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!heap -s says my heap is 17TB big--is this an LFH issue w/windbg?

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Michael Gebis

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Dec 9, 2009, 10:16:09 PM12/9/09

I have seen several crash dumps where the output of !heap -s seems to show a
bug in windbg, although perhaps it could be heap corruption. The heap at
02030000 reports a Reserv size of 17181653060k, which is approximately 10000
times too large. The entire row is pretty dubious. Compare with the output
for !address, which shows RegionUsageHeap as 1826500KB.

This dump was generated for a 32 bit process that was very tight on memory,
but should have been otherwise ok--in other words, I think other than being
low on memory, the process was OK. I believe the memory usage indicated by
!address is correct.

Note that the heap in question is an LFH. Is windbg getting confused
because it's an LFH? !heap seems to work ok most of the time on LFHs, though.

0:000> !heap -s
LFH Key : 0xeaafe2e0
Heap Flags Reserv Commit Virt Free List UCR Virt Lock Fast
(k) (k) (k) (k) length blocks cont. heap
-----------------------------------------------------------------------------
00140000 00000002 32768 5756 7844 1879 533 169 0 329 L
External fragmentation 32 % (533 free blocks)
Virtual address fragmentation 26 % (169 uncommited ranges)
00240000 00001002 64 24 24 2 1 1 0 0 L
00250000 00008000 64 12 12 10 1 1 0 0
003f0000 00001002 64 16 16 2 2 1 0 0 L
02010000 00001002 64 64 64 2 1 0 0 0 L
02050000 00001003 256 8 8 2 1 1 0 bad
020c0000 00001003 256 4 4 2 1 1 0 bad
02100000 00001003 256 4 4 2 1 1 0 bad
02140000 00001003 256 4 4 2 1 1 0 bad
02180000 00001003 256 4 4 2 1 1 0 bad
021c0000 00001002 256 12 12 4 1 1 0 0 L
02030000 00001002 17181653060 13506030208 17181473425 12892 2973
1200321552 0 49d LFH
Virtual address fragmentation 21 % (1200321552 uncommited ranges)
02280000 00001002 256 52 52 3 1 1 0 0 L
022c0000 00001002 64 48 48 40 2 1 0 0 L
023f0000 00000002 1024 24 24 3 1 1 0 0 L
02600000 00001002 256 68 68 2 1 1 0 0 L
02da0000 00001002 256 12 12 4 1 1 0 0 L
04230000 00001002 64 12 12 4 1 1 0 0 L
04240000 00001002 64 12 12 3 1 1 0 0 L
02520000 00001002 64 28 28 5 1 1 0 0 L
-----------------------------------------------------------------------------

!addresss, top portion removed. These values seem correct:
-------------------- Usage SUMMARY --------------------------
TotSize ( KB) Pct(Tots) Pct(Busy) Usage
1936000 ( 25816) : 01.23% 01.27% : RegionUsageIsVAD
3e46000 ( 63768) : 03.04% 00.00% : RegionUsageFree
3646000 ( 55576) : 02.65% 02.73% : RegionUsageImage
7a00000 ( 124928) : 05.96% 06.14% : RegionUsageStack
7a000 ( 488) : 00.02% 00.02% : RegionUsageTeb
6f7b1000 ( 1826500) : 87.10% 89.83% : RegionUsageHeap
0 ( 0) : 00.00% 00.00% : RegionUsagePageHeap
1000 ( 4) : 00.00% 00.00% : RegionUsagePeb
1000 ( 4) : 00.00% 00.00% : RegionUsageProcessParametrs
1000 ( 4) : 00.00% 00.00% : RegionUsageEnvironmentBlock
Tot: 7fff0000 (2097088 KB) Busy: 7c1aa000 (2033320 KB)

-------------------- Type SUMMARY --------------------------
TotSize ( KB) Pct(Tots) Usage
3e46000 ( 63768) : 03.04% : <free>
3646000 ( 55576) : 02.65% : MEM_IMAGE
86c000 ( 8624) : 00.41% : MEM_MAPPED
782f8000 ( 1969120) : 93.90% : MEM_PRIVATE

-------------------- State SUMMARY --------------------------
TotSize ( KB) Pct(Tots) Usage
335a9000 ( 841380) : 40.12% : MEM_COMMIT
3e46000 ( 63768) : 03.04% : MEM_FREE
48c01000 ( 1191940) : 56.84% : MEM_RESERVE

Largest free region: Base 02640000 - Size 006c0000 (6912 KB)

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