On Wed, 26 Apr 2017 09:27:31 +0530 Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx> wrote:
> Though migrating gigantic HugeTLB pages does not sound much like real
> world use case, they can be affected by memory errors. Hence migration
> at the PGD level HugeTLB pages should be supported just to enable soft
> and hard offline use cases.
>
> While allocating the new gigantic HugeTLB page, it should not matter
> whether new page comes from the same node or not. There would be very
> few gigantic pages on the system afterall, we should not be bothered
> about node locality when trying to save a big page from crashing.
>
> This introduces a new HugeTLB allocator called alloc_huge_page_nonid()
> which will scan over all online nodes on the system and allocate a
> single HugeTLB page.
>
> ...
>
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1669,6 +1669,23 @@ struct page *__alloc_buddy_huge_page_with_mpol(struct hstate *h,
> return __alloc_buddy_huge_page(h, vma, addr, NUMA_NO_NODE);
> }
>
> +struct page *alloc_huge_page_nonid(struct hstate *h)
> +{
> + struct page *page = NULL;
> + int nid = 0;
> +
> + spin_lock(&hugetlb_lock);
> + if (h->free_huge_pages - h->resv_huge_pages > 0) {
> + for_each_online_node(nid) {
> + page = dequeue_huge_page_node(h, nid);
> + if (page)
> + break;
> + }
> + }
> + spin_unlock(&hugetlb_lock);
> + return page;
> +}
> +
> /*
> * This allocation function is useful in the context where vma is irrelevant.
> * E.g. soft-offlining uses this function because it only cares physical
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index fe64d7729a8e..d4f5710cf3f7 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1481,11 +1481,15 @@ EXPORT_SYMBOL(unpoison_memory);
> static struct page *new_page(struct page *p, unsigned long private, int **x)
> {
> int nid = page_to_nid(p);
> - if (PageHuge(p))
> + if (PageHuge(p)) {
> + if (hstate_is_gigantic(page_hstate(compound_head(p))))
> + return alloc_huge_page_nonid(page_hstate(compound_head(p)));
> +
> return alloc_huge_page_node(page_hstate(compound_head(p)),
> nid);
> - else
> + } else {
> return __alloc_pages_node(nid, GFP_HIGHUSER_MOVABLE, 0);
> + }
> }
Rather than adding alloc_huge_page_nonid(), would it be neater to teach
alloc_huge_page_node() (actually dequeue_huge_page_node()) to understand
nid==NUMA_NO_NODE?
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