Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757496Ab2JZIvN (ORCPT ); Fri, 26 Oct 2012 04:51:13 -0400 Received: from mga02.intel.com ([134.134.136.20]:50995 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755492Ab2JZIvK (ORCPT ); Fri, 26 Oct 2012 04:51:10 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.80,653,1344236400"; d="scan'208";a="232835934" Message-ID: <1351241467.2207.13.camel@ymzhang.sh.intel.com> Subject: Re: [PATCH] hrtimer:__run_hrtimer races with enqueue_hrtimer From: Yanmin Zhang Reply-To: yanmin_zhang@linux.intel.com To: "he, bo" Cc: Thomas Gleixner , linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar , yanmin.zhang@intel.com Date: Fri, 26 Oct 2012 16:51:07 +0800 In-Reply-To: <1351219917.28400.6.camel@hebo> References: <1351219917.28400.6.camel@hebo> Organization: Intel. Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.2- Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3486 Lines: 54 On Fri, 2012-10-26 at 10:51 +0800, he, bo wrote: > From: Yanmin Zhang > > We hit a kernel panic at __run_hrtimer=>BUG_ON(timer->state != HRTIMER_STATE_CALLBACK). > <2>[ 10.226053, 3] kernel BUG at /home/android/xiaobing/ymz/r4/hardware/intel/linux-2.6/kernel/hrtimer.c:1228! > <0>[ 10.235682, 3] invalid opcode: 0000 [#1] PREEMPT SMP > <4>[ 10.240716, 3] Modules linked in: wl12xx_sdio wl12xx mac80211 cfg80211 compat btwilink rmi4(C) fmdrv_chr st_drv matrix(C) > <4>[ 10.251651, 3] > <4>[ 10.253391, 3] Pid: 68, comm: kworker/3:4 Tainted: G WC 3.0.34-140430-g2af538d #45 Intel Corporation CloverTrail/FFRD > <4>[ 10.264674, 3] EIP: 0060:[] EFLAGS: 00010002 CPU: 3 > <4>[ 10.270411, 3] EIP is at __run_hrtimer+0xbd/0x240 > <4>[ 10.275091, 3] EAX: 00000001 EBX: f67fb6b8 ECX: f57b4000 EDX: 00007301 > <4>[ 10.281602, 3] ESI: c1d614c0 EDI: f67fb680 EBP: f57b5dd8 ESP: f57b5da8 > <4>[ 10.288113, 3] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 > <0>[ 10.293754, 3] Process kworker/3:4 (pid: 68, ti=f57b4000 task=f57aa730 task.ti=f57b4000) > <0>[ 10.301827, 3] Stack: > <4>[ 10.304083, 3] 00000000 c1afef40 f57b5dd8 c167a6e0 f67fb680 20b366e3 f67fb6b8 f57b5e14 > <4>[ 10.312069, 3] 00000001 f67fb6b8 00000001 f67fb680 f57b5e28 c126d1e5 f57b5e08 c126f325 > <4>[ 10.320055, 3] 00000000 86b9868d 00000001 86b9868d 00000001 00000003 ffffffff 7fffffff > <0>[ 10.328041, 3] Call Trace: > <4>[ 10.330742, 3] [] ? gburst_thread_stop.isra.25+0x40/0x40 > <4>[ 10.336988, 3] [] hrtimer_interrupt+0xd5/0x250 > <4>[ 10.342368, 3] [] ? sched_clock_cpu+0xe5/0x150 > <4>[ 10.347753, 3] [] smp_apic_timer_interrupt+0x54/0x88 > <4>[ 10.353654, 3] [] ? trace_hardirqs_off_thunk+0xc/0x14 > <4>[ 10.359643, 3] [] apic_timer_interrupt+0x2f/0x34 > <4>[ 10.365199, 3] [] ? sub_preempt_count+0x1f/0x50 > <4>[ 10.370669, 3] [] delay_tsc+0x3a/0xc0 > <6>[ 10.371589, 0] android_work: did not send uevent (0 0 (null)) > <4>[ 10.381171, 3] [] __const_udelay+0x23/0x30 > <4>[ 10.386207, 3] [] mdfld_dsi_send_dcs+0x12a/0x5d0 > <4>[ 10.391760, 3] [] ? _raw_spin_unlock_irqrestore+0x26/0x50 > <4>[ 10.398101, 3] [] ? ospm_power_using_hw_begin+0xa1/0x350 > <4>[ 10.399053, 3] [] ? __mutex_lock_slowpath+0x1ff/0x2f0 > <4>[ 10.399069, 3] [] mdfld_dbi_update_panel+0x21e/0x2d0 > <4>[ 10.399085, 3] [] mdfld_te_handler_work+0x71/0x80 > <4>[ 10.399099, 3] [] process_one_work+0xfe/0x3f0 > <4>[ 10.399114, 3] [] ? mdfld_async_flip_te_handler+0xf0/0xf0 > > Basically, __run_hrtimer has a race with enqueue_hrtimer. When __run_hrtimer calls > the timer callback fn, another thread might call enqueue_hrtimer or hrtimer_start > to requeue it, and the timer->state is equal to HRTIMER_STATE_CALLBACK|HRTIMER_STATE_ENQUEUED, > which causes the BUG_ON(timer->state != HRTIMER_STATE_CALLBACK) checking fails. > > The patch fixes it by checking only bit HRTIMER_STATE_CALLBACK. The patch has an issue that enqueue_hrtimer doesn't check if the timer is queued. I will send a new patch. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/