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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>
This commit is contained in:
Naoya Horiguchi 2010-09-08 10:19:37 +09:00 committed by Andi Kleen
parent 6de2b1aab9
commit a9869b837c
1 changed files with 13 additions and 22 deletions
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35
mm/hugetlb.c
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@ -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);