From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Date: Tue, 19 Jul 2011 14:47:59 -0400 From: Vivek Goyal Subject: Re: [RFC][PATCH -mmotm 0/4] Improvement of pstore/kmsg_dump in kexec/panic path Message-ID: <20110719184759.GC7001@redhat.com> References: <5C4C569E8A4B9B42A84A977CF070A35B2C199C64C2@USINDEVS01.corp.hds.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <5C4C569E8A4B9B42A84A977CF070A35B2C199C64C2@USINDEVS01.corp.hds.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=twosheds.infradead.org@lists.infradead.org To: Seiji Aguchi Cc: "dzickus@redhat.com" , Satoru Moriya , "dle-develop@lists.sourceforge.net" , "tony.luck@intel.com" , "hpa@zytor.com" , "kexec@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-mtd@lists.infradead.org" , "Eric W. Biederman" , KOSAKI Motohiro , Jarod Wilson , Americo Wang , Andrew Morton , Matthew Garrett T24gVHVlLCBKdWwgMTksIDIwMTEgYXQgMDI6MjM6MjZQTSAtMDQwMCwgU2VpamkgQWd1Y2hpIHdy b3RlOgo+IEhpLAo+IAo+IFtVcHN0cmVhbSBzdGF0dXNdCj4gICAgRGlzY3Vzc2lvbiBhYm91dCBr bXNnX2R1bXAoKSBpbiBrZHVtcCBwYXRoOiAKPiAgICAgLSBFcmljIGFuZCBWaXZlayBhcmUgd29y cmllZCBhYm91dCByZWxpYWJpbGl0eSBvZiBleGlzdGluZyBrbXNnX2R1bXAoKS4KPiAgICAgLSBF c3BlY2lhbGx5LCBWaXZlayB3b3VsZCBsaWtlIHRvIHJlbW92ZSBhIFJDVSAgZnVuY3Rpb24gY2Fs bCBjaGFpbiBpbiBrZHVtcCBwYXRoCj4g44CA44CA44CAIHdoaWNoIGtlcm5lbCBtb2R1bGVzIGNh biByZWdpc3RlciB0aGVpciBmdW5jdGlvbiBjYWxscyBmcmVlbHkuIAo+IAo+ICAgIERpc2N1c3Np b24gYWJvdXQgcHN0b3JlIGluIG5taV9oYW5kZXIuCj4gICAgIC0gRG9uIFppY2t1cyBmb3VuZCBh biBpc3N1ZSBvZiBwc3RvcmUgaW4gbm1pX2hhbmRsZXIgZHVlIHRvIGl0cyBtdXRleF9sb2NrLgoK WW91IGRpZCBub3QgYW5zd2VyIG15IHF1ZXN0aW9ucyBpbiB0aGUgbGFzdCBwb3N0aW5nIG1haWwg dGhyZWFkIGFuZCBnb25lCmFoZWFkIHdpdGggdGhlIG5ldyBwb3N0aW5nLiBIb3cgYXJlIHdlIHN1 cHBvc2VkIHRvIGRpc2N1c3Mgc29tZXRoaW5nLiBUaGlzCmhhcyBiZWVuIGEgcHJvYmxlbSBvbiB0 aGlzIG1haWwgdGhyZWFkIHNpbmNlIHRoZSBiZWdpbm5laW5nLiBUaGVyZSBpcwpsaXR0bGUgb3Bl biBkaXNjdXNzaW9uLiAKClNvIGlmIHlvdSB3YW50IHRvIG1ha2UgYW55IHByb2dyZXNzIGluIHRo aXMgZGlyZWN0aW9uLCB3aGF0IHdpbGwgaGVscAppcyBvcGVuIGRpc2N1c3Npb24uCgpMb2NraW5n IGlzIGdvaW5nIHRvIGJlIGEgcHJvYmxlbS4gU28gYXRsZWFzdCB3ZSBjYW4gcmVtb3ZlIGttc2df ZHVtcCgpCmluZnJhc3RydWN0dXJlIGZyb20gcmVib290IHBhdGguIFdoeSBjYW4ndCB3ZSBsb2cg c29tZXRoaW5nIGluIHVzZXIKc3BhY2Ugd2hlbiB1c2VyIGluaXRpYXRlcyBhIHJlYm9vdCwgbGV0 IGl0IGdldCBsb2dnZWQgaW4gL3Zhci9sb2cvbWVzc2FnZXMKYW5kIHRoZW4gdW1vdW50IHRoZSBm aWxlIHJvb3QgYW5kIGdvIGFoZWFkIHdpdGggcmVib290LiBXaHkgZG9lcyBrZXJuZWwKbmVlZCB0 byBjYXB0dXJlIHRoYXQgaW5mbyBpbiBOVlJBTS4KCklmIHdlIGNhbiBnZXQgcmlkIG9mIGFsbCB0 aGUgbG9nZ2luZyB0aGluZyBvbiByZWJvb3QgcGF0aCwgdGhlbiBhdCBsZWFzdAppdCBkb2VzIG5v dCBuZWVkIHRvIGJlIGxvY2sgcHJvdGVjdGVkIHdpdGggY3Jhc2ggcGF0aC4KClRoYW5rcwpWaXZl awoKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18Ka2V4ZWMg bWFpbGluZyBsaXN0CmtleGVjQGxpc3RzLmluZnJhZGVhZC5vcmcKaHR0cDovL2xpc3RzLmluZnJh ZGVhZC5vcmcvbWFpbG1hbi9saXN0aW5mby9rZXhlYwo= From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 19 Jul 2011 14:47:59 -0400 From: Vivek Goyal To: Seiji Aguchi Subject: Re: [RFC][PATCH -mmotm 0/4] Improvement of pstore/kmsg_dump in kexec/panic path Message-ID: <20110719184759.GC7001@redhat.com> References: <5C4C569E8A4B9B42A84A977CF070A35B2C199C64C2@USINDEVS01.corp.hds.