From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id CDE6583D for ; Thu, 21 Jul 2016 10:36:46 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 72F2D116 for ; Thu, 21 Jul 2016 10:36:46 +0000 (UTC) Message-ID: <1469097402.120686.129.camel@infradead.org> From: David Woodhouse To: Hannes Reinecke , Sergey Senozhatsky Date: Thu, 21 Jul 2016 11:36:42 +0100 In-Reply-To: References: <20160719034717.GA24189@swordfish> <535ebaec-1653-3077-d17b-feb847fd51d2@suse.com> <20160719073346.GB24189@swordfish> <9794ced1-3c45-c548-9520-15d1b66aef31@suse.com> <20160719074631.GC24189@swordfish> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-YJHZymYw6kwBcVB+lOho" Mime-Version: 1.0 Cc: ksummit-discuss@lists.linuxfoundation.org Subject: Re: [Ksummit-discuss] [TECH TOPIC] asynchronous printk List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --=-YJHZymYw6kwBcVB+lOho Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2016-07-19 at 10:02 +0200, Hannes Reinecke wrote: > > so why would the system die before we console_unlock()? > >=20 > Errm. > Because it doesn't have any other chance? > Like, hard lockup? > Power down? > Hardware dead? >=20 > Slightly puzzled, Right. This was exactly the kind of hang I was chasing shortly before last year's KS =E2=80=94 an interrupt storm killing the box (because of a tendency in network drivers to return IRQ_HANDLED and not really care if we *had* done so, which ISTR arguing with DaveM about separately). Sometimes you don't get a nice clean panic. Sometimes you just get a lockup or a hard reset. Which is also why it doesn't help much to try to use the level of an individual printk to determine whether it should be synchronous or not. In this case it was all KERN_DEBUG messages from the network driver, which I was logging to the serial port so I could see what was happening... but which weren't making it out the port before the lockup. A viable solution to fix this might be a 'synchronous' flag on the console itself =E2=80=94 so I could boot with 'console=3DttyS0,synchronous'= and