // Make sure the address space was not deleted, if so,
        // return an error.
        //

        if (Process->Flags & PS_PROCESS_FLAGS_VM_DELETED) {
            Status = STATUS_PROCESS_IS_TERMINATING;
            goto ErrorReleaseVad;
        }

        //
        // Find a (or validate the) starting address.
        //

        if (CapturedBase == NULL) {

            if (AllocationType & MEM_TOP_DOWN) {

                //
                // Start from the top of memory downward.
                //

                Status = MiFindEmptyAddressRangeDown (Process->VadRoot,
                                                      CapturedRegionSize,
                                                      TopAddress,
                                                      X64K,
                                                      &StartingAddress);
            }
            else {

                Status = MiFindEmptyAddressRange (CapturedRegionSize,
                                                  X64K,
                                                  (ULONG)ZeroBits,
                                                  &StartingAddress);
            }

            if (!NT_SUCCESS (Status)) {
                goto ErrorReleaseVad;
            }

            //
            // Calculate the ending address based on the top address.
            //

            EndingAddress = (PVOID)(((ULONG_PTR)StartingAddress +
                                  CapturedRegionSize - 1L) | (PAGE_SIZE - 1L));

            if (EndingAddress > TopAddress) {

                //
                // The allocation does not honor the zero bits argument.
                //

                Status = STATUS_NO_MEMORY;
                goto ErrorReleaseVad;
            }
        }
        else {

            //
            // See if a VAD overlaps with this starting/ending address pair.
            //

            if (MiCheckForConflictingVadExistence (Process, StartingAddress, EndingAddress) == TRUE) {

                Status = STATUS_CONFLICTING_ADDRESSES;
                goto ErrorReleaseVad;
            }
        }

        //
        // An unoccupied address range has been found, finish initializing
        // the virtual address descriptor to describe this range, then
        // insert it into the tree.
        //

        Vad->StartingVpn = MI_VA_TO_VPN (StartingAddress);
        Vad->EndingVpn = MI_VA_TO_VPN (EndingAddress);

        LOCK_WS_UNSAFE (Process);

        Status = MiInsertVad (Vad);

        if (!NT_SUCCESS(Status)) {

            UNLOCK_WS_UNSAFE (Process);

ErrorReleaseVad:

            //
            // The quota charge in InsertVad failed, deallocate the pool
            // and return an error.
            //

            UNLOCK_ADDRESS_SPACE (Process);

            ExFreePool (Vad);

            if (AllocationType & MEM_PHYSICAL) {
                ExFreePool (PhysicalView);
            }
            else if (BitMapSize != 0) {
                ExFreePool (PhysicalView);
                ExFreePool (BitMap);
                PsReturnProcessNonPagedPoolQuota (Process, BitMapSize);
            }

            goto ErrorReturn1;
        }

        //
        // Initialize page directory and table pages for the physical range.
        //

        if (AllocationType & MEM_PHYSICAL) {

            if (MiCreatePageTablesForPhysicalRange (Process,
                                                    StartingAddress,
                                                    EndingAddress) == FALSE) {

                PreviousVad = MiGetPreviousVad (Vad);
                NextVad = MiGetNextVad (Vad);

                MiRemoveVad (Vad);

                //
                // Return commitment for page table pages if possible.
                //

                MiReturnPageTablePageCommitment (StartingAddress,
                                                 EndingAddress,
                                                 Process,
                                                 PreviousVad,
                                                 NextVad);

                UNLOCK_WS_AND_ADDRESS_SPACE (Process);
                ExFreePool (Vad);
                ExFreePool (PhysicalView);
                Status = STATUS_INSUFFICIENT_RESOURCES;
                goto ErrorReturn1;
            }

            PhysicalView->StartVa = StartingAddress;
            PhysicalView->EndVa = EndingAddress;

            //
            // Insert the physical view into this process' list using a
            // nonpaged wrapper since the PFN lock is required.
            //

            ASSERT (PhysicalView->u.LongFlags == MI_PHYSICAL_VIEW_AWE);
            MiAweViewInserter (Process, PhysicalView);
        }
        else if (BitMapSize != 0) {

            PhysicalView->StartVa = StartingAddress;
            PhysicalView->EndVa = EndingAddress;

            MiPhysicalViewInserter (Process, PhysicalView);
        }

        //
        // Unlock the working set lock, page faults can now be taken.
        //

        UNLOCK_WS_UNSAFE (Process);

        //
        // Update the current virtual size in the process header, the
        // address space lock protects this operation.
        //

        CapturedRegionSize = (PCHAR)EndingAddress - (PCHAR)StartingAddress + 1L;
        Process->VirtualSize += CapturedRegionSize;

        if (Process->VirtualSize > Process->PeakVirtualSize) {
            Process->PeakVirtualSize = Process->VirtualSize;
        }

#if defined(_MIALT4K_)

        if (Process->Wow64Process != NULL) {

            if (OriginalBase == NULL) {

                OriginalRegionSize = ROUND_TO_4K_PAGES(OriginalRegionSize);

                EndingAddress =  (PVOID)(((ULONG_PTR) StartingAddress +
                                OriginalRegionSize - 1L) | (PAGE_4K - 1L));

            }
            else {

                EndingAddress = (PVOID)(((ULONG_PTR)OriginalBase +
                                OriginalRegionSize - 1L) | (PAGE_4K - 1L));
            }

            CapturedRegionSize = (PCHAR)EndingAddress - (PCHAR)StartingAddress + 1L;

            //
            // Set the alternate permission table
            //

            AltFlags = (AllocationType & MEM_COMMIT) ? ALT_COMMIT : 0;

            MiProtectFor4kPage (StartingAddress,
                                CapturedRegionSize,
                                ProtectionMask,
                                ALT_ALLOCATE|AltFlags,
                                Process);
        }

#endif

        //
        // Release the address space lock, lower IRQL, detach, and dereference
        // the process object.
        //

        UNLOCK_ADDRESS_SPACE(Process);
        if (Attached == TRUE) {
            KeUnstackDetachProcess (&ApcState);
        }

        if (ProcessHandle != NtCurrentProcess()) {
            ObDereferenceObject (Process);
        }

        //
        // Establish an exception handler and write the size and base
        // address.
        //

        try {

            *RegionSize = CapturedRegionSize;
            *BaseAddress = StartingAddress;

        } except (EXCEPTION_EXECUTE_HANDLER) {

            //
            // Return success at this point even if the results
            // cannot be written.
            //

            NOTHING;
        }

        return STATUS_SUCCESS;
    }

    //
    // Commit previously reserved pages.  Note that these pages could
    // be either private or a section.
    //

    if (AllocationType == MEM_RESET) {

        //
        // Round up to page boundaries so good data is not reset.
        //

        EndingAddress = (PVOID)((ULONG_PTR)PAGE_ALIGN ((ULONG_PTR)CapturedBase +
                                    CapturedRegionSize) - 1);
        StartingAddress = (PVOID)PAGE_ALIGN((PUCHAR)CapturedBase + PAGE_SIZE - 1);
        if (StartingAddress > EndingAddress) {
            Status = STATUS_CONFLICTING_ADDRESSES;
            goto ErrorReturn1;
        }
    }
    else {
        EndingAddress = (PVOID)(((ULONG_PTR)CapturedBase +
                                CapturedRegionSize - 1) | (PAGE_SIZE - 1));
        StartingAddress = (PVOID)PAGE_ALIGN(CapturedBase);
    }

    CapturedRegionSize = (PCHAR)EndingAddress - (PCHAR)StartingAddress + 1;

    LOCK_ADDRESS_SPACE (Process);

    //
    // Make sure the address space was not deleted, if so,
    // return an error.
    //

    if (Process->Flags & PS_PROCESS_FLAGS_VM_DELETED) {
        Status = STATUS_PROCESS_IS_TERMINATING;
        goto ErrorReturn0;
    }

