From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-185.mta0.migadu.com (out-185.mta0.migadu.com [91.218.175.185]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0E2301E4928 for ; Tue, 13 May 2025 03:13:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.185 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747106036; cv=none; b=m7+wPf/fzWlQgeKYlWRHDRgkN+w6/G0m2DSlNR9sZ/31FJifPhkoSZx9I/HENzf3v3G+MeHLC6KYFmn+Lb6AKDi/dbab7c1JNbleDzoIXEKd2+tGCdvK18+1VRKUgMnZMp+xgm+8/MvZ1H5DS0h0b0ZhHmysUNhJwqgjiUudXYU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747106036; c=relaxed/simple; bh=e5zcqxXqQpR2JMymlF/KWPHcfisuz8s1WaeQLc69vnQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aLAoW5CwCSF7+3Hd4GhFZ+zcIGB1/wla1GGaiZnjRD7VTWXPnOxAiRd/Hg2nnrAJAjCjJapnoIpYkOpLeIWcj7N2wcZruT/+ln0lg/yjZAAwN4MlKSBv/tvHUka6v6zURmK2Y3sQXOI2FjO8L8ej5pah2uoH4CmFp0ikDpFPwNA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=ooSsm/BG; arc=none smtp.client-ip=91.218.175.185 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="ooSsm/BG" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1747106031; 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=BPiRuCw/bD9XYJlwvKtjg4J90L1EW0IfWXzhcocLuzg=; b=ooSsm/BGkm7jLt7WeCVzcIeXfSfmLTTxu3NEHROcON2zE6dLycnVCdS6+Pirr61u6vkq4u euHpiYkfCAx2oacQVM//UVnoD5lrLUEW6o3iX/cgHCN3dSAZ0N3CB7eKx5dyzXrhUClRXc QwDnQ1oHgBA0T+GBQDkE5Eg074eoGKI= 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: [RFC PATCH 3/7] memcg: make mod_memcg_state re-entrant safe against irqs Date: Mon, 12 May 2025 20:13:12 -0700 Message-ID: <20250513031316.2147548-4-shakeel.butt@linux.dev> In-Reply-To: <20250513031316.2147548-1-shakeel.butt@linux.dev> References: <20250513031316.2147548-1-shakeel.butt@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Let's make mod_memcg_state re-entrant safe against irqs. The only thing needed is to convert the usage of __this_cpu_add() to this_cpu_add(). In addition, with re-entrant safety, there is no need to disable irqs. mod_memcg_state() is not safe against nmi, so let's add warning if someone tries to call it in nmi context. Signed-off-by: Shakeel Butt --- include/linux/memcontrol.h | 20 ++------------------ mm/memcontrol.c | 12 ++++++++---- 2 files changed, 10 insertions(+), 22 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index ed9acb68652a..84e2cea7e666 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -911,19 +911,9 @@ struct mem_cgroup *mem_cgroup_get_oom_group(struct task_struct *victim, struct mem_cgroup *oom_domain); void mem_cgroup_print_oom_group(struct mem_cgroup *memcg); -void __mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx, - int val); - /* idx can be of type enum memcg_stat_item or node_stat_item */ -static inline void mod_memcg_state(struct mem_cgroup *memcg, - enum memcg_stat_item idx, int val) -{ - unsigned long flags; - - local_irq_save(flags); - __mod_memcg_state(memcg, idx, val); - local_irq_restore(flags); -} +void mod_memcg_state(struct mem_cgroup *memcg, + enum memcg_stat_item idx, int val); static inline void mod_memcg_page_state(struct page *page, enum memcg_stat_item idx, int val) @@ -1390,12 +1380,6 @@ static inline void mem_cgroup_print_oom_group(struct mem_cgroup *memcg) { } -static inline void __mod_memcg_state(struct mem_cgroup *memcg, - enum memcg_stat_item idx, - int nr) -{ -} - static inline void mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx, int nr) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 62450e7991d8..373d36cae069 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -681,12 +681,12 @@ static int memcg_state_val_in_pages(int idx, int val) } /** - * __mod_memcg_state - update cgroup memory statistics + * mod_memcg_state - update cgroup memory statistics * @memcg: the memory cgroup * @idx: the stat item - can be enum memcg_stat_item or enum node_stat_item * @val: delta to add to the counter, can be negative */ -void __mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx, +void mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx, int val) { int i = memcg_stats_index(idx); @@ -698,9 +698,13 @@ 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; + if (WARN_ONCE(in_nmi(), "%s: called in nmi context for stat item %d\n", + __func__, idx)) + return; + cpu = get_cpu(); - __this_cpu_add(memcg->vmstats_percpu->state[i], val); + this_cpu_add(memcg->vmstats_percpu->state[i], val); val = memcg_state_val_in_pages(idx, val); memcg_rstat_updated(memcg, val, cpu); trace_mod_memcg_state(memcg, idx, val); @@ -2969,7 +2973,7 @@ static void drain_obj_stock(struct obj_stock_pcp *stock) memcg = get_mem_cgroup_from_objcg(old); - __mod_memcg_state(memcg, MEMCG_KMEM, -nr_pages); + mod_memcg_state(memcg, MEMCG_KMEM, -nr_pages); memcg1_account_kmem(memcg, -nr_pages); if (!mem_cgroup_is_root(memcg)) memcg_uncharge(memcg, nr_pages); -- 2.47.1