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Tue, 18 Feb 2020 16:57:28 +0000 From: Nicholas Johnson To: Lukas Wunner CC: Bjorn Helgaas , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" Subject: Re: Stack trace when removing Thunderbolt devices while kernel shutting down Thread-Topic: Stack trace when removing Thunderbolt devices while kernel shutting down Thread-Index: AQHV5mZRaprLG3S8P026BwNeB/+bQKghC8YAgAAgZ4A= Date: Tue, 18 Feb 2020 16:57:29 +0000 Message-ID: References: <20200218150124.stvsj2rozxrgxw2h@wunner.de> In-Reply-To: <20200218150124.stvsj2rozxrgxw2h@wunner.de> Accept-Language: en-AU, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-clientproxiedby: ME2P282CA0002.AUSP282.PROD.OUTLOOK.COM (2603:10c6:220:4d::14) To PSXP216MB0438.KORP216.PROD.OUTLOOK.COM (2603:1096:300:d::20) x-incomingtopheadermarker: OriginalChecksum:B3B09E2AF88F9165573A5A9E08408064B44B394555A156180D18E1114A1D48D8;UpperCasedChecksum:E7029EC3C24986F9D6299ED3B4C0D82F2E15D5B398FB6B55C3CBFE6A566AE424;SizeAsReceived:7908;Count:50 x-ms-exchange-messagesentrepresentingtype: 1 x-tmn: [u2pNdPck2pP3YEtywLf4ax5T+YtmCgu9R7hitZL8ThMWKkHylnFZoN1XcOZe8pzr] x-microsoft-original-message-id: <20200218165723.GA1561@nicholas-dell-linux> x-ms-publictraffictype: Email x-incomingheadercount: 50 x-eopattributedmessage: 0 x-ms-office365-filtering-correlation-id: 214e0517-a7e7-4433-1a26-08d7b493a3a9 x-ms-traffictypediagnostic: HK2APC01HT199: x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: WIStGC8ICfYXHTk5rT7cAUCjh7khb4GlyitfgkrRBr6d/6myTIotlX3iR78p+dvigyEpSYCHOUbHc830NyrKjmtXg0suMiREpY6qHeYt6UeBo+b/V8BBOqg+KQXWc0tLhWD1xqUKBKMQzoKorV51sf066zCHmC2JywYXBfRf6lIe7Wm/dA6lNqluM6MmTVa47a9G6rlJ27aMwEJz1SC1NSVz8Aa6g8s7uENOIeCOH4s= x-ms-exchange-antispam-messagedata: gH+v5fegLd77G3xJe60l5SwERwuGCw800BDkPGfWhuIsAaN8bEZhsPg6yye027MowVYILUMVW+2cAU1KuWUnkCog3FAhnPeIbqDCRQNerrRjaRPJj3kNE7vc3l+nUy23hLUkf7agM9f8InIQm06Y1JwxRQsF8oT2VyTUpJUhBNsY/Hv8si0kvAcoLeTyeAKbiKMudSb+9UCl+hMs2nRyLQ== x-ms-exchange-transport-forked: True Content-Type: text/plain; charset="us-ascii" Content-ID: <28AF0E9A9D798F4AA88A109EFF30722B@KORP216.PROD.OUTLOOK.COM> Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-OriginatorOrg: outlook.com X-MS-Exchange-CrossTenant-RMS-PersistedConsumerOrg: 00000000-0000-0000-0000-000000000000 X-MS-Exchange-CrossTenant-Network-Message-Id: 214e0517-a7e7-4433-1a26-08d7b493a3a9 X-MS-Exchange-CrossTenant-rms-persistedconsumerorg: 00000000-0000-0000-0000-000000000000 X-MS-Exchange-CrossTenant-originalarrivaltime: 18 Feb 2020 16:57:29.8583 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Internet X-MS-Exchange-CrossTenant-id: 84df9e7f-e9f6-40af-b435-aaaaaaaaaaaa X-MS-Exchange-Transport-CrossTenantHeadersStamped: HK2APC01HT199 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 18, 2020 at 04:01:24PM +0100, Lukas Wunner wrote: > On Tue, Feb 18, 2020 at 02:18:40PM +0000, Nicholas Johnson wrote: > > If I surprise remove Thunderbolt 3 devices just as the kernel is > > shutting down, I get stack dumps, when those devices would not normally > > cause stack dumps if the kernel were not shutting down. > > > > Because the kernel is shutting down, it makes it difficult to capture > > the logs without a serial console. > > Hold a camera in front of the screen and try to capture the messages > as an MP4 movie which can be uploaded to YouTube or something. https://www.youtube.com/watch?v=sDcYmbz7GME The above is unlisted and will not appear in any search, so it will not confuse my subscribers, but anybody with the link can view it (public). I am still not sure I like the sound of my own voice. *cringe* > > If the output moves too fast to capture it, artificially slow it down > by adding a udelay() to call_console_drivers() in kernel/printk/printk.c. If you cannot get anything useful out of the aforementioned video, then I will do this tomorrow evening. It is almost 1am now. > > Thanks, > > Lukas By the way, this is not just with Linux v5.6-rcX. I have noticed this for some time but it has been lower down my list in terms of priority and urgency. I half expected it to be of no interest. I should have mentioned it earlier, but before I might not have had as much time to help investigate. I am currently looking for new kernel development tasks because my previous ones are done. Thanks, Nicholas