Excessive Non-Page Pool (NPP) Memory Usage of 3.9TB May Be Seen When Using Windbg Build 6.12.0002.633


When using the external build of the Windows Debugging Tools (Windbg) version 6.12.0002.633 and using the external symbol server, you may see an excessive amount of Non-Paged Pool memory usage which exceeds the maximum limits.

Pushing the Limits of Windows: Paged and Nonpaged Pool


The issue is caused by a known problem in the public debug extension kdexts.dll.


Microsoft is aware of this problem and it is under investigation. It is scheduled to be corrected in the next release of Windbg. At this time no release date or correcting version number is available. Since Windbg is incorporated with the Software Development Kit (SDK), the next update may occur with the next major release of the Windows. 

To work around the problem you can either download and use one of the previous versions of Windbg or wait for the next released version.

Debugging Tools: More Information and Previous Versions

Debugging Tools for Windows 32-bit Versions

Debugging Tools for Windows 64-bit Versions

Steps to Reproduce:

Download Windows Debugging Tools which is available in the SDK from the following hyperlink

Select the respective platform for your version of Windows
x86 - GRMSDK_EN_DVD.iso567.3MB
x64 - GRMSDKX_EN_DVD.iso570.9MB

Install at a minimum Windbg

Create a folder on the root of drive C:\ named “websymbols” which will be used for a local symbol store

Open Windbg and set the “Symbol file path...” from the File drop down menu to the local and external symbol server as follows;

Open a memory dump file in Windbg and run the command !vm, you may see something similar to the following;

NonPagedPool Usage: 996199185 (3984796740 Kb)   <- Excessive NPP usage 3.9 TB

More Information

You will notice after running the command !vm, the kernel memory usage for NonPagedPool memory will show an excessive amount.

13: kd> !vm

*** Virtual Memory Usage ***
 Physical Memory:     8385672 (  33542688 Kb)
 Page File: \??\C:\pagefile.sys
   Current:  33542688 Kb  Free Space:  33542684 Kb
   Minimum:  33542688 Kb  Maximum:     52619164 Kb
Unimplemented error for MiSystemVaTypeCount
 Available Pages:     7790160 (  31160640 Kb)
 ResAvail Pages:      8005771 (  32023084 Kb)
 Locked IO Pages:           0 (         0 Kb)
 Free System PTEs:   33555212 ( 134220848 Kb)
 Modified Pages:        22972 (     91888 Kb)
 Modified PF Pages:     22888 (     91552 Kb)
 NonPagedPool 0 Used:       0 (         0 Kb)
 NonPagedPoolNx 0 Used:  4191 (     16764 Kb)
 NonPagedPool 1 Used:       0 (         0 Kb)
 NonPagedPoolNx 1 Used:  4749 (     18996 Kb)
 NonPagedPool Usage: 996199185 (3984796740 Kb) <- Excessive NPP usage 3.9 TB
 NonPagedPoolNx Usage:  20017 (     80068 Kb)
 NonPagedPool Max:    6267384 (  25069536 Kb)
 ********** Excessive NonPaged Pool Usage *****
 PagedPool 0 Usage:     29878 (    119512 Kb)
 PagedPool 1 Usage:      5051 (     20204 Kb)
 PagedPool 2 Usage:       520 (      2080 Kb)
 PagedPool Usage:       35449 (    141796 Kb)
 PagedPool Maximum:  33554432 ( 134217728 Kb)


Article ID: 2509968 - Last Review: Feb 17, 2011 - Revision: 1

Platform SDK Redistributable: CAPICOM