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 X-Spam-Level: X-Spam-Status: No, score=-9.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9F3DDC55179 for ; Wed, 28 Oct 2020 22:29:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3A9FC2070E for ; Wed, 28 Oct 2020 22:29:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="QoYJthvw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387577AbgJ1W3V (ORCPT ); Wed, 28 Oct 2020 18:29:21 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:60843 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387547AbgJ1W3P (ORCPT ); Wed, 28 Oct 2020 18:29:15 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1603924153; 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; bh=UE3dvpTXYD1TxjvaPfVy+gsIUVv7GO6zARCwT2Egia8=; b=QoYJthvwTM+H8U5F84maiSz4O0uUx5pLHD+O8UwCd/Je7VcWYcOv8dRmbECmBGpNDi0Brc uq0DKNtmvA1voIeT8m7XjXGBdp0QDnOmFNlQPYRvZL5UcJw0Y56dMXRayJc5oro7pONn3Q n6lK8+BmjKZn+XbyVAIs7bqYcBxoLdA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-581-lnOqo2DdOK-TTluihTk1Og-1; Wed, 28 Oct 2020 14:26:42 -0400 X-MC-Unique: lnOqo2DdOK-TTluihTk1Og-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A3A88805F1E; Wed, 28 Oct 2020 18:26:40 +0000 (UTC) Received: from localhost.localdomain.com (ovpn-66-92.rdu2.redhat.com [10.10.66.92]) by smtp.corp.redhat.com (Postfix) with ESMTP id BF4985C1D7; Wed, 28 Oct 2020 18:26:36 +0000 (UTC) From: Qian Cai To: "Paul E. McKenney" Cc: Peter Zijlstra , Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Qian Cai Subject: [PATCH] arm64/smp: Move rcu_cpu_starting() earlier Date: Wed, 28 Oct 2020 14:26:14 -0400 Message-Id: <20201028182614.13655-1-cai@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The call to rcu_cpu_starting() in secondary_start_kernel() is not early enough in the CPU-hotplug onlining process, which results in lockdep splats as follows: WARNING: suspicious RCU usage ----------------------------- kernel/locking/lockdep.c:3497 RCU-list traversed in non-reader section!! other info that might help us debug this: RCU used illegally from offline CPU! rcu_scheduler_active = 1, debug_locks = 1 no locks held by swapper/1/0. Call trace: dump_backtrace+0x0/0x3c8 show_stack+0x14/0x60 dump_stack+0x14c/0x1c4 lockdep_rcu_suspicious+0x134/0x14c __lock_acquire+0x1c30/0x2600 lock_acquire+0x274/0xc48 _raw_spin_lock+0xc8/0x140 vprintk_emit+0x90/0x3d0 vprintk_default+0x34/0x40 vprintk_func+0x378/0x590 printk+0xa8/0xd4 __cpuinfo_store_cpu+0x71c/0x868 cpuinfo_store_cpu+0x2c/0xc8 secondary_start_kernel+0x244/0x318 This is avoided by moving the call to rcu_cpu_starting up near the beginning of the secondary_start_kernel() function. Link: https://lore.kernel.org/lkml/160223032121.7002.1269740091547117869.tip-bot2@tip-bot2/ Signed-off-by: Qian Cai --- arch/arm64/kernel/smp.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 82e75fc2c903..09c96f57818c 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -222,6 +222,7 @@ asmlinkage notrace void secondary_start_kernel(void) if (system_uses_irq_prio_masking()) init_gic_priority_masking(); + rcu_cpu_starting(cpu); preempt_disable(); trace_hardirqs_off(); -- 2.28.0