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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1747248148; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=pnF7krW2jVoclxTmKq2Rm1VmAZ/F/mXL38we6iUw/xE=; b=O82arQvGzNDNLe5lnOtBcCE5uvdvACBYJ1PalJjlxxRDPRFgkRaG6x0Uchr66drqz47Jjr PXA6t11IzYBcrVXHGHNqjFWOsEV5uJE2n3iLvDJ3zn0qpesRQJXDy2quVFbtLTIlVna6ae XZZLZPbQIYDaDTrGf0FrrUl72yz+7IM= From: Shakeel Butt To: Andrew Morton Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Vlastimil Babka , Alexei Starovoitov , Sebastian Andrzej Siewior , Harry Yoo , Yosry Ahmed , bpf@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Subject: [PATCH v2 2/7] memcg: move preempt disable to callers of memcg_rstat_updated Date: Wed, 14 May 2025 11:41:53 -0700 Message-ID: <20250514184158.3471331-3-shakeel.butt@linux.dev> In-Reply-To: <20250514184158.3471331-1-shakeel.butt@linux.dev> References: <20250514184158.3471331-1-shakeel.butt@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 8DADC14000F X-Stat-Signature: 7rmc8q9twk87auagoxewtp67637ziaoj X-HE-Tag: 1747248149-353239 X-HE-Meta: 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 9E8kngnF 8qm4+/9p8BKj3O6vNP8TVUYSs/doVNo3JbPIsqCr0DEvmP2NSmMnuuilWlZm4ErRj4gurUtbZQFX/Ff4Geu2DUPgWjRFK9dW/yihqxDz0B0io0ex1xER/D+j+kiMWlTQlq5ZrO2ZX3UCW16KJ5KaYHXurBd+f7F2yYVRGXTCTm9r3BK4CHmH6CJ5Lu4tp+Fq/9Hjwbu46zn3kuYR+tr2KMTzAiGlTiHYo/jlB 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: List-Subscribe: List-Unsubscribe: Let's move the explicit preempt disable code to the callers of memcg_rstat_updated and also remove the memcg_stats_lock and related functions which ensures the callers of stats update functions have disabled preemption because now the stats update functions are explicitly disabling preemption. Signed-off-by: Shakeel Butt Acked-by: Vlastimil Babka --- mm/memcontrol.c | 74 +++++++++++++------------------------------------ 1 file changed, 19 insertions(+), 55 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 2464a58fbf17..1750d86012f3 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -557,48 +557,22 @@ static u64 flush_last_time; #define FLUSH_TIME (2UL*HZ) -/* - * Accessors to ensure that preemption is disabled on PREEMPT_RT because it can - * not rely on this as part of an acquired spinlock_t lock. These functions are - * never used in hardirq context on PREEMPT_RT and therefore disabling preemtion - * is sufficient. - */ -static void memcg_stats_lock(void) -{ - preempt_disable_nested(); - VM_WARN_ON_IRQS_ENABLED(); -} - -static void __memcg_stats_lock(void) -{ - preempt_disable_nested(); -} - -static void memcg_stats_unlock(void) -{ - preempt_enable_nested(); -} - - static bool memcg_vmstats_needs_flush(struct memcg_vmstats *vmstats) { return atomic64_read(&vmstats->stats_updates) > MEMCG_CHARGE_BATCH * num_online_cpus(); } -static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val) +static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val, + int cpu) { struct memcg_vmstats_percpu __percpu *statc_pcpu; struct memcg_vmstats_percpu *statc; - int cpu; unsigned int stats_updates; if (!val) return; - /* Don't assume callers have preemption disabled. */ - cpu = get_cpu(); - cgroup_rstat_updated(memcg->css.cgroup, cpu); statc_pcpu = memcg->vmstats_percpu; for (; statc_pcpu; statc_pcpu = statc->parent_pcpu) { @@ -619,7 +593,6 @@ static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val) stats_updates = this_cpu_xchg(statc_pcpu->stats_updates, 0); atomic64_add(stats_updates, &statc->vmstats->stats_updates); } - put_cpu(); } static void __mem_cgroup_flush_stats(struct mem_cgroup *memcg, bool force) @@ -717,6 +690,7 @@ void __mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx, int val) { int i = memcg_stats_index(idx); + int cpu; if (mem_cgroup_disabled()) return; @@ -724,12 +698,14 @@ void __mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx, if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) return; - memcg_stats_lock(); + cpu = get_cpu(); + __this_cpu_add(memcg->vmstats_percpu->state[i], val); val = memcg_state_val_in_pages(idx, val); - memcg_rstat_updated(memcg, val); + memcg_rstat_updated(memcg, val, cpu); trace_mod_memcg_state(memcg, idx, val); - memcg_stats_unlock(); + + put_cpu(); } #ifdef CONFIG_MEMCG_V1 @@ -758,6 +734,7 @@ static void __mod_memcg_lruvec_state(struct lruvec *lruvec, struct mem_cgroup_per_node *pn; struct mem_cgroup *memcg; int i = memcg_stats_index(idx); + int cpu; if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) return; @@ -765,24 +742,7 @@ static void __mod_memcg_lruvec_state(struct lruvec *lruvec, pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec); memcg = pn->memcg; - /* - * The caller from rmap relies on disabled preemption because they never - * update their counter from in-interrupt context. For these two - * counters we check that the update is never performed from an - * interrupt context while other caller need to have disabled interrupt. - */ - __memcg_stats_lock(); - if (IS_ENABLED(CONFIG_DEBUG_VM)) { - switch (idx) { - case NR_ANON_MAPPED: - case NR_FILE_MAPPED: - case NR_ANON_THPS: - WARN_ON_ONCE(!in_task()); - break; - default: - VM_WARN_ON_IRQS_ENABLED(); - } - } + cpu = get_cpu(); /* Update memcg */ __this_cpu_add(memcg->vmstats_percpu->state[i], val); @@ -791,9 +751,10 @@ static void __mod_memcg_lruvec_state(struct lruvec *lruvec, __this_cpu_add(pn->lruvec_stats_percpu->state[i], val); val = memcg_state_val_in_pages(idx, val); - memcg_rstat_updated(memcg, val); + memcg_rstat_updated(memcg, val, cpu); trace_mod_memcg_lruvec_state(memcg, idx, val); - memcg_stats_unlock(); + + put_cpu(); } /** @@ -873,6 +834,7 @@ void __count_memcg_events(struct mem_cgroup *memcg, enum vm_event_item idx, unsigned long count) { int i = memcg_events_index(idx); + int cpu; if (mem_cgroup_disabled()) return; @@ -880,11 +842,13 @@ void __count_memcg_events(struct mem_cgroup *memcg, enum vm_event_item idx, if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) return; - memcg_stats_lock(); + cpu = get_cpu(); + __this_cpu_add(memcg->vmstats_percpu->events[i], count); - memcg_rstat_updated(memcg, count); + memcg_rstat_updated(memcg, count, cpu); trace_count_memcg_events(memcg, idx, count); - memcg_stats_unlock(); + + put_cpu(); } unsigned long memcg_events(struct mem_cgroup *memcg, int event) -- 2.47.1