UFFDIO_RWPROTECT(2const)                              UFFDIO_RWPROTECT(2const)

NAME
       UFFDIO_RWPROTECT - read-write-protect or un-protect a userfaultfd-
       registered memory range

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #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 */
       };

DESCRIPTION
       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.

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

ERRORS
       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.

STANDARDS
       Linux.

HISTORY
       Linux 7.2.

EXAMPLES
       See userfaultfd(2).

SEE ALSO
       ioctl(2), ioctl_userfaultfd(2), userfaultfd(2)

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

Linux man-pages 6.19              2026-05-28          UFFDIO_RWPROTECT(2const)