NAME

       mincore — determine residency of memory pages

LIBRARY

       Standard C Library (libc, -lc)

SYNOPSIS

       #include <sys/mman.h>

       int
       mincore(const void *addr, size_t len, char *vec);

DESCRIPTION

       The  mincore()  system  call  determines  whether  each  of the pages in the region beginning at addr and
       continuing for len bytes is resident or mapped, depending on the value of sysctl vm.mincore_mapped.   The
       status  is  returned in the vec array, one character per page.  Each character is either 0 if the page is
       not resident, or a combination of the following flags (defined in <sys/mman.h>):

       MINCORE_INCORE            Page is in core (resident).

       MINCORE_REFERENCED        Page has been referenced by us.

       MINCORE_MODIFIED          Page has been modified by us.

       MINCORE_REFERENCED_OTHER  Page has been referenced.

       MINCORE_MODIFIED_OTHER    Page has been modified.

       MINCORE_SUPER             Page is part of a large (“super”) page.

       The information returned by mincore() may be out of date by the time the system call returns.   The  only
       way to ensure that a page is resident is to lock it into memory with the mlock(2) system call.

       If  the vm.mincore_mapped sysctl is set to a non-zero value (default), only the current process' mappings
       of the pages in the specified virtual address range are examined.  This does not preclude the system from
       returning MINCORE_REFERENCED_OTHER and MINCORE_MODIFIED_OTHER statuses.  Otherwise, if the  sysctl  value
       is  zero,  all resident pages backing the specified address range are examined, regardless of the mapping
       state.

RETURN VALUES

       The mincore() function returns the value 0 if successful; otherwise the value  -1  is  returned  and  the
       global variable errno is set to indicate the error.

ERRORS

       The mincore() system call will fail if:

       [ENOMEM]           The virtual address range specified by the addr and len arguments is not fully mapped.

       [EFAULT]           The vec argument points to an illegal address.

SEE ALSO

       madvise(2), mlock(2), mprotect(2), msync(2), munmap(2), getpagesize(3)

HISTORY

       The mincore() system call first appeared in 4.4BSD.

Debian                                           January 7, 2019                                      MINCORE(2)