The MMWSL_INSTANCE is the first part of an MMWSL_FULL, which is in turn the continuation of the ancient MMWSL structure after its separation into parts for the 1607 release of Windows 10.


As an internal structure with little, if any, visibility outside the kernel, the MMWSL_INSTANCE varies greatly between versions and even between builds.

Version Size (x86) Size (x64)
1607 0xD4 0x01A0
1703 to 2004 0x18 0x28


These sizes, and the names, offsets and types in the tables that follow, are from Microsoft’s symbol files for the kernel.

Offset (x86) Offset (x64) Definition Versions Remarks
0x00 0x00
1607 only previously at 0x0C and 0x18 in MMWSL
MMPTE *NextPteToTrim;
1703 and higher  
0x04 0x08
ULONG_PTR NextAgingSlot;
1607 only previously at 0x14 and 0x28 in MMWSL
MMPTE *NextPteToAge;
1703 and higher  
0x08 0x10
ULONG_PTR NextAccessClearingSlot;
1607 only previously at 0x18 and 0x30 in MMWSL
MMPTE *NextPteToAccessClear;
1703 and higher  
0x0C 0x18
ULONG LastAccessClearingRemainder;
1607 and higher previously at 0x1C and 0x38 in MMWSL
0x10 0x1C
ULONG LastAgingRemainder;
1607 and higher previously at 0x20 and 0x3C in MMWSL
0x14 (1607) 0x20 (1607)
ULONG_PTR ActiveWsleCounts [0x10];
1607 only previously at 0x3C and 0x70 in MMWSL
0x54 (1607) 0xA0 (1607)
1607 only previously at 0x7C and 0xF0 in MMWSL
0x14 0x20
ULONG_PTR LockedEntries;
1703 and higher  

The MI_ACTIVE_WSLE_LISTHEAD has just Flink and Blink members that are each a ULONG_PTR.