UFFDIO_ZEROPAGE(2const) UFFDIO_ZEROPAGE(2const)
NAME
UFFDIO_ZEROPAGE - zero out a memory range registered with userfaultfd
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#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
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
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
EAGAIN The number of bytes zeroed (i.e., the value returned in the ze-
ropage 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 in-
valid.
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
Linux.
HISTORY
Linux 4.3.
EXAMPLES
See userfaultfd(2).
SEE ALSO
ioctl(2), ioctl_userfaultfd(2), userfaultfd(2)
linux.git/Documentation/admin-guide/mm/userfaultfd.rst
Linux man-pages 6.9.1 2024-06-17 UFFDIO_ZEROPAGE(2const)
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