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([2404:9dc0:cd01::14]) by smtp.gmail.com with ESMTPSA id f6-20020aa782c6000000b005d6dff9bbecsm10442070pfn.62.2023.03.08.22.33.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 08 Mar 2023 22:33:14 -0800 (PST) Message-ID: Date: Thu, 9 Mar 2023 14:33:05 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; 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 Content-Language: en-US To: Kirill Tkhai , 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> From: Qi Zheng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: A02EA40017 X-Stat-Signature: c6c8daeq1b81k9y1t1ftdizyeea1wz7i X-HE-Tag: 1678343597-684210 X-HE-Meta: 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 Zae/G2AJ 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 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 2023/3/9 06:13, Kirill Tkhai wrote: > 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? Yeah, will change to it. > > 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, > -- Thanks, Qi