    FoundVad = MiCheckForConflictingVad (Process, StartingAddress, EndingAddress);

    if (FoundVad == NULL) {

        //
        // No virtual address is reserved at the specified base address,
        // return an error.
        //

        Status = STATUS_CONFLICTING_ADDRESSES;
        goto ErrorReturn0;
    }

    if (FoundVad->u.VadFlags.UserPhysicalPages == 1) {
        Status = STATUS_CONFLICTING_ADDRESSES;
        goto ErrorReturn0;
    }

    //
    // Ensure that the starting and ending addresses are all within
    // the same virtual address descriptor.
    //

    if ((MI_VA_TO_VPN (StartingAddress) < FoundVad->StartingVpn) ||
        (MI_VA_TO_VPN (EndingAddress) > FoundVad->EndingVpn)) {

        //
        // Not within the section virtual address descriptor,
        // return an error.
        //

        Status = STATUS_CONFLICTING_ADDRESSES;
        goto ErrorReturn0;
    }

    if (FoundVad->u.VadFlags.CommitCharge == MM_MAX_COMMIT) {

        //
        // This is a special VAD, don't let any commits occur.
        //

        Status = STATUS_CONFLICTING_ADDRESSES;
        goto ErrorReturn0;
    }

#if defined(_MIALT4K_)

    WowProcess = Process->Wow64Process;
    OriginalProtectionMask = 0;

    if (WowProcess != NULL) {

        OriginalProtectionMask = MiMakeProtectionMask (Protect);

        if (OriginalProtectionMask == MM_INVALID_PROTECTION) {
            Status = STATUS_INVALID_PAGE_PROTECTION;
            goto ErrorReturn0;
        }

        if (StartingAddress >= (PVOID)MM_MAX_WOW64_ADDRESS) {
            Status = STATUS_CONFLICTING_ADDRESSES;
            goto ErrorReturn0;
        }

        //
        // If protection changes on this region are allowed then proceed.
        //

        if (FoundVad->u.VadFlags.NoChange == 0) {

            NativePageProtection = MiMakeProtectForNativePage (StartingAddress,
                                                               Protect,
                                                               Process);

            ProtectionMask = MiMakeProtectionMask (NativePageProtection);

            if (ProtectionMask == MM_INVALID_PROTECTION) {
                Status = STATUS_INVALID_PAGE_PROTECTION;
                goto ErrorReturn0;
            }
        }
    }

#endif

    if (AllocationType == MEM_RESET) {

        LOCK_WS_UNSAFE (Process);

        Status = MiResetVirtualMemory (StartingAddress,
                                       EndingAddress,
                                       FoundVad,
                                       Process);

        UNLOCK_WS_AND_ADDRESS_SPACE (Process);
        goto done;
    }

    if (FoundVad->u.VadFlags.PrivateMemory == 0) {

        Status = STATUS_SUCCESS;

        //
        // The no cache option is not allowed for sections.
        //

        if (Protect & PAGE_NOCACHE) {
            Status = STATUS_INVALID_PAGE_PROTECTION;
            goto ErrorReturn0;
        }

        if (FoundVad->u.VadFlags.NoChange == 1) {

            //
            // An attempt is made at changing the protection
            // of a SEC_NO_CHANGE section.
            //

            Status = MiCheckSecuredVad (FoundVad,
                                        CapturedBase,
                                        CapturedRegionSize,
                                        ProtectionMask);

            if (!NT_SUCCESS (Status)) {
                goto ErrorReturn0;
            }
        }

        if (FoundVad->ControlArea->FilePointer != NULL) {
            if (FoundVad->u2.VadFlags2.ExtendableFile == 0) {

                //
                // Only page file backed sections can be committed.
                //

                Status = STATUS_ALREADY_COMMITTED;
                goto ErrorReturn0;
            }

            //
            // Commit the requested portions of the extendable file.
            //

            RtlZeroMemory (&Section, sizeof(SECTION));
            ControlArea = FoundVad->ControlArea;
            Section.Segment = ControlArea->Segment;
            Section.u.LongFlags = ControlArea->u.LongFlags;
            Section.InitialPageProtection = PAGE_READWRITE;
            NewSize.QuadPart = FoundVad->u2.VadFlags2.FileOffset;
            NewSize.QuadPart = NewSize.QuadPart << 16;
            NewSize.QuadPart += 1 +
                   ((PCHAR)EndingAddress - (PCHAR)MI_VPN_TO_VA (FoundVad->StartingVpn));
        
            //
            // The working set and address space mutexes must be
            // released prior to calling MmExtendSection otherwise
            // a deadlock with the filesystem can occur.
            //
            // Prevent the control area from being deleted while
            // the (potential) extension is ongoing.
            //

            MiFlushAcquire (ControlArea);

            UNLOCK_ADDRESS_SPACE (Process);
            
            Status = MmExtendSection (&Section, &NewSize, FALSE);
        
            MiFlushRelease (ControlArea);

            if (NT_SUCCESS(Status)) {

                LOCK_ADDRESS_SPACE (Process);

                //
                // The Vad and/or the control area may have been changed
                // or deleted before the mutexes were regained above.
                // So everything must be revalidated.  Note that
                // if anything has changed, success is silently
                // returned just as if the protection change had failed.
                // It is the caller's fault if any of these has gone
                // away and they will suffer.
                //

                if (Process->Flags & PS_PROCESS_FLAGS_VM_DELETED) {
                    // Status = STATUS_PROCESS_IS_TERMINATING;
                    goto ErrorReturn0;
                }

                FoundVad = MiCheckForConflictingVad (Process,
                                                     StartingAddress,
                                                     EndingAddress);
        
                if (FoundVad == NULL) {
        
                    //
                    // No virtual address is reserved at the specified
                    // base address, return an error.
                    //
                    // Status = STATUS_CONFLICTING_ADDRESSES;

                    goto ErrorReturn0;
                }
        
                if (ControlArea != FoundVad->ControlArea) {
                    goto ErrorReturn0;
                }

                if (FoundVad->u.VadFlags.UserPhysicalPages == 1) {
                    // Status = STATUS_CONFLICTING_ADDRESSES;

                    goto ErrorReturn0;
                }
        
                if (FoundVad->u.VadFlags.CommitCharge == MM_MAX_COMMIT) {
                    //
                    // This is a special VAD, no commits are allowed.
                    //
                    // Status = STATUS_CONFLICTING_ADDRESSES;

                    goto ErrorReturn0;
                }
        
                //
                // Ensure that the starting and ending addresses are
                // all within the same virtual address descriptor.
                //
        
                if ((MI_VA_TO_VPN (StartingAddress) < FoundVad->StartingVpn) ||
                    (MI_VA_TO_VPN (EndingAddress) > FoundVad->EndingVpn)) {
        
                    //
                    // Not within the section virtual address
                    // descriptor, return an error.
                    //
                    // Status = STATUS_CONFLICTING_ADDRESSES;

                    goto ErrorReturn0;
                }

                if (FoundVad->u.VadFlags.NoChange == 1) {
    
                    //
                    // An attempt is made at changing the protection
                    // of a SEC_NO_CHANGE section.
                    //
    
                    NTSTATUS Status2;

                    Status2 = MiCheckSecuredVad (FoundVad,
                                                 CapturedBase,
                                                 CapturedRegionSize,
                                                 ProtectionMask);
    
                    if (!NT_SUCCESS (Status2)) {
                        goto ErrorReturn0;
                    }
                }
    
                if (FoundVad->ControlArea->FilePointer == NULL) {
                    goto ErrorReturn0;
                }

                if (FoundVad->u2.VadFlags2.ExtendableFile == 0) {
                    goto ErrorReturn0;
                }