get a debuggable system again, Or maybe it would be simpler to have a system-wide control which makes all consoles synchronous, if that's easier. Either way, we do need the option, and we need it to apply to *all* output, not just KERN_EMERG messages. --=20 David Woodhouse Open Source Technology Centre David.Woodhouse@intel.com Intel Corporation --=-YJHZymYw6kwBcVB+lOho Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCEeAw ggXiMIIDyqADAgECAhBrp4p9CteI1lEK+Vnk57ThMA0GCSqGSIb3DQEBCwUAMH0xCzAJBgNVBAYT AklMMRYwFAYDVQQKEw1TdGFydENvbSBMdGQuMSswKQYDVQQLEyJTZWN1cmUgRGlnaXRhbCBDZXJ0 aWZpY2F0ZSBTaWduaW5nMSkwJwYDVQQDEyBTdGFydENvbSBDZXJ0aWZpY2F0aW9uIEF1dGhvcml0 eTAeFw0xNTEyMTYwMTAwMDVaFw0zMDEyMTYwMTAwMDVaMHUxCzAJBgNVBAYTAklMMRYwFAYDVQQK Ew1TdGFydENvbSBMdGQuMSkwJwYDVQQLEyBTdGFydENvbSBDZXJ0aWZpY2F0aW9uIEF1dGhvcml0 eTEjMCEGA1UEAxMaU3RhcnRDb20gQ2xhc3MgMSBDbGllbnQgQ0EwggEiMA0GCSqGSIb3DQEBAQUA A4IBDwAwggEKAoIBAQC9fdr3w6J9g/Zbgv3bW1+uHht1wLUZr5gkrLtXedg17AkefMyUGwrQdvwO bhajcVmnKVxhrUwkZPXRAwZZosRHfEIi5FH7x6SV/8Sp5lZEuiMnvMFG2MzLA84J6Ws5T4NfXZ0q n4TPgnr3X2vPVS51M7Ua9nIJgn8jvTra4eyyQzxvuA/GZwKg7VQfDCmCS+kICslYYWgXOMt2xlsS slxLce0CGWRsT8EpMyt1iDflSjXZIsE7m1uTyHaKZspMLyIyz6mySu8j8BWWHpChNNeTrFuhVfrO AyDPFJVUvKZCLKBhibTLloyy+LatoWELrjdI4a8StZY8+dIR9t4APXGzAgMBAAGjggFkMIIBYDAO BgNVHQ8BAf8EBAMCAQYwHQYDVR0lBBYwFAYIKwYBBQUHAwIGCCsGAQUFBwMEMBIGA1UdEwEB/wQI MAYBAf8CAQAwMgYDVR0fBCswKTAnoCWgI4YhaHR0cDovL2NybC5zdGFydHNzbC5jb20vc2ZzY2Eu Y3JsMGYGCCsGAQUFBwEBBFowWDAkBggrBgEFBQcwAYYYaHR0cDovL29jc3Auc3RhcnRzc2wuY29t MDAGCCsGAQUFBzAChiRodHRwOi8vYWlhLnN0YXJ0c3NsLmNvbS9jZXJ0cy9jYS5jcnQwHQYDVR0O BBYEFCSBbDlhvkkPj7cbRivJKLUnSG1oMB8GA1UdIwQYMBaAFE4L7xqkQFulF2mHMMo0aEPQQa7y MD8GA1UdIAQ4MDYwNAYEVR0gADAsMCoGCCsGAQUFBwIBFh5odHRwOi8vd3d3LnN0YXJ0c3NsLmNv bS9wb2xpY3kwDQYJKoZIhvcNAQELBQADggIBAIvj94fsAYuErQ8BAluc4SMnIwS9NPBwAm5SH9uh 2NCXTq7im61g7F1LIiNI/+wq37fUuaMbz4g7VarKQTgf8ubs0p7NZWcIe7Bvem2AWaXBsxsaRTYw 5kG3DN8pd1hSEUuFoTa7DmNeFe8tiK1BrL3rbA/m48jp4AiFXgvxprJrW7izsyetOrRHPbkW4Y07 v29MdhaPv3u1JELyszXqOzjIYo4sWlC8iDQXwgSW/ntvWy2n4LuiaozlCfXl149tKeqvwlvrla2Y