---
name: "UFFDIO_UNREGISTER"
section: "2const"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/UFFDIO_UNREGISTER"
---

# UFFDIO\_UNREGISTER(2const)

unregister a memory address range from userfaultfd

## NAME

UFFDIO\_UNREGISTER - unregister a memory address range from userfaultfd

## LIBRARY

Standard C library (*libc*, *-lc*)

## SYNOPSIS

```
#include <linux/userfaultfd.h>  /* Definition of UFFD* constants */
#include <sys/ioctl.h>
```

**int ioctl(int** *fd***, UFFDIO\_UNREGISTER, const struct uffdio\_range \****argp***);**

## DESCRIPTION

Unregister a memory address range from userfaultfd. The pages in the range must be “compatible” (see [**UFFDIO\_REGISTER**(2const)](/UFFDIO_REGISTER/2const.md)).

## RETURN VALUE

On success, 0 is returned. On error, -1 is returned and *errno* is set to indicate the error.

## ERRORS

- **EINVAL**

  Either *argp-\>start* or the *argp-\>len* fields was not a multiple of the system page size; or the *argp-\>len* field was zero; or these fields were otherwise invalid.

- **EINVAL**

  There as an incompatible mapping in the specified address range.

- **EINVAL**

  There was no mapping in the specified address range.

## STANDARDS

Linux.

## HISTORY

Linux 4.3.

## EXAMPLES

See [**userfaultfd**(2)](/userfaultfd/2.md).

## SEE ALSO

[**ioctl**(2)](/ioctl/2.md), [**ioctl\_userfaultfd**(2)](/ioctl_userfaultfd/2.md), [**UFFDIO\_REGISTER**(2const)](/UFFDIO_REGISTER/2const.md), [**userfaultfd**(2)](/userfaultfd/2.md)

*linux.git/Documentation/admin-guide/mm/userfaultfd.rst*