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[37.188.249.36]) by smtp.gmail.com with ESMTPSA id 128sm29510735wme.39.2020.05.13.02.05.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 May 2020 02:05:03 -0700 (PDT) Date: Wed, 13 May 2020 11:05:02 +0200 From: Michal Hocko To: Zefan Li Cc: Johannes Weiner , Vladimir Davydov , Cgroups , linux-mm@kvack.org, Andrew Morton Subject: Re: [PATCH] memcg: Fix memcg_kmem_bypass() for remote memcg charging Message-ID: <20200513090502.GV29153@dhcp22.suse.cz> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed 13-05-20 15:28:28, Li Zefan wrote: > While trying to use remote memcg charging in an out-of-tree kernel module > I found it's not working, because the current thread is a workqueue thread. > > Signed-off-by: Zefan Li > --- > > No need to queue this for v5.7 as currently no upstream users of this memcg > feature suffer from this bug. > > --- > mm/memcontrol.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index a3b97f1..db836fc 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2802,6 +2802,8 @@ static void memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg, > > static inline bool memcg_kmem_bypass(void) > { > + if (unlikely(current->active_memcg)) > + return false; I am confused. Why the check below is insufficient? It checks for both mm and PF_KTHREAD? > if (in_interrupt() || !current->mm || (current->flags & PF_KTHREAD)) > return true; > return false; > -- > 2.7.4 -- Michal Hocko SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: Re: [PATCH] memcg: Fix memcg_kmem_bypass() for remote memcg charging Date: Wed, 13 May 2020 11:05:02 +0200 Message-ID: <20200513090502.GV29153@dhcp22.suse.cz> References: Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Zefan Li Cc: Johannes Weiner , Vladimir Davydov , Cgroups , linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Andrew Morton On Wed 13-05-20 15:28:28, Li Zefan wrote: > While trying to use remote memcg charging in an out-of-tree kernel module > I found it's not working, because the current thread is a workqueue thread. > > Signed-off-by: Zefan Li > --- > > No need to queue this for v5.7 as currently no upstream users of this memcg > feature suffer from this bug. > > --- > mm/memcontrol.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index a3b97f1..db836fc 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2802,6 +2802,8 @@ static void memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg, > > static inline bool memcg_kmem_bypass(void) > { > + if (unlikely(current->active_memcg)) > + return false; I am confused. Why the check below is insufficient? It checks for both mm and PF_KTHREAD? > if (in_interrupt() || !current->mm || (current->flags & PF_KTHREAD)) > return true; > return false; > -- > 2.7.4 -- Michal Hocko SUSE Labs