On Wed, 5 Dec 2012 16:47:36 -0500
Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> wrote:
> This patch fixes the warning from __list_del_entry() which is triggered
> when a process tries to do free_huge_page() for a hwpoisoned hugepage.
>
> Originally, page->lru of hugetlbfs head page was dangling when the
> hugepage was in use. This behavior has changed by commit 0edaecfab218d7
> ("hugetlb: add a list for tracking in-use HugeTLB pages"), where hugepages
> in use are linked to hugepage_activelist. HWpoisoned hugepages should not
> be charged to any process, so we introduce another list to link hwpoisoned
> hugepages.
>
> ...
>
> --- v3.7-rc8.orig/include/linux/hugetlb.h
> +++ v3.7-rc8/include/linux/hugetlb.h
> @@ -230,6 +230,9 @@ struct hstate {
> unsigned long nr_overcommit_huge_pages;
> struct list_head hugepage_activelist;
> struct list_head hugepage_freelists[MAX_NUMNODES];
> +#ifdef CONFIG_MEMORY_FAILURE
> + struct list_head hugepage_hwpoisonedlist;
> +#endif
> unsigned int nr_huge_pages_node[MAX_NUMNODES];
> unsigned int free_huge_pages_node[MAX_NUMNODES];
> unsigned int surplus_huge_pages_node[MAX_NUMNODES];
> diff --git v3.7-rc8.orig/mm/hugetlb.c v3.7-rc8/mm/hugetlb.c
> index 59a0059..e61a749 100644
> --- v3.7-rc8.orig/mm/hugetlb.c
> +++ v3.7-rc8/mm/hugetlb.c
> @@ -1939,6 +1939,7 @@ void __init hugetlb_add_hstate(unsigned order)
> for (i = 0; i < MAX_NUMNODES; ++i)
> INIT_LIST_HEAD(&h->hugepage_freelists[i]);
> INIT_LIST_HEAD(&h->hugepage_activelist);
> + INIT_LIST_HEAD(&h->hugepage_hwpoisonedlist);
> h->next_nid_to_alloc = first_node(node_states[N_HIGH_MEMORY]);
> h->next_nid_to_free = first_node(node_states[N_HIGH_MEMORY]);
> snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
> @@ -3170,7 +3171,7 @@ int dequeue_hwpoisoned_huge_page(struct page *hpage)
>
> spin_lock(&hugetlb_lock);
> if (is_hugepage_on_freelist(hpage)) {
> - list_del(&hpage->lru);
> + list_move(&hpage->lru, &h->hugepage_hwpoisonedlist);
> set_page_refcounted(hpage);
> h->free_huge_pages--;
> h->free_huge_pages_node[nid]--;
Do we actually need to new list? We could use list_del_init() to leave
the page's list_head pointing at itself. In this state, it is its own
list_head and further list_del()s are a no-op.
I don't know whether this would trigger list-debug warnings.
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