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 43948C433F5 for ; Tue, 12 Apr 2022 08:29:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358510AbiDLIbP (ORCPT ); Tue, 12 Apr 2022 04:31:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42852 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353580AbiDLHZr (ORCPT ); Tue, 12 Apr 2022 03:25:47 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C413F43AE4; Tue, 12 Apr 2022 00:01:48 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 5ED0460B2E; Tue, 12 Apr 2022 07:01:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 69C05C385A6; Tue, 12 Apr 2022 07:01:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649746907; bh=YiaJDBbTcuhQHMi1q1uJq5SwFO2vcgROG+bHHXW7V2Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vOaR6hY8Bc/z49kFiI34yVD2ajrvI1bMOFP2Euqu9jCap5cnEH763JsPtgfHZVh3A jmK9INguS4RS9kePAID5BFi4zZT9r5FDYESFz8TP7xSjDW8ziDogLitxCltWwlNLtN jvPCgXGzU3g8kzPipAzxTcOb3bk/ZPwrw1jL0nPw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Phil Auld , Dietmar Eggemann , Will Deacon , Sasha Levin Subject: [PATCH 5.16 174/285] arch/arm64: Fix topology initialization for core scheduling Date: Tue, 12 Apr 2022 08:30:31 +0200 Message-Id: <20220412062948.690247666@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220412062943.670770901@linuxfoundation.org> References: <20220412062943.670770901@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Phil Auld [ Upstream commit 5524cbb1bfcdff0cad0aaa9f94e6092002a07259 ] Arm64 systems rely on store_cpu_topology() to call update_siblings_masks() to transfer the toplogy to the various cpu masks. This needs to be done before the call to notify_cpu_starting() which tells the scheduler about each cpu found, otherwise the core scheduling data structures are setup in a way that does not match the actual topology. With smt_mask not setup correctly we bail on `cpumask_weight(smt_mask) == 1` for !leaders in: notify_cpu_starting() cpuhp_invoke_callback_range() sched_cpu_starting() sched_core_cpu_starting() which leads to rq->core not being correctly set for !leader-rq's. Without this change stress-ng (which enables core scheduling in its prctl tests in newer versions -- i.e. with PR_SCHED_CORE support) causes a warning and then a crash (trimmed for legibility): [ 1853.805168] ------------[ cut here ]------------ [ 1853.809784] task_rq(b)->core != rq->core [ 1853.809792] WARNING: CPU: 117 PID: 0 at kernel/sched/fair.c:11102 cfs_prio_less+0x1b4/0x1c4 ... [ 1854.015210] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 ... [ 1854.231256] Call trace: [ 1854.233689] pick_next_task+0x3dc/0x81c [ 1854.237512] __schedule+0x10c/0x4cc [ 1854.240988] schedule_idle+0x34/0x54 Fixes: 9edeaea1bc45 ("sched: Core-wide rq->lock") Signed-off-by: Phil Auld Reviewed-by: Dietmar Eggemann Tested-by: Dietmar Eggemann Link: https://lore.kernel.org/r/20220331153926.25742-1-pauld@redhat.com Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- arch/arm64/kernel/smp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 27df5c1e6baa..3b46041f2b97 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -234,6 +234,7 @@ asmlinkage notrace void secondary_start_kernel(void) * Log the CPU info before it is marked online and might get read. */ cpuinfo_store_cpu(); + store_cpu_topology(cpu); /* * Enable GIC and timers. @@ -242,7 +243,6 @@ asmlinkage notrace void secondary_start_kernel(void) ipi_setup(cpu); - store_cpu_topology(cpu); numa_add_cpu(cpu); /* -- 2.35.1