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <5C4C569E8A4B9B42A84A977CF070A35B2C199C64C2@USINDEVS01.corp.hds.com> Cc: "dzickus@redhat.com" , Satoru Moriya , "dle-develop@lists.sourceforge.net" , "tony.luck@intel.com" , "hpa@zytor.com" , "kexec@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-mtd@lists.infradead.org" , "Eric W. Biederman" , KOSAKI Motohiro , Jarod Wilson , Americo Wang , Andrew Morton , Matthew Garrett List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, Jul 19, 2011 at 02:23:26PM -0400, Seiji Aguchi wrote: > Hi, > > [Upstream status] > Discussion about kmsg_dump() in kdump path: > - Eric and Vivek are worried about reliability of existing kmsg_dump(). > - Especially, Vivek would like to remove a RCU function call chain in kdump path > 　　　 which kernel modules can register their function calls freely. > > Discussion about pstore in nmi_hander. > - Don Zickus found an issue of pstore in nmi_handler due to its mutex_lock. You did not answer my questions in the last posting mail thread and gone ahead with the new posting. How are we supposed to discuss something. This has been a problem on this mail thread since the beginneing. There is little open discussion. So if you want to make any progress in this direction, what will help is open discussion. Locking is going to be a problem. So atleast we can remove kmsg_dump() infrastructure from reboot path. Why can't we log something in user space when user initiates a reboot, let it get logged in /var/log/messages and then umount the file root and go ahead with reboot. Why does kernel need to capture that info in NVRAM. If we can get rid of all the logging thing on reboot path, then at least it does not need to be lock protected with crash path. Thanks Vivek From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751749Ab1GSSsQ (ORCPT ); Tue, 19 Jul 2011 14:48:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:32634 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751103Ab1GSSsP (ORCPT ); Tue, 19 Jul 2011 14:48:15 -0400 Date: Tue, 19 Jul 2011 14:47:59 -0400 From: Vivek Goyal To: Seiji Aguchi Cc: "kexec@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-mtd@lists.infradead.org" , "Eric W. Biederman" , KOSAKI Motohiro , Americo Wang , Matthew Garrett , "tony.luck@intel.com" , Andrew Morton , Jarod Wilson , "hpa@zytor.com" , "dzickus@redhat.com" , "dle-develop@lists.sourceforge.net" , Satoru Moriya Subject: Re: [RFC][PATCH -mmotm 0/4] Improvement of pstore/kmsg_dump in kexec/panic path Message-ID: <20110719184759.GC7001@redhat.com> References: <5C4C569E8A4B9B42A84A977CF070A35B2C199C64C2@USINDEVS01.corp.hds.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <5C4C569E8A4B9B42A84A977CF070A35B2C199C64C2@USINDEVS01.corp.hds.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 19, 2011 at 02:23:26PM -0400, Seiji Aguchi wrote: > Hi, > > [Upstream status] > Discussion about kmsg_dump() in kdump path: > - Eric and Vivek are worried about reliability of existing kmsg_dump(). > - Especially, Vivek would like to remove a RCU function call chain in kdump path > 　　　 which kernel modules can register their function calls freely. > > Discussion about pstore in nmi_hander. > - Don Zickus found an issue of pstore in nmi_handler due to its mutex_lock. You did not answer my questions in the last posting mail thread and gone ahead with the new posting. How are we supposed to discuss something. This has been a problem on this mail thread since the beginneing. There is little open discussion. So if you want to make any progress in this direction, what will help is open discussion. Locking is going to be a problem. So atleast we can remove kmsg_dump() infrastructure from reboot path. Why can't we log something in user space when user initiates a reboot, let it get logged in /var/log/messages and then umount the file root and go ahead with reboot. Why does kernel need to capture that info in NVRAM. If we can get rid of all the logging thing on reboot path, then at least it does not need to be lock protected with crash path. Thanks Vivek