From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C79D6C3ABD8 for ; Fri, 16 May 2025 18:33:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B676F6B00A0; Fri, 16 May 2025 14:33:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B3E4E6B00A1; Fri, 16 May 2025 14:33:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A07716B00A2; Fri, 16 May 2025 14:33:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 832C26B00A0 for ; Fri, 16 May 2025 14:33:35 -0400 (EDT) Received: from smtpin11.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id E2FE1E3601 for ; Fri, 16 May 2025 18:33:36 +0000 (UTC) X-FDA: 83449619232.11.90DD6F4 Received: from out-188.mta1.migadu.com (out-188.mta1.migadu.com [95.215.58.188]) by imf26.hostedemail.com (Postfix) with ESMTP id 3DF98140011 for ; Fri, 16 May 2025 18:33:34 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=wGT+sTxw; spf=pass (imf26.hostedemail.com: domain of shakeel.butt@linux.dev designates 95.215.58.188 as permitted sender) smtp.mailfrom=shakeel.butt@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1747420415; a=rsa-sha256; cv=none; b=fvagsOC9hSzltX4935bPlOsqhPEoUV5GUsopYMYOa8MYWoDNs1I0cKNxBxKYFFHYeTvjQr TrTmrNQ9eNAncau0r9k+L6LLk6XJqJ4MQpw1nG+3+7a1urm0ZW0jcnEeQ+0T7AL1un4dIO qwkgCfuY704qqiEpSXyET4L7gSQFO9k= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=wGT+sTxw; spf=pass (imf26.hostedemail.com: domain of shakeel.butt@linux.dev designates 95.215.58.188 as permitted sender) smtp.mailfrom=shakeel.butt@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1747420415; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=1SZJx0aaLO11/z+3A95G9xQwNAh1dQNdtZG0PH2m5B0=; b=wC9D7IRVzhETO7Jg/9f1LnjfQHne9NnpwjNxdiObUSWThP0MznMoOD9oKFyDqvSf9dZBrL tBgoMLqg3fKCjlkh6LOsj3WBTMOLiCbhPmx4lXiED4aax153iHXXSsN7J7Bki60bF8uuYb V3k88/8WvYQo4/981EMw5jZmdIXkO6o= 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=1747420413; 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=1SZJx0aaLO11/z+3A95G9xQwNAh1dQNdtZG0PH2m5B0=; b=wGT+sTxw8c5WygTZyHNWxHhaBeB2Db0T1IwGsnrjo6DRHxIVPalq/OKAbL348LKt8va1ok aKSVg6JumoxRhbeUydIJnLCYaUZl1g3qyRWzBYmuyhOu/Iqm6w+cA2tmqB2KV7rna+FWdP 5QoUGw+Hj0IkXGCzjaLre2twvGqg3tg= 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 , Peter Zijlstra , Mathieu Desnoyers , Tejun Heo , bpf@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Subject: [PATCH v3 5/5] memcg: make memcg_rstat_updated nmi safe Date: Fri, 16 May 2025 11:32:31 -0700 Message-ID: <20250516183231.1615590-6-shakeel.butt@linux.dev> In-Reply-To: <20250516183231.1615590-1-shakeel.butt@linux.dev> References: <20250516183231.1615590-1-shakeel.butt@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 3DF98140011 X-Stat-Signature: zy9jnfbchr8aqp6y95599u6399yx165p X-HE-Tag: 1747420414-24325 X-HE-Meta: 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 mLK9Qel+ PKYJJWyNm5uaWhTtbjrr7VewPGsTcMbZEPKRSkcm8RpGbaB7G66J/B+S/GQiqZmyZq77oBLhtRGGD7+6EApVz5yf8fW1Git0EAULgdTfG/fsxDql43O93dy1/i31tx3jaCVQvTVCMp17wKjSiV2zskmBjwOmVXdfxNFtGdq15awi+3GrDp2I4v9Vy4mJJoLyEx7BrT/t/jaRYW60L83sK3kTpzyJUrai3H24V 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: Currently kernel maintains memory related stats updates per-cgroup to optimize stats flushing. The stats_updates is defined as atomic64_t which is not nmi-safe on some archs. Actually we don't really need 64bit atomic as the max value stats_updates can get should be less than nr_cpus * MEMCG_CHARGE_BATCH. A normal atomic_t should suffice. Also the function cgroup_rstat_updated() is still not nmi-safe but there is parallel effort to make it nmi-safe, so until then let's ignore it in the nmi context. Signed-off-by: Shakeel Butt Acked-by: Vlastimil Babka --- mm/memcontrol.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index e96c5d1ca912..2ace30fcd0e6 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -533,7 +533,7 @@ struct memcg_vmstats { unsigned long events_pending[NR_MEMCG_EVENTS]; /* Stats updates since the last flush */ - atomic64_t stats_updates; + atomic_t stats_updates; }; /* @@ -559,7 +559,7 @@ static u64 flush_last_time; static bool memcg_vmstats_needs_flush(struct memcg_vmstats *vmstats) { - return atomic64_read(&vmstats->stats_updates) > + return atomic_read(&vmstats->stats_updates) > MEMCG_CHARGE_BATCH * num_online_cpus(); } @@ -573,7 +573,9 @@ static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val, if (!val) return; - cgroup_rstat_updated(memcg->css.cgroup, cpu); + /* TODO: add to cgroup update tree once it is nmi-safe. */ + if (!in_nmi()) + cgroup_rstat_updated(memcg->css.cgroup, cpu); statc_pcpu = memcg->vmstats_percpu; for (; statc_pcpu; statc_pcpu = statc->parent_pcpu) { statc = this_cpu_ptr(statc_pcpu); @@ -591,7 +593,7 @@ static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val, continue; stats_updates = this_cpu_xchg(statc_pcpu->stats_updates, 0); - atomic64_add(stats_updates, &statc->vmstats->stats_updates); + atomic_add(stats_updates, &statc->vmstats->stats_updates); } } @@ -599,7 +601,7 @@ static void __mem_cgroup_flush_stats(struct mem_cgroup *memcg, bool force) { bool needs_flush = memcg_vmstats_needs_flush(memcg->vmstats); - trace_memcg_flush_stats(memcg, atomic64_read(&memcg->vmstats->stats_updates), + trace_memcg_flush_stats(memcg, atomic_read(&memcg->vmstats->stats_updates), force, needs_flush); if (!force && !needs_flush) @@ -4132,8 +4134,8 @@ static void mem_cgroup_css_rstat_flush(struct cgroup_subsys_state *css, int cpu) } WRITE_ONCE(statc->stats_updates, 0); /* We are in a per-cpu loop here, only do the atomic write once */ - if (atomic64_read(&memcg->vmstats->stats_updates)) - atomic64_set(&memcg->vmstats->stats_updates, 0); + if (atomic_read(&memcg->vmstats->stats_updates)) + atomic_set(&memcg->vmstats->stats_updates, 0); } static void mem_cgroup_fork(struct task_struct *task) -- 2.47.1