From patchwork Wed Oct 19 22:46:59 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. McKenney" X-Patchwork-Id: 13012447 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 8C669C4321E for ; Wed, 19 Oct 2022 22:47:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230387AbiJSWrG (ORCPT ); Wed, 19 Oct 2022 18:47:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36244 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230234AbiJSWrD (ORCPT ); Wed, 19 Oct 2022 18:47:03 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8820717FD5C; Wed, 19 Oct 2022 15:47:02 -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 22755619D6; Wed, 19 Oct 2022 22:47:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5060CC43149; Wed, 19 Oct 2022 22:47:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1666219621; bh=CDl8H2MGOjWvC458fdEn7dT11YxGntP9ARrgviEeMhY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tuC9VoJUsxYY/4c+0Pc8LrQ1NGvAKs1dMjfH9r+iKyPsUll5AXr+M8mzGLDsSgWsc wNZkFN8/urxwPLqOoviVRke4/rJGfytC7VoI/4ExKL6ikIH8zSDpmSs7VGFH1rf/bT AE9DZl2rrmOoaHRLKi9uSR2a6dK851gFDFHp3a04uSuhov9GeK36VtvC5mCmne1dpU PAn+ouBxcTUFL9Civ4mINIPu8vnvSSs6P5heivUd6ApQ9BEkJmoKY9dvA6huIWeH/+ Ew+TTrGXjp4GD/qunPYACNRTIUTSMSBEAwcN98aCDMgs1y03E41YnNyklrkA2rCEXJ dZAatlp2GWijA== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id B2E8E5C0B8F; Wed, 19 Oct 2022 15:47:00 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, rostedt@goodmis.org, Zqiang , Joel Fernandes , "Paul E . McKenney" Subject: [PATCH rcu 8/8] rcu: Fix __this_cpu_read() lockdep warning in rcu_force_quiescent_state() Date: Wed, 19 Oct 2022 15:46:59 -0700 Message-Id: <20221019224659.2499511-8-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20221019224652.GA2499358@paulmck-ThinkPad-P17-Gen-1> References: <20221019224652.GA2499358@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org From: Zqiang Running rcutorture with non-zero fqs_duration module parameter in a kernel built with CONFIG_PREEMPTION=y results in the following splat: BUG: using __this_cpu_read() in preemptible [00000000] code: rcu_torture_fqs/398 caller is __this_cpu_preempt_check+0x13/0x20 CPU: 3 PID: 398 Comm: rcu_torture_fqs Not tainted 6.0.0-rc1-yoctodev-standard+ Call Trace: dump_stack_lvl+0x5b/0x86 dump_stack+0x10/0x16 check_preemption_disabled+0xe5/0xf0 __this_cpu_preempt_check+0x13/0x20 rcu_force_quiescent_state.part.0+0x1c/0x170 rcu_force_quiescent_state+0x1e/0x30 rcu_torture_fqs+0xca/0x160 ? rcu_torture_boost+0x430/0x430 kthread+0x192/0x1d0 ? kthread_complete_and_exit+0x30/0x30 ret_from_fork+0x22/0x30 The problem is that rcu_force_quiescent_state() uses __this_cpu_read() in preemptible code instead of the proper raw_cpu_read(). This commit therefore changes __this_cpu_read() to raw_cpu_read(). Signed-off-by: Zqiang Reviewed-by: Joel Fernandes (Google) Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index f6561aa401c04..1e1d333d07ffe 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2410,7 +2410,7 @@ void rcu_force_quiescent_state(void) struct rcu_node *rnp_old = NULL; /* Funnel through hierarchy to reduce memory contention. */ - rnp = __this_cpu_read(rcu_data.mynode); + rnp = raw_cpu_read(rcu_data.mynode); for (; rnp != NULL; rnp = rnp->parent) { ret = (READ_ONCE(rcu_state.gp_flags) & RCU_GP_FLAG_FQS) || !raw_spin_trylock(&rnp->fqslock);