NAME¶

UFFDIO_POISON - mark an address range as "poisoned"

LIBRARY¶

Standard C library (libc, -lc)

SYNOPSIS¶

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

int ioctl(int fd, UFFDIO_POISON, ...);

#include <linux/userfaultfd.h>

struct uffdio_poison {
	struct uffdio_range  range;
	                  /* Range to install poison PTE markers in */
	__u64   mode;     /* Flags controlling the behavior of poison */
	__s64   updated;  /* Number of bytes poisoned, or negated error */
};

DESCRIPTION¶

Mark an address range as "poisoned". Future accesses to these addresses will raise a SIGBUS signal. Unlike MADV_HWPOISON this works by installing page table entries, rather than "really" poisoning the underlying physical pages. This means it only affects this particular address space.

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

UFFDIO_POISON_MODE_DONTWAKE

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

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

RETURN VALUE¶

On success, 0 is returned. In this case, the entire area was poisoned.

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 updated 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.

EEXIST

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

ENOENT

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

ENOMEM

Allocating memory for page table entries failed.

ESRCH

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

STANDARDS¶

Linux.

HISTORY¶

Linux 6.6.

EXAMPLES¶

See userfaultfd(2).

SEE ALSO¶

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

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