Re: [RFC v2 1/4] mm: make alloc_pages_exact_node pass __GFP_THISNODE

[Vlastimil Babka]

On 07/27/2015 05:39 PM, Johannes Weiner wrote:
> On Fri, Jul 24, 2015 at 04:45:23PM +0200, Vlastimil Babka wrote:
> > @@ -310,11 +326,18 @@ static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask,
> >   	return __alloc_pages(gfp_mask, order, node_zonelist(nid, gfp_mask));
> >   }
> >
> > +/*
> > + * Allocate pages, restricting the allocation to the node given as nid. The
> > + * node must be valid and online. This is achieved by adding __GFP_THISNODE
> > + * to gfp_mask.
> > + */
> >   static inline struct page *alloc_pages_exact_node(int nid, gfp_t gfp_mask,
> >   						unsigned int order)
> >   {
> >   	VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES || !node_online(nid));
> >
> > +	gfp_mask |= __GFP_THISNODE;
> > +
> >   	return __alloc_pages(gfp_mask, order, node_zonelist(nid, gfp_mask));
> >   }
>
> The "exact" name is currently ambiguous within the allocator API, and
> it's bad that we have _exact_node() and _exact_nid() with entirely
> different meanings. It'd be good to make "thisnode" refer to specific
> and exclusive node requests, and "exact" to mean page allocation
> chunks that are not in powers of two.

Ugh, good point.

> Would you consider renaming this function to alloc_pages_thisnode() as
> part of this series?

Sure, let's do it properly while at it. Yet "thisnode" is somewhat 
misleading name as it might imply the cpu's local node. The same applies 
to __GFP_THISNODE. So maybe find a better name for both? restrict_node? 
single_node?

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