On Wed 16-11-16 14:55:04, Huang Shijie wrote:
> There are three ways we can allocate a new gigantic page:
>
> 1. When the NUMA is not enabled, use alloc_gigantic_page() to get
> the gigantic page.
>
> 2. The NUMA is enabled, but the vma is NULL.
> There is no memory policy we can refer to.
> So create a @nodes_allowed, initialize it with init_nodemask_of_mempolicy()
> or init_nodemask_of_node(). Then use alloc_fresh_gigantic_page() to get
> the gigantic page.
>
> 3. The NUMA is enabled, and the vma is valid.
> We can follow the memory policy of the @vma.
>
> Get @nodes_allowed by huge_nodemask(), and use alloc_fresh_gigantic_page()
> to get the gigantic page.
Again __hugetlb_alloc_gigantic_page is not used and it is hard to deduce
its usage from this commit. The above shouldn't be really much different from
what we do in alloc_pages_vma so please make sure to check it before
coming up with something hugetlb specific.
> Signed-off-by: Huang Shijie <shijie.huang@xxxxxxx>
> ---
> Since the huge_nodemask() is changed, we have to change this function a little.
>
> ---
> mm/hugetlb.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 63 insertions(+)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 6995087..c33bddc 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1502,6 +1502,69 @@ int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
>
> /*
> * There are 3 ways this can get called:
> + *
> + * 1. When the NUMA is not enabled, use alloc_gigantic_page() to get
> + * the gigantic page.
> + *
> + * 2. The NUMA is enabled, but the vma is NULL.
> + * Create a @nodes_allowed, and use alloc_fresh_gigantic_page() to get
> + * the gigantic page.
> + *
> + * 3. The NUMA is enabled, and the vma is valid.
> + * Use the @vma's memory policy.
> + * Get @nodes_allowed by huge_nodemask(), and use alloc_fresh_gigantic_page()
> + * to get the gigantic page.
> + */
> +static struct page *__hugetlb_alloc_gigantic_page(struct hstate *h,
> + struct vm_area_struct *vma, unsigned long addr, int nid)
> +{
> + NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
> + struct page *page = NULL;
> +
> + /* Not NUMA */
> + if (!IS_ENABLED(CONFIG_NUMA)) {
> + if (nid == NUMA_NO_NODE)
> + nid = numa_mem_id();
> +
> + page = alloc_gigantic_page(nid, huge_page_order(h));
> + if (page)
> + prep_compound_gigantic_page(page, huge_page_order(h));
> +
> + NODEMASK_FREE(nodes_allowed);
> + return page;
> + }
> +
> + /* NUMA && !vma */
> + if (!vma) {
> + if (nid == NUMA_NO_NODE) {
> + if (!init_nodemask_of_mempolicy(nodes_allowed)) {
> + NODEMASK_FREE(nodes_allowed);
> + nodes_allowed = &node_states[N_MEMORY];
> + }
> + } else if (nodes_allowed) {
> + init_nodemask_of_node(nodes_allowed, nid);
> + } else {
> + nodes_allowed = &node_states[N_MEMORY];
> + }
> +
> + page = alloc_fresh_gigantic_page(h, nodes_allowed, true);
> +
> + if (nodes_allowed != &node_states[N_MEMORY])
> + NODEMASK_FREE(nodes_allowed);
> +
> + return page;
> + }
> +
> + /* NUMA && vma */
> + if (huge_nodemask(vma, addr, nodes_allowed))
> + page = alloc_fresh_gigantic_page(h, nodes_allowed, true);
> +
> + NODEMASK_FREE(nodes_allowed);
> + return page;
> +}
> +
> +/*
> + * There are 3 ways this can get called:
> * 1. With vma+addr: we use the VMA's memory policy
> * 2. With !vma, but nid=NUMA_NO_NODE: We try to allocate a huge
> * page from any node, and let the buddy allocator itself figure
> --
> 2.5.5
>
--
Michal Hocko
SUSE Labs
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