Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758423AbbGQO7P (ORCPT ); Fri, 17 Jul 2015 10:59:15 -0400 Received: from mail-pa0-f46.google.com ([209.85.220.46]:33183 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758395AbbGQO7O convert rfc822-to-8bit (ORCPT ); Fri, 17 Jul 2015 10:59:14 -0400 Subject: Re: [RFC 2/3] arm64: refactor save_stack_trace() Mime-Version: 1.0 (Apple Message framework v1283) Content-Type: text/plain; charset=us-ascii From: Jungseok Lee In-Reply-To: <20150717104144.6588b2f7@gandalf.local.home> Date: Fri, 17 Jul 2015 23:59:12 +0900 Cc: Mark Rutland , Catalin Marinas , Will Deacon , "linux-kernel@vger.kernel.org" , AKASHI Takahiro , "broonie@kernel.org" , "david.griego@linaro.org" , "olof@lixom.net" , "linux-arm-kernel@lists.infradead.org" Content-Transfer-Encoding: 8BIT Message-Id: <0886A996-40E1-49E9-823C-85E55A858716@gmail.com> References: <55A646EE.6030402@linaro.org> <20150715105536.42949ea9@gandalf.local.home> <20150715121337.3b31aa84@gandalf.local.home> <55A6FA82.9000901@linaro.org> <55A703F3.8050203@linaro.org> <20150716102405.2cc8c406@gandalf.local.home> <12F47692-3010-4886-B87D-3D7820609177@gmail.com> <20150716113115.45a17f17@gandalf.local.home> <20150716121658.7982fdf5@gandalf.local.home> <20150717124054.GE26091@leverpostej> <20150717090009.720f6bd0@gandalf.local.home> <77EA0F10-D5F6-48BD-8652-3B979A978659@gmail.com> <20150717104144.6588b2f7@gandalf.local.home> To: Steven Rostedt X-Mailer: Apple Mail (2.1283) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3318 Lines: 76 On Jul 17, 2015, at 11:41 PM, Steven Rostedt wrote: > On Fri, 17 Jul 2015 23:28:13 +0900 > Jungseok Lee wrote: > > >> >> I have reviewed and tested the kernel including this patch and only [RFC 1/3]. > > Thanks! Can you repost patch 1 with the changes I recommended, so that > I can get an Acked-by from the arm64 maintainers and pull all the > changes in together. This is fine for a 4.3 release, right? That is, it > doesn't need to go into 4.2-rcs. > Welcome! It's not hard to repost a patch, but I feel like we have to wait for Akashi's response. Also, it might be needed to consider Mark's comment on arch part. If they are okay, I will proceed. >> >> Now, the number of entries and max_stack_size are always okay, but unexpected functions, >> such as ftrace_ops_no_ops and ftrace_call, are *sometimes* listed as follows. >> >> $ cat /sys/kernel/debug/tracing/stack_trace >> >> Depth Size Location (49 entries) >> ----- ---- -------- >> 0) 4456 16 arch_counter_read+0xc/0x24 >> 1) 4440 16 ktime_get+0x44/0xb4 >> 2) 4424 48 get_drm_timestamp+0x30/0x40 >> 3) 4376 16 drm_get_last_vbltimestamp+0x94/0xb4 >> 4) 4360 80 drm_handle_vblank+0x84/0x3c0 >> 5) 4280 144 mdp5_irq+0x118/0x130 >> 6) 4136 80 msm_irq+0x2c/0x68 >> 7) 4056 32 handle_irq_event_percpu+0x60/0x210 >> 8) 4024 96 handle_irq_event+0x50/0x80 >> 9) 3928 64 handle_fasteoi_irq+0xb0/0x178 >> 10) 3864 48 generic_handle_irq+0x38/0x54 >> 11) 3816 32 __handle_domain_irq+0x68/0xbc >> 12) 3784 64 gic_handle_irq+0x38/0x88 >> 13) 3720 280 el1_irq+0x64/0xd8 >> 14) 3440 168 ftrace_ops_no_ops+0xb4/0x16c >> 15) 3272 64 ftrace_call+0x0/0x4 >> 16) 3208 16 _raw_spin_lock_irqsave+0x14/0x70 >> 17) 3192 32 msm_gpio_set+0x44/0xb4 >> 18) 3160 48 _gpiod_set_raw_value+0x68/0x148 >> 19) 3112 64 gpiod_set_value+0x40/0x70 >> 20) 3048 32 gpio_led_set+0x3c/0x94 >> 21) 3016 48 led_set_brightness+0x50/0xa4 >> 22) 2968 32 led_trigger_event+0x4c/0x78 >> 23) 2936 48 mmc_request_done+0x38/0x84 >> 24) 2888 32 sdhci_tasklet_finish+0xcc/0x12c >> 25) 2856 48 tasklet_action+0x64/0x120 >> 26) 2808 48 __do_softirq+0x114/0x2f0 >> 27) 2760 128 irq_exit+0x98/0xd8 >> 28) 2632 32 __handle_domain_irq+0x6c/0xbc >> 29) 2600 64 gic_handle_irq+0x38/0x88 >> 30) 2536 280 el1_irq+0x64/0xd8 >> 31) 2256 168 ftrace_ops_no_ops+0xb4/0x16c >> 32) 2088 64 ftrace_call+0x0/0x4 > > Like I stated before, the above looks to be an interrupt coming in > while the tracing was happening. This looks legitimate to me. I'm > guessing that arm64 uses one stack for normal context and interrupt > context, where as x86 uses a separate stack for interrupt context. Okay. Thanks for a kind explanation. Best Regards Jungseok Lee-- 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/