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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | STANDARDS | HISTORY | EXAMPLES | SEE ALSO | COLOPHON |
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UFFDIO_RWPROTECT(2const) UFFDIO_RWPROTECT(2const)
UFFDIO_RWPROTECT - read-write-protect or un-protect a userfaultfd-
registered memory range
Standard C library (libc, -lc)
#include <linux/userfaultfd.h> /* Definition of UFFD* constants */
#include <sys/ioctl.h>
int ioctl(int fd, UFFDIO_RWPROTECT, struct uffdio_rwprotect *argp);
#include <linux/userfaultfd.h>
struct uffdio_rwprotect {
struct uffdio_range range; /* Range to change RWP on */
__u64 mode; /* Mode flags */
};
Read-write-protect or un-protect a userfaultfd-registered memory
range registered with mode UFFDIO_REGISTER_MODE_RWP.
The following mode bits are supported:
UFFDIO_RWPROTECT_MODE_RWP
When this mode bit is set, the ioctl installs read-write
protection on every page present in the range specified by
.range. Otherwise the ioctl removes read-write protection
from the range, which is also how a fault handler resolves
an UFFD_PAGEFAULT_FLAG_RWP notification.
UFFDIO_RWPROTECT_MODE_DONTWAKE
When this mode bit is set, do not wake up any thread that
waits for page-fault resolution after the operation. This
can be specified only if UFFDIO_RWPROTECT_MODE_RWP is not
specified.
Read-write protection only affects pages that are currently
populated in the range; unmapped addresses are left untouched.
For anonymous mappings, protection is preserved across page
reclaim (the marker rides on the swap entry) and migration. For
shmem and file-backed mappings, protection is dropped when the
backing page is reclaimed. Callers must also re-arm a range with
UFFDIO_RWPROTECT after any operation that explicitly drops the
underlying page: MADV_DONTNEED on anonymous memory, hole-punch on
shmem, truncation of a file mapping.
On success, 0 is returned. On error, -1 is returned and errno is
set to indicate the error.
EINVAL The start or the len field of the uffdio_range structure
was not a multiple of the system page size, or len was
zero, or the specified range was otherwise invalid, or an
invalid mode bit was specified, or
UFFDIO_RWPROTECT_MODE_DONTWAKE was specified together with
UFFDIO_RWPROTECT_MODE_RWP.
EAGAIN The process was interrupted; retry this call.
ENOENT The range specified in .range is not valid; for example,
the virtual address does not exist, or part of the range is
not registered with UFFDIO_REGISTER_MODE_RWP.
EFAULT Encountered a generic fault during processing.
Linux.
Linux 7.2.
See userfaultfd(2).
ioctl(2), ioctl_userfaultfd(2), userfaultfd(2)
linux.git/Documentation/admin-guide/mm/userfaultfd.rst
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
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⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
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2026-09-09. If you discover any rendering problems in this HTML
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Linux man-pages 6.19 2026-05-28 UFFDIO_RWPROTECT(2const)
Pages that refer to this page: ioctl_userfaultfd(2), UFFDIO_REGISTER(2const)
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HTML rendering created 2026-09-09 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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