hugetlb: fix dynamic pool resize failure case

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.

Signed-off-by: Adam Litke <agl@us.ibm.com>
Acked-by: Dave Hansen <haveblue@us.ibm.com>
Cc: David Gibson <hermes@gibson.dropbear.id.au>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Ken Chen <kenchen@google.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 2 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 82efecbab96f..ae2959bb59cb 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -302,8 +302,17 @@ 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;