mm/hugetlb.c: add cond_resched_lock() in return_unused_surplus_pages()

soft lockup in freeing gigantic hugepage fixed in commit 55f67141a892 "mm:
hugetlb: fix softlockup when a large number of hugepages are freed." can
happen in return_unused_surplus_pages(), so let's fix it.

Signed-off-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index dd30f22b35e0..246192929a2d 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1172,6 +1172,7 @@ static void return_unused_surplus_pages(struct hstate *h,
         while (nr_pages--) {
                 if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1))
                         break;
+                cond_resched_lock(&hugetlb_lock);
         }
 }