[PATCH] hugetlb: Fix dynamic pool resize failure case

[Adam Litke <agl@us.ibm.com>]

Changes since V1
	Added a comment explaining the free logic in gather_surplus_pages.

When gather_surplus_pages() fails to allocate enough huge pages to satisfy
the requested reservation, it frees what it did allocate back to the buddy
allocator.  put_page() should be called instead of update_and_free_page()
to ensure that pool counters are updated as appropriate and the page's
refcount is decremented.

Andrew: This should apply cleanly to my patches in the -mm tree.

Signed-off-by: Adam Litke <agl@us.ibm.com>
---

 mm/hugetlb.c |   13 +++++++++++--
 1 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 9b3dfac..ce66c72 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -281,8 +281,17 @@ free:
 		list_del(&page->lru);
 		if ((--needed) >= 0)
 			enqueue_huge_page(page);
-		else
-			update_and_free_page(page);
+		else {
+			/*
+			 * Decrement the refcount and free the page using its
+			 * destructor.  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.
+			 */
+			spin_unlock(&hugetlb_lock);
+			put_page(page);
+			spin_lock(&hugetlb_lock);
+		}
 	}
 
 	return ret;

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