UFFDIO_ZEROPAGE - zero out a memory range registered with userfaultfd

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.

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.

See userfaultfd(2).

Linux 4.3.

Standard C library (libc, -lc)

UFFDIO_ZEROPAGE - zero out a memory range registered with userfaultfd

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.

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)

Linux.

#include<linux/userfaultfd.h> /* Definition of UFFD* constants */ #include<sys/ioctl.h>intioctl(intfd,UFFDIO_ZEROPAGE,structuffdio_zeropage*argp);#include<linux/userfaultfd.h>structuffdio_zeropage{structuffdio_rangerange;__u64mode; /* Flags controlling behavior */ __s64zeropage; /* Number of bytes zeroed */ };