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 AA7C8C4167B for ; Mon, 11 Dec 2023 13:55:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343759AbjLKNzB (ORCPT ); Mon, 11 Dec 2023 08:55:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48672 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343915AbjLKNya (ORCPT ); Mon, 11 Dec 2023 08:54:30 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DEB04268B for ; Mon, 11 Dec 2023 05:53:31 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 577E0C433C8; Mon, 11 Dec 2023 13:53:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1702302811; bh=YsRlnuUe4K9wHZHF9mJAsvi2nDDK8UcmxqE7+XJC5K8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ajiqL3gD8ZT0pzzKGH8o4cMWIIJq8fwsWtFBABB0fI5YaDHTkjldZIMxgTX8gXM3c QfVTOMIw/HuhRVz8jfG3MtL3pvUsgP2AZ8EbQujds6Q4ekB7sbxmgn0BEknKCTTt7T OzKLC+SWLkfQjuZpPMsfwJjf+2iUeHCBE7xLiEwM4PlG9UmpUw6Dqi6aaS1fkK7c1/ k2vOOJ7IrQXIGOo8hm+cfW6/Ib11fR7LHIewiulatZpi5OlPORFvjCTZXZvOl9CuRm xSbkLmMMfKSkV0bL8WOerf9/qmw5VvlT7MEF/NrxIGnrnOUg3K9fd9l3XO9rSsovWS IHdBcCL61zwmQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Stefan Wiehler , Huacai Chen , Thomas Bogendoerfer , Sasha Levin , peterz@infradead.org, jiaxun.yang@flygoat.com, chenhuacai@kernel.org, tglx@linutronix.de, linux-mips@vger.kernel.org Subject: [PATCH AUTOSEL 6.6 36/47] mips/smp: Call rcutree_report_cpu_starting() earlier Date: Mon, 11 Dec 2023 08:50:37 -0500 Message-ID: <20231211135147.380223-36-sashal@kernel.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231211135147.380223-1-sashal@kernel.org> References: <20231211135147.380223-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.6.5 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Stefan Wiehler [ Upstream commit 55702ec9603ebeffb15e6f7b113623fe1d8872f4 ] rcutree_report_cpu_starting() must be called before clockevents_register_device() to avoid the following lockdep splat triggered by calling list_add() when CONFIG_PROVE_RCU_LIST=y: WARNING: suspicious RCU usage ... ----------------------------- kernel/locking/lockdep.c:3680 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: [] show_stack+0x64/0x158 [] dump_stack_lvl+0x90/0xc4 [] __lock_acquire+0x1404/0x2940 [] lock_acquire+0x14c/0x448 [] _raw_spin_lock_irqsave+0x50/0x88 [] clockevents_register_device+0x60/0x1e8 [] r4k_clockevent_init+0x220/0x3a0 [] start_secondary+0x50/0x3b8 raw_smp_processor_id() is required in order to avoid calling into lockdep before RCU has declared the CPU to be watched for readers. See also commit 29368e093921 ("x86/smpboot: Move rcu_cpu_starting() earlier"), commit de5d9dae150c ("s390/smp: move rcu_cpu_starting() earlier") and commit 99f070b62322 ("powerpc/smp: Call rcu_cpu_starting() earlier"). Signed-off-by: Stefan Wiehler Reviewed-by: Huacai Chen Signed-off-by: Thomas Bogendoerfer Signed-off-by: Sasha Levin --- arch/mips/kernel/smp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c index 8fbef537fb885..82e2e051b4161 100644 --- a/arch/mips/kernel/smp.c +++ b/arch/mips/kernel/smp.c @@ -351,10 +351,11 @@ early_initcall(mips_smp_ipi_init); */ asmlinkage void start_secondary(void) { - unsigned int cpu; + unsigned int cpu = raw_smp_processor_id(); cpu_probe(); per_cpu_trap_init(false); + rcutree_report_cpu_starting(cpu); mips_clockevent_init(); mp_ops->init_secondary(); cpu_report(); @@ -366,7 +367,6 @@ asmlinkage void start_secondary(void) */ calibrate_delay(); - cpu = smp_processor_id(); cpu_data[cpu].udelay_val = loops_per_jiffy; set_cpu_sibling_map(cpu); -- 2.42.0