summaryrefslogblamecommitdiffstats
path: root/private/ntos/mm/mmquota.c
blob: 614b57a4d696eae2d749446dfcf29bf99df09f8d (plain) (tree)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050

























































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































                                                                                                                      
/*++

Copyright (c) 1989  Microsoft Corporation

Module Name:

   mmquota.c

Abstract:

    This module contains the routines which implement the quota and
    commitment charging for memory management.

Author:

    Lou Perazzoli (loup) 12-December-89

Revision History:

--*/

#include "mi.h"

#define MM_MAXIMUM_QUOTA_OVERCHARGE 9

#define MM_DONT_EXTEND_SIZE 512

#define MM_COMMIT_POPUP_MAX ((512*1024)/PAGE_SIZE)

#define MM_EXTEND_COMMIT ((1024*1024)/PAGE_SIZE)

ULONG MmPeakCommitment;

ULONG MmExtendedCommit;

extern ULONG MmAllocatedPagedPool;

extern ULONG MmAllocatedNonPagedPool;


ULONG MiOverCommitCallCount;
extern EPROCESS_QUOTA_BLOCK PspDefaultQuotaBlock;


VOID
MiCauseOverCommitPopup(
    ULONG NumberOfPages,
    ULONG Extension
    );


ULONG
FASTCALL
MiChargePageFileQuota (
    IN ULONG QuotaCharge,
    IN PEPROCESS CurrentProcess
    )

/*++

Routine Description:

    This routine checks to ensure the user has sufficient page file
    quota remaining and, if so, charges the quota.  If not an exception
    is raised.

Arguments:

    QuotaCharge - Supplies the quota amount to charge.

    CurrentProcess - Supplies a pointer to the current process.

Return Value:

    TRUE if the quota was successfully charged, raises an exception
    otherwise.

Environment:

    Kernel mode, APCs disable, WorkingSetLock and AddressCreation mutexes
    held.

--*/

{
    ULONG NewPagefileValue;
    PEPROCESS_QUOTA_BLOCK QuotaBlock;
    KIRQL OldIrql;

    QuotaBlock = CurrentProcess->QuotaBlock;

retry_charge:
    if ( QuotaBlock != &PspDefaultQuotaBlock) {
        ExAcquireFastLock (&QuotaBlock->QuotaLock,&OldIrql);
do_charge:
        NewPagefileValue = QuotaBlock->PagefileUsage + QuotaCharge;

        if (NewPagefileValue > QuotaBlock->PagefileLimit) {
            ExRaiseStatus (STATUS_PAGEFILE_QUOTA_EXCEEDED);
        }

        QuotaBlock->PagefileUsage = NewPagefileValue;

        if (NewPagefileValue > QuotaBlock->PeakPagefileUsage) {
            QuotaBlock->PeakPagefileUsage = NewPagefileValue;
        }

        NewPagefileValue = CurrentProcess->PagefileUsage + QuotaCharge;
        CurrentProcess->PagefileUsage = NewPagefileValue;

        if (NewPagefileValue > CurrentProcess->PeakPagefileUsage) {
            CurrentProcess->PeakPagefileUsage = NewPagefileValue;
        }
        ExReleaseFastLock (&QuotaBlock->QuotaLock,OldIrql);
    } else {
        ExAcquireFastLock (&PspDefaultQuotaBlock.QuotaLock,&OldIrql);

        if ( (QuotaBlock = CurrentProcess->QuotaBlock) != &PspDefaultQuotaBlock) {
            ExReleaseFastLock(&PspDefaultQuotaBlock.QuotaLock,OldIrql);
            goto retry_charge;
        }
        goto do_charge;
    }
    return TRUE;
}

VOID
MiReturnPageFileQuota (
    IN ULONG QuotaCharge,
    IN PEPROCESS CurrentProcess
    )

/*++

Routine Description:

    This routine releases page file quota.

Arguments:

    QuotaCharge - Supplies the quota amount to charge.

    CurrentProcess - Supplies a pointer to the current process.

Return Value:

    none.

Environment:

    Kernel mode, APCs disable, WorkingSetLock and AddressCreation mutexes
    held.