#if defined(_MIALT4K_)

                if (WowProcess != NULL) {

                   StartingAddressFor4k = (PVOID)PAGE_4K_ALIGN(OriginalBase);

                   EndingAddressFor4k = (PVOID)(((ULONG_PTR)OriginalBase +
                                         OriginalRegionSize - 1) | (PAGE_4K - 1));

                   CapturedRegionSizeFor4k = (ULONG_PTR)EndingAddressFor4k -
                                        (ULONG_PTR)StartingAddressFor4k + 1L;

                   if ((FoundVad->u.VadFlags.ImageMap == 1) ||
                       (FoundVad->u2.VadFlags2.CopyOnWrite == 1)) {

                       //
                       // Only set the MM_PROTECTION_COPY_MASK if the new protection includes
                       // MM_PROTECTION_WRITE_MASK, otherwise, it will be considered as MM_READ
                       // inside MiProtectFor4kPage().
                       //

                       if ((OriginalProtectionMask & MM_PROTECTION_WRITE_MASK) == MM_PROTECTION_WRITE_MASK) {
                           OriginalProtectionMask |= MM_PROTECTION_COPY_MASK;
                       }
                   }

                   MiProtectFor4kPage (StartingAddressFor4k,
                                       CapturedRegionSizeFor4k,
                                       OriginalProtectionMask,
                                       ALT_COMMIT,
                                       Process);
                }
#endif

                MiSetProtectionOnSection (Process,
                                          FoundVad,
                                          StartingAddress,
                                          EndingAddress,
                                          Protect,
                                          &OldProtect,
                                          TRUE,
                                          &Locked);

                //
                //      ***  WARNING ***
                //
                // The alternate PTE support routines called by
                // MiSetProtectionOnSection may have deleted the old (small)
                // VAD and replaced it with a different (large) VAD - if so,
                // the old VAD is freed and cannot be referenced.
                //

                UNLOCK_ADDRESS_SPACE (Process);
            }

            goto ErrorReturn1;
        }

        StartingPte = MiGetProtoPteAddress (FoundVad,
                                            MI_VA_TO_VPN(StartingAddress));
        LastPte = MiGetProtoPteAddress (FoundVad,
                                        MI_VA_TO_VPN(EndingAddress));

#if 0
        if (AllocationType & MEM_CHECK_COMMIT_STATE) {

            //
            // Make sure none of the pages are already committed.
            //

            ExAcquireFastMutexUnsafe (&MmSectionCommitMutex);

            PointerPte = StartingPte;

            while (PointerPte <= LastPte) {

                //
                // Check to see if the prototype PTE is committed.
                // Note that prototype PTEs cannot be decommitted so
                // the PTEs only need to be checked for zeroes.
                //

                if (PointerPte->u.Long != 0) {
                    ExReleaseFastMutexUnsafe (&MmSectionCommitMutex);
                    UNLOCK_ADDRESS_SPACE (Process);
                    Status = STATUS_ALREADY_COMMITTED;
                    goto ErrorReturn1;
                }
                PointerPte += 1;
            }

            ExReleaseFastMutexUnsafe (&MmSectionCommitMutex);
        }

#endif //0

        //
        // Check to ensure these pages can be committed if this
        // is a page file backed segment.  Note that page file quota
        // has already been charged for this.
        //

        PointerPte = StartingPte;
        QuotaCharge = 1 + LastPte - StartingPte;

        CopyOnWriteCharge = 0;

        if (MI_IS_PTE_PROTECTION_COPY_WRITE(ProtectionMask)) {

            //
            // If the protection is copy on write, charge for
            // the copy on writes.
            //

            CopyOnWriteCharge = QuotaCharge;
        }

        //
        // Charge commitment for the range.
        //

        ChargedExactQuota = FALSE;
        ChargedJobCommit = FALSE;

        if (CopyOnWriteCharge != 0) {

            Status = PsChargeProcessPageFileQuota (Process, CopyOnWriteCharge);

            if (!NT_SUCCESS (Status)) {
                UNLOCK_ADDRESS_SPACE (Process);
                goto ErrorReturn1;
            }

            //
            // Note this job charging is unusual because it is not
            // followed by an immediate process charge.
            //

            if (Process->CommitChargeLimit) {
                if (Process->CommitCharge + CopyOnWriteCharge > Process->CommitChargeLimit) {
                    if (Process->Job) {
                        PsReportProcessMemoryLimitViolation ();
                    }
                    UNLOCK_ADDRESS_SPACE (Process);
                    PsReturnProcessPageFileQuota (Process, CopyOnWriteCharge);
                    Status = STATUS_COMMITMENT_LIMIT;
                    goto ErrorReturn1;
                }
            }

            if (Process->JobStatus & PS_JOB_STATUS_REPORT_COMMIT_CHANGES) {
                if (PsChangeJobMemoryUsage(CopyOnWriteCharge) == FALSE) {
                    UNLOCK_ADDRESS_SPACE (Process);
                    PsReturnProcessPageFileQuota (Process, CopyOnWriteCharge);
                    Status = STATUS_COMMITMENT_LIMIT;
                    goto ErrorReturn1;
                }
                ChargedJobCommit = TRUE;
            }
        }

        do {
            if (MiChargeCommitment (QuotaCharge + CopyOnWriteCharge, NULL) == TRUE) {
                break;
            }

            //
            // Reduce the charge we are asking for if possible.
            //

            if (ChargedExactQuota == TRUE) {

                //
                // We have already tried for the precise charge,
                // so just return an error.
                //

                ExReleaseFastMutexUnsafe (&MmSectionCommitMutex);

                if (CopyOnWriteCharge != 0) {

                    if (ChargedJobCommit == TRUE) {
                        PsChangeJobMemoryUsage (-(SSIZE_T)CopyOnWriteCharge);
                    }
                    UNLOCK_ADDRESS_SPACE (Process);
                    PsReturnProcessPageFileQuota (Process, CopyOnWriteCharge);
                }
                else {
                    UNLOCK_ADDRESS_SPACE (Process);
                }
                Status = STATUS_COMMITMENT_LIMIT;
                goto ErrorReturn1;
            }

            //
            // The commitment charging of quota failed, calculate the
            // exact quota taking into account pages that may already be
            // committed and retry the operation.
            //

            ExAcquireFastMutexUnsafe (&MmSectionCommitMutex);

            while (PointerPte <= LastPte) {

                //
                // Check to see if the prototype PTE is committed.
                // Note that prototype PTEs cannot be decommitted so
                // PTEs only need to be checked for zeroes.
                //

                if (PointerPte->u.Long != 0) {
                    QuotaCharge -= 1;
                }
                PointerPte += 1;
            }

            PointerPte = StartingPte;

            ChargedExactQuota = TRUE;

            //
            // If the entire range is committed then there's nothing to charge.
            //

            if (QuotaCharge + CopyOnWriteCharge == 0) {
                ExReleaseFastMutexUnsafe (&MmSectionCommitMutex);
                QuotaFree = 0;
                goto FinishedCharging;
            }

        } while (TRUE);

        if (ChargedExactQuota == FALSE) {
            ExAcquireFastMutexUnsafe (&MmSectionCommitMutex);
        }

        //
        // Commit all the pages.
        //

        Segment = FoundVad->ControlArea->Segment;
        TempPte = Segment->SegmentPteTemplate;
        ASSERT (TempPte.u.Long != 0);

        QuotaFree = 0;

        while (PointerPte <= LastPte) {

            if (PointerPte->u.Long != 0) {

                //
                // Page is already committed, back out commitment.
                //

                QuotaFree += 1;
            }
            else {
                MI_WRITE_INVALID_PTE (PointerPte, TempPte);
            }
            PointerPte += 1;
        }

