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 CC354C3ABC5 for ; Wed, 14 May 2025 05:08:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C9A7B6B00C0; Wed, 14 May 2025 01:08:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C217E6B00C2; Wed, 14 May 2025 01:08:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A758A6B00C3; Wed, 14 May 2025 01:08:36 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 7D7666B00C0 for ; Wed, 14 May 2025 01:08:36 -0400 (EDT) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id B4A625969D for ; Wed, 14 May 2025 05:08:36 +0000 (UTC) X-FDA: 83440333032.22.F7574CA Received: from out-171.mta0.migadu.com (out-171.mta0.migadu.com [91.218.175.171]) by imf29.hostedemail.com (Postfix) with ESMTP id 0ABAB120003 for ; Wed, 14 May 2025 05:08:34 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=clfLkUdZ; spf=pass (imf29.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=1747199315; 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=zTCWWrV0l4ME9vJBQdx9lnHLC7UBjeIHK4sO6n82O0w=; b=Tf6Hkta7NDU9y///OyI4MaQQAxlXY0COTxD0q4Jll1wNkpJ7Ry1OB8Hoot0SCXWpikeAMd V0Fze95wrr7Kp4spV3cQZXA4nPWo/DiTT5F3kv4mouC4vwDN7w5jCwiMvhZcpTUjTx16C8 qGbVx1LlO4wFScE7fsJFa33FaWTWFYs= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=clfLkUdZ; spf=pass (imf29.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=1747199315; a=rsa-sha256; cv=none; b=JNwwv/DdhkE9vF+JjhGRYOMpJ1+mCbpT7M+dcd8FUsicGDNlBAQEGKui5gRHOGxNBY8Ju6 gs1FftH72rjB8Tfev/wpLBTOQYxyMmTiNfselEvYIawubxhy32EYCLI8uCXxk2d23rNrH7 ZrGDrT/SxYykZIg8RC9JZeK5T1OnubU= 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=1747199313; 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=zTCWWrV0l4ME9vJBQdx9lnHLC7UBjeIHK4sO6n82O0w=; b=clfLkUdZQCeY4LqSnalnqCiuGz+eMS9VvbrRqDlJq//1jNxS3/xkzuZH0dAccVoNF2esh9 AoAfroMAbkmB8hJml6UIrG23bU6WvwkGvr/OeR1DT+8bEraK8BLD3NB2tddQZPLwAPo/7V ddblr4d4JckNJE3bSKj7MOy1KgFTcPw= 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 1/7] memcg: memcg_rstat_updated re-entrant safe against irqs Date: Tue, 13 May 2025 22:08:07 -0700 Message-ID: <20250514050813.2526843-2-shakeel.butt@linux.dev> In-Reply-To: <20250514050813.2526843-1-shakeel.butt@linux.dev> References: <20250514050813.2526843-1-shakeel.butt@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Queue-Id: 0ABAB120003 X-Rspamd-Server: rspam09 X-Stat-Signature: yr6ixc31bh75jbdrj1rafqqoih7duc4o X-HE-Tag: 1747199314-407536 X-HE-Meta: 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 ykVYMfib OVcOY+fb18xnEVnuwRCmD2XejVe+8sPM22mNdlG0RzC+tu39pqwATcsVhdFJOOLvvsy/sb83suJgp4YzZFUIx9/kkOQO5nyev61dd/r9fUZq0GJgM2pKxfz8ALbuhKmGnPNacHoOoki2JAobGV6l2JSXzZ6SYYaLOAfxOcQZoZuVLq0JltfIkcAIaemBKjXsxWkt4poubyEa6S2hcdVaYv5jKlBkbjRZCWwJL 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: The function memcg_rstat_updated() is used to track the memcg stats updates for optimizing the flushes. At the moment, it is not re-entrant safe and the callers disabled irqs before calling. However to achieve the goal of updating memcg stats without irqs, memcg_rstat_updated() needs to be re-entrant safe against irqs. This patch makes memcg_rstat_updated() re-entrant safe using this_cpu_* ops. On archs with CONFIG_ARCH_HAS_NMI_SAFE_THIS_CPU_OPS, this patch is also making memcg_rstat_updated() nmi safe. Signed-off-by: Shakeel Butt --- mm/memcontrol.c | 34 ++++++++++++++++++++-------------- 1 file changed, 20 insertions(+), 14 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a713f160d669..cb10bcd1028d 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -506,8 +506,8 @@ struct memcg_vmstats_percpu { unsigned int stats_updates; /* Cached pointers for fast iteration in memcg_rstat_updated() */ - struct memcg_vmstats_percpu *parent; - struct memcg_vmstats *vmstats; + struct memcg_vmstats_percpu __percpu *parent_pcpu; + struct memcg_vmstats *vmstats; /* The above should fit a single cacheline for memcg_rstat_updated() */ @@ -589,32 +589,38 @@ static bool memcg_vmstats_needs_flush(struct memcg_vmstats *vmstats) static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val) { - struct memcg_vmstats_percpu *statc; - int cpu = smp_processor_id(); + struct memcg_vmstats_percpu __percpu *statc_pcpu; + int cpu; unsigned int stats_updates; if (!val) return; + /* Don't assume callers have preemption disabled. */ + cpu = get_cpu(); + css_rstat_updated(&memcg->css, cpu); - statc = this_cpu_ptr(memcg->vmstats_percpu); - for (; statc; statc = statc->parent) { + statc_pcpu = memcg->vmstats_percpu; + for (; statc_pcpu; statc_pcpu = this_cpu_ptr(statc_pcpu)->parent_pcpu) { /* * If @memcg is already flushable then all its ancestors are * flushable as well and also there is no need to increase * stats_updates. */ - if (memcg_vmstats_needs_flush(statc->vmstats)) + if (memcg_vmstats_needs_flush(this_cpu_ptr(statc_pcpu)->vmstats)) break; - stats_updates = READ_ONCE(statc->stats_updates) + abs(val); - WRITE_ONCE(statc->stats_updates, stats_updates); + stats_updates = this_cpu_add_return(statc_pcpu->stats_updates, + abs(val)); if (stats_updates < MEMCG_CHARGE_BATCH) continue; - atomic64_add(stats_updates, &statc->vmstats->stats_updates); - WRITE_ONCE(statc->stats_updates, 0); + stats_updates = this_cpu_xchg(statc_pcpu->stats_updates, 0); + if (stats_updates) + atomic64_add(stats_updates, + &this_cpu_ptr(statc_pcpu)->vmstats->stats_updates); } + put_cpu(); } static void __mem_cgroup_flush_stats(struct mem_cgroup *memcg, bool force) @@ -3716,7 +3722,7 @@ static void mem_cgroup_free(struct mem_cgroup *memcg) static struct mem_cgroup *mem_cgroup_alloc(struct mem_cgroup *parent) { - struct memcg_vmstats_percpu *statc, *pstatc; + struct memcg_vmstats_percpu *statc, __percpu *pstatc_pcpu; struct mem_cgroup *memcg; int node, cpu; int __maybe_unused i; @@ -3747,9 +3753,9 @@ static struct mem_cgroup *mem_cgroup_alloc(struct mem_cgroup *parent) for_each_possible_cpu(cpu) { if (parent) - pstatc = per_cpu_ptr(parent->vmstats_percpu, cpu); + pstatc_pcpu = parent->vmstats_percpu; statc = per_cpu_ptr(memcg->vmstats_percpu, cpu); - statc->parent = parent ? pstatc : NULL; + statc->parent_pcpu = parent ? pstatc_pcpu : NULL; statc->vmstats = memcg->vmstats; } -- 2.47.1