centos man page for alloc_contig_range

ALLOC_CONTIG_RANGE(9)					    Memory Management in Linux					     ALLOC_CONTIG_RANGE(9)

NAME
       alloc_contig_range - - tries to allocate given range of pages

SYNOPSIS
       int alloc_contig_range(unsigned long start, unsigned long end, unsigned migratetype);

ARGUMENTS
       start
	   start PFN to allocate

       end
	   one-past-the-last PFN to allocate

       migratetype
	   migratetype of the underlaying pageblocks (either #MIGRATE_MOVABLE or #MIGRATE_CMA). All pageblocks in range must have the same
	   migratetype and it must be either of the two.

DESCRIPTION
       The PFN range does not have to be pageblock or MAX_ORDER_NR_PAGES aligned, however it's the caller's responsibility to guarantee that we
       are the only thread that changes migrate type of pageblocks the pages fall in.

       The PFN range must belong to a single zone.

       Returns zero on success or negative error code. On success all pages which PFN is in [start, end) are allocated for the caller and need to
       be freed with free_contig_range.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014						     ALLOC_CONTIG_RANGE(9)