Re: "struct page" and allocating high memory

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On 28-04-08 22:15, Rene Herman wrote:
On 27-04-08 18:44, Robert P. J. Day wrote:

  so what does that comment mean?  it seems to be exactly backwards
from what i'm used to believing.

The comment seems confused yes. alloc_pages() is just the buddy allocator and gets you contiguous pages. For vmalloc() purposes, an array of struct page * is allocated, allocating one page at a time with alloc_page() (in __vmalloc_area_node).

Err. That's more me who seems confused. The vmalloc() bit is correct and yes, alloc_pages() is "just the buddy allocator and gets you [physically] contiguous pages" but that in fact ofcourse means the comment is fine. The single struct page * is fine for a higher order alloc_pages, since its's adjacent struct page pointers in the mem_map. That is:

	struct page *page = alloc_pages(gfp_mask, order);

means your struct page structures are at *page to *(page + 2^order) in the node's mem_map, even if they are highmem pages.

Rene.

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