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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8EBC0C54EE9 for ; Sun, 25 Sep 2022 18:13:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232159AbiIYSNv (ORCPT ); Sun, 25 Sep 2022 14:13:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43248 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229567AbiIYSNs (ORCPT ); Sun, 25 Sep 2022 14:13:48 -0400 Received: from mail-qt1-x82d.google.com (mail-qt1-x82d.google.com [IPv6:2607:f8b0:4864:20::82d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 022CE2C651; Sun, 25 Sep 2022 11:13:45 -0700 (PDT) Received: by mail-qt1-x82d.google.com with SMTP id w2so2947138qtv.9; Sun, 25 Sep 2022 11:13:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date; bh=ol4j9TJWDPz3Qh7DXbjGbnzN/8qpAI4uxo5G63wTCHQ=; b=ordxroTyTkekhrZldeVYHj2fcfKR6pIwcMZmdUIYjVspGJJdpzk+HjvHLVdSM/91yx I3rK414ZlsJaCZ0hnQ1401jjcwyf61xZeDnP8mLl5e1oSrtGsfrm9uIs1UugH+S3mOvU kYIaRC5GmHXU6BYNL1B5MS1x0KA8i+uDQUii+vSSu6WuKzqhZ0Hft+wLyTJFcjZz1sNF +b1NuwMpORmKreqwO++n/8FEJ2W0q3xYTl02Vj3gxl2omzVQPZbPrFAxkHFmtt2xIf12 2cF7IuufSBf7ofuoIC8Hqp9/RKYExy7odxhC70eYqoqPuWRDCjFZNom+K/iwl0QxB0js Rlmw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date; bh=ol4j9TJWDPz3Qh7DXbjGbnzN/8qpAI4uxo5G63wTCHQ=; b=IEv61+eG7vn7/S1e8TS1+MzQlDurIApoLcDxjt/8xru2rGe1UQCxgisZagQEp9IS4P k6PFu9frOpnf2B7egGlDQcZo5ZaTZeQpkfCosBuaRSj6tuThdsgtCX5iAyWXlxcjAmKl bEP69h1XYSOS9LChJJMxRp66S2KGQRbXkXOguFZnsOGe3/30vhDr+cP3T1epSCpr+lbu 0cIBKSrNO4umU+B1MD36RKujs7oA5CIV3LeQjQ+D5yu0qLoj6JYSFQAs6vQmVS6420zk ciLe0x1MIu0YxKdOiStBYQ8gBOJP1yU3iU4cRNwsVWeqpyR2NH0WMEHfxDtrVBjvIUt+ WKZw== X-Gm-Message-State: ACrzQf3nuIHO1verDQlxOXghaRn8ra0JdxAeHqdPhy5ZS/Atyrmr4E+T G0xzH8kSwHo99FO4Bs7oB6M= X-Google-Smtp-Source: AMsMyM6MgFJcPb8g6JKoJsQBYkdhTOcjP1cigSdK1tRq9n/c1uN158a++e19q0Wv/pX9yXDlUxhs0A== X-Received: by 2002:ac8:7d85:0:b0:35c:bf28:d2c3 with SMTP id c5-20020ac87d85000000b0035cbf28d2c3mr16032005qtd.81.1664129623640; Sun, 25 Sep 2022 11:13:43 -0700 (PDT) Received: from localhost ([2601:4c1:c100:2270:7be8:ebb8:b71d:18b9]) by smtp.gmail.com with ESMTPSA id m10-20020ac807ca000000b00342f05defd1sm9129423qth.66.2022.09.25.11.13.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 25 Sep 2022 11:13:43 -0700 (PDT) Date: Sun, 25 Sep 2022 11:13:42 -0700 From: Yury Norov To: Valentin Schneider Cc: netdev@vger.kernel.org, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, Saeed Mahameed , Leon Romanovsky , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Andy Shevchenko , Rasmus Villemoes , Ingo Molnar , Peter Zijlstra , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Mel Gorman , Greg Kroah-Hartman , Heiko Carstens , Tony Luck , Jonathan Cameron , Gal Pressman , Tariq Toukan , Jesse Brandeburg Subject: Re: [PATCH v4 5/7] sched/topology: Introduce sched_numa_hop_mask() Message-ID: References: <20220923132527.1001870-1-vschneid@redhat.com> <20220923155542.1212814-4-vschneid@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sun, Sep 25, 2022 at 11:05:18AM -0700, Yury Norov wrote: > On Fri, Sep 23, 2022 at 04:55:40PM +0100, Valentin Schneider wrote: > > Tariq has pointed out that drivers allocating IRQ vectors would benefit > > from having smarter NUMA-awareness - cpumask_local_spread() only knows > > about the local node and everything outside is in the same bucket. > > > > sched_domains_numa_masks is pretty much what we want to hand out (a cpumask > > of CPUs reachable within a given distance budget), introduce > > sched_numa_hop_mask() to export those cpumasks. > > > > Link: http://lore.kernel.org/r/20220728191203.4055-1-tariqt@nvidia.com > > Signed-off-by: Valentin Schneider > > --- > > include/linux/topology.h | 12 ++++++++++++ > > kernel/sched/topology.c | 31 +++++++++++++++++++++++++++++++ > > 2 files changed, 43 insertions(+) > > > > diff --git a/include/linux/topology.h b/include/linux/topology.h > > index 4564faafd0e1..3e91ae6d0ad5 100644 > > --- a/include/linux/topology.h > > +++ b/include/linux/topology.h > > @@ -245,5 +245,17 @@ static inline const struct cpumask *cpu_cpu_mask(int cpu) > > return cpumask_of_node(cpu_to_node(cpu)); > > } > > > > +#ifdef CONFIG_NUMA > > +extern const struct cpumask *sched_numa_hop_mask(int node, int hops); > > +#else > > +static inline const struct cpumask *sched_numa_hop_mask(int node, int hops) > > +{ > > + if (node == NUMA_NO_NODE && !hops) > > + return cpu_online_mask; > > + > > + return ERR_PTR(-EOPNOTSUPP); > > +} > > +#endif /* CONFIG_NUMA */ > > + > > > > #endif /* _LINUX_TOPOLOGY_H */ > > diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c > > index 8739c2a5a54e..ee77706603c0 100644 > > --- a/kernel/sched/topology.c > > +++ b/kernel/sched/topology.c > > @@ -2067,6 +2067,37 @@ int sched_numa_find_closest(const struct cpumask *cpus, int cpu) > > return found; > > } > > > > +/** > > + * sched_numa_hop_mask() - Get the cpumask of CPUs at most @hops hops away. > > + * @node: The node to count hops from. > > + * @hops: Include CPUs up to that many hops away. 0 means local node. > > + * > > + * Requires rcu_lock to be held. Returned cpumask is only valid within that > > + * read-side section, copy it if required beyond that. > > + * > > + * Note that not all hops are equal in distance; see sched_init_numa() for how > > + * distances and masks are handled. > > + * > > + * Also note that this is a reflection of sched_domains_numa_masks, which may change > > + * during the lifetime of the system (offline nodes are taken out of the masks). > > + */ > > +const struct cpumask *sched_numa_hop_mask(int node, int hops) > > +{ > > + struct cpumask ***masks = rcu_dereference(sched_domains_numa_masks); > > + > > + if (node == NUMA_NO_NODE && !hops) > > + return cpu_online_mask; > > + > > + if (node >= nr_node_ids || hops >= sched_domains_numa_levels) > > + return ERR_PTR(-EINVAL); > > This looks like a sanity check. If so, it should go before the snippet > above, so that client code would behave consistently. > > > + > > + if (!masks) > > + return NULL; > > In (node == NUMA_NO_NODE && !hops) case you return online cpus. Here > you return NULL just to convert it to cpu_online_mask in the caller. > This looks inconsistent. So, together with the above comment, this > makes me feel that you'd do it like this: > > const struct cpumask *sched_numa_hop_mask(int node, int hops) > { > struct cpumask ***masks; > > if (node >= nr_node_ids || hops >= sched_domains_numa_levels) > { > #ifdef CONFIG_SCHED_DEBUG > pr_err(...); > #endif > return ERR_PTR(-EINVAL); > } It's an exported function, and any lame driver may crash the system by dereferencing a random pointer. You need to check the node for -2, -3, etc, because only -1 is a valid negative value. For hops, it should be an unsigned int. Right? > > if (node == NUMA_NO_NODE && !hops) > return cpu_online_mask; /* or NULL */ > > masks = rcu_dereference(sched_domains_numa_masks); > if (!masks) > return cpu_online_mask; /* or NULL */ > > return masks[hops][node]; > }