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[2a03:2880:ff::face:b00c]) by smtp.gmail.com with ESMTPSA id s20-20020a170902989400b001c5b8087fe5sm4250869plp.94.2023.10.06.11.46.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 06 Oct 2023 11:46:31 -0700 (PDT) From: Nhat Pham To: akpm@linux-foundation.org Cc: riel@surriel.com, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeelb@google.com, muchun.song@linux.dev, tj@kernel.org, lizefan.x@bytedance.com, shuah@kernel.org, mike.kravetz@oracle.com, yosryahmed@google.com, fvdl@google.com, linux-mm@kvack.org, kernel-team@meta.com, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org Subject: [PATCH v4 1/4] memcontrol: add helpers for hugetlb memcg accounting Date: Fri, 6 Oct 2023 11:46:26 -0700 Message-Id: <20231006184629.155543-2-nphamcs@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231006184629.155543-1-nphamcs@gmail.com> References: <20231006184629.155543-1-nphamcs@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" This patch exposes charge committing and cancelling as parts of the memory controller interface. These functionalities are useful when the try_charge() and commit_charge() stages have to be separated by other actions in between (which can fail). One such example is the new hugetlb accounting behavior in the following patch. The patch also adds a helper function to obtain a reference to the current task's memcg. Acked-by: Michal Hocko Acked-by: Johannes Weiner Signed-off-by: Nhat Pham --- include/linux/memcontrol.h | 21 ++++++++++++++ mm/memcontrol.c | 59 ++++++++++++++++++++++++++++++-------- 2 files changed, 68 insertions(+), 12 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index e0cfab58ab71..42bf7e9b1a2f 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -653,6 +653,8 @@ static inline bool mem_cgroup_below_min(struct mem_cgro= up *target, page_counter_read(&memcg->memory); } =20 +void mem_cgroup_commit_charge(struct folio *folio, struct mem_cgroup *memc= g); + int __mem_cgroup_charge(struct folio *folio, struct mm_struct *mm, gfp_t g= fp); =20 /** @@ -704,6 +706,8 @@ static inline void mem_cgroup_uncharge_list(struct list= _head *page_list) __mem_cgroup_uncharge_list(page_list); } =20 +void mem_cgroup_cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pa= ges); + void mem_cgroup_migrate(struct folio *old, struct folio *new); =20 /** @@ -760,6 +764,8 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_str= uct *p); =20 struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm); =20 +struct mem_cgroup *get_mem_cgroup_from_current(void); + struct lruvec *folio_lruvec_lock(struct folio *folio); struct lruvec *folio_lruvec_lock_irq(struct folio *folio); struct lruvec *folio_lruvec_lock_irqsave(struct folio *folio, @@ -1245,6 +1251,11 @@ static inline bool mem_cgroup_below_min(struct mem_c= group *target, return false; } =20 +static inline void mem_cgroup_commit_charge(struct folio *folio, + struct mem_cgroup *memcg) +{ +} + static inline int mem_cgroup_charge(struct folio *folio, struct mm_struct *mm, gfp_t gfp) { @@ -1269,6 +1280,11 @@ static inline void mem_cgroup_uncharge_list(struct l= ist_head *page_list) { } =20 +static inline void mem_cgroup_cancel_charge(struct mem_cgroup *memcg, + unsigned int nr_pages) +{ +} + static inline void mem_cgroup_migrate(struct folio *old, struct folio *new) { } @@ -1306,6 +1322,11 @@ static inline struct mem_cgroup *get_mem_cgroup_from= _mm(struct mm_struct *mm) return NULL; } =20 +static inline struct mem_cgroup *get_mem_cgroup_from_current(void) +{ + return NULL; +} + static inline struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css) { diff --git a/mm/memcontrol.c b/mm/memcontrol.c index d1a322a75172..0219befeae38 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1086,6 +1086,27 @@ struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_= struct *mm) } EXPORT_SYMBOL(get_mem_cgroup_from_mm); =20 +/** + * get_mem_cgroup_from_current - Obtain a reference on current task's memc= g. + */ +struct mem_cgroup *get_mem_cgroup_from_current(void) +{ + struct mem_cgroup *memcg; + + if (mem_cgroup_disabled()) + return NULL; + +again: + rcu_read_lock(); + memcg =3D mem_cgroup_from_task(current); + if (!css_tryget(&memcg->css)) { + rcu_read_unlock(); + goto again; + } + rcu_read_unlock(); + return memcg; +} + static __always_inline bool memcg_kmem_bypass(void) { /* Allow remote memcg charging from any context. */ @@ -2873,7 +2894,12 @@ static inline int try_charge(struct mem_cgroup *memc= g, gfp_t gfp_mask, return try_charge_memcg(memcg, gfp_mask, nr_pages); } =20 -static inline void cancel_charge(struct mem_cgroup *memcg, unsigned int nr= _pages) +/** + * mem_cgroup_cancel_charge() - cancel an uncommitted try_charge() call. + * @memcg: memcg previously charged. + * @nr_pages: number of pages previously charged. + */ +void mem_cgroup_cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pa= ges) { if (mem_cgroup_is_root(memcg)) return; @@ -2898,6 +2924,22 @@ static void commit_charge(struct folio *folio, struc= t mem_cgroup *memcg) folio->memcg_data =3D (unsigned long)memcg; } =20 +/** + * mem_cgroup_commit_charge - commit a previously successful try_charge(). + * @folio: folio to commit the charge to. + * @memcg: memcg previously charged. + */ +void mem_cgroup_commit_charge(struct folio *folio, struct mem_cgroup *memc= g) +{ + css_get(&memcg->css); + commit_charge(folio, memcg); + + local_irq_disable(); + mem_cgroup_charge_statistics(memcg, folio_nr_pages(folio)); + memcg_check_events(memcg, folio_nid(folio)); + local_irq_enable(); +} + #ifdef CONFIG_MEMCG_KMEM /* * The allocated objcg pointers array is not accounted directly. @@ -6105,7 +6147,7 @@ static void __mem_cgroup_clear_mc(void) =20 /* we must uncharge all the leftover precharges from mc.to */ if (mc.precharge) { - cancel_charge(mc.to, mc.precharge); + mem_cgroup_cancel_charge(mc.to, mc.precharge); mc.precharge =3D 0; } /* @@ -6113,7 +6155,7 @@ static void __mem_cgroup_clear_mc(void) * we must uncharge here. */ if (mc.moved_charge) { - cancel_charge(mc.from, mc.moved_charge); + mem_cgroup_cancel_charge(mc.from, mc.moved_charge); mc.moved_charge =3D 0; } /* we must fixup refcnts and charges */ @@ -7020,20 +7062,13 @@ void mem_cgroup_calculate_protection(struct mem_cgr= oup *root, static int charge_memcg(struct folio *folio, struct mem_cgroup *memcg, gfp_t gfp) { - long nr_pages =3D folio_nr_pages(folio); int ret; =20 - ret =3D try_charge(memcg, gfp, nr_pages); + ret =3D try_charge(memcg, gfp, folio_nr_pages(folio)); if (ret) goto out; =20 - css_get(&memcg->css); - commit_charge(folio, memcg); - - local_irq_disable(); - mem_cgroup_charge_statistics(memcg, nr_pages); - memcg_check_events(memcg, folio_nid(folio)); - local_irq_enable(); + mem_cgroup_commit_charge(folio, memcg); out: return ret; } --=20 2.34.1