From patchwork Mon May 2 14:22:12 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. McKenney" X-Patchwork-Id: 8992771 Return-Path: X-Original-To: patchwork-linux-omap@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 01401BF29F for ; Mon, 2 May 2016 14:39:17 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id E9351201B4 for ; Mon, 2 May 2016 14:39:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D1F1E20219 for ; Mon, 2 May 2016 14:39:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753978AbcEBOi7 (ORCPT ); Mon, 2 May 2016 10:38:59 -0400 Received: from e18.ny.us.ibm.com ([129.33.205.208]:40178 "EHLO e18.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753916AbcEBOiy (ORCPT ); Mon, 2 May 2016 10:38:54 -0400 Received: from localhost by e18.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Mon, 2 May 2016 10:38:50 -0400 X-IBM-Helo: d01dlp01.pok.ibm.com X-IBM-MailFrom: paulmck@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org;linux-omap@vger.kernel.org Received: from b01cxnp22033.gho.pok.ibm.com (b01cxnp22033.gho.pok.ibm.com [9.57.198.23]) by d01dlp01.pok.ibm.com (Postfix) with ESMTP id D3A7338C805F; Mon, 2 May 2016 10:38:49 -0400 (EDT) Received: from d01av01.pok.ibm.com (d01av01.pok.ibm.com [9.56.224.215]) by b01cxnp22033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u42EcnMA35979430; Mon, 2 May 2016 14:38:49 GMT Received: from d01av01.pok.ibm.com (localhost [127.0.0.1]) by d01av01.pok.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u42Ecl3x026110; Mon, 2 May 2016 10:38:49 -0400 Received: from paulmck-ThinkPad-W541 ([9.70.82.191]) by d01av01.pok.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id u42EckSk026070; Mon, 2 May 2016 10:38:47 -0400 Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id CB9F416C2A49; Mon, 2 May 2016 07:22:18 -0700 (PDT) From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: tony@atomide.com, mingo@kernel.org, linux@arm.linux.org.uk, rostedt@goodmis.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, "Paul E. McKenney" Subject: [PATCH omap 2/6] arm: Use more _rcuidle tracepoints to allow use from idle Date: Mon, 2 May 2016 07:22:12 -0700 Message-Id: <1462198936-3496-2-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 2.5.2 In-Reply-To: <20160502142117.GA2911@linux.vnet.ibm.com> References: <20160502142117.GA2911@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16050214-0045-0000-0000-00000414CA8B X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused Sender: linux-omap-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org X-Spam-Status: No, score=-7.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Further testing with false negatives suppressed by commit 293e2421fe25 ("rcu: Remove superfluous versions of rcu_read_lock_sched_held()") identified a few more unprotected uses of RCU from the idle loop. Because RCU actively ignores idle-loop code (for energy-efficiency reasons, among other things), using RCU from the idle loop can result in too-short grace periods, in turn resulting in arbitrary misbehavior. The resulting lockdep-RCU splats are as follows: ------------------------------------------------------------------------ =============================== [ INFO: suspicious RCU usage. ] 4.6.0-rc5-next-20160426+ #1112 Not tainted ------------------------------- include/trace/events/ipi.h:35 suspicious rcu_dereference_check() usage! other info that might help us debug this: RCU used illegally from idle CPU! rcu_scheduler_active = 1, debug_locks = 0 RCU used illegally from extended quiescent state! no locks held by swapper/0/0. stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.6.0-rc5-next-20160426+ #1112 Hardware name: Generic OMAP4 (Flattened Device Tree) [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (dump_stack+0xb0/0xe4) [] (dump_stack) from [] (smp_cross_call+0xbc/0x188) [] (smp_cross_call) from [] (generic_exec_single+0x9c/0x15c) [] (generic_exec_single) from [] (smp_call_function_single_async+0 x38/0x9c) [] (smp_call_function_single_async) from [] (cpuidle_coupled_poke_others+0x8c/0xa8) [] (cpuidle_coupled_poke_others) from [] (cpuidle_enter_state_coupled+0x26c/0x390) [] (cpuidle_enter_state_coupled) from [] (cpu_startup_entry+0x198/0x3a0) [] (cpu_startup_entry) from [] (start_kernel+0x354/0x3c8) [] (start_kernel) from [<8000807c>] (0x8000807c) ------------------------------------------------------------------------ Warning from omap3 =============================== [ INFO: suspicious RCU usage. ] 4.6.0-rc5-next-20160426+ #1112 Not tainted ------------------------------- include/trace/events/rpm.h:63 suspicious rcu_dereference_check() usage! other info that might help us debug this: RCU used illegally from idle CPU! rcu_scheduler_active = 1, debug_locks = 0 RCU used illegally from extended quiescent state! 1 lock held by swapper/0/0: #0: (&(&dev->power.lock)->rlock){-.-...}, at: [] __pm_runtime_suspend+0x54/0x84 stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.6.0-rc5-next-20160426+ #1112 Hardware name: Generic OMAP36xx (Flattened Device Tree) [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (dump_stack+0xb0/0xe4) [] (dump_stack) from [] (rpm_suspend+0x604/0x7e4) [] (rpm_suspend) from [] (__pm_runtime_suspend+0x64/0x84) [] (__pm_runtime_suspend) from [] (omap2_gpio_prepare_for_idle+0x5c/0x70) [] (omap2_gpio_prepare_for_idle) from [] (omap_sram_idle+0x140/0x244) [] (omap_sram_idle) from [] (omap3_enter_idle_bm+0xfc/0x1ec) [] (omap3_enter_idle_bm) from [] (cpuidle_enter_state+0x80/0x3d4) [] (cpuidle_enter_state) from [] (cpu_startup_entry+0x198/0x3a0) [] (cpu_startup_entry) from [] (start_kernel+0x354/0x3c8) [] (start_kernel) from [<8000807c>] (0x8000807c) ------------------------------------------------------------------------ Reported-by: Tony Lindgren Signed-off-by: Paul E. McKenney Tested-by: Tony Lindgren Cc: Russell King Cc: Steven Rostedt Cc: Cc: --- arch/arm/kernel/smp.c | 2 +- drivers/base/power/runtime.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index baee70267f29..7afe48ae5d76 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -486,7 +486,7 @@ static const char *ipi_types[NR_IPI] __tracepoint_string = { static void smp_cross_call(const struct cpumask *target, unsigned int ipinr) { - trace_ipi_raise(target, ipi_types[ipinr]); + trace_ipi_raise_rcuidle(target, ipi_types[ipinr]); __smp_cross_call(target, ipinr); } diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c index 4c7055009bd6..ad115568ce58 100644 --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -419,7 +419,7 @@ static int rpm_suspend(struct device *dev, int rpmflags) struct device *parent = NULL; int retval; - trace_rpm_suspend(dev, rpmflags); + trace_rpm_suspend_rcuidle(dev, rpmflags); repeat: retval = rpm_check_suspend_allowed(dev); @@ -549,7 +549,7 @@ static int rpm_suspend(struct device *dev, int rpmflags) } out: - trace_rpm_return_int(dev, _THIS_IP_, retval); + trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval); return retval;