--*/

{

    PEPROCESS_QUOTA_BLOCK QuotaBlock;
    KIRQL OldIrql;

    QuotaBlock = CurrentProcess->QuotaBlock;

retry_return:
    if ( QuotaBlock != &PspDefaultQuotaBlock) {
        ExAcquireFastLock (&QuotaBlock->QuotaLock, &OldIrql);
do_return:
        ASSERT (CurrentProcess->PagefileUsage >= QuotaCharge);
        CurrentProcess->PagefileUsage -= QuotaCharge;

        ASSERT (QuotaBlock->PagefileUsage >= QuotaCharge);
        QuotaBlock->PagefileUsage -= QuotaCharge;
        ExReleaseFastLock(&QuotaBlock->QuotaLock,OldIrql);
    } else {
        ExAcquireFastLock (&PspDefaultQuotaBlock.QuotaLock, &OldIrql);
        if ( (QuotaBlock = CurrentProcess->QuotaBlock) != &PspDefaultQuotaBlock ) {
            ExReleaseFastLock(&PspDefaultQuotaBlock.QuotaLock,OldIrql);
            goto retry_return;
        }
        goto do_return;
    }
    return;
}

VOID
FASTCALL
MiChargeCommitment (
    IN ULONG QuotaCharge,
    IN PEPROCESS Process OPTIONAL
    )

/*++

Routine Description:

    This routine checks to ensure the system has sufficient page file
    space remaining.  If not an exception is raised.

Arguments:

    QuotaCharge - Supplies the quota amount to charge.

    Process - Optionally supplies the current process IF AND ONLY IF
              the working set mutex is held.  If the paging file
              is being extended, the working set mutex is released if
              this is non-null.

Return Value:

    none.

Environment:

    Kernel mode, APCs disable, WorkingSetLock and AddressCreation mutexes
    held.

--*/

{
    KIRQL OldIrql;
    ULONG NewCommitValue;
    MMPAGE_FILE_EXPANSION PageExtend;
    NTSTATUS status;
    PLIST_ENTRY NextEntry;

    ASSERT (QuotaCharge < 0x100000);

    ExAcquireFastLock (&MmChargeCommitmentLock, &OldIrql);

    NewCommitValue = MmTotalCommittedPages + QuotaCharge;

    while (NewCommitValue > MmTotalCommitLimit) {

        ExReleaseFastLock (&MmChargeCommitmentLock, OldIrql);

        if (Process != NULL) {
            UNLOCK_WS (Process);
        }
        //
        // Queue a message to the segment dereferencing / pagefile extending
        // thread to see if the page file can be extended.  This is done
        // in the context of a system thread due to mutexes which may
        // currently be held.
        //

        PageExtend.RequestedExpansionSize = QuotaCharge;
        PageExtend.Segment = NULL;
        KeInitializeEvent (&PageExtend.Event, NotificationEvent, FALSE);

        ExAcquireFastLock (&MmDereferenceSegmentHeader.Lock, &OldIrql);
        InsertTailList ( &MmDereferenceSegmentHeader.ListHead,
                         &PageExtend.DereferenceList);
        ExReleaseFastLock (&MmDereferenceSegmentHeader.Lock, OldIrql);

        KeReleaseSemaphore (&MmDereferenceSegmentHeader.Semaphore, 0L, 1L, TRUE);

        //
        // Wait for the thread to extend the paging file, with a
        // one second timeout.
        //

        status = KeWaitForSingleObject (&PageExtend.Event,
                                        Executive,
                                        KernelMode,
                                        FALSE,
                                        (QuotaCharge < 10) ?
                                              &MmOneSecond : &MmTwentySeconds);

        if (status == STATUS_TIMEOUT) {

            //
            // The wait has timed out, if this request has not
            // been processed, remove it from the list and check
            // to see if we should allow this request to succeed.
            // This prevents a deadlock between the file system
            // trying to allocate memory in the FSP and the
            // segment dereferencing thread trying to close a
            // file object, and waiting in the file system.
            //

            //
            // Check to see if this request is still in the list,
            // and if so, remove it.
            //

            KdPrint(("MMQUOTA: wait timed out, page-extend= %lx, quota = %lx\n",
                       &PageExtend, QuotaCharge));

            ExAcquireFastLock (&MmDereferenceSegmentHeader.Lock, &OldIrql);

