I have an app built with C# and WPF, running on Windows 8. The C# code calls external C++ dll's using Interop. After a series of actions, memory usage up to near 2GB, so a memory leak is suspected. I created a dump of the process and try to analyze it with WinDbg, by command `!address -summary`, I got the following message:

```
--- Usage Summary ---------------- RgnCount ----------- Total Size -------- %ofBusy %ofTotal
Free                                    482      7ff`4d11b000 (   7.997 Tb)           99.97%
<unknown>                              1208        0`7573d000 (   1.835 Gb)  65.64%    0.02%
Heap                                   1664        0`1e1ab000 ( 481.668 Mb)  16.82%    0.01%
Image                                  1294        0`19f98000 ( 415.594 Mb)  14.52%    0.00%
Stack                                   261        0`053ce000 (  83.805 Mb)   2.93%    0.00%
Other                                    23        0`001d8000 (   1.844 Mb)   0.06%    0.00%
TEB                                      87        0`000ae000 ( 696.000 kb)   0.02%    0.00%
PEB                                       1        0`00001000 (   4.000 kb)   0.00%    0.00%

--- Type Summary (for busy) ------ RgnCount ----------- Total Size -------- %ofBusy %ofTotal
MEM_PRIVATE                            2634        0`922ae000 (   2.284 Gb)  81.69%    0.03%
MEM_IMAGE                              1787        0`1b38d000 ( 435.551 Mb)  15.21%    0.01%
MEM_MAPPED                               90        0`05807000 (  88.027 Mb)   3.07%    0.00%

--- State Summary ---------------- RgnCount ----------- Total Size -------- %ofBusy %ofTotal
MEM_FREE                                509      7ff`4d1ae000 (   7.997 Tb)           99.97%
MEM_COMMIT                             3346        0`9205e000 (   2.282 Gb)  81.61%    0.03%
MEM_RESERVE                            1165        0`20de4000 ( 525.891 Mb)  18.37%    0.01%

--- Protect Summary (for commit) - RgnCount ----------- Total Size -------- %ofBusy %ofTotal
PAGE_READWRITE                         1577        0`73295000 (   1.799 Gb)  64.36%    0.02%
PAGE_EXECUTE_READ                       183        0`1212e000 ( 289.180 Mb)  10.10%    0.00%
PAGE_READONLY                           941        0`082f9000 ( 130.973 Mb)   4.57%    0.00%
PAGE_READWRITE|PAGE_WRITECOMBINE         24        0`03aad000 (  58.676 Mb)   2.05%    0.00%
PAGE_EXECUTE_READWRITE                  131        0`00bcc000 (  11.797 Mb)   0.41%    0.00%
PAGE_READWRITE|PAGE_GUARD                87        0`00191000 (   1.566 Mb)   0.05%    0.00%
PAGE_NOACCESS                           399        0`0018f000 (   1.559 Mb)   0.05%    0.00%
<unknown>                                 1        0`00004000 (  16.000 kb)   0.00%    0.00%
PAGE_EXECUTE                              2        0`00003000 (  12.000 kb)   0.00%    0.00%
PAGE_WRITECOPY                            1        0`00002000 (   8.000 kb)   0.00%    0.00%

--- Largest Region by Usage ----------- Base Address -------- Region Size ----------
Free                                     a1`9f910000      754`5f4fc000 (   7.330 Tb)
<unknown>                                a1`4fc30000        0`17ffc000 ( 383.984 Mb)
Heap                                     a1`1c421000        0`00dff000 (  13.996 Mb)
Image                                     0`6c991000        0`0174e000 (  23.305 Mb)
Stack                                    a1`160c0000        0`000fb000 (1004.000 kb)
Other                                    a1`4e480000        0`00181000 (   1.504 Mb)
TEB                                     7f5`fee0c000        0`00002000 (   8.000 kb)
PEB                                     7f5`ff14c000        0`00001000 (   4.000 kb)

```

Why the Free block is so large? Within the summary, any clue where memory leak could be?