UFFDIO_ZEROPAGE(2const) — Linux manual page

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | STANDARDS | HISTORY | EXAMPLES | SEE ALSO | COLOPHON

UFFDIO_ZEROPAGE(2const)                          UFFDIO_ZEROPAGE(2const)

NAME         top

       UFFDIO_ZEROPAGE - zero out a memory range registered with
       userfaultfd

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

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

       int ioctl(int fd, UFFDIO_ZEROPAGE, struct uffdio_zeropage *argp);

       #include <linux/userfaultfd.h>

       struct uffdio_zeropage {
           struct uffdio_range  range;
           __u64                mode;      /* Flags controlling behavior */
           __s64                zeropage;  /* Number of bytes zeroed */
       };

DESCRIPTION         top

       Zero out a memory range registered with userfaultfd.

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

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

       The zeropage field is used by the kernel to return the number of
       bytes that was actually zeroed, or an error in the same manner as
       UFFDIO_COPY.  If the value returned in the zeropage field doesn't
       match the value that was specified in range.len, the operation
       fails with the error EAGAIN.  The zeropage field is output-only;
       it is not read by the UFFDIO_ZEROPAGE operation.

RETURN VALUE         top

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

ERRORS         top

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

       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.

       ESRCH (since Linux 4.13)
              The faulting process has exited at the time of a
              UFFDIO_ZEROPAGE operation.

STANDARDS         top

       Linux.

HISTORY         top

       Linux 4.3.

EXAMPLES         top

       See userfaultfd(2).

SEE ALSO         top

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

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

COLOPHON         top

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Linux man-pages 6.9.1          2024-06-17        UFFDIO_ZEROPAGE(2const)

Pages that refer to this page: ioctl_userfaultfd(2)