[PATCH 5.9 174/255] mm: memcontrol: fix missing wakeup polling thread

Greg Kroah-Hartman
2020-11-17T13:39:22Z

From: Muchun Song <songmuchun@bytedance.com>

[ Upstream commit 8b21ca0218d29cc6bb7028125c7e5a10dfb4730c ]

When we poll the swap.events, we can miss being woken up when the swap
event occurs. Because we didn't notify.

Fixes: f3a53a3a1e5b ("mm, memcontrol: implement memory.swap.events")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Yafang Shao <laoar.shao@gmail.com>
Cc: Chris Down <chris@chrisdown.name>
Cc: Tejun Heo <tj@kernel.org>
Link: https://lkml.kernel.org/r/20201105161936.98312-1-songmuchun@bytedance.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/memcontrol.h | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index d0b036123c6ab..fa635207fe96d 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -897,12 +897,19 @@ static inline void count_memcg_event_mm(struct mm_struct *mm,
static inline void memcg_memory_event(struct mem_cgroup *memcg,
enum memcg_memory_event event)
{
+ bool swap_event = event == MEMCG_SWAP_HIGH || event == MEMCG_SWAP_MAX ||
+ event == MEMCG_SWAP_FAIL;
+
atomic_long_inc(&memcg->memory_events_local[event]);
- cgroup_file_notify(&memcg->events_local_file);
+ if (!swap_event)
+ cgroup_file_notify(&memcg->events_local_file);

do {
atomic_long_inc(&memcg->memory_events[event]);
- cgroup_file_notify(&memcg->events_file);
+ if (swap_event)
+ cgroup_file_notify(&memcg->swap_events_file);
+ else
+ cgroup_file_notify(&memcg->events_file);

if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
break;
--
2.27.0