            NextEntry = MmDereferenceSegmentHeader.ListHead.Flink;

            while (NextEntry != &MmDereferenceSegmentHeader.ListHead) {

                //
                // Check to see if this is the entry we are waiting for.
                //

                if (NextEntry == &PageExtend.DereferenceList) {

                    //
                    // Remove this entry.
                    //

                    RemoveEntryList (&PageExtend.DereferenceList);
                    ExReleaseFastLock (&MmDereferenceSegmentHeader.Lock, OldIrql);

                    if (Process != NULL) {
                        LOCK_WS (Process);
                    }

                    //
                    // If the quota is small enough, commit it otherwize
                    // return an error.
                    //

                    if (QuotaCharge < MM_MAXIMUM_QUOTA_OVERCHARGE) {

                        //
                        // Try the can't expand routine, note that
                        // this could raise an exception.
                        //

                        MiChargeCommitmentCantExpand (QuotaCharge, FALSE);
                    } else {

                        //
                        // Put up a popup and grant an extension if
                        // possible.
                        //

                        MiCauseOverCommitPopup (QuotaCharge, MM_EXTEND_COMMIT);
                    }
                    return;
                }
                NextEntry = NextEntry->Flink;
            }

            ExReleaseFastLock (&MmDereferenceSegmentHeader.Lock, OldIrql);

            //
            // Entry is being processed, wait for completion.
            //

            KdPrint (("MMQUOTA: rewaiting...\n"));

            KeWaitForSingleObject (&PageExtend.Event,
                                   Executive,
                                   KernelMode,
                                   FALSE,
                                   NULL);
        }

        if (Process != NULL) {
            LOCK_WS (Process);
        }

        if (PageExtend.ActualExpansion == 0) {
            MiCauseOverCommitPopup (QuotaCharge, MM_EXTEND_COMMIT);
            return;
        }

        ExAcquireFastLock (&MmChargeCommitmentLock, &OldIrql);
        NewCommitValue = MmTotalCommittedPages + QuotaCharge;
    }

    MmTotalCommittedPages = NewCommitValue;
    if (MmTotalCommittedPages > MmPeakCommitment) {
        MmPeakCommitment = MmTotalCommittedPages;
    }

    ExReleaseFastLock (&MmChargeCommitmentLock, OldIrql);
    return;
}

VOID
FASTCALL
MiChargeCommitmentCantExpand (
    IN ULONG QuotaCharge,
    IN ULONG MustSucceed
    )

/*++

Routine Description:

    This routine charges the specified committment without attempting
    to expand paging file and waiting for the expansion.  The routine
    determines if the paging file space is exhausted, and if so,
    it attempts to assertain if the paging file space could be expanded.

    If it appears as though the paging file space can't be expanded,
    it raises an exception.

Arguments:

    QuotaCharge - Supplies the quota amount to charge.

Return Value:

    none.

Environment:

    Kernel mode, APCs disabled.

--*/

{
    KIRQL OldIrql;
    ULONG NewCommitValue;
    ULONG ExtendAmount;

    ExAcquireFastLock (&MmChargeCommitmentLock, &OldIrql);

    //
    // If the overcommitment is bigger than 512 pages, don't extend.
    //

    NewCommitValue = MmTotalCommittedPages + QuotaCharge;

    if (!MustSucceed) {
        if (((LONG)((LONG)NewCommitValue - (LONG)MmTotalCommitLimit)) >
                                                         MM_DONT_EXTEND_SIZE) {
            ExReleaseFastLock (&MmChargeCommitmentLock, OldIrql);
            ExRaiseStatus (STATUS_COMMITMENT_LIMIT);
        }
    }

    ExtendAmount = NewCommitValue - MmTotalCommitLimit;
    MmTotalCommittedPages = NewCommitValue;

    if (NewCommitValue > (MmTotalCommitLimit + 20)) {

        //
        // Attempt to expand the paging file, but don't wait
        // to see if it succeeds.
        //

        if (MmAttemptForCantExtend.InProgress != FALSE) {

            //
            // An expansion request is already in progress, assume
            // this will succeed.
            //

            ExReleaseFastLock (&MmChargeCommitmentLock, OldIrql);
            return;
        }

        MmAttemptForCantExtend.InProgress = TRUE;
        ExReleaseFastLock (&MmChargeCommitmentLock, OldIrql);

