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UFFDIO_POISON(2const) — Linux manual page

NAME \|LIBRARY \|SYNOPSIS \|DESCRIPTION \|RETURN VALUE \|ERRORS \|STANDARDS \|HISTORY \|EXAMPLES \|SEE ALSO \|COLOPHON

UFFDIO_POISON(2const)UFFDIO_POISON(2const)

NAME top

       UFFDIO_POISON - mark an address range as "poisoned"

LIBRARY top

       Standard C library (libc,-lc)

SYNOPSIS top

#include <linux/userfaultfd.h>/* Definition ofUFFD*constants */#include <sys/ioctl.h>int ioctl(intfd, 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 top

       Mark an address range as "poisoned".  Future accesses to these       addresses will raise aSIGBUSsignal.  UnlikeMADV_HWPOISONthis       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 inmode to change the       behavior of theUFFDIO_POISONoperation:UFFDIO_POISON_MODE_DONTWAKE              Do not wake up the thread that waits for page-fault              resolution.       Theupdated field is used by the kernel to return the number of       bytes that were actually poisoned, or an error in the same manner       asUFFDIO_COPY.  If the value returned in theupdated field       doesn't match the value that was specified inrange.len, the       operation fails with the errorEAGAIN.  Theupdated field is       output-only; it is not read by theUFFDIO_POISONoperation.

RETURN VALUE top

       On success, 0 is returned.  In this case, the entire area was       poisoned.       On error, -1 is returned anderrno is set to indicate the error.

ERRORS top

EAGAINThe number of bytes mapped (i.e., the value returned in theupdated field) does not equal the value that was specified              in therange.len field.EINVALEitherrange.start orrange.len was not a multiple of the              system page size; orrange.len was zero; or the range              specified was invalid.EINVALAn invalid bit was specified in themode field.EEXISTOne or more pages were already mapped in the given range.ENOENTThe faulting process has changed its virtual memory layout              simultaneously with an outstandingUFFDIO_POISONoperation.ENOMEMAllocating memory for page table entries failed.ESRCHThe faulting process has exited at the time of aUFFDIO_POISONoperation.

STANDARDS top

       Linux.

HISTORY top

       Linux 6.6.

EXAMPLES top

       Seeuserfaultfd(2).

COLOPHON top

       This page is part of theman-pages (Linux kernel and C library       user-space interface documentation) project.  Information about       the project can be found at        ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report       for this manual page, see       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.       This page was obtained from the tarball man-pages-6.15.tar.gz       fetched from       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on       2025-08-11.  If you discover any rendering problems in this HTML       version of the page, or you believe there is a better or more up-       to-date source for the page, or you have corrections or       improvements to the information in this COLOPHON (which isnot       part of the original manual page), send a mail to       man-pages@man7.orgLinux man-pages 6.15            2025-05-17UFFDIO_POISON(2const)

Pages that refer to this page:ioctl_userfaultfd(2)

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