        //
        // Subtract out any excess, then update the segment charges.
        // Note only segment commit is excess - process commit must
        // remain fully charged.
        //

        if (ChargedExactQuota == FALSE) {
            ASSERT (QuotaCharge >= QuotaFree);
            QuotaCharge -= QuotaFree;

            //
            // Return the QuotaFree excess commitment after the
            // mutexes are released to remove needless contention.
            //
        }
        else {

            //
            // Exact quota was charged so zero this to signify
            // there is no excess to return.
            //

            QuotaFree = 0;
        }

        if (QuotaCharge != 0) {
            Segment->NumberOfCommittedPages += QuotaCharge;
            InterlockedExchangeAddSizeT (&MmSharedCommit, QuotaCharge);

            MM_TRACK_COMMIT (MM_DBG_COMMIT_ALLOCVM_SEGMENT, QuotaCharge);
        }

        ExReleaseFastMutexUnsafe (&MmSectionCommitMutex);

        //
        // Update the per-process charges.
        //

        if (CopyOnWriteCharge != 0) {
            FoundVad->u.VadFlags.CommitCharge += CopyOnWriteCharge;
            Process->CommitCharge += CopyOnWriteCharge;

            MI_INCREMENT_TOTAL_PROCESS_COMMIT (CopyOnWriteCharge);

            if (Process->CommitCharge > Process->CommitChargePeak) {
                Process->CommitChargePeak = Process->CommitCharge;
            }

            MM_TRACK_COMMIT (MM_DBG_COMMIT_ALLOCVM_PROCESS, CopyOnWriteCharge);
        }

FinishedCharging:

#if defined(_MIALT4K_)

        //
        // Update the alternate table before PTEs are created
        // for the protection change.
        //

        if (WowProcess != NULL) {

            StartingAddressFor4k = (PVOID)PAGE_4K_ALIGN(OriginalBase);

            EndingAddressFor4k = (PVOID)(((ULONG_PTR)OriginalBase +
                                       OriginalRegionSize - 1) | (PAGE_4K - 1));

            CapturedRegionSizeFor4k = (ULONG_PTR)EndingAddressFor4k -
                (ULONG_PTR)StartingAddressFor4k + 1L;

            if ((FoundVad->u.VadFlags.ImageMap == 1) ||
                (FoundVad->u2.VadFlags2.CopyOnWrite == 1)) {

                //
                // Only set the MM_PROTECTION_COPY_MASK if the new protection includes
                // MM_PROTECTION_WRITE_MASK, otherwise, it will be considered as MM_READ
                // inside MiProtectFor4kPage().
                //

                if ((OriginalProtectionMask & MM_PROTECTION_WRITE_MASK) == MM_PROTECTION_WRITE_MASK) {
                    OriginalProtectionMask |= MM_PROTECTION_COPY_MASK;
                }

            }

            //
            // Set the alternate permission table.
            //

            MiProtectFor4kPage (StartingAddressFor4k,
                                CapturedRegionSizeFor4k,
                                OriginalProtectionMask,
                                ALT_COMMIT,
                                Process);
        }
        else {

            //
            // Initializing these is not needed for
            // correctness but without it the compiler cannot compile this code
            // W4 to check for use of uninitialized variables.
            //

            StartingAddressFor4k = NULL;
            CapturedRegionSizeFor4k = 0;
        }

#endif

        //
        // Change all the protections to be protected as specified.
        //

        MiSetProtectionOnSection (Process,
                                  FoundVad,
                                  StartingAddress,
                                  EndingAddress,
                                  Protect,
                                  &OldProtect,
                                  TRUE,
                                  &Locked);
    
        //
        //      ***  WARNING ***
        //
        // The alternate PTE support routines called by
        // MiSetProtectionOnSection may have deleted the old (small)
        // VAD and replaced it with a different (large) VAD - if so,
        // the old VAD is freed and cannot be referenced.
        //

        UNLOCK_ADDRESS_SPACE (Process);

        //
        // Return any excess segment commit that may have been charged.
        //

        if (QuotaFree != 0) {
            MiReturnCommitment (QuotaFree);
            MM_TRACK_COMMIT (MM_DBG_COMMIT_RETURN_ALLOCVM_SEGMENT, QuotaFree);
        }

        if (Attached == TRUE) {
            KeUnstackDetachProcess (&ApcState);
        }

        if (ProcessHandle != NtCurrentProcess()) {
            ObDereferenceObject (Process);
        }

#if defined(_MIALT4K_)
        if (WowProcess != NULL) {
            CapturedRegionSize = CapturedRegionSizeFor4k;
            StartingAddress = StartingAddressFor4k;
        }
#endif

        try {
            *RegionSize = CapturedRegionSize;
            *BaseAddress = StartingAddress;

        } except (EXCEPTION_EXECUTE_HANDLER) {

            //
            // Return success at this point even if the results
            // cannot be written.
            //

            NOTHING;
        }

        return STATUS_SUCCESS;
    }

    //
    // PAGE_WRITECOPY is not valid for private pages.
    //

    if ((Protect & PAGE_WRITECOPY) ||
        (Protect & PAGE_EXECUTE_WRITECOPY)) {
        Status = STATUS_INVALID_PAGE_PROTECTION;
        goto ErrorReturn0;
    }

    //
    // Ensure none of the pages are already committed as described
    // in the virtual address descriptor.
    //
#if 0
    if (AllocationType & MEM_CHECK_COMMIT_STATE) {
        if ( !MiIsEntireRangeDecommitted(StartingAddress,
                                         EndingAddress,
                                         FoundVad,
                                         Process)) {

            //
            // Previously reserved pages have been committed, or
            // an error occurred, release mutex and return status.
            //

            Status = STATUS_ALREADY_COMMITTED;
            goto ErrorReturn0;
        }
    }
#endif //0

    //
    // Build a demand zero PTE with the proper protection.
    //

    TempPte = ZeroPte;
    TempPte.u.Soft.Protection = ProtectionMask;

    DecommittedPte = ZeroPte;
    DecommittedPte.u.Soft.Protection = MM_DECOMMIT;

    if (FoundVad->u.VadFlags.MemCommit) {
        CommitLimitPte = MiGetPteAddress (MI_VPN_TO_VA (FoundVad->EndingVpn));
    }
    else {
        CommitLimitPte = NULL;
    }

    //
    // The address range has not been committed, commit it now.
    // Note that for private pages, commitment is handled by
    // explicitly updating PTEs to contain Demand Zero entries.
    //

    PointerPde = MiGetPdeAddress (StartingAddress);
    PointerPte = MiGetPteAddress (StartingAddress);
    LastPte = MiGetPteAddress (EndingAddress);

    //
    // Check to ensure these pages can be committed.
    //

    QuotaCharge = 1 + LastPte - PointerPte;

    //
    // Charge quota and commitment for the range.
    //

    ChargedExactQuota = FALSE;

    do {

        ChargedJobCommit = FALSE;

        if (Process->CommitChargeLimit) {
            if (Process->CommitCharge + QuotaCharge > Process->CommitChargeLimit) {
                if (Process->Job) {
                    PsReportProcessMemoryLimitViolation ();
                }
                Status = STATUS_COMMITMENT_LIMIT;
                goto Failed;
            }
        }
        if (Process->JobStatus & PS_JOB_STATUS_REPORT_COMMIT_CHANGES) {
            if (PsChangeJobMemoryUsage(QuotaCharge) == FALSE) {
                Status = STATUS_COMMITMENT_LIMIT;
                goto Failed;
            }
            ChargedJobCommit = TRUE;
        }

        if (MiChargeCommitment (QuotaCharge, NULL) == FALSE) {
            Status = STATUS_COMMITMENT_LIMIT;
            goto Failed;
        }

        Status = PsChargeProcessPageFileQuota (Process, QuotaCharge);
        if (!NT_SUCCESS (Status)) {
            MiReturnCommitment (QuotaCharge);
            goto Failed;
        }

