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Thu, 23 Apr 2026 13:34:47 -0700 (PDT) From: Joshua Hahn To: linux-mm@kvack.org Cc: Tejun Heo , Johannes Weiner , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: [RFC PATCH 1/9 v2] cgroup: Introduce memory_tiered_limits cgroup mount option Date: Thu, 23 Apr 2026 13:34:35 -0700 Message-ID: <20260423203445.2914963-2-joshua.hahnjy@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260423203445.2914963-1-joshua.hahnjy@gmail.com> References: <20260423203445.2914963-1-joshua.hahnjy@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Introduce a cgroup mount option memory_tiered_limits to enable tier-proportional scaling of the memory cgroup controller limits memory.{min, low, high, max}. The mount option currently does not have any effect. Later commits will scale memcg limits proportional to the system's toptier:total capacity ratio. Signed-off-by: Joshua Hahn --- include/linux/cgroup-defs.h | 5 +++++ include/linux/memcontrol.h | 14 ++++++++++++++ kernel/cgroup/cgroup.c | 12 ++++++++++++ 3 files changed, 31 insertions(+) diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index bb92f5c169ca2..0b6861f4faece 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -128,6 +128,11 @@ enum { * Enable legacy local pids.events. */ CGRP_ROOT_PIDS_LOCAL_EVENTS = (1 << 20), + + /* + * Enable tier-proportional scaling of limits for the memory controller. + */ + CGRP_ROOT_MEMORY_TIERED_LIMITS = (1 << 21), }; /* cftype->flags */ diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index dc3fa687759b4..be45641e890e4 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -533,6 +533,15 @@ static inline bool mem_cgroup_disabled(void) return !cgroup_subsys_enabled(memory_cgrp_subsys); } +static inline bool mem_cgroup_tiered_limits(void) +{ +#ifdef CONFIG_NUMA + return cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_TIERED_LIMITS; +#else + return false; +#endif +} + static inline void mem_cgroup_protection(struct mem_cgroup *root, struct mem_cgroup *memcg, unsigned long *min, @@ -1084,6 +1093,11 @@ static inline bool mem_cgroup_disabled(void) return true; } +static inline bool mem_cgroup_tiered_limits(void) +{ + return false; +} + static inline void memcg_memory_event(struct mem_cgroup *memcg, enum memcg_memory_event event) { diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index babf7b4560488..6a34d0e179dc5 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -1989,6 +1989,7 @@ enum cgroup2_param { Opt_memory_recursiveprot, Opt_memory_hugetlb_accounting, Opt_pids_localevents, + Opt_memory_tiered_limits, nr__cgroup2_params }; @@ -1999,6 +2000,7 @@ static const struct fs_parameter_spec cgroup2_fs_parameters[] = { fsparam_flag("memory_recursiveprot", Opt_memory_recursiveprot), fsparam_flag("memory_hugetlb_accounting", Opt_memory_hugetlb_accounting), fsparam_flag("pids_localevents", Opt_pids_localevents), + fsparam_flag("memory_tiered_limits", Opt_memory_tiered_limits), {} }; @@ -2031,6 +2033,9 @@ static int cgroup2_parse_param(struct fs_context *fc, struct fs_parameter *param case Opt_pids_localevents: ctx->flags |= CGRP_ROOT_PIDS_LOCAL_EVENTS; return 0; + case Opt_memory_tiered_limits: + ctx->flags |= CGRP_ROOT_MEMORY_TIERED_LIMITS; + return 0; } return -EINVAL; } @@ -2072,6 +2077,11 @@ static void apply_cgroup_root_flags(unsigned int root_flags) cgrp_dfl_root.flags |= CGRP_ROOT_PIDS_LOCAL_EVENTS; else cgrp_dfl_root.flags &= ~CGRP_ROOT_PIDS_LOCAL_EVENTS; + + if (root_flags & CGRP_ROOT_MEMORY_TIERED_LIMITS) + cgrp_dfl_root.flags |= CGRP_ROOT_MEMORY_TIERED_LIMITS; + else + cgrp_dfl_root.flags &= ~CGRP_ROOT_MEMORY_TIERED_LIMITS; } } @@ -2089,6 +2099,8 @@ static int cgroup_show_options(struct seq_file *seq, struct kernfs_root *kf_root seq_puts(seq, ",memory_hugetlb_accounting"); if (cgrp_dfl_root.flags & CGRP_ROOT_PIDS_LOCAL_EVENTS) seq_puts(seq, ",pids_localevents"); + if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_TIERED_LIMITS) + seq_puts(seq, ",memory_tiered_limits"); return 0; } -- 2.52.0