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SubjectRe: [PATCH] [10/18] Factor out new huge page preparation code into separate function
On (17/03/08 02:58), Andi Kleen didst pronounce:
> Needed to avoid code duplication in follow up patches.
>
> This happens to fix a minor bug. When alloc_bootmem_node returns
> a fallback node on a different node than passed the old code
> would have put it into the free lists of the wrong node.
> Now it would end up in the freelist of the correct node.
>

It fixes a real bug for sure. It may be possible with that bug to leak
pages onto a linked list with bogus counters.

Possibly another candidate patch to move to the start of the series so
they can be merged and tested separetly?

> Signed-off-by: Andi Kleen <ak@suse.de>
>
> ---
> mm/hugetlb.c | 21 +++++++++++++--------
> 1 file changed, 13 insertions(+), 8 deletions(-)
>
> Index: linux/mm/hugetlb.c
> ===================================================================
> --- linux.orig/mm/hugetlb.c
> +++ linux/mm/hugetlb.c
> @@ -200,6 +200,17 @@ static int adjust_pool_surplus(struct hs
> return ret;
> }
>
> +static void huge_new_page(struct hstate *h, struct page *page)
> +{

prep_new_huge_page() as it has a similar responsibility to
prep_new_page() ? Just at a glance, huge_new_page() implies to me that
it calls alloc_pages_node()

> + unsigned nid = pfn_to_nid(page_to_pfn(page));
> + set_compound_page_dtor(page, free_huge_page);
> + spin_lock(&hugetlb_lock);
> + h->nr_huge_pages++;
> + h->nr_huge_pages_node[nid]++;
> + spin_unlock(&hugetlb_lock);
> + put_page(page); /* free it into the hugepage allocator */
> +}
> +
> static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
> {
> struct page *page;
> @@ -207,14 +218,8 @@ static struct page *alloc_fresh_huge_pag
> page = alloc_pages_node(nid,
> htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|__GFP_NOWARN,
> huge_page_order(h));
> - if (page) {
> - set_compound_page_dtor(page, free_huge_page);
> - spin_lock(&hugetlb_lock);
> - h->nr_huge_pages++;
> - h->nr_huge_pages_node[nid]++;
> - spin_unlock(&hugetlb_lock);
> - put_page(page); /* free it into the hugepage allocator */
> - }
> + if (page)
> + huge_new_page(h, page);
>
> return page;
> }
>

--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab


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