ZwFlushVirtualMemory function (ntifs.h)
The ZwFlushVirtualMemory routine flushes a range of virtual addresses within the virtual address space of a specified process which map to a data file back out to the data file if they have been modified.
Syntax
NTSYSAPI NTSTATUS ZwFlushVirtualMemory(
[in] HANDLE ProcessHandle,
[in, out] PVOID *BaseAddress,
[in, out] PSIZE_T RegionSize,
[out] PIO_STATUS_BLOCK IoStatus
);
Parameters
[in] ProcessHandle
An open handle for the process in whose context the pages to be flushed reside. Use the NtCurrentProcess macro, defined in Ntddk.h, to specify the current process.
[in, out] BaseAddress
A pointer to the base address of the virtual address range.
On entry, this parameter specifies a pointer to the initial value of the base address of the region of pages to flush.
On return, this parameter provides a pointer to a variable that will receive the base address of the flushed region.
[in, out] RegionSize
The size, in bytes, of the virtual address range.
On entry, this parameter specifies a pointer to the initial value of the size in bytes of the region of pages to flush to disk. This argument is rounded up to the next host-page-size boundary by the ZwFlushVirtualMemory. If this value is specified as zero, the mapped range from the base address to the end of the range is flushed.
On return, this parameter specifies a pointer to a variable that will receive the actual size in bytes of the flushed region of pages.
[out] IoStatus
A pointer to an IO_STATUS_BLOCK structure. This structure is where the value of the I/O status for the last attempted I/O operation is stored on output.
Return value
ZwFlushVirtualMemory returns either STATUS_SUCCESS or an error status code. Possible error status codes include the following:
| Return code | Description |
|---|---|
| STATUS_ACCESS_DENIED | The specified ProcessHandle parameter was not a valid process handle. |
| STATUS_INSUFFICIENT_RESOURCES | Additional resources required by this function were not available. |
| STATUS_INVALID_PARAMETER_2 | The BaseAddress specified was an invalid address within the virtual address space or the RegionSize was invalid. |
| STATUS_INVALID_HANDLE | The specified ProcessHandle parameter was not a valid process handle. |
| STATUS_NOT_MAPPED_VIEW | No virtual address space descriptor could be located for the supplied BaseAddress. |
| STATUS_PROCESS_IS_TERMINATING | The process and the associated virtual address space was deleted. |
| STATUS_FILE_LOCK_CONFLICT | The file system encountered a locking conflict. |
Remarks
This routine accepts, as input parameters, a range of addresses in virtual memory that map a data file. If any memory in this range has been modified since the file was copied to memory, the routine flushes this memory back to the data file.
For more information about memory management support for kernel-mode drivers, see Memory Management for Windows Drivers.
Note
If the call to the ZwFlushVirtualMemory function occurs in user mode, you should use the name "NtFlushVirtualMemory" instead of "ZwFlushVirtualMemory".
For calls from kernel-mode drivers, the NtXxx and ZwXxx versions of a Windows Native System Services routine can behave differently in the way that they handle and interpret input parameters. For more information about the relationship between the NtXxx and ZwXxx versions of a routine, see Using Nt and Zw Versions of the Native System Services Routines.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows XP |
| Target Platform | Universal |
| Header | ntifs.h (include Ntifs.h) |
| Library | NtosKrnl.lib |
| DLL | NtosKrnl.exe |
| IRQL | PASSIVE_LEVEL |