On Fri, 24 Jul 2015, Vlastimil Babka wrote:
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index 15928f0..c50848e 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -300,6 +300,22 @@ __alloc_pages(gfp_t gfp_mask, unsigned int order,
> return __alloc_pages_nodemask(gfp_mask, order, zonelist, NULL);
> }
>
> +/*
> + * An optimized version of alloc_pages_node(), to be only used in places where
> + * the overhead of the check for nid == -1 could matter.
We don't actually check for nid == -1, or nid == NUMA_NO_NODE, in any of
the functions. I would just state that nid must be valid and possible to
allocate from when passed to this function.
> + */
> +static inline struct page *
> +__alloc_pages_node(int nid, gfp_t gfp_mask, unsigned int order)
> +{
> + VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES || !node_online(nid));
> +
> + return __alloc_pages(gfp_mask, order, node_zonelist(nid, gfp_mask));
> +}
> +
> +/*
> + * Allocate pages, preferring the node given as nid. When nid equals -1,
> + * prefer the current CPU's node.
> + */
We've done quite a bit of work to refer only to NUMA_NO_NODE, so we'd like
to avoid hardcoded -1 anywhere we can.
> static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask,
> unsigned int order)
> {
> @@ -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.
Not sure we need to point out that __GPF_THISNODE does this, it stands out
pretty well in the function already :)
> + */
> 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));
> }
>
[snip]
I assume you looked at the collapse_huge_page() case and decided that it
needs no modification since the gfp mask is used later for other calls?
> diff --git a/mm/migrate.c b/mm/migrate.c
> index f53838f..d139222 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1554,10 +1554,8 @@ static struct page *alloc_misplaced_dst_page(struct page *page,
> struct page *newpage;
>
> newpage = alloc_pages_exact_node(nid,
> - (GFP_HIGHUSER_MOVABLE |
> - __GFP_THISNODE | __GFP_NOMEMALLOC |
> - __GFP_NORETRY | __GFP_NOWARN) &
> - ~GFP_IOFS, 0);
> + (GFP_HIGHUSER_MOVABLE | __GFP_NOMEMALLOC |
> + __GFP_NORETRY | __GFP_NOWARN) & ~GFP_IOFS, 0);
>
> return newpage;
> }
[snip]
What about the alloc_pages_exact_node() in new_page_node()?
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