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authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>2010-09-08 01:19:37 (GMT)
committerAndi Kleen <ak@linux.intel.com>2010-10-08 07:32:45 (GMT)
commita9869b837c098732bad84939015c0eb391b23e41 (patch)
tree00ba63997470724e2704c9b7c995c91672b53c7b /mm/hugetlb.c
parent6de2b1aab94355482bd2accdc115666509667458 (diff)
hugetlb: move refcounting in hugepage allocation inside hugetlb_lock
Currently alloc_huge_page() raises page refcount outside hugetlb_lock. but it causes race when dequeue_hwpoison_huge_page() runs concurrently with alloc_huge_page(). To avoid it, this patch moves set_page_refcounted() in hugetlb_lock. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andi Kleen <ak@linux.intel.com>
Diffstat (limited to 'mm/hugetlb.c')
-rw-r--r--mm/hugetlb.c35
1 files changed, 13 insertions, 22 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index deb7beb..636be5d 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -509,6 +509,7 @@ static struct page *dequeue_huge_page_node(struct hstate *h, int nid)
return NULL;
page = list_entry(h->hugepage_freelists[nid].next, struct page, lru);
list_del(&page->lru);
+ set_page_refcounted(page);
h->free_huge_pages--;
h->free_huge_pages_node[nid]--;
return page;
@@ -868,12 +869,6 @@ static struct page *alloc_buddy_huge_page(struct hstate *h, int nid)
spin_lock(&hugetlb_lock);
if (page) {
- /*
- * This page is now managed by the hugetlb allocator and has
- * no users -- drop the buddy allocator's reference.
- */
- put_page_testzero(page);
- VM_BUG_ON(page_count(page));
r_nid = page_to_nid(page);
set_compound_page_dtor(page, free_huge_page);
/*
@@ -936,16 +931,13 @@ retry:
spin_unlock(&hugetlb_lock);
for (i = 0; i < needed; i++) {
page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
- if (!page) {
+ if (!page)
/*
* We were not able to allocate enough pages to
* satisfy the entire reservation so we free what
* we've allocated so far.
*/
- spin_lock(&hugetlb_lock);
- needed = 0;
goto free;
- }
list_add(&page->lru, &surplus_list);
}
@@ -972,31 +964,31 @@ retry:
needed += allocated;
h->resv_huge_pages += delta;
ret = 0;
-free:
+
+ spin_unlock(&hugetlb_lock);
/* Free the needed pages to the hugetlb pool */
list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
if ((--needed) < 0)
break;
list_del(&page->lru);
+ /*
+ * This page is now managed by the hugetlb allocator and has
+ * no users -- drop the buddy allocator's reference.
+ */
+ put_page_testzero(page);
+ VM_BUG_ON(page_count(page));
enqueue_huge_page(h, page);
}
/* Free unnecessary surplus pages to the buddy allocator */
+free:
if (!list_empty(&surplus_list)) {
- spin_unlock(&hugetlb_lock);
list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
list_del(&page->lru);
- /*
- * The page has a reference count of zero already, so
- * call free_huge_page directly instead of using
- * put_page. This must be done with hugetlb_lock
- * unlocked which is safe because free_huge_page takes
- * hugetlb_lock before deciding how to free the page.
- */
- free_huge_page(page);
+ put_page(page);
}
- spin_lock(&hugetlb_lock);
}
+ spin_lock(&hugetlb_lock);
return ret;
}
@@ -1123,7 +1115,6 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
}
}
- set_page_refcounted(page);
set_page_private(page, (unsigned long) mapping);
vma_commit_reservation(h, vma, addr);

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