        //
        // Queue a message to the segment dereferencing / pagefile extending
        // thread to see if the page file can be extended.  This is done
        // in the context of a system thread due to mutexes which may
        // currently be held.
        //

        if (QuotaCharge > ExtendAmount) {
            ExtendAmount = QuotaCharge;
        }

        MmAttemptForCantExtend.RequestedExpansionSize = ExtendAmount;
        ExAcquireFastLock (&MmDereferenceSegmentHeader.Lock, &OldIrql);
        InsertTailList ( &MmDereferenceSegmentHeader.ListHead,
                         &MmAttemptForCantExtend.DereferenceList);
        ExReleaseFastLock (&MmDereferenceSegmentHeader.Lock, OldIrql);

        KeReleaseSemaphore (&MmDereferenceSegmentHeader.Semaphore, 0L, 1L, FALSE);

        return;
    }

    ExReleaseFastLock (&MmChargeCommitmentLock, OldIrql);
    return;
}

VOID
FASTCALL
MiReturnCommitment (
    IN ULONG QuotaCharge
    )

/*++

Routine Description:

    This routine releases page file quota.

Arguments:

    QuotaCharge - Supplies the quota amount to charge.

    CurrentProcess - Supplies a pointer to the current process.

Return Value:

    none.

Environment:

    Kernel mode, APCs disable, WorkingSetLock and AddressCreation mutexes
    held.

--*/

{
    KIRQL OldIrql;

    ExAcquireFastLock (&MmChargeCommitmentLock, &OldIrql);

    ASSERT (MmTotalCommittedPages >= QuotaCharge);

    MmTotalCommittedPages -= QuotaCharge;

    ExReleaseFastLock (&MmChargeCommitmentLock, OldIrql);
    return;
}

ULONG
MiCalculatePageCommitment (
    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 the commit charge
    for  the pages within the range.

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:

    Commitment charge for the range.

Environment:

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

--*/

{
    PMMPTE PointerPte;
    PMMPTE LastPte;
    PMMPTE PointerPde;
    PMMPTE TempEnd;
    ULONG NumberOfCommittedPages = 0;

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

    if (Vad->u.VadFlags.MemCommit == 1) {

        TempEnd = EndingAddress;

        //
        // All the pages are committed within this range.
        //

        NumberOfCommittedPages = BYTES_TO_PAGES ((ULONG)TempEnd -
                                                       (ULONG)StartingAddress);


        //
        // Examine the PTEs to determine how many pages are committed.
        //

        LastPte = MiGetPteAddress (TempEnd);

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

            //
            // No PDE exists for the starting address, therefore the page
            // is not committed.
            //

            PointerPde += 1;
            PointerPte = MiGetVirtualAddressMappedByPte (PointerPde);
            if (PointerPte > LastPte) {
                goto DoneCommit;
            }
        }

        while (PointerPte <= LastPte) {

            if (((ULONG)PointerPte & (PAGE_SIZE - 1)) == 0) {

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

                PointerPde = MiGetPteAddress (PointerPte);

                if (!MiDoesPdeExistAndMakeValid(PointerPde, Process, FALSE)) {

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

                    PointerPde += 1;

                    PointerPte = MiGetVirtualAddressMappedByPte (PointerPde);

                    //
                    // Check next page.
                    //

                    continue;
                }
            }

            //
            // The PDE exists, examine the PTE.
            //

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

                //
                // Has this page been explicitly decommited?
                //

                if (MiIsPteDecommittedPage (PointerPte)) {

                    //
                    // This page is decommitted, remove it from the count.
                    //

                    NumberOfCommittedPages -= 1;

                }
            }

            PointerPte += 1;
        }

DoneCommit:

        if (TempEnd == EndingAddress) {
            return NumberOfCommittedPages;
        }

    }

    //
    // Examine non committed range.
    //

    LastPte = MiGetPteAddress (EndingAddress);

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

        //
        // No PDE exists for the starting address, therefore the page
        // is not committed.
        //

        PointerPde += 1;
        PointerPte = MiGetVirtualAddressMappedByPte (PointerPde);
        if (PointerPte > LastPte) {
           return NumberOfCommittedPages;
        }
    }

    while (PointerPte <= LastPte) {

        if (((ULONG)PointerPte & (PAGE_SIZE - 1)) == 0) {

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

            PointerPde = MiGetPteAddress (PointerPte);

            if (!MiDoesPdeExistAndMakeValid(PointerPde, Process, FALSE)) {

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

                PointerPde += 1;