klue/quWp9j9ou4T/OY0CXMuY+B8wNK0ohd2D4ShgFlMSjzAFRoHGKF81snTr2d1A7Ew02oF6UQy CkC2aNNsK5cWOojBar5c7HplX9aHYUCZouxIeU28SONJAxnATgR4cJ2jrpmYSz/kliUJ46S6UpVD o/ebn9c6PaM/XtDYCCaM/7XX6wc3s++sbQ7CtCn1Ax7df6ufQbwyO0V+oFa9H0KAsjHMzcwk3EV2 B2NLatidKE/m7G+rB9m+FlVgIiSp0mGlg43QO9Kh1+JqvTCIzv2bJJkmPMLQJNuKKwHNL8F4GGp6 jbAV+WL+LDeGfVcq8DHS3LrD+xyYEXQBiqZEdiPVOMxLDSUCXsDO0uCWpaNQ8j6y6S9p0xE/Ga0p eVLadVHhqf9nXqKaxnr358VgfrxzUIrvOaOjMIIF+TCCBOGgAwIBAgIQaRjuleoVgt0XsPAUByve JDANBgkqhkiG9w0BAQsFADB1MQswCQYDVQQGEwJJTDEWMBQGA1UEChMNU3RhcnRDb20gTHRkLjEp MCcGA1UECxMgU3RhcnRDb20gQ2VydGlmaWNhdGlvbiBBdXRob3JpdHkxIzAhBgNVBAMTGlN0YXJ0 Q29tIENsYXNzIDEgQ2xpZW50IENBMB4XDTE2MDMxMjE2MjEyNVoXDTE3MDMxMjE2MjEyNVowQjEc MBoGA1UEAwwTZHdtdzJAaW5mcmFkZWFkLm9yZzEiMCAGCSqGSIb3DQEJARYTZHdtdzJAaW5mcmFk ZWFkLm9yZzCCAiIwDQYJKoZIhvcNAQEBBQADggIPADCCAgoCggIBANBDAiGnoeOIQJ/Aolutct4z x6Yt3dOUI5d0YnydAMNOiyVLXzHuuuVjUpk/6nRxg1FN3e0i3TWe5MjSTD98760qWoAuF2g5BGU+ tN/GUsyws26ZWOt82w7xhn4dcI8EhmASUtwDTZs5ZXPQzSkuNs6uX5SY0eKPlBNHkAtMf39hNc4m liy6WRDKApZxA1vCbiHsJQZdNEBYO35022bu8PZBe6LSAFKoncoGMHl1xNEkN6kfOJFYnLqBYeXO 2mDA8KZ4h15EnQyyHGSghN92OUTc9stAWEt9a+q6TCtyW5zNgYTaaOtE41t5x2xDAgsnNU7sVM8f wSR3tYeW9IqTgU6eDUllb1a9FK7es3+j9UDg7OxNv9rnXIda6TdXlGWYfFltujF7FMwTofq3UG7t w68Ugk0MMfpZadhPhjYLI/qXiEDgQi8Xr+eWSo5P0ygaLvAz8OPcWAt8RG5Y8Id9hpb5neW1HTAR Q+k8lbpkx2wDPHZEft0ITROOupf76f9CNF4jYcyCKZNnjSsKeJv69VX1TsVaeqT1LJUEudXLa/BK FSb7x5M1KF4z46yImJrnagI19Nk/ufWn1usBXqXh8pY8cVN/I7C+TDPBY5SqIceTq7DaHZp19JQU IIWlyRsm2d4UoVcgIdTjX57Odap4Pjzrfp2RmC6hvkW2hQ5EreIPAgMBAAGjggG2MIIBsjAOBgNV HQ8BAf8EBAMCBLAwHQYDVR0lBBYwFAYIKwYBBQUHAwIGCCsGAQUFBwMEMAkGA1UdEwQCMAAwHQYD VR0OBBYEFBDmK2IjZJ7MKmBK0A7J/tKaSIdoMB8GA1UdIwQYMBaAFCSBbDlhvkkPj7cbRivJKLUn SG1oMG8GCCsGAQUFBwEBBGMwYTAkBggrBgEFBQcwAYYYaHR0cDovL29jc3Auc3RhcnRzc2wuY29t MDkGCCsGAQUFBzAChi1odHRwOi8vYWlhLnN0YXJ0c3NsLmNvbS9jZXJ0cy9zY2EuY2xpZW50MS5j cnQwOAYDVR0fBDEwLzAtoCugKYYnaHR0cDovL2NybC5zdGFydHNzbC5jb20vc2NhLWNsaWVudDEu Y3JsMB4GA1UdEQQXMBWBE2R3bXcyQGluZnJhZGVhZC5vcmcwIwYDVR0SBBwwGoYYaHR0cDovL3d3 