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Mon, 11 Jan 2021 13:44:14 -0500 Received: from mail-ed1-x531.google.com (mail-ed1-x531.google.com [IPv6:2a00:1450:4864:20::531]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 36AC5C061786; Mon, 11 Jan 2021 10:43:34 -0800 (PST) Received: by mail-ed1-x531.google.com with SMTP id v26so768150eds.13; Mon, 11 Jan 2021 10:43:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=HdavPfho2y2aZPaSzJ50dkLev1j8QD0jxgYpMcuQTxo=; b=qD8xUYRdDKGqeMdTnSxWls6Jl/yNJ5ruqkG/XcNRXfZX+T4BdbjtK0o5I9jmPVn/ce B1vYupIurWRK8Ripfkjh9RZ3Xb+Y6nLJMbpPocyjLxcCoWr9RJcKG6VYZWdFfCGLor2/ 0hEnjDBxzrMNKyuFAYJuEVMRWlb+Ot34fRTIPGe9LImLoG/eAQCRnR+Hl6v/obd5kViB JQrkMo6EakYHJpOicqguAI2E+5c7K3LmuXBokuV+5xx1jgHTju64Osy+M4MQkwplx0hV rgPn9LiebSR79SiwTfP+jipp+5QZPjxm9Hkupu8D7UQENDXA2aresoMBMIRN0yHdDLfc RWog== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=HdavPfho2y2aZPaSzJ50dkLev1j8QD0jxgYpMcuQTxo=; b=Jl0r/RPloKCe0JDMasy+Tcz8PPf8HZA0NAOzNnIrWAKIx8d7NEj3HYvigf7+Edm7C6 XCkuhHKljAr8EhOJAh0/LV+6sW7JbYYJDaApSOugym1exudo/oNTKAdYJhtZt4NXrKa4 r6Mm9+j27jrhMn+8ySPD+Slns0m+/2vHuQyszI1VUhNn+prfDPyvNJK3A5cs7+EEEn+a KoTUoGCKVkvRpMlQrhgrw2PcNS4eKXDFT/MIBqtdnJkhjcVCP4M2kz8LExHYL/kO9yEq 5Yq67Mfcn8rW8XqJxQbfwIlQyRvcvMtII2wjtlQhRUhieRniShCfDzfON4zSoCUlfr7T 6hTA== X-Gm-Message-State: AOAM533+XfG2Hr52mBcJ1gcVQP1oq+lEoLuhjWHkVdBS5rH0/33slDY5 RAz1U3LEzR3NFlldMvUS3/8UOEgRlGcry9NOg64= X-Google-Smtp-Source: ABdhPJzTsIe/iQOwZjvQaOYH8kv6w6GD4dQu8EwThJ5A/fDtjZbMK6SYYVlOsmOQY3B4Iojo1tH7nyJeXbt5Y+fbTHs= X-Received: by 2002:a50:d552:: with SMTP id f18mr553663edj.168.1610390612990; Mon, 11 Jan 2021 10:43:32 -0800 (PST) MIME-Version: 1.0 References: <20210105225817.1036378-1-shy828301@gmail.com> <20210105225817.1036378-11-shy828301@gmail.com> <777d47b3-65f7-5727-2d21-dbef93e7d1ed@virtuozzo.com> In-Reply-To: <777d47b3-65f7-5727-2d21-dbef93e7d1ed@virtuozzo.com> From: Yang Shi Date: Mon, 11 Jan 2021 10:43:20 -0800 Message-ID: Subject: Re: [v3 PATCH 10/11] mm: memcontrol: reparent nr_deferred when memcg offline To: Kirill Tkhai Cc: Roman Gushchin , Shakeel Butt , Dave Chinner , Johannes Weiner , Michal Hocko , Andrew Morton , Linux MM , Linux FS-devel Mailing List , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 6, 2021 at 3:35 AM Kirill Tkhai wrote: > > On 06.01.2021 01:58, Yang Shi wrote: > > Now shrinker's nr_deferred is per memcg for memcg aware shrinkers, add to parent's > > corresponding nr_deferred when memcg offline. > > > > Signed-off-by: Yang Shi > > --- > > include/linux/memcontrol.h | 1 + > > mm/memcontrol.c | 1 + > > mm/vmscan.c | 29 +++++++++++++++++++++++++++++ > > 3 files changed, 31 insertions(+) > > > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > > index 5599082df623..d1e52e916cc2 100644 > > --- a/include/linux/memcontrol.h > > +++ b/include/linux/memcontrol.h > > @@ -1586,6 +1586,7 @@ extern int memcg_alloc_shrinker_info(struct mem_cgroup *memcg); > > extern void memcg_free_shrinker_info(struct mem_cgroup *memcg); > > extern void memcg_set_shrinker_bit(struct mem_cgroup *memcg, > > int nid, int shrinker_id); > > +extern void memcg_reparent_shrinker_deferred(struct mem_cgroup *memcg); > > #else > > #define mem_cgroup_sockets_enabled 0 > > static inline void mem_cgroup_sk_alloc(struct sock *sk) { }; > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index 126f1fd550c8..19e555675582 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -5284,6 +5284,7 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) > > page_counter_set_low(&memcg->memory, 0); > > > > memcg_offline_kmem(memcg); > > + memcg_reparent_shrinker_deferred(memcg); > > wb_memcg_offline(memcg); > > > > drain_all_stock(memcg); > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index d9795fb0f1c5..71056057d26d 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -396,6 +396,35 @@ static long set_nr_deferred_memcg(long nr, int nid, struct shrinker *shrinker, > > return atomic_long_add_return(nr, &info->nr_deferred[shrinker->id]); > > } > > > > +void memcg_reparent_shrinker_deferred(struct mem_cgroup *memcg) > > +{ > > + int i, nid; > > + long nr; > > + struct mem_cgroup *parent; > > + struct memcg_shrinker_info *child_info, *parent_info; > > + > > + parent = parent_mem_cgroup(memcg); > > + if (!parent) > > + parent = root_mem_cgroup; > > + > > + /* Prevent from concurrent shrinker_info expand */ > > + down_read(&shrinker_rwsem); > > + for_each_node(nid) { > > + child_info = rcu_dereference_protected( > > + memcg->nodeinfo[nid]->shrinker_info, > > + true); > > + parent_info = rcu_dereference_protected( > > + parent->nodeinfo[nid]->shrinker_info, > > + true); > > Simple assignment can't take such lots of space, we have to do something with that. > > Number of these > > rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info, true) > > became too big, and we can't allow every of them takes 3 lines. > > We should introduce a short helper to dereferrence this, so we will be able to give > out attention to really difficult logic instead of wasting it on parsing this. > > child_info = memcg_shrinker_info(memcg, nid); > or > child_info = memcg_shrinker_info_protected(memcg, nid); > > Both of them fit in single line. > > struct memcg_shrinker_info *memcg_shrinker_info_protected( > struct mem_cgroup *memcg, int nid) > { > return rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info, > lockdep_assert_held(&shrinker_rwsem)); > } Thanks for the suggestion, it makes sense to me. Will incorporate it in v4. > > > > + for (i = 0; i < shrinker_nr_max; i++) { > > + nr = atomic_long_read(&child_info->nr_deferred[i]); > > + atomic_long_add(nr, > > + &parent_info->nr_deferred[i]); > > Why new line is here? In case of you merge it up, it will be even shorter then previous line. Just keep in 80 lines. We could relax it. > > > + } > > + } > > + up_read(&shrinker_rwsem); > > +} > > + > > static bool cgroup_reclaim(struct scan_control *sc) > > { > > return sc->target_mem_cgroup; > > > >