                PointerPte = MiGetVirtualAddressMappedByPte (PointerPde);

                //
                // Check next page.
                //

                continue;
            }
        }

        //
        // The PDE exists, examine the PTE.
        //

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

            //
            // This page is committed, count it.
            //

            NumberOfCommittedPages += 1;
        }

        PointerPte += 1;
    }

    return NumberOfCommittedPages;
}

VOID
MiReturnPageTablePageCommitment (
    IN PVOID StartingAddress,
    IN PVOID EndingAddress,
    IN PEPROCESS CurrentProcess,
    IN PMMVAD PreviousVad,
    IN PMMVAD NextVad
    )

/*++

Routine Description:

    This routine returns commitment for COMPLETE page table pages which
    span the virtual address range.  For example (assuming 4k pages),
    if the StartingAddress =  64k and the EndingAddress = 5mb, no
    page table charges would be freed as a complete page table page is
    not covered by the range.  However, if the StartingAddress was 4mb
    and the EndingAddress was 9mb, 1 page table page would be freed.

Arguments:

    StartingAddress - Supplies the starting address of the range.

    EndingAddress - Supplies the ending address of the range.

    CurrentProcess - Supplies a pointer to the current process.

    PreviousVad - Supplies a pointer to the previous VAD, NULL if none.

    NextVad - Supplies a pointer to the next VAD, NULL if none.

Return Value:

    None.

Environment:

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

--*/

{
    ULONG NumberToClear;
    LONG FirstPage;
    LONG LastPage;
    LONG PreviousPage;
    LONG NextPage;

    //
    // Check to see if any page table pages would be freed.
    //

    ASSERT (StartingAddress != EndingAddress);

    if (PreviousVad == NULL) {
        PreviousPage = -1;
    } else {
        PreviousPage = MiGetPdeOffset (PreviousVad->EndingVa);
    }

    if (NextVad == NULL) {
        NextPage = MiGetPdeOffset (MM_HIGHEST_USER_ADDRESS) + 1;
    } else {
        NextPage = MiGetPdeOffset (NextVad->StartingVa);
    }

    ASSERT (PreviousPage <= NextPage);

    FirstPage = MiGetPdeOffset (StartingAddress);

    LastPage = MiGetPdeOffset(EndingAddress);

    if (PreviousPage == FirstPage) {

        //
        // A VAD is within the starting page table page.
        //

        FirstPage += 1;
    }

    if (NextPage == LastPage) {

        //
        // A VAD is within the ending page table page.
        //

        LastPage -= 1;
    }

    //
    // Indicate that the page table page is not in use.
    //

    if (FirstPage > LastPage) {
        return;
    }

    NumberToClear = 1 + LastPage - FirstPage;

    while (FirstPage <= LastPage) {
        ASSERT (MI_CHECK_BIT (MmWorkingSetList->CommittedPageTables,
                              FirstPage));
        MI_CLEAR_BIT (MmWorkingSetList->CommittedPageTables, FirstPage);
        FirstPage += 1;
    }

    MmWorkingSetList->NumberOfCommittedPageTables -= NumberToClear;
    MiReturnCommitment (NumberToClear);
    MiReturnPageFileQuota (NumberToClear, CurrentProcess);
    CurrentProcess->CommitCharge -= NumberToClear;

    return;
}


VOID
MiCauseOverCommitPopup(
    ULONG NumberOfPages,
    IN ULONG Extension
    )

/*++

Routine Description:

    This function causes an over commit popup to occur. If a popup is pending it returns
    FALSE. Otherwise, it queues a popup to a noncritical worker thread.

    In all cases, MiOverCommitCallCount is incremented once for each call.

Arguments:

    None.

Return Value:

    TRUE - An overcommit popup was queued

    FALSE - An overcommit popup is still pending and will not be queued.

