VirtualUnlock

The VirtualUnlock function unlocks a specified range of pages in the virtual address space of a process, enabling the system to swap the pages out to the paging file if necessary.

BOOL VirtualUnlock(
  LPVOID lpAddress,  // address of first byte of range
  DWORD dwSize       // number of bytes in range
);
 

Parameters

lpAddress

Pointer to the base address of the region of pages to be unlocked.

dwSize

Specifies the size, in bytes, of the region being unlocked. The region of affected pages includes all pages containing one or more bytes in the range from the lpAddress parameter to (lpAddress+dwSize). This means that a 2-byte range straddling a page boundary causes both pages to be unlocked.

Return Values

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, call GetLastError.

Remarks

For the function to succeed, the range specified need not match a range passed to a previous call to the VirtualLock function, but all pages in the range must be locked.

Windows NT: Calling VirtualUnlock on a range of memory that is not locked releases the pages from the process's working set.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 98 or later.
  Windows CE: Unsupported.
  Header: Declared in winbase.h.
  Import Library: Use kernel32.lib.

See Also

Memory Management Overview, Memory Management Functions, VirtualLock