.\" Copyright 2016, IBM Corporation.
.\" Written by Mike Rapoport <rppt@linux.vnet.ibm.com>
.\" Copyright 2016, Michael Kerrisk <mtk.manpages@gmail.com>
.\" Copyright 2024, Alejandro Colomar <alx@kernel.org>
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH UFFDIO_CONTINUE 2const (date) "Linux man-pages (unreleased)"
.SH NAME
UFFDIO_CONTINUE
\-
resolve a minor page fault
.SH LIBRARY
Standard C library
.RI ( libc ,\~ \-lc )
.SH SYNOPSIS
.nf
.BR "#include <linux/userfaultfd.h>" "  /* Definition of " UFFD* " constants */"
.B #include <sys/ioctl.h>
.P
.BI "int ioctl(int " fd ", UFFDIO_CONTINUE, struct uffdio_continue *" argp );
.P
.B #include <linux/userfaultfd.h>
.P
.fi
.EX
.B struct uffdio_continue {
.B "    struct uffdio_range  range;"
                     /* Range to install PTEs for and continue */
.BR "    __u64   mode;" "    /* Flags controlling the behavior of continue */"
.BR "    __s64   mapped;" "  /* Number of bytes mapped, or negated error */"
.B };
.EE
.SH DESCRIPTION
Resolve a minor page fault
by installing page table entries
for existing pages in the page cache.
.P
The following value may be bitwise ORed in
.I mode
to change the behavior of the
.B UFFDIO_CONTINUE
operation:
.TP
.B UFFDIO_CONTINUE_MODE_DONTWAKE
Do not wake up the thread that waits for page-fault resolution.
.P
The
.I mapped
field is used by the kernel
to return the number of bytes that were actually mapped,
or an error in the same manner as
.BR UFFDIO_COPY .
If the value returned in the
.I mapped
field doesn't match the value that was specified in
.IR range.len ,
the operation fails with the error
.BR EAGAIN .
The
.I mapped
field is output-only;
it is not read by the
.B UFFDIO_CONTINUE
operation.
.SH RETURN VALUE
This
.BR ioctl (2)
operation returns 0 on success.
In this case,
the entire area was mapped.
On error, \-1 is returned and
.I errno
is set to indicate the error.
.SH ERRORS
.TP
.B EAGAIN
The number of bytes mapped
(i.e., the value returned in the
.I mapped
field)
does not equal the value that was specified in the
.I range.len
field.
.TP
.B EEXIST
One or more pages were already mapped in the given range.
.TP
.B EFAULT
No existing page could be found in the page cache for the given range.
.TP
.B EINVAL
Either
.I range.start
or
.I range.len
was not a multiple of the system page size; or
.I range.len
was zero; or the range specified was invalid.
.TP
.B EINVAL
An invalid bit was specified in the
.I mode
field.
.TP
.B ENOENT
The faulting process has changed its virtual memory layout simultaneously with
an outstanding
.B UFFDIO_CONTINUE
operation.
.TP
.B ENOMEM
Allocating memory needed to setup the page table mappings failed.
.TP
.B ESRCH
The faulting process has exited at the time of a
.B UFFDIO_CONTINUE
operation.
.SH STANDARDS
Linux.
.SH HISTORY
Linux 5.13.
.SH EXAMPLES
See
.BR userfaultfd (2).
.SH SEE ALSO
.BR ioctl (2),
.BR ioctl_userfaultfd (2),
.BR userfaultfd (2)
.P
.I linux.git/\:Documentation/\:admin\-guide/\:mm/\:userfaultfd.rst