dy5zdGFydHNzbC5jb20vMEYGA1UdIAQ/MD0wOwYLKwYBBAGBtTcBAgQwLDAqBggrBgEFBQcCARYe aHR0cDovL3d3dy5zdGFydHNzbC5jb20vcG9saWN5MA0GCSqGSIb3DQEBCwUAA4IBAQAn5wvdgC0V kS226sFKAbqPnmVhc9jgrbsiXUcpdtYEzv6EZonARIeRC1UlIzK7jzZFRe95W5y4/qlcPQDoAeZL cSsbpW3AYPFFWdRgVp/eIR3iy9C5KEcAbkJES2lRUZWyRqAceW1Gur9kfvjM5H0kM6BBwJfCtoqo WragTXfsIXGNsF0F+60mUYYsKFPZzPmyz9J0Dr0xx9Lcp4fbD6UckDWCNJt2AJAiEPt/vPiiBzU8 edaRzkYhzxd9f3pZAzhlzIf2CgTrGtKSL2X1bS/b3siREjQLhVrlGw4qxqllqER3APrDzyijLFuc CWpS8hxjTmYcNZSibv+3Oy6uU+wqMIIF+TCCBOGgAwIBAgIQaRjuleoVgt0XsPAUByveJDANBgkq hkiG9w0BAQsFADB1MQswCQYDVQQGEwJJTDEWMBQGA1UEChMNU3RhcnRDb20gTHRkLjEpMCcGA1UE CxMgU3RhcnRDb20gQ2VydGlmaWNhdGlvbiBBdXRob3JpdHkxIzAhBgNVBAMTGlN0YXJ0Q29tIENs YXNzIDEgQ2xpZW50IENBMB4XDTE2MDMxMjE2MjEyNVoXDTE3MDMxMjE2MjEyNVowQjEcMBoGA1UE AwwTZHdtdzJAaW5mcmFkZWFkLm9yZzEiMCAGCSqGSIb3DQEJARYTZHdtdzJAaW5mcmFkZWFkLm9y ZzCCAiIwDQYJKoZIhvcNAQEBBQADggIPADCCAgoCggIBANBDAiGnoeOIQJ/Aolutct4zx6Yt3dOU I5d0YnydAMNOiyVLXzHuuuVjUpk/6nRxg1FN3e0i3TWe5MjSTD98760qWoAuF2g5BGU+tN/GUsyw s26ZWOt82w7xhn4dcI8EhmASUtwDTZs5ZXPQzSkuNs6uX5SY0eKPlBNHkAtMf39hNc4mliy6WRDK ApZxA1vCbiHsJQZdNEBYO35022bu8PZBe6LSAFKoncoGMHl1xNEkN6kfOJFYnLqBYeXO2mDA8KZ4 h15EnQyyHGSghN92OUTc9stAWEt9a+q6TCtyW5zNgYTaaOtE41t5x2xDAgsnNU7sVM8fwSR3tYeW 9IqTgU6eDUllb1a9FK7es3+j9UDg7OxNv9rnXIda6TdXlGWYfFltujF7FMwTofq3UG7tw68Ugk0M MfpZadhPhjYLI/qXiEDgQi8Xr+eWSo5P0ygaLvAz8OPcWAt8RG5Y8Id9hpb5neW1HTARQ+k8lbpk x2wDPHZEft0ITROOupf76f9CNF4jYcyCKZNnjSsKeJv69VX1TsVaeqT1LJUEudXLa/BKFSb7x5M1 KF4z46yImJrnagI19Nk/ufWn1usBXqXh8pY8cVN/I7C+TDPBY5SqIceTq7DaHZp19JQUIIWlyRsm 2d4UoVcgIdTjX57Odap4Pjzrfp2RmC6hvkW2hQ5EreIPAgMBAAGjggG2MIIBsjAOBgNVHQ8BAf8E BAMCBLAwHQYDVR0lBBYwFAYIKwYBBQUHAwIGCCsGAQUFBwMEMAkGA1UdEwQCMAAwHQYDVR0OBBYE FBDmK2IjZJ7MKmBK0A7J/tKaSIdoMB8GA1UdIwQYMBaAFCSBbDlhvkkPj7cbRivJKLUnSG1oMG8G CCsGAQUFBwEBBGMwYTAkBggrBgEFBQcwAYYYaHR0cDovL29jc3Auc3RhcnRzc2wuY29tMDkGCCsG AQUFBzAChi1odHRwOi8vYWlhLnN0YXJ0c3NsLmNvbS9jZXJ0cy9zY2EuY2xpZW50MS5jcnQwOAYD VR0fBDEwLzAtoCugKYYnaHR0cDovL2NybC5zdGFydHNzbC5jb20vc2NhLWNsaWVudDEuY3JsMB4G A1UdEQQXMBWBE2R3bXcyQGluZnJhZGVhZC5vcmcwIwYDVR0SBBwwGoYYaHR0cDovL3d3dy5zdGFy