        MM_TRACK_COMMIT (MM_DBG_COMMIT_ALLOCVM_PROCESS2, QuotaCharge);

        FoundVad->u.VadFlags.CommitCharge += QuotaCharge;
        Process->CommitCharge += QuotaCharge;

        MI_INCREMENT_TOTAL_PROCESS_COMMIT (QuotaCharge);

        if (Process->CommitCharge > Process->CommitChargePeak) {
            Process->CommitChargePeak = Process->CommitCharge;
        }

        //
        // Successful so break out now.
        //

        break;

Failed:
        //
        // Charging of commitment failed.  Release the held mutexes and return
        // the failure status to the user.
        //

        if (ChargedJobCommit == TRUE) {
            PsChangeJobMemoryUsage (0 - QuotaCharge);
        }

        if (ChargedExactQuota == TRUE) {

            //
            // We have already tried for the precise charge,
            // return an error.
            //

            goto ErrorReturn;
        }

        LOCK_WS_UNSAFE (Process);

        //
        // Quota charge failed, calculate the exact quota
        // taking into account pages that may already be
        // committed, subtract this from the total and retry the operation.
        //

        QuotaFree = MiCalculatePageCommitment (StartingAddress,
                                               EndingAddress,
                                               FoundVad,
                                               Process);

        if (QuotaFree == 0) {
            goto ErrorReturn;
        }

        ChargedExactQuota = TRUE;
        QuotaCharge -= QuotaFree;
        ASSERT ((SSIZE_T)QuotaCharge >= 0);

        if (QuotaCharge == 0) {

            //
            // All the pages are already committed so just march on.
            // Explicitly set status to success as code above may have
            // generated a failure status when overcharging.
            //

            Status = STATUS_SUCCESS;
            break;
        }

    } while (TRUE);

    QuotaFree = 0;

    if (ChargedExactQuota == FALSE) {
        LOCK_WS_UNSAFE (Process);
    }

    //
    // Fill in all the page directory and page table pages with the
    // demand zero PTE.
    //

    MiMakePdeExistAndMakeValid (PointerPde, Process, FALSE);

    while (PointerPte <= LastPte) {

        if (MiIsPteOnPdeBoundary (PointerPte)) {

            PointerPde = MiGetPteAddress (PointerPte);

            //
            // Pointing to the next page table page, make
            // a page table page exist and make it valid.
            //

            MiMakePdeExistAndMakeValid (PointerPde, Process, FALSE);
        }

        if (PointerPte->u.Long == 0) {

            if (PointerPte <= CommitLimitPte) {

                //
                // This page is implicitly committed.
                //

                QuotaFree += 1;

            }

            //
            // Increment the count of non-zero page table entries
            // for this page table and the number of private pages
            // for the process.
            //

            Va = MiGetVirtualAddressMappedByPte (PointerPte);
            UsedPageTableHandle = MI_GET_USED_PTES_HANDLE (Va);

            MI_INCREMENT_USED_PTES_BY_HANDLE (UsedPageTableHandle);

            MI_WRITE_INVALID_PTE (PointerPte, TempPte);
        }
        else {
            if (PointerPte->u.Long == DecommittedPte.u.Long) {

                //
                // Only commit the page if it is already decommitted.
                //

                MI_WRITE_INVALID_PTE (PointerPte, TempPte);
            }
            else {
                QuotaFree += 1;

                //
                // Make sure the protection for the page is right.
                //

                if (!ChangeProtection &&
                    (Protect != MiGetPageProtection (PointerPte,
                                                     Process,
                                                     FALSE))) {
                    ChangeProtection = TRUE;
                }
            }
        }
        PointerPte += 1;
    }

    UNLOCK_WS_UNSAFE (Process);

#if defined(_MIALT4K_)

    if (WowProcess != NULL) {

        StartingAddress = (PVOID) PAGE_4K_ALIGN(OriginalBase);

        EndingAddress = (PVOID)(((ULONG_PTR)OriginalBase +
                                OriginalRegionSize - 1) | (PAGE_4K - 1));

        CapturedRegionSize = (ULONG_PTR)EndingAddress -
                                  (ULONG_PTR)StartingAddress + 1L;

        //
        // Update the alternate permission table.
        //

        MiProtectFor4kPage (StartingAddress,
                            CapturedRegionSize,
                            OriginalProtectionMask,
                            ALT_COMMIT,
                            Process);
    }
#endif

    if ((ChargedExactQuota == FALSE) && (QuotaFree != 0)) {

        FoundVad->u.VadFlags.CommitCharge -= QuotaFree;
        ASSERT ((LONG_PTR)FoundVad->u.VadFlags.CommitCharge >= 0);
        Process->CommitCharge -= QuotaFree;
        UNLOCK_ADDRESS_SPACE (Process);

        MI_INCREMENT_TOTAL_PROCESS_COMMIT (0 - QuotaFree);

        MiReturnCommitment (QuotaFree);
        MM_TRACK_COMMIT (MM_DBG_COMMIT_RETURN_ALLOCVM2, QuotaFree);

        PsReturnProcessPageFileQuota (Process, QuotaFree);
        if (ChargedJobCommit) {
            PsChangeJobMemoryUsage (-(SSIZE_T)QuotaFree);
        }
    }
    else {
        UNLOCK_ADDRESS_SPACE (Process);
    }

    //
    // Previously reserved pages have been committed or an error occurred.
    // Detach, dereference process and return status.
    //

done:

    if (ChangeProtection) {
        PVOID Start;
        SIZE_T Size;
        ULONG LastProtect;

        Start = StartingAddress;
        Size = CapturedRegionSize;
        MiProtectVirtualMemory (Process,
                                &Start,
                                &Size,
                                Protect,
                                &LastProtect);
    }

    if (Attached == TRUE) {
        KeUnstackDetachProcess (&ApcState);
    }

    if (ProcessHandle != NtCurrentProcess()) {
        ObDereferenceObject (Process);
    }

    //
    // Establish an exception handler and write the size and base
    // address.
    //

    try {

        *RegionSize = CapturedRegionSize;
        *BaseAddress = StartingAddress;

    } except (EXCEPTION_EXECUTE_HANDLER) {
        return GetExceptionCode();
    }

    return Status;

ErrorReturn:
        UNLOCK_WS_UNSAFE (Process);

ErrorReturn0:
        UNLOCK_ADDRESS_SPACE (Process);

ErrorReturn1:
        if (Attached == TRUE) {
            KeUnstackDetachProcess (&ApcState);
        }
        if (ProcessHandle != NtCurrentProcess()) {
            ObDereferenceObject (Process);
        }
        return Status;
}

NTSTATUS
MiResetVirtualMemory (
    IN PVOID StartingAddress,
    IN PVOID EndingAddress,
    IN PMMVAD Vad,
    IN PEPROCESS Process
    )

/*++

Routine Description:


Arguments:

    StartingAddress - Supplies the starting address of the range.

    RegionsSize - Supplies the size.

    Process - Supplies the current process.

Return Value:

Environment:

    Kernel mode, APCs disabled, WorkingSetMutex and AddressCreation mutexes
    held.

