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s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=HdavPfho2y2aZPaSzJ50dkLev1j8QD0jxgYpMcuQTxo=; b=EjElL/Vxl81zguA3lIlekoS6gJMee7TkwjCiNx4Wdabss8ypSDYozQrYzh/jNx5OPY 8YkofM/OfFasGzwTg3TDt1/7T/kJYkwze62BJJ+5EaadXkCnAkbvQE7Q1Cd95ERBuutI 7Ym4Rc3HQMb2BHWuW39JlQWa+YoLxXF/Dx4BusZkSVQSVe8we8S2lbbTXDPY86fB0zkv dXmVba4X0dX/4iE5X6Wxqd74r8Av3aG+2cVWFkx2xiCNtiEKmAjrvMPGfn1RANMct2ox B12ngE8lAecsI+B7YRMpuED5XdjTlVbpvF+EF8CG8yoxMRKpAVHSi8M1Cfx4njCNj55t 2hIA== X-Gm-Message-State: AOAM532AiL+TYTnifQzK/EbmXsRcKpk++yh8l6EDI6ffOdQEMEglatlt jq/Bo2it3CYqCPZwajmpirMd3DovXl4p/gcZRQg= 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" 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, 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; > > > >