From: Muchun Song <songmuchun@xxxxxxxxxxxxx> Subject: mm: memcontrol: fix missing wakeup polling thread When we poll the swap.events, we can miss being woken up when the swap event occurs. Because we didn't notify. Link: https://lkml.kernel.org/r/20201105161936.98312-1-songmuchun@xxxxxxxxxxxxx Fixes: f3a53a3a1e5b ("mm, memcontrol: implement memory.swap.events") Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx> Cc: Roman Gushchin <guro@xxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Yafang Shao <laoar.shao@xxxxxxxxx> Cc: Chris Down <chris@xxxxxxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/memcontrol.h | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/include/linux/memcontrol.h~mm-memcontrol-fix-missing-wakeup-polling-thread +++ a/include/linux/memcontrol.h @@ -900,12 +900,19 @@ static inline void count_memcg_event_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; _