--*/

{
    PMMPTE PointerPte;
    PMMPTE ProtoPte;
    PMMPTE PointerPde;
    PMMPTE PointerPpe;
    PMMPTE PointerPxe;
    PMMPTE LastPte;
    MMPTE PteContents;
    ULONG Waited;
    LOGICAL PfnHeld;
    ULONG First;
    KIRQL OldIrql;
    PMMPFN Pfn1;
    PMMCLONE_BLOCK CloneBlock;
    PMMCLONE_DESCRIPTOR CloneDescriptor;

    if (Vad->u.VadFlags.PrivateMemory == 0) {

        if (Vad->ControlArea->FilePointer != NULL) {

            //
            // Only page file backed sections can be committed.
            //

            return STATUS_USER_MAPPED_FILE;
        }
    }

    PfnHeld = FALSE;

    //
    // Initializing OldIrql is not needed for correctness, but without it
    // the compiler cannot compile this code W4 to check for use of
    // uninitialized variables.
    //

    OldIrql = PASSIVE_LEVEL;

    First = TRUE;
    PointerPte = MiGetPteAddress (StartingAddress);
    LastPte = MiGetPteAddress (EndingAddress);

    MmLockPagableSectionByHandle (ExPageLockHandle);

    //
    // Examine all the PTEs in the range.
    //

    while (PointerPte <= LastPte) {

        if (MiIsPteOnPdeBoundary (PointerPte) || (First)) {

            if (MiIsPteOnPpeBoundary (PointerPte)) {

                if (MiIsPteOnPxeBoundary (PointerPte)) {

                    PointerPxe = MiGetPpeAddress (PointerPte);

                    if (!MiDoesPxeExistAndMakeValid(PointerPxe,
                                                    Process,
                                                    PfnHeld,
                                                    &Waited)) {

                        //
                        // This extended page directory parent entry is empty,
                        // go to the next one.
                        //

                        PointerPxe += 1;
                        PointerPpe = MiGetVirtualAddressMappedByPte (PointerPxe);
                        PointerPde = MiGetVirtualAddressMappedByPte (PointerPpe);
                        PointerPte = MiGetVirtualAddressMappedByPte (PointerPde);
                        continue;
                    }
                }

                PointerPpe = MiGetPdeAddress (PointerPte);

                if (!MiDoesPpeExistAndMakeValid(PointerPpe,
                                                Process,
                                                PfnHeld,
                                                &Waited)) {

                    //
                    // This page directory parent entry is empty,
                    // go to the next one.
                    //

                    PointerPpe += 1;
                    PointerPde = MiGetVirtualAddressMappedByPte (PointerPpe);
                    PointerPte = MiGetVirtualAddressMappedByPte (PointerPde);
                    continue;
                }
            }

            //
            // Pointing to the next page table page, make
            // a page table page exist and make it valid.
            //

            First = FALSE;
            PointerPde = MiGetPteAddress (PointerPte);
            if (!MiDoesPdeExistAndMakeValid(PointerPde,
                                            Process,
                                            PfnHeld,
                                            &Waited)) {

                //
                // This page directory entry is empty, go to the next one.
                //

                PointerPde += 1;
                PointerPte = MiGetVirtualAddressMappedByPte (PointerPde);
                continue;
            }
        }

        PteContents = *PointerPte;
        ProtoPte = NULL;

        if ((PteContents.u.Hard.Valid == 0) &&
            (PteContents.u.Soft.Prototype == 1))  {

            //
            // This is a prototype PTE, evaluate the prototype PTE.  Note that
            // the fact it is a prototype PTE does not guarantee that this is a
            // regular or long VAD - it may be a short VAD in a forked process,
            // so check PrivateMemory before referencing the FirstPrototypePte
            // field.
            //

            if ((Vad->u.VadFlags.PrivateMemory == 0) &&
                (Vad->FirstPrototypePte != NULL)) {
                    ProtoPte = MiGetProtoPteAddress(Vad,
                                            MI_VA_TO_VPN (
                                            MiGetVirtualAddressMappedByPte(PointerPte)));
            }
            else {
                CloneBlock = (PMMCLONE_BLOCK)MiPteToProto (PointerPte);
                ProtoPte = (PMMPTE) CloneBlock;
                CloneDescriptor = MiLocateCloneAddress (Process, (PVOID)CloneBlock);
                ASSERT (CloneDescriptor != NULL);
            }

            if (!PfnHeld) {
                PfnHeld = TRUE;
                LOCK_PFN (OldIrql);
            }

            //
            // The working set mutex may be released in order to make the
            // prototype PTE which resides in paged pool resident.  If this
            // occurs, the page directory and/or page table of the original
            // user address may get trimmed.  Account for that here.
            //

            if (MiMakeSystemAddressValidPfnWs (ProtoPte, Process) != 0) {

                //
                // Working set mutex was released, restart from the top.
                //

                First = TRUE;
                continue;
            }

            PteContents = *ProtoPte;
        }
        if (PteContents.u.Hard.Valid == 1) {
            if (!PfnHeld) {
                PfnHeld = TRUE;
                LOCK_PFN (OldIrql);
                continue;
            }

            Pfn1 = MI_PFN_ELEMENT (PteContents.u.Hard.PageFrameNumber);
            if (Pfn1->u3.e2.ReferenceCount == 1) {

                //
                // Only this process has the page mapped.
                //

                MI_SET_MODIFIED (Pfn1, 0, 0x20);
                MiReleasePageFileSpace (Pfn1->OriginalPte);
                Pfn1->OriginalPte.u.Soft.PageFileHigh = 0;
            }

            if ((!ProtoPte) && (MI_IS_PTE_DIRTY (PteContents))) {

                //
                // Clear the dirty bit and flush tb if it is NOT a prototype
                // PTE.
                //

                MI_SET_PTE_CLEAN (PteContents);
                KeFlushSingleTb (MiGetVirtualAddressMappedByPte (PointerPte),
                                 TRUE,
                                 FALSE,
                                 (PHARDWARE_PTE)PointerPte,
                                 PteContents.u.Flush);
            }

        }
        else if (PteContents.u.Soft.Transition == 1) {
            if (!PfnHeld) {
                PfnHeld = TRUE;
                LOCK_PFN (OldIrql);
                continue;
            }
            Pfn1 = MI_PFN_ELEMENT (PteContents.u.Trans.PageFrameNumber);
            if ((Pfn1->u3.e1.PageLocation == ModifiedPageList) &&
                (Pfn1->u3.e2.ReferenceCount == 0)) {

                //
                // Remove from the modified list, release the page
                // file space and insert on the standby list.
                //

                MI_SET_MODIFIED (Pfn1, 0, 0x21);
                MiUnlinkPageFromList (Pfn1);
                MiReleasePageFileSpace (Pfn1->OriginalPte);
                Pfn1->OriginalPte.u.Soft.PageFileHigh = 0;
                MiInsertPageInList (&MmStandbyPageListHead,
                                    MI_GET_PAGE_FRAME_FROM_TRANSITION_PTE(&PteContents));
            }
        }
        else {
            if (PteContents.u.Soft.PageFileHigh != 0) {
                if (!PfnHeld) {
                    LOCK_PFN (OldIrql);
                }
                MiReleasePageFileSpace (PteContents);
                if (ProtoPte) {
                    ProtoPte->u.Soft.PageFileHigh = 0;
                }
                UNLOCK_PFN (OldIrql);
                PfnHeld = FALSE;
                if (!ProtoPte) {
                    PointerPte->u.Soft.PageFileHigh = 0;
                }
            }
            else {
                if (PfnHeld) {
                    UNLOCK_PFN (OldIrql);
                }
                PfnHeld = FALSE;
            }
        }
        PointerPte += 1;
    }
    if (PfnHeld) {
        UNLOCK_PFN (OldIrql);
    }

    MmUnlockPagableImageSection (ExPageLockHandle);

    return STATUS_SUCCESS;
}

LOGICAL
MiCreatePageTablesForPhysicalRange (
    IN PEPROCESS Process,
    IN PVOID StartingAddress,
    IN PVOID EndingAddress
    )

/*++

Routine Description:

    This routine initializes page directory and page table pages for a
    user-controlled physical range of pages.

Arguments:

    Process - Supplies the current process.

    StartingAddress - Supplies the starting address of the range.

    EndingAddress - Supplies the ending address of the range.

Return Value:

    TRUE if the page tables were created, FALSE if not.