dHNzbC5jb20vMEYGA1UdIAQ/MD0wOwYLKwYBBAGBtTcBAgQwLDAqBggrBgEFBQcCARYeaHR0cDov L3d3dy5zdGFydHNzbC5jb20vcG9saWN5MA0GCSqGSIb3DQEBCwUAA4IBAQAn5wvdgC0VkS226sFK AbqPnmVhc9jgrbsiXUcpdtYEzv6EZonARIeRC1UlIzK7jzZFRe95W5y4/qlcPQDoAeZLcSsbpW3A YPFFWdRgVp/eIR3iy9C5KEcAbkJES2lRUZWyRqAceW1Gur9kfvjM5H0kM6BBwJfCtoqoWragTXfs IXGNsF0F+60mUYYsKFPZzPmyz9J0Dr0xx9Lcp4fbD6UckDWCNJt2AJAiEPt/vPiiBzU8edaRzkYh zxd9f3pZAzhlzIf2CgTrGtKSL2X1bS/b3siREjQLhVrlGw4qxqllqER3APrDzyijLFucCWpS8hxj TmYcNZSibv+3Oy6uU+wqMYIEXjCCBFoCAQEwgYkwdTELMAkGA1UEBhMCSUwxFjAUBgNVBAoTDVN0 YXJ0Q29tIEx0ZC4xKTAnBgNVBAsTIFN0YXJ0Q29tIENlcnRpZmljYXRpb24gQXV0aG9yaXR5MSMw IQYDVQQDExpTdGFydENvbSBDbGFzcyAxIENsaWVudCBDQQIQaRjuleoVgt0XsPAUByveJDANBglg hkgBZQMEAgEFAKCCAaUwGAYJKoZIhvcNAQkDMQsGCSqGSIb3DQEHATAcBgkqhkiG9w0BCQUxDxcN MTYwNzIxMTAzNjQyWjAvBgkqhkiG9w0BCQQxIgQgJKzgwOHFbltU0x8iK8x0PSRTqZ6BCZh83r6C cq1tvCswgZoGCSsGAQQBgjcQBDGBjDCBiTB1MQswCQYDVQQGEwJJTDEWMBQGA1UEChMNU3RhcnRD b20gTHRkLjEpMCcGA1UECxMgU3RhcnRDb20gQ2VydGlmaWNhdGlvbiBBdXRob3JpdHkxIzAhBgNV BAMTGlN0YXJ0Q29tIENsYXNzIDEgQ2xpZW50IENBAhBpGO6V6hWC3Rew8BQHK94kMIGcBgsqhkiG 9w0BCRACCzGBjKCBiTB1MQswCQYDVQQGEwJJTDEWMBQGA1UEChMNU3RhcnRDb20gTHRkLjEpMCcG A1UECxMgU3RhcnRDb20gQ2VydGlmaWNhdGlvbiBBdXRob3JpdHkxIzAhBgNVBAMTGlN0YXJ0Q29t IENsYXNzIDEgQ2xpZW50IENBAhBpGO6V6hWC3Rew8BQHK94kMA0GCSqGSIb3DQEBAQUABIICAG6b 7mIg7uC5yL0GgCH4ArAzpIpJ4NnNVrRQcnw/+K6nOe3SeNbE6YIxQsGFdRI1Y+JA4hPKAioRxpBx XzSmE3nNTElsD6B3rSWGfyifUbYbwWyc6dJ/OxKUbH5zaL6fZMBRIiuGxNktCXVaxvzJIZsVUY2o nsBkpYGBSLphdIExrOXv+VLsGz74J3JxACEMi7l7c0dwXpMVOAOG7MokD4KtKAM2tiOXKySsTzIz FsJ23FnBAHyhhRxPlqmwuOPdGZl98GCrQDYYzLIX/Ve3Z2X8MGC34S7wvBwx0tjvWfuWxKvAg3Yt v4LA/c2id/+D3WeGF1qaXeDSk5vmm2k4GBVgEWfi7mwcAAYrcGRR+H0kNIpEXXpDDR8BHgR6V2AU 3ALghpwKpUgDwFFohOLKpSkqxkhdKVnWDKU462FXv8h/bM59TCM1kFBDLdIyH3AfdLDICpb8Qr87 R++XH6yGswyL1/9BOmWqjY47Y+onJchmlTWZ7HGb1SxocHn7kEkcB4OsQ7BOb0CsY4UrGG8za5IQ d9iGVIe71OBgOMWycvs75RnSkocWj5rqKJHkq5O7uJwSwtOVhkWpFOZj1DoEf7u4LV6Lf4OiTTPz T6+84c61nVylZY+WFGvJTr6/xMg4PgYlwLOLEeLP5p8ao5cUgKNYsEpMm7wRekVtI9FPC6/xAAAA AAAA --=-YJHZymYw6kwBcVB+lOho--