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