UFFDIO_CONTINUE - resolve a minor page fault

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.

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.

See userfaultfd(2).

Linux 5.13.

Standard C library (libc, -lc)

UFFDIO_CONTINUE - resolve a minor page fault

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.

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_CONTINUE(2const)

Linux.

#include<linux/userfaultfd.h> /* Definition of UFFD* constants */ #include<sys/ioctl.h>intioctl(intfd,UFFDIO_CONTINUE,structuffdio_continue*argp);#include<linux/userfaultfd.h>structuffdio_continue{structuffdio_rangerange; /* Range to install PTEs for and continue */ __u64mode; /* Flags controlling the behavior of continue */ __s64mapped; /* Number of bytes mapped, or negated error */ };