From mboxrd@z Thu Jan 1 00:00:00 1970 From: Muchun Song Subject: [PATCH v5 01/11] mm: memcontrol: remove dead code and comments Date: Mon, 30 May 2022 15:49:09 +0800 Message-ID: <20220530074919.46352-2-songmuchun@bytedance.com> References: <20220530074919.46352-1-songmuchun@bytedance.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=WXoATc+zbrMinz5NUa5ozUC0jOTcvkPC5pLx07yWbkQ=; b=2EM02glyaZI9nPq2vkW6z3/AzXTv1u6Z3Rb2QQefVH2nhduDyPrtPjKRtHjq9g90FL /CXIjNPgSxLJM/RId9CYNnMZuVQ2pkO7ccabdIFa4HHSHA22NFUd7VSEbTAmRcx/C6Pq 1pdgBVjlr98ujtH4tl4OIxO4C9vjDL2OV1l6eX7q5T7QIEW73W0PuuVZ0rsRAwIrHCPg S5PL5p6FQyEYK+6qwGC/x1J2tkW2NOXpHu8+XmlEjKSJrbZ7iHrjCEv2VhtwhI52Hprp /qpQJFNAyYI3aTojFpHR+FncgU4BMwjh8nFipSkRzIzlSa7UB+xBxhdfY6PXixqlVlL5 l6zQ== In-Reply-To: <20220530074919.46352-1-songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org> List-ID: Content-Type: text/plain; charset="us-ascii" To: hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org, mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, roman.gushchin-fxUVXftIFDnyG1zEObXtfA@public.gmane.org, shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, duanxiongchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org, longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, Muchun Song Since no-hierarchy mode is deprecated after commit bef8620cd8e0 ("mm: memcg: deprecate the non-hierarchical mode") so parent_mem_cgroup() cannot return a NULL except root memcg, however, root memcg cannot be offline, so it is safe to drop the check of returned value of parent_mem_cgroup(). Remove those dead code. The comments in memcg_offline_kmem() above memcg_reparent_list_lrus() are out of date since commit 5abc1e37afa0 ("mm: list_lru: allocate list_lru_one only when needed") There is no ordering requirement between memcg_reparent_list_lrus() and memcg_reparent_objcgs(), so remove those outdated comments. Signed-off-by: Muchun Song --- include/linux/memcontrol.h | 3 +-- mm/memcontrol.c | 16 ---------------- mm/vmscan.c | 6 +----- 3 files changed, 2 insertions(+), 23 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 89b14729d59f..0833be256134 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -851,8 +851,7 @@ static inline struct mem_cgroup *lruvec_memcg(struct lruvec *lruvec) * parent_mem_cgroup - find the accounting parent of a memcg * @memcg: memcg whose parent to find * - * Returns the parent memcg, or NULL if this is the root or the memory - * controller is in legacy no-hierarchy mode. + * Returns the parent memcg, or NULL if this is the root. */ static inline struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg) { diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 598fece89e2b..13da256ff2e4 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3622,17 +3622,7 @@ static void memcg_offline_kmem(struct mem_cgroup *memcg) return; parent = parent_mem_cgroup(memcg); - if (!parent) - parent = root_mem_cgroup; - memcg_reparent_objcgs(memcg, parent); - - /* - * After we have finished memcg_reparent_objcgs(), all list_lrus - * corresponding to this cgroup are guaranteed to remain empty. - * The ordering is imposed by list_lru_node->lock taken by - * memcg_reparent_list_lrus(). - */ memcg_reparent_list_lrus(memcg, parent); } #else @@ -6593,10 +6583,6 @@ void mem_cgroup_calculate_protection(struct mem_cgroup *root, return; parent = parent_mem_cgroup(memcg); - /* No parent means a non-hierarchical mode on v1 memcg */ - if (!parent) - return; - if (parent == root) { memcg->memory.emin = READ_ONCE(memcg->memory.min); memcg->memory.elow = READ_ONCE(memcg->memory.low); @@ -7050,8 +7036,6 @@ static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg) break; } memcg = parent_mem_cgroup(memcg); - if (!memcg) - memcg = root_mem_cgroup; } return memcg; } diff --git a/mm/vmscan.c b/mm/vmscan.c index 1678802e03e7..8c6054e06087 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -409,13 +409,9 @@ void reparent_shrinker_deferred(struct mem_cgroup *memcg) { int i, nid; long nr; - struct mem_cgroup *parent; + struct mem_cgroup *parent = parent_mem_cgroup(memcg); struct 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) { -- 2.11.0