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 68F5CC3DA6D for ; Mon, 19 May 2025 06:32:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 48D456B0099; Mon, 19 May 2025 02:32:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 415226B009A; Mon, 19 May 2025 02:32:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2B8EC6B009B; Mon, 19 May 2025 02:32:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 073546B0099 for ; Mon, 19 May 2025 02:32:42 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 6513D8131B for ; Mon, 19 May 2025 06:32:46 +0000 (UTC) X-FDA: 83458689132.04.1ECAD94 Received: from out-171.mta0.migadu.com (out-171.mta0.migadu.com [91.218.175.171]) by imf02.hostedemail.com (Postfix) with ESMTP id B6EBF80015 for ; Mon, 19 May 2025 06:32:44 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=FdGqUyA8; spf=pass (imf02.hostedemail.com: domain of shakeel.butt@linux.dev designates 91.218.175.171 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=1747636364; 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=3J9VYeJdzFyFt/r30VdtnojDV07sIKVHy9ZuJmlHEhM=; b=ep9j8hrbeDEX5pYOaUEmNTw1yFU5UPTk2PLjFCSeMzMXp349Grt0qqxbjkEgxS9+h56TiW MNCTTklldrsa6b++hfcy/j94iemK7GT8wzMfDlDMNAqsEDMEX6CY9j5QFt1GT4gaL1K1As 3y0WBmspvBDvFaAjTJSf1DpKsjGQIsU= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=FdGqUyA8; spf=pass (imf02.hostedemail.com: domain of shakeel.butt@linux.dev designates 91.218.175.171 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=1747636364; a=rsa-sha256; cv=none; b=CngzmYH7DNwbH/6kKUpq566XY98RnJAW43P4uaZE1ZVDZ6Fkh4QtsLauPGKrU6wv+OOBKO yh817JIKNsYvm8QUjQ0NrJVgdYtNbze7yjdTch1hHBhRKH6+zv6VQJfpNco7LlSNxWC32O UD7qQTeWIZPnWSBH02bILrOOTTbYUPI= 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=1747636363; 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=3J9VYeJdzFyFt/r30VdtnojDV07sIKVHy9ZuJmlHEhM=; b=FdGqUyA8q/wu0MKPYl/Jd5WQk+valS0uXcqTSrA7HeaS0rJKtXWinY6tqJzFissWdtw6RX 0ioq/9nJJ3AKb3g2n9fiz1T+vUsLgok+WaiU286qyo6C817DiOPSSYJTNxwjk5xEsn1riP ZRpyRBdJ+CYP1NQ+BcccZAfMmvm/szI= 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 v4 5/5] memcg: make memcg_rstat_updated nmi safe Date: Sun, 18 May 2025 23:31:42 -0700 Message-ID: <20250519063142.111219-6-shakeel.butt@linux.dev> In-Reply-To: <20250519063142.111219-1-shakeel.butt@linux.dev> References: <20250519063142.111219-1-shakeel.butt@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Queue-Id: B6EBF80015 X-Rspamd-Server: rspam09 X-Stat-Signature: 8rbi9kijmgorsxmj38ij1w9krygwaix9 X-HE-Tag: 1747636364-457424 X-HE-Meta: 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 aF2oREyh h0Cqyf2KUq+x+Rmq/4pz15rBzzAvWnIGFMNzBrXMattzpGDakXQzpqpbyJroJ0jikOUxPYzuQH977Zs7QUVpXnJBqYVnC7DfA6eyDROY2OEvY0Cf5z/2WSzM44X61st24aZUVp6nOipNPgi0C1dTwOzpt9sENGONFcHkSTu1XJTD1QnZnacNyaHcUqARRBKLWVLNS4oe7INsY2SQQtkyB6l289S0uN17MdnKu 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 f1a46c29dde8..59d969283cc0 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) @@ -4120,8 +4122,8 @@ 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