Environment:

    Kernel mode, APCs disabled, WorkingSetMutex and AddressCreation mutexes
    held.

--*/

{
    MMPTE PteContents;
    PMMPTE LastPte;
    PMMPTE LastPde;
    PMMPTE LastPpe;
    PMMPTE PointerPte;
    PMMPTE PointerPde;
    PMMPTE PointerPpe;
    PVOID UsedPageTableHandle;
    LOGICAL FirstTime;
    KIRQL OldIrql;
    PMMPFN Pfn1;
    PFN_NUMBER PagesNeeded;

    FirstTime = TRUE;
    PointerPpe = MiGetPpeAddress (StartingAddress);
    PointerPde = MiGetPdeAddress (StartingAddress);
    PointerPte = MiGetPteAddress (StartingAddress);
    LastPpe = MiGetPpeAddress (EndingAddress);
    LastPde = MiGetPdeAddress (EndingAddress);
    LastPte = MiGetPteAddress (EndingAddress);

    //
    // Charge resident available pages for all of the page directory and table
    // pages as they will not be paged until the VAD is freed.
    //

    if (LastPte != PointerPte) {
        PagesNeeded = MI_COMPUTE_PAGES_SPANNED (PointerPte,
                                                LastPte - PointerPte);

#if (_MI_PAGING_LEVELS >= 3)
        if (LastPde != PointerPde) {
            PagesNeeded += MI_COMPUTE_PAGES_SPANNED (PointerPde,
                                                     LastPde - PointerPde);
#if (_MI_PAGING_LEVELS >= 4)
            if (LastPpe != PointerPpe) {
                PagesNeeded += MI_COMPUTE_PAGES_SPANNED (PointerPpe,
                                                         LastPpe - PointerPpe);
            }
#endif
        }
#endif
    }
    else {
        PagesNeeded = 1;
#if (_MI_PAGING_LEVELS >= 3)
        PagesNeeded += 1;
#endif
#if (_MI_PAGING_LEVELS >= 4)
        PagesNeeded += 1;
#endif
    }

    MmLockPagableSectionByHandle (ExPageLockHandle);

    LOCK_PFN (OldIrql);

    if ((SPFN_NUMBER)PagesNeeded > MI_NONPAGABLE_MEMORY_AVAILABLE() - 20) {
        UNLOCK_PFN (OldIrql);
        MmUnlockPagableImageSection (ExPageLockHandle);
        return FALSE;
    }

    MmResidentAvailablePages -= PagesNeeded;
    MM_BUMP_COUNTER(58, PagesNeeded);
    UNLOCK_PFN (OldIrql);

    //
    // Initializing UsedPageTableHandle is not needed for correctness
    // but without it the compiler cannot compile this code
    // W4 to check for use of uninitialized variables.
    //

    UsedPageTableHandle = NULL;

    //
    // Fill in all the page table pages with the zero PTE.
    //

    while (PointerPte <= LastPte) {

        if (MiIsPteOnPdeBoundary (PointerPte) || FirstTime == TRUE) {

            PointerPde = MiGetPteAddress (PointerPte);

            //
            // Pointing to the next page table page, make
            // a page table page exist and make it valid.
            //
            // Note this ripples sharecounts through the paging hierarchy so
            // there is no need to up sharecounts to prevent trimming of the
            // page directory (and parent) page as making the page table
            // valid below does this automatically.
            //

            MiMakePdeExistAndMakeValid (PointerPde, Process, FALSE);

            //
            // Up the sharecount so the page table page will not get
            // trimmed even if it has no currently valid entries.
            //

            PteContents = *PointerPde;
            Pfn1 = MI_PFN_ELEMENT (PteContents.u.Hard.PageFrameNumber);
            LOCK_PFN (OldIrql);
            Pfn1->u2.ShareCount += 1;
            UNLOCK_PFN (OldIrql);

            FirstTime = FALSE;
            UsedPageTableHandle = MI_GET_USED_PTES_HANDLE (StartingAddress);
        }

        ASSERT (PointerPte->u.Long == 0);

        //
        // Increment the count of non-zero page table entries
        // for this page table - even though this entry is still zero,
        // this is a special case.
        //

        MI_INCREMENT_USED_PTES_BY_HANDLE (UsedPageTableHandle);

        PointerPte += 1;
        StartingAddress = (PVOID)((PUCHAR)StartingAddress + PAGE_SIZE);
    }
    MmUnlockPagableImageSection (ExPageLockHandle);
    return TRUE;
}

VOID
MiDeletePageTablesForPhysicalRange (
    IN PVOID StartingAddress,
    IN PVOID EndingAddress
    )

/*++

Routine Description:

    This routine deletes page directory and page table pages for a
    user-controlled physical range of pages.

    Even though PTEs may be zero in this range, UsedPageTable counts were
    incremented for these special ranges and must be decremented now.

Arguments:

    StartingAddress - Supplies the starting address of the range.

    EndingAddress - Supplies the ending address of the range.

Return Value:

    None.

Environment:

    Kernel mode, APCs disabled, WorkingSetMutex and AddressCreation mutexes
    held.

--*/

{
    PVOID TempVa;
    MMPTE PteContents;
    PMMPTE LastPte;
    PMMPTE LastPde;
    PMMPTE LastPpe;
    PMMPTE PointerPte;
    PMMPTE PointerPde;
    PFN_NUMBER PagesNeeded;
    PEPROCESS CurrentProcess;
    PVOID UsedPageTableHandle;
    KIRQL OldIrql;
    PMMPFN Pfn1;
    PMMPTE PointerPpe;
#if (_MI_PAGING_LEVELS >= 4)
    PMMPTE PointerPxe;
#endif

    CurrentProcess = PsGetCurrentProcess();

    PointerPpe = MiGetPpeAddress (StartingAddress);
    PointerPde = MiGetPdeAddress (StartingAddress);
    PointerPte = MiGetPteAddress (StartingAddress);
    LastPpe = MiGetPpeAddress (EndingAddress);
    LastPde = MiGetPdeAddress (EndingAddress);
    LastPte = MiGetPteAddress (EndingAddress);

    UsedPageTableHandle = MI_GET_USED_PTES_HANDLE (StartingAddress);

    //
    // Each PTE is already zeroed - just delete the containing pages.
    //
    // Restore resident available pages for all of the page directory and table
    // pages as they can now be paged again.
    //

    if (LastPte != PointerPte) {
        PagesNeeded = MI_COMPUTE_PAGES_SPANNED (PointerPte,
                                                LastPte - PointerPte);
#if (_MI_PAGING_LEVELS >= 3)
        if (LastPde != PointerPde) {
            PagesNeeded += MI_COMPUTE_PAGES_SPANNED (PointerPde,
                                                     LastPde - PointerPde);
#if (_MI_PAGING_LEVELS >= 4)
            if (LastPpe != PointerPpe) {
                PagesNeeded += MI_COMPUTE_PAGES_SPANNED (PointerPpe,
                                                         LastPpe - PointerPpe);
            }
#endif
        }
#endif
    }
    else {
        PagesNeeded = 1;
#if (_MI_PAGING_LEVELS >= 3)
        PagesNeeded += 1;
#endif
#if (_MI_PAGING_LEVELS >= 4)
        PagesNeeded += 1;
#endif
    }

    MmLockPagableSectionByHandle (ExPageLockHandle);

    LOCK_PFN (OldIrql);

    MmResidentAvailablePages += PagesNeeded;
    MM_BUMP_COUNTER(59, PagesNeeded);

    while (PointerPte <= LastPte) {

        ASSERT (PointerPte->u.Long == 0);

        PointerPte += 1;

