R> __get_free_pages(GFP_KERNEL, 12)
R>

The flags argument works in the same way as with kmalloc; usually either GFP_KERNEL or GFP_ATOMIC is used, perhaps with the addition of the __GFP_DMA flag (for memory that can be used for direct memory access operations) or __GFP_HIGHMEM when high memory can be used. order is the base-two logarithm of the number of pages you are requesting or freeing (i.e., log2 N). For example, order is 0 if you want one page and 3 if you request eight pages. If order is too big (no contiguous area of that size is available), the page allocation will fail. The maximum value of order was 5 in Linux 2.0 (corresponding to 32 pages) and 9 with later versions (corresponding to 512 pages: 2 MB on most platforms). Anyway, the bigger order is, the more likely it is that the allocation will fail.