On 28-04-08 22:51, Rene Herman wrote:
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.
Okay, sorry, before I really completely confuse the hell out of this list,
allow me to reformulate this time being careful with the terminology. I was
still thinking myself when I said that.
... since its adjacent struct page structures 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 - 1 (which
are addresses inside the node's mem_map) even if they are highmem pages.
Rene.
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