        MI_DECREMENT_USED_PTES_BY_HANDLE (UsedPageTableHandle);

        if ((MiIsPteOnPdeBoundary(PointerPte)) || (PointerPte > LastPte)) {

            //
            // The virtual address is on a page directory boundary or it is
            // the last address in the entire range.
            //
            // If all the entries have been eliminated from the previous
            // page table page, delete the page table page itself.
            //

            PointerPde = MiGetPteAddress (PointerPte - 1);
            ASSERT (PointerPde->u.Hard.Valid == 1);

            //
            // Down the sharecount on the finished page table page.
            //

            PteContents = *PointerPde;
            Pfn1 = MI_PFN_ELEMENT (PteContents.u.Hard.PageFrameNumber);
            ASSERT (Pfn1->u2.ShareCount > 1);
            Pfn1->u2.ShareCount -= 1;

            //
            // If all the entries have been eliminated from the previous
            // page table page, delete the page table page itself.
            //

            if (MI_GET_USED_PTES_FROM_HANDLE (UsedPageTableHandle) == 0) {
                ASSERT (PointerPde->u.Long != 0);

#if (_MI_PAGING_LEVELS >= 3)
                UsedPageTableHandle = MI_GET_USED_PTES_HANDLE (PointerPte - 1);
                MI_DECREMENT_USED_PTES_BY_HANDLE (UsedPageTableHandle);
#endif

                TempVa = MiGetVirtualAddressMappedByPte(PointerPde);
                MiDeletePte (PointerPde,
                             TempVa,
                             FALSE,
                             CurrentProcess,
                             NULL,
                             NULL);

#if (_MI_PAGING_LEVELS >= 3)
                if ((MiIsPteOnPpeBoundary(PointerPte)) || (PointerPte > LastPte)) {
    
                    PointerPpe = MiGetPteAddress (PointerPde);
                    ASSERT (PointerPpe->u.Hard.Valid == 1);
    
                    //
                    // If all the entries have been eliminated from the previous
                    // page directory page, delete the page directory page too.
                    //
    
                    if (MI_GET_USED_PTES_FROM_HANDLE (UsedPageTableHandle) == 0) {
                        ASSERT (PointerPpe->u.Long != 0);

#if (_MI_PAGING_LEVELS >= 4)
                        UsedPageTableHandle = MI_GET_USED_PTES_HANDLE (PointerPde - 1);
                        MI_DECREMENT_USED_PTES_BY_HANDLE (UsedPageTableHandle);
#endif

                        TempVa = MiGetVirtualAddressMappedByPte(PointerPpe);
                        MiDeletePte (PointerPpe,
                                     TempVa,
                                     FALSE,
                                     CurrentProcess,
                                     NULL,
                                     NULL);

#if (_MI_PAGING_LEVELS >= 4)
                        PointerPxe = MiGetPdeAddress (PointerPde);
                        if (MI_GET_USED_PTES_FROM_HANDLE (UsedPageTableHandle) == 0) {
                            ASSERT (PointerPxe->u.Long != 0);
                            TempVa = MiGetVirtualAddressMappedByPte(PointerPxe);
                            MiDeletePte (PointerPxe,
                                         TempVa,
                                         FALSE,
                                         CurrentProcess,
                                         NULL,
                                         NULL);
                        }
#endif    
                    }
                }
#endif
            }

            if (PointerPte > LastPte) {
                break;
            }

            //
            // Release the PFN lock.  This prevents a single thread
            // from forcing other high priority threads from being
            // blocked while a large address range is deleted.
            //

            UNLOCK_PFN (OldIrql);
            UsedPageTableHandle = MI_GET_USED_PTES_HANDLE ((PVOID)((PUCHAR)StartingAddress + PAGE_SIZE));
            LOCK_PFN (OldIrql);
        }

        StartingAddress = (PVOID)((PUCHAR)StartingAddress + PAGE_SIZE);
    }

    UNLOCK_PFN (OldIrql);

    MmUnlockPagableImageSection (ExPageLockHandle);

    //
    // All done, return.
    //

    return;
}


//
// Commented out, no longer used.
//
#if 0
LOGICAL
MiIsEntireRangeDecommitted (
    IN PVOID StartingAddress,
    IN PVOID EndingAddress,
    IN PMMVAD Vad,
    IN PEPROCESS Process
    )

/*++

Routine Description:

    This routine examines the range of pages from the starting address
    up to and including the ending address and returns TRUE if every
    page in the range is either not committed or decommitted, FALSE otherwise.

Arguments:

    StartingAddress - Supplies the starting address of the range.

    EndingAddress - Supplies the ending address of the range.

    Vad - Supplies the virtual address descriptor which describes the range.

    Process - Supplies the current process.

Return Value:

    TRUE if the entire range is either decommitted or not committed.
    FALSE if any page within the range is committed.

Environment:

    Kernel mode, APCs disabled, WorkingSetMutex and AddressCreation mutexes
    held.

--*/

{
    PMMPTE PointerPte;
    PMMPTE LastPte;
    PMMPTE PointerPde;
    ULONG Waited;
    ULONG FirstTime;
    PVOID Va;

    FirstTime = TRUE;
    PointerPde = MiGetPdeAddress (StartingAddress);
    PointerPte = MiGetPteAddress (StartingAddress);
    LastPte = MiGetPteAddress (EndingAddress);

    //
    // Set the Va to the starting address + 8, this solves problems
    // associated with address 0 (NULL) being used as a valid virtual
    // address and NULL in the VAD commitment field indicating no pages
    // are committed.
    //

    Va = (PVOID)((PCHAR)StartingAddress + 8);

    //
    // A page table page exists, examine the individual PTEs to ensure
    // none are in the committed state.
    //

    while (PointerPte <= LastPte) {

        //
        // Check to see if a page table page (PDE) exists if the PointerPte
        // address is on a page boundary or this is the first time through
        // the loop.
        //

        if (MiIsPteOnPdeBoundary (PointerPte) || (FirstTime)) {

            //
            // This is a PDE boundary, check to see if the entire
            // PDE page exists.
            //

            FirstTime = FALSE;
            PointerPde = MiGetPteAddress (PointerPte);

            while (!MiDoesPdeExistAndMakeValid (PointerPde,
                                                Process,
                                                FALSE,
                                                &Waited)) {

                //
                // No PDE exists for the starting address, check the VAD
                // to see whether the pages are committed or not.
                //

                PointerPde += 1;
                PointerPte = MiGetVirtualAddressMappedByPte (PointerPde);

                if (PointerPte > LastPte) {

                    //
                    // No page table page exists, if explicit commitment
                    // via VAD indicates PTEs of zero should be committed,
                    // return an error.
                    //

                    if (EndingAddress <= Vad->CommittedAddress) {

                        //
                        // The entire range is committed, return an error.
                        //

                        return FALSE;
                    }
                    else {

                        //
                        // All pages are decommitted, return TRUE.
                        //

                        return TRUE;
                    }
                }

                Va = MiGetVirtualAddressMappedByPte (PointerPte);

                //
                // Make sure the range thus far is not committed.
                //

                if (Va <= Vad->CommittedAddress) {

                    //
                    // This range is committed, return an error.
                    //

                    return FALSE;
                }
            }
        }

        //
        // The page table page exists, check each PTE for commitment.
        //

        if (PointerPte->u.Long == 0) {

            //
            // This PTE for the page is zero, check the VAD.
            //

            if (Va <= Vad->CommittedAddress) {

                //
                // The entire range is committed, return an error.
                //

                return FALSE;
            }
        }
        else {

            //
            // Has this page been explicitly decommitted?
            //

            if (!MiIsPteDecommittedPage (PointerPte)) {

                //
                // This page is committed, return an error.
                //

                return FALSE;
            }
        }
        PointerPte += 1;
        Va = (PVOID)((PCHAR)(Va) + PAGE_SIZE);
    }
    return TRUE;
}
#endif //0

#if DBG
VOID
MmFooBar(VOID){}
#endif