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h=From:In-Reply-To:Cc:Date:References:To:Subject:Message-ID; b=m/K4SAMixCFnJYFJuDaEImnoqRs9V3PWl35JDYzoPPiAQd4e5Q1W+Ss1AevMuzfus btyY1DBhgSzcVh8rkeLKUmVvQZyrqbXGx9aEaZWFshTtHvVzTsl9BghaISWCViNHJw tKBVK0UfeyJRTxLJhRpOjoXsbsFKCBrHi8Yg+Xs8= Message-ID: Date: Thu, 9 Mar 2023 01:13:46 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH v4 1/8] mm: vmscan: add a map_nr_max field to shrinker_info To: Qi Zheng , akpm@linux-foundation.org, hannes@cmpxchg.org, shakeelb@google.com, mhocko@kernel.org, roman.gushchin@linux.dev, muchun.song@linux.dev, david@redhat.com, shy828301@gmail.com, rppt@kernel.org Cc: sultan@kerneltoast.com, dave@stgolabs.net, penguin-kernel@I-love.SAKURA.ne.jp, paulmck@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20230307065605.58209-1-zhengqi.arch@bytedance.com> <20230307065605.58209-2-zhengqi.arch@bytedance.com> Content-Language: en-US From: Kirill Tkhai In-Reply-To: <20230307065605.58209-2-zhengqi.arch@bytedance.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 4DB06160024 X-Rspam-User: X-Stat-Signature: 1pofahr5j4fa1u11w9kbqjzypogmgedi X-HE-Tag: 1678313633-349456 X-HE-Meta: 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 M6KrYZVL VMJ07zs1FycLeKIFjg0TylQS4NrCer3CIORe7Y//6gz91Rp89ywe8RpyBNiAxm9RGhf0Ag/7vJJdzD+8YgP2JTtb396JQ1Pa7DzaEQfh9meIUoUuj4wtyUAzKoBgqXKI9R7yhEkBWHZnP3FeCpWY1VHW/JCw6RQ6Z5fokZchNwiiTpqnZeAM8RZ33CbAGLEb5Se7bdrwT66HpMBowJSxdLu9PnLvo35n+ZsKJ7ZbcUOsmLXaegNcNW65ZUtqLHv1pM41dITACtlJuinaI7KXDWQ/qtKjHWCjaW0cZM3LICE+bPTG/j1jnBHkJpcOPVTYK/s+51YLp2Byd2RaKMSpxa5JEh92zBnqvaNxwvMxY6jyo2ofdDWrup6SsUC57ycOyozIEBUwiHsbqQQ2FrNSXKl2abBtpIsxrctrjpiHgPBRAi7XPgPvr/4SrUUGzdRogiFSCmkmJVOn7Lfc= 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: Hi, On 07.03.2023 09:55, Qi Zheng wrote: > To prepare for the subsequent lockless memcg slab shrink, > add a map_nr_max field to struct shrinker_info to records > its own real shrinker_nr_max. > > Suggested-by: Kirill Tkhai > Signed-off-by: Qi Zheng > --- > include/linux/memcontrol.h | 1 + > mm/vmscan.c | 41 ++++++++++++++++++++++---------------- > 2 files changed, 25 insertions(+), 17 deletions(-) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index b6eda2ab205d..aa69ea98e2d8 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -97,6 +97,7 @@ struct shrinker_info { > struct rcu_head rcu; > atomic_long_t *nr_deferred; > unsigned long *map; > + int map_nr_max; > }; > > struct lruvec_stats_percpu { > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 9414226218f0..2dcc01682026 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -224,9 +224,16 @@ static struct shrinker_info *shrinker_info_protected(struct mem_cgroup *memcg, > lockdep_is_held(&shrinker_rwsem)); > } > > +static inline bool need_expand(int new_nr_max, int old_nr_max) > +{ > + return round_up(new_nr_max, BITS_PER_LONG) > > + round_up(old_nr_max, BITS_PER_LONG); > +} > + > static int expand_one_shrinker_info(struct mem_cgroup *memcg, > int map_size, int defer_size, > - int old_map_size, int old_defer_size) > + int old_map_size, int old_defer_size, > + int new_nr_max) > { > struct shrinker_info *new, *old; > struct mem_cgroup_per_node *pn; > @@ -240,12 +247,17 @@ static int expand_one_shrinker_info(struct mem_cgroup *memcg, > if (!old) > return 0; > > + /* Already expanded this shrinker_info */ > + if (!need_expand(new_nr_max, old->map_nr_max)) need_expand() looks confusing here. It's strange that we round_up(old->map_nr_max), despite old->map never may exceed old->map_nr_max. Won't plain if (new_nr_max <= old->map_nr_max) look clearer here? The rest in patch looks OK for me. > + continue; > + > new = kvmalloc_node(sizeof(*new) + size, GFP_KERNEL, nid); > if (!new) > return -ENOMEM; > > new->nr_deferred = (atomic_long_t *)(new + 1); > new->map = (void *)new->nr_deferred + defer_size; > + new->map_nr_max = new_nr_max; > > /* map: set all old bits, clear all new bits */ > memset(new->map, (int)0xff, old_map_size); > @@ -295,6 +307,7 @@ int alloc_shrinker_info(struct mem_cgroup *memcg) > } > info->nr_deferred = (atomic_long_t *)(info + 1); > info->map = (void *)info->nr_deferred + defer_size; > + info->map_nr_max = shrinker_nr_max; > rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_info, info); > } > up_write(&shrinker_rwsem); > @@ -302,23 +315,14 @@ int alloc_shrinker_info(struct mem_cgroup *memcg) > return ret; > } > > -static inline bool need_expand(int nr_max) > -{ > - return round_up(nr_max, BITS_PER_LONG) > > - round_up(shrinker_nr_max, BITS_PER_LONG); > -} > - > static int expand_shrinker_info(int new_id) > { > int ret = 0; > - int new_nr_max = new_id + 1; > + int new_nr_max = round_up(new_id + 1, BITS_PER_LONG); > int map_size, defer_size = 0; > int old_map_size, old_defer_size = 0; > struct mem_cgroup *memcg; > > - if (!need_expand(new_nr_max)) > - goto out; > - > if (!root_mem_cgroup) > goto out; > > @@ -332,7 +336,8 @@ static int expand_shrinker_info(int new_id) > memcg = mem_cgroup_iter(NULL, NULL, NULL); > do { > ret = expand_one_shrinker_info(memcg, map_size, defer_size, > - old_map_size, old_defer_size); > + old_map_size, old_defer_size, > + new_nr_max); > if (ret) { > mem_cgroup_iter_break(NULL, memcg); > goto out; > @@ -352,9 +357,11 @@ void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id) > > rcu_read_lock(); > info = rcu_dereference(memcg->nodeinfo[nid]->shrinker_info); > - /* Pairs with smp mb in shrink_slab() */ > - smp_mb__before_atomic(); > - set_bit(shrinker_id, info->map); > + if (!WARN_ON_ONCE(shrinker_id >= info->map_nr_max)) { > + /* Pairs with smp mb in shrink_slab() */ > + smp_mb__before_atomic(); > + set_bit(shrinker_id, info->map); > + } > rcu_read_unlock(); > } > } > @@ -432,7 +439,7 @@ void reparent_shrinker_deferred(struct mem_cgroup *memcg) > for_each_node(nid) { > child_info = shrinker_info_protected(memcg, nid); > parent_info = shrinker_info_protected(parent, nid); > - for (i = 0; i < shrinker_nr_max; i++) { > + for (i = 0; i < child_info->map_nr_max; i++) { > nr = atomic_long_read(&child_info->nr_deferred[i]); > atomic_long_add(nr, &parent_info->nr_deferred[i]); > } > @@ -899,7 +906,7 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid, > if (unlikely(!info)) > goto unlock; > > - for_each_set_bit(i, info->map, shrinker_nr_max) { > + for_each_set_bit(i, info->map, info->map_nr_max) { > struct shrink_control sc = { > .gfp_mask = gfp_mask, > .nid = nid,