GET_USER_PAGES_FAST(9)              Memory Management in Linux             GET_USER_PAGES_FAST(9)



NAME
       get_user_pages_fast - pin user pages in memory

SYNOPSIS
       int get_user_pages_fast(unsigned long start, int nr_pages, int write,
                               struct page ** pages);

ARGUMENTS
       start
           starting user address

       nr_pages
           number of pages from start to pin

       write
           whether pages will be written to

       pages
           array that receives pointers to the pages pinned. Should be at least nr_pages long.

DESCRIPTION
       Returns number of pages pinned. This may be fewer than the number requested. If nr_pages
       is 0 or negative, returns 0. If no pages were pinned, returns -errno.

       get_user_pages_fast provides equivalent functionality to get_user_pages, operating on
       current and current->mm, with force=0 and vma=NULL. However unlike get_user_pages, it must
       be called without mmap_sem held.

       get_user_pages_fast may take mmap_sem and page table locks, so no assumptions can be made
       about lack of locking. get_user_pages_fast is to be implemented in a way that is
       advantageous (vs get_user_pages) when the user memory area is already faulted in and
       present in ptes. However if the pages have to be faulted in, it may turn out to be
       slightly slower so callers need to carefully consider what to use. On many architectures,
       get_user_pages_fast simply falls back to get_user_pages.

COPYRIGHT
Kernel Hackers Manual 4.8.                 January 2017                    GET_USER_PAGES_FAST(9)