Messages in this thread | | | From | Muchun Song <> | Date | Fri, 6 Nov 2020 00:01:12 +0800 | Subject | Re: [External] Re: [PATCH] mm: memcontrol: fix missing wakeup polling thread |
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On Thu, Nov 5, 2020 at 11:52 PM Johannes Weiner <hannes@cmpxchg.org> wrote: > > On Wed, Nov 04, 2020 at 08:55:58PM +0800, Muchun Song wrote: > > When wen poll the memory.swap.events, we can miss being waked 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> > > Good catch! > > > --- > > include/linux/memcontrol.h | 18 ++++++++++++++++-- > > 1 file changed, 16 insertions(+), 2 deletions(-) > > > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > > index 0f4dd7829fb2..2456cb737329 100644 > > --- a/include/linux/memcontrol.h > > +++ b/include/linux/memcontrol.h > > @@ -1071,15 +1071,29 @@ static inline void count_memcg_event_mm(struct mm_struct *mm, > > rcu_read_unlock(); > > } > > > > +static inline bool is_swap_memory_event(enum memcg_memory_event event) > > +{ > > + return event == MEMCG_SWAP_HIGH || event == MEMCG_SWAP_MAX || > > + event == MEMCG_SWAP_FAIL; > > +} > > Please inline this, it's not really worth the indirection. > > > static inline void memcg_memory_event(struct mem_cgroup *memcg, > > enum memcg_memory_event event) > > { > > + bool swap_event = is_swap_memory_event(event); > > + struct cgroup_file *cfile; > > + > > atomic_long_inc(&memcg->memory_events_local[event]); > > - cgroup_file_notify(&memcg->events_local_file); > > + if (swap_event) { > > + cfile = &memcg->swap_events_file; > > + } else { > > + cfile = &memcg->events_file; > > + cgroup_file_notify(&memcg->events_local_file); > > + } > > > > do { > > atomic_long_inc(&memcg->memory_events[event]); > > - cgroup_file_notify(&memcg->events_file); > > + cgroup_file_notify(cfile); > > This loop is a walk up the hierarchy and memcg keeps changing, so you > cannot cache cfile up front. > > if (swap_event) > cgroup_file_notify(&memcg->swap_events_file); > else > cgroup_file_notify(&memcg->events_file);
Oh, Yeah, Thanks for reminding me.
-- Yours, Muchun
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