From 7ea8574e5fa31f43d8098a028f12ba6a9c9f3530 Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@suse.cz>
Date: Fri, 29 Aug 2014 15:18:42 -0700
Subject: [PATCH] hugetlb_cgroup: use lockdep_assert_held rather than
 spin_is_locked

spin_lock may be an empty struct for !SMP configurations and so
arch_spin_is_locked may return unconditional 0 and trigger the VM_BUG_ON
even when the lock is held.

Replace spin_is_locked by lockdep_assert_held.  We will not BUG anymore
but it is questionable whether crashing makes a lot of sense in the
uncharge path.  Uncharge happens after the last page reference was
released so nobody should touch the page and the function doesn't update
any shared state except for res counter which uses synchronization of
its own.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/hugetlb_cgroup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
index 9eebfadeeee1..a67c26e0f360 100644
--- a/mm/hugetlb_cgroup.c
+++ b/mm/hugetlb_cgroup.c
@@ -217,7 +217,7 @@ void hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages,
 
 	if (hugetlb_cgroup_disabled())
 		return;
-	VM_BUG_ON(!spin_is_locked(&hugetlb_lock));
+	lockdep_assert_held(&hugetlb_lock);
 	h_cg = hugetlb_cgroup_from_page(page);
 	if (unlikely(!h_cg))
 		return;
-- 
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