Re: [PATCH] Allocate memory cgroup structures in local nodes v2

[Johannes Weiner <hannes@cmpxchg.org>]

On Wed, May 04, 2011 at 01:26:23PM -0700, Andi Kleen wrote:
> diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
> index 9905501..a362215 100644
> --- a/mm/page_cgroup.c
> +++ b/mm/page_cgroup.c
> @@ -134,7 +134,7 @@ static void *__init_refok alloc_page_cgroup(size_t size, int nid)
>  {
>  	void *addr = NULL;
>  
> -	addr = alloc_pages_exact(size, GFP_KERNEL | __GFP_NOWARN);
> +	addr = alloc_pages_exact_node(nid, GFP_KERNEL | __GFP_NOWARN, size);

alloc_pages_exact_node is not the 'specify node as well'-version of
alloc_pages_exact, it refers to 'exact node'.  Thus the
free_pages_exact call is no longer the right counter-part.

alloc_pages_exact_node takes an order, not a size argument.

alloc_pages_exact_node returns a pointer to the struct page, not to
the allocated memory, like all other alloc_pages* functions with the
exception of alloc_pages_exact.

I don't think any of those mistakes even triggers a compiler warning.
Wow.  This API is so thoroughly fscked beyond belief that I think the
only way to top this is to have one of the functions invert the bits
of its return value depending on the parity of the uptime counter.