--*/

{
    KIRQL OldIrql;
    ULONG MiOverCommitPending;

    if (NumberOfPages > MM_COMMIT_POPUP_MAX) {
        ExRaiseStatus (STATUS_COMMITMENT_LIMIT);
        return;
    }

    MiOverCommitPending =
        !IoRaiseInformationalHardError(STATUS_COMMITMENT_LIMIT, NULL, NULL);

    ExAcquireFastLock (&MmChargeCommitmentLock, &OldIrql);

    if (( MiOverCommitPending ) && (MiOverCommitCallCount > 0)) {

        //
        // There is already a popup outstanding and we have not
        // returned any of the quota.
        //

        ExReleaseFastLock (&MmChargeCommitmentLock, OldIrql);
        ExRaiseStatus (STATUS_COMMITMENT_LIMIT);
        return;
    }

    MiOverCommitCallCount += 1;

    MmTotalCommitLimit += Extension;
    MmExtendedCommit += Extension;
    MmTotalCommittedPages += NumberOfPages;

    if (MmTotalCommittedPages > MmPeakCommitment) {
        MmPeakCommitment = MmTotalCommittedPages;
    }

    ExReleaseFastLock (&MmChargeCommitmentLock, OldIrql);

    return;
}


ULONG MmTotalPagedPoolQuota;
ULONG MmTotalNonPagedPoolQuota;

BOOLEAN
MmRaisePoolQuota(
    IN POOL_TYPE PoolType,
    IN ULONG OldQuotaLimit,
    OUT PULONG NewQuotaLimit
    )

/*++

Routine Description:

    This function is called (with a spinlock) whenever PS detects a quota
    limit has been exceeded. The purpose of this function is to attempt to
    increase the specified quota.

Arguments:

    PoolType - Supplies the pool type of the quota to be raised

    OldQuotaLimit - Supplies the current quota limit for this pool type

    NewQuotaLimit - Returns the new limit

Return Value:

    TRUE - The API succeeded and the quota limit was raised.

    FASLE - We were unable to raise the quota limit.

Environment:

    Kernel mode, QUOTA SPIN LOCK HELD!!

--*/

{
    ULONG Limit;

    if (PoolType == PagedPool) {

        //
        // Check commit limit and make sure at least 1mb is available.
        // Check to make sure 4mb of paged pool still exists.
        //

        if ((MmSizeOfPagedPoolInBytes >> PAGE_SHIFT) <
            (MmAllocatedPagedPool + ((MMPAGED_QUOTA_CHECK) >> PAGE_SHIFT))) {

            return FALSE;
        }

        MmTotalPagedPoolQuota += (MMPAGED_QUOTA_INCREASE);
        *NewQuotaLimit = OldQuotaLimit + (MMPAGED_QUOTA_INCREASE);
        return TRUE;

    } else {

        if ( MmAllocatedNonPagedPool + ((1*1024*1024) >> PAGE_SHIFT) < (MmMaximumNonPagedPoolInBytes >> PAGE_SHIFT)) {
            goto aok;
            }

        //
        // Make sure 200 pages and 5mb of nonpaged pool expansion
        // available.  Raise quota by 64k.
        //

        if ((MmAvailablePages < 200) ||
            (MmResidentAvailablePages < ((MMNONPAGED_QUOTA_CHECK) >> PAGE_SHIFT))) {

            return FALSE;
        }

        if (MmAvailablePages > ((4*1024*1024) >> PAGE_SHIFT)) {
            Limit = (1*1024*1024) >> PAGE_SHIFT;
        } else {
            Limit = (4*1024*1024) >> PAGE_SHIFT;
        }

        if ((MmMaximumNonPagedPoolInBytes >> PAGE_SHIFT) <
            (MmAllocatedNonPagedPool + Limit)) {

            return FALSE;
        }
aok:
        MmTotalNonPagedPoolQuota += (MMNONPAGED_QUOTA_INCREASE);
        *NewQuotaLimit = OldQuotaLimit + (MMNONPAGED_QUOTA_INCREASE);
        return TRUE;
    }
}


VOID
MmReturnPoolQuota(
    IN POOL_TYPE PoolType,
    IN ULONG ReturnedQuota
    )

/*++

Routine Description:

    Returns pool quota.

Arguments:

    PoolType - Supplies the pool type of the quota to be returned.

    ReturnedQuota - Number of bytes returned.

Return Value:

    NONE.

Environment:

    Kernel mode, QUOTA SPIN LOCK HELD!!

--*/

{

    if (PoolType == PagedPool) {
        MmTotalPagedPoolQuota -= ReturnedQuota;
    } else {
        MmTotalNonPagedPoolQuota -= ReturnedQuota;
    }

    return;
}