From nobody Fri Sep 12 10:02:59 2025 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 AA5B1EE49A8 for ; Sat, 19 Aug 2023 14:15:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233287AbjHSOPB (ORCPT ); Sat, 19 Aug 2023 10:15:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44592 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233218AbjHSOO6 (ORCPT ); Sat, 19 Aug 2023 10:14:58 -0400 Received: from mail-oi1-x236.google.com (mail-oi1-x236.google.com [IPv6:2607:f8b0:4864:20::236]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 06AF19ECB for ; Sat, 19 Aug 2023 07:12:47 -0700 (PDT) Received: by mail-oi1-x236.google.com with SMTP id 5614622812f47-3a7d4030621so1171270b6e.3 for ; Sat, 19 Aug 2023 07:12:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1692454366; x=1693059166; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=igV7SREietQ24odTG+SOK9M1ry44nQsh1uk2kgh31uI=; b=YHzUfnhp2ULvFItZJ3o9nXuTnirno2N6SDjG259/ov8RQGn1YKf8iAafsV/TZmzM9G +JnpUr2gmWptKe9x+JSvawiBnbrHhC0ttUD2okQ/G1fkWvTO+q+8WWnRri6umDq+AeyL uI0r086HHFLAzxmjNMoczkq3+6neOsKWrv7/U+R0BktdT2UnHnqO2MbZ02/Sv0a3y64w uVF4L/O5aitTTPQbj/ImVhoNslyY90UeKiLJpC1hbba+hqARYZbe+jJxR1t91g/UGIRk cj0t8on3AEkxlEMjodaPmpu584rPPq3QYwFMKZXzjDyKDOj1sI+dorfQbPfPplhlCTXI V2Hw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692454366; x=1693059166; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=igV7SREietQ24odTG+SOK9M1ry44nQsh1uk2kgh31uI=; b=R3I6FrJoOiR1df06L/eq+2jpjyvA1NOfjqaIh5poa07OXgmZy9MGqTSjlCyCxd1rJ8 hp2RgYT7MOJfFxmV5ztutwQ0I8O0MnS6T5YkdIzGT4C56b21BKEz+AF8e0e9bjiba/jr Ks7uRfEodk+1XE1CafpaE11+i8tR8X+S1jkl7dwDY6ZLb8VRyrm7sFZrU/R7U7+E5ses 4vbvv5y0J4ghYoGe/BSLN/rlqfhI1D77abKXRdGjqPH7d9n1Xa2ToJ3wbii2Sn0rpnW2 TCDtxO14Dj90bkzlQrbKwiJmkX//xdsLE4d4AHN8Bilc+xI5YuWMm6YkMMr8ZF+F2SD0 t8mQ== X-Gm-Message-State: AOJu0YzMIpNV55dV29m4DHXZMtVJVbnU58W8xGqgRFpXwOdhz8hnsHcC PDjbTfB50fDegVmlBFZdpgEgIuuLH4o= X-Google-Smtp-Source: AGHT+IHSqqEDImaL7LnYyBklQgJU18/Wzpv/z+7QriCsXPpQMlpRzLKW65D8myoE3i10msbA9KqjvA== X-Received: by 2002:a05:6358:e486:b0:135:499b:a68c with SMTP id by6-20020a056358e48600b00135499ba68cmr488750rwb.8.1692454365835; Sat, 19 Aug 2023 07:12:45 -0700 (PDT) Received: from localhost ([32.218.242.113]) by smtp.gmail.com with ESMTPSA id r11-20020a0ccc0b000000b00631fea4d5bcsm1466439qvk.95.2023.08.19.07.12.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 19 Aug 2023 07:12:45 -0700 (PDT) From: Yury Norov To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Yury Norov , Ingo Molnar , Peter Zijlstra , Andrew Morton , Ben Segall , Daniel Bristot de Oliveira , Dietmar Eggemann , Jacob Keller , Jakub Kicinski , Juri Lelli , Mel Gorman , Steven Rostedt , Tariq Toukan , Valentin Schneider , Vincent Guittot , shiju.jose@huawei.com, jonathan.cameron@huawei.com, prime.zeng@huawei.com, linuxarm@huawei.com, yangyicong@hisilicon.com, Andy Shevchenko , Rasmus Villemoes , Guenter Roeck Subject: [PATCH v2 3/6] sched: fix sched_numa_find_nth_cpu() in CPU-less case Date: Sat, 19 Aug 2023 07:12:35 -0700 Message-Id: <20230819141239.287290-4-yury.norov@gmail.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230819141239.287290-1-yury.norov@gmail.com> References: <20230819141239.287290-1-yury.norov@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" When the node provided by user is CPU-less, corresponding record in sched_domains_numa_masks is not set. Trying to dereference it in the following code leads to kernel crash. To avoid it, start searching from the nearest node with CPUs. Fixes: cd7f55359c90 ("sched: add sched_numa_find_nth_cpu()") Reported-by: Yicong Yang Closes: https://lore.kernel.org/lkml/CAAH8bW8C5humYnfpW3y5ypwx0E-09A3QxFE1J= FzR66v+mO4XfA@mail.gmail.com/T/ Reported-by: Guenter Roeck Closes: https://lore.kernel.org/lkml/ZMHSNQfv39HN068m@yury-ThinkPad/T/#mf64= 31cb0b7f6f05193c41adeee444bc95bf2b1c4 Signed-off-by: Yury Norov Reviewed-by: Yicong Yang --- kernel/sched/topology.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index d3a3b2646ec4..c6e89afa0d65 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -2113,12 +2113,16 @@ static int hop_cmp(const void *a, const void *b) */ int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node) { - struct __cmp_key k =3D { .cpus =3D cpus, .node =3D node, .cpu =3D cpu }; + struct __cmp_key k =3D { .cpus =3D cpus, .cpu =3D cpu }; struct cpumask ***hop_masks; int hop, ret =3D nr_cpu_ids; =20 rcu_read_lock(); =20 + /* CPU-less node entries are uninitialized in sched_domains_numa_masks */ + node =3D numa_nearest_node(node, N_CPU); + k.node =3D node; + k.masks =3D rcu_dereference(sched_domains_numa_masks); if (!k.masks) goto unlock; --=20 2.39.2