NAME

       mincore - determine whether pages are resident in memory

SYNOPSIS

       #include <unistd.h>
       #include <sys/mman.h>

       int mincore(void *addr, size_t length, unsigned char *vec);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       mincore():
           Since glibc 2.19:
               _DEFAULT_SOURCE
           Glibc 2.19 and earlier:
               _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

       mincore()  returns  a  vector  that  indicates  whether pages of the calling process's virtual memory are
       resident in core (RAM), and so will not cause a disk access  (page  fault)  if  referenced.   The  kernel
       returns  residency  information  about  the pages starting at the address addr, and continuing for length
       bytes.

       The addr argument must be a multiple of the system page size.  The length argument need not be a multiple
       of  the  page  size,  but  since residency information is returned for whole pages, length is effectively
       rounded up to the next multiple of the page size.   One  may  obtain  the  page  size  (PAGE_SIZE)  using
       sysconf(_SC_PAGESIZE).

       The  vec  argument must point to an array containing at least (length+PAGE_SIZE-1) / PAGE_SIZE bytes.  On
       return, the least significant bit of each byte will  be  set  if  the  corresponding  page  is  currently
       resident  in memory, and be clear otherwise.  (The settings of the other bits in each byte are undefined;
       these bits are reserved for possible later use.)  Of course the information returned in  vec  is  only  a
       snapshot:  pages that are not locked in memory can come and go at any moment, and the contents of vec may
       already be stale by the time this call returns.

RETURN VALUE

       On success, mincore() returns zero.  On error, -1 is returned, and errno is set appropriately.

ERRORS

       EAGAIN kernel is temporarily out of resources.

       EFAULT vec points to an invalid address.

       EINVAL addr is not a multiple of the page size.

       ENOMEM length is greater than (TASK_SIZE - addr).  (This could occur if a negative value is specified for
              length,  since  that  value will be interpreted as a large unsigned integer.)  In Linux 2.6.11 and
              earlier, the error EINVAL was returned for this condition.

       ENOMEM addr to addr + length contained unmapped memory.

VERSIONS

       Available since Linux 2.3.99pre1 and glibc 2.2.

CONFORMING TO

       mincore() is not specified in POSIX.1, and it is not available on all UNIX implementations.

BUGS

       Before kernel 2.6.21, mincore() did not return correct  information  for  MAP_PRIVATE  mappings,  or  for
       nonlinear mappings (established using remap_file_pages(2)).

SEE ALSO

       fincore(1), madvise(2), mlock(2), mmap(2), posix_fadvise(2), posix_madvise(3)

COLOPHON

       This  page  is  part  of  release  5.10  of  the  Linux man-pages project.  A description of the project,
       information  about  reporting  bugs,  and  the  latest  version  of  this   page,   can   be   found   at
       https://www.kernel.org/doc/man-pages/.