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ioctl_userfaultfd(2) — Linux manual page

ioctl_userfaultfd(2)       System Calls Manualioctl_userfaultfd(2)

NAME        top

       ioctl_userfaultfd - create a file descriptor for handling page       faults in user space

LIBRARY        top

       Standard C library (libc,-lc)

SYNOPSIS        top

#include <linux/userfaultfd.h>/* Definition ofUFFD*constants */#include <sys/ioctl.h>int ioctl(intfd, intop, ...);

DESCRIPTION        top

       Variousioctl(2) operations can be performed on a userfaultfd       object (created by a call touserfaultfd(2)) using calls of the       form:           ioctl(fd, op, argp);       In the above,fd is a file descriptor referring to a userfaultfd       object,op is one of the operations listed below, andargp is a       pointer to a data structure that is specific toop.       The variousioctl(2) operations are described below.  TheUFFDIO_API,UFFDIO_REGISTER, andUFFDIO_UNREGISTERoperations are       used toconfigure userfaultfd behavior.  These operations allow       the caller to choose what features will be enabled and what kinds       of events will be delivered to the application.  The remaining       operations arerange operations.  These operations enable the       calling application to resolve page-fault events.UFFDIO_API(2const)UFFDIO_REGISTER(2const)UFFDIO_UNREGISTER(2const)UFFDIO_COPY(2const)UFFDIO_MOVE(2const)UFFDIO_ZEROPAGE(2const)UFFDIO_WAKE(2const)UFFDIO_WRITEPROTECT(2const)UFFDIO_CONTINUE(2const)UFFDIO_POISON(2const)

RETURN VALUE        top

       On success, 0 is returned.  On error, -1 is returned, anderrno is       set to indicate the error.

ERRORS        top

       The following general errors can occur for all of the operations       described above:EFAULTargp does not point to a valid memory address.EINVAL(For all operations exceptUFFDIO_API.)  The userfaultfd              object has not yet been enabled (via theUFFDIO_API              operation).

STANDARDS        top

       Linux.

EXAMPLES        top

       Seeuserfaultfd(2).

SEE ALSO        top

ioctl(2),mmap(2),userfaultfd(2)linux.git/Documentation/admin-guide/mm/userfaultfd.rst

COLOPHON        top

       This page is part of theman-pages (Linux kernel and C library       user-space interface documentation) project.  Information about       the project can be found at        ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report       for this manual page, see       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.       This page was obtained from the tarball man-pages-6.15.tar.gz       fetched from       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on       2025-08-11.  If you discover any rendering problems in this HTML       version of the page, or you believe there is a better or more up-       to-date source for the page, or you have corrections or       improvements to the information in this COLOPHON (which isnot       part of the original manual page), send a mail to       man-pages@man7.orgLinux man-pages 6.15            2025-05-17ioctl_userfaultfd(2)

Pages that refer to this page:ioctl(2), UFFDIO_API(2const), UFFDIO_CONTINUE(2const), UFFDIO_COPY(2const), UFFDIO_MOVE(2const), UFFDIO_POISON(2const), UFFDIO_REGISTER(2const), UFFDIO_UNREGISTER(2const), UFFDIO_WAKE(2const), UFFDIO_WRITEPROTECT(2const), UFFDIO_ZEROPAGE(2const), userfaultfd(2)

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