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PAGEMAP_SCAN(2const) — Linux manual page

PAGEMAP_SCAN(2const)PAGEMAP_SCAN(2const)

NAME        top

       PAGEMAP_SCAN - get and/or clear page flags

LIBRARY        top

       Standard C library (libc,-lc)

SYNOPSIS        top

#include <linux/fs.h>/* Definition ofPAGE*andPM_*constants */#include <sys/ioctl.h>int ioctl(intpagemap_fd, PAGEMAP_SCAN, struct pm_scan_arg *arg);#include <linux/fs.h>struct pm_scan_arg {__u64  size;__u64  flags;__u64  start;__u64  end;__u64  walk_end;__u64  vec;__u64  vec_len;__u64  max_pages;__u64  category_inverted;__u64  category_mask;__u64  category_anyof_mask;__u64  return_mask;};struct page_region {__u64  start;__u64  end;__u64  categories;};

DESCRIPTION        top

       Thisioctl(2) is used to get and optionally clear some specific       flags from page table entries.  The information is returned withPAGE_SIZEgranularity.       To start tracking the written state (flag) of a page or range of       memory, theUFFD_FEATURE_WP_ASYNCmust be enabled byUFFDIO_APIioctl(2) onuserfaultfdand memory range must be registered withUFFDIO_REGISTER ioctl(2) inUFFDIO_REGISTER_MODE_WPmode.Supported page flags       The following page table entry flags are supported:PAGE_IS_WPALLOWED              The page has asynchronous write-protection enabled.PAGE_IS_WRITTEN              The page has been written to from the time it was write              protected.PAGE_IS_FILE              The page is file backed.PAGE_IS_PRESENT              The page is present in the memory.PAGE_IS_SWAPPED              The page is swapped.PAGE_IS_PFNZERO              The page has zero PFN.PAGE_IS_HUGE              The page is THP or Hugetlb backed.Supported operations       The get operation is always performed if the output buffer is       specified.  The other operations are as following:PM_SCAN_WP_MATCHING              Write protect the matched pages.PM_SCAN_CHECK_WPASYNC              Abort the scan when a page is found which doesn't have the              Userfaultfd Asynchronous Write protection enabled.Thestruct pm_scan_arg argumentsizeThis field should be set to the size of the structure in              bytes, as insizeof(struct pm_scan_arg).flagsThe operations to be performed are specified in it.startThe starting address of the scan is specified in it.endThe ending address of the scan is specified in it.walk_end              The kernel returns the scan's ending address in it.  Thewalk_end equal toend means that scan has completed on the              entire range.vecThe address ofpage_region array for output.vec_len              The length of thepage_region struct array.max_pages              It is the optional limit for the number of output pages              required.category_invertedPAGE_IS_* categories which values match if 0 instead of 1.category_mask              Skip pages for which anyPAGE_IS_* category doesn't match.category_anyof_mask              Skip pages for which noPAGE_IS_* category matches.return_maskPAGE_IS_* categories that are to be reported inpage_region.

RETURN VALUE        top

       On error, -1 is returned, anderrno is set to indicate the error.

ERRORS        top

       Error codes can be one of, but are not limited to, the following:EINVALInvalid arguments i.e., invalidsize of the argument,              invalidflags, invalidcategories, thestart address isn't              aligned withPAGE_SIZE, orvec_len is specified whenvec is              NULL.EFAULTInvalidarg pointer, invalidvec pointer, or invalid              address range specified bystart andend.ENOMEMNo memory is available.EINTRFetal signal is pending.

STANDARDS        top

       Linux.

HISTORY        top

       Linux 6.7.

SEE ALSO        top

ioctl(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            2025-05-17PAGEMAP_SCAN(2const)

Pages that refer to this page:ioctl_fs(2)

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