[PATCH v9 20/20] mm/memcg: add debug checking in lock_page_memcg

[Alex Shi]

This extra irq disable/enable and BUG_ON checking costs 5% readtwice
performance on a 2 socket * 26 cores * HT box. So put it into
CONFIG_PROVE_LOCKING.

Signed-off-by: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: cgroups@xxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 mm/memcontrol.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2d71e53ead88..8d7f6336f15c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2026,6 +2026,12 @@ struct mem_cgroup *lock_page_memcg(struct page *page)
 	if (unlikely(!memcg))
 		return NULL;
 
+#ifdef CONFIG_PROVE_LOCKING
+	local_irq_save(flags);
+	might_lock(&memcg->move_lock);
+	local_irq_restore(flags);
+#endif
+
 	if (atomic_read(&memcg->moving_account) <= 0)
 		return memcg;
 
-- 
1.8.3.1