NAME

       UFFDIO_CONTINUE - resolve a minor page fault

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

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

       int ioctl(int fd, UFFDIO_CONTINUE, struct uffdio_continue *argp);

       #include <linux/userfaultfd.h>

       struct uffdio_continue {
           struct uffdio_range  range;
                            /* Range to install PTEs for and continue */
           __u64   mode;    /* Flags controlling the behavior of continue */
           __s64   mapped;  /* Number of bytes mapped, or negated error */
       };

DESCRIPTION

       Resolve a minor page fault by installing page table entries for existing pages in the page
       cache.

       The following  value  may  be  bitwise  ORed  in  mode  to  change  the  behavior  of  the
       UFFDIO_CONTINUE operation:

       UFFDIO_CONTINUE_MODE_DONTWAKE
              Do not wake up the thread that waits for page-fault resolution.

       The  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 UFFDIO_COPY.   If  the  value  returned  in  the
       mapped  field doesn't match the value that was specified in range.len, the operation fails
       with the error  EAGAIN.   The  mapped  field  is  output-only;  it  is  not  read  by  the
       UFFDIO_CONTINUE operation.

RETURN VALUE

       This  ioctl(2)  operation returns 0 on success.  In this case, the entire area was mapped.
       On error, -1 is returned and errno is set to indicate the error.

ERRORS

       EAGAIN The number of bytes mapped (i.e., the value returned in the mapped field) does  not
              equal the value that was specified in the range.len field.

       EEXIST One or more pages were already mapped in the given range.

       EFAULT No existing page could be found in the page cache for the given range.

       EINVAL Either  range.start  or  range.len  was  not a multiple of the system page size; or
              range.len was zero; or the range specified was invalid.

       EINVAL An invalid bit was specified in the mode field.

       ENOENT The faulting process has changed its virtual memory layout simultaneously  with  an
              outstanding UFFDIO_CONTINUE operation.

       ENOMEM Allocating memory needed to setup the page table mappings failed.

       ESRCH  The faulting process has exited at the time of a UFFDIO_CONTINUE operation.

STANDARDS

       Linux.

HISTORY

       Linux 5.13.

EXAMPLES

       See userfaultfd(2).

SEE ALSO

       ioctl(2), ioctl_userfaultfd(2), userfaultfd(2)

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