From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756579AbeDZOzt (ORCPT ); Thu, 26 Apr 2018 10:55:49 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:49010 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756326AbeDZOzq (ORCPT ); Thu, 26 Apr 2018 10:55:46 -0400 Date: Thu, 26 Apr 2018 10:55:44 -0400 (EDT) From: Mikulas Patocka X-X-Sender: mpatocka@file01.intranet.prod.int.rdu2.redhat.com To: James Bottomley cc: David Rientjes , dm-devel@redhat.com, eric.dumazet@gmail.com, mst@redhat.com, netdev@vger.kernel.org, jasowang@redhat.com, Randy Dunlap , linux-kernel@vger.kernel.org, Matthew Wilcox , Michal Hocko , linux-mm@kvack.org, edumazet@google.com, Andrew Morton , virtualization@lists.linux-foundation.org, David Miller , Vlastimil Babka Subject: Re: [dm-devel] [PATCH v5] fault-injection: introduce kvmalloc fallback options In-Reply-To: <1524697697.4100.23.camel@HansenPartnership.com> Message-ID: References: <20180421144757.GC14610@bombadil.infradead.org> <20180423151545.GU17484@dhcp22.suse.cz> <20180424125121.GA17484@dhcp22.suse.cz> <20180424162906.GM17484@dhcp22.suse.cz> <20180424170349.GQ17484@dhcp22.suse.cz> <20180424173836.GR17484@dhcp22.suse.cz> <1114eda5-9b1f-4db8-2090-556b4a37c532@infradead.org> <1524694663.4100.21.camel@HansenPartnership.com> <1524697697.4100.23.camel@HansenPartnership.com> User-Agent: Alpine 2.02 (LRH 1266 2009-07-14) MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="185206533-886270301-1524754049=:9108" Content-ID: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --185206533-886270301-1524754049=:9108 Content-Type: TEXT/PLAIN; CHARSET=ISO-8859-15 Content-Transfer-Encoding: 8BIT Content-ID: On Wed, 25 Apr 2018, James Bottomley wrote: > > BTW. even developers who compile their own kernel should have this > > enabled by a CONFIG option - because if the developer sees the option > > when browsing through menuconfig, he may enable it. If he doesn't see > > the option, he won't even know that such an option exists. > > I may be an atypical developer but I'd rather have a root canal than > browse through menuconfig options. The way to get people to learn > about new debugging options is to blog about it (or write an lwn.net > article) which google will find the next time I ask it how I debug XXX. > Google (probably as a service to humanity) rarely turns up Kconfig > options in response to a query. >>From my point of view, this feature should be as little disruptive to the developer as possible. It should work automatically behind the scenes without the developer or the tester even knowing that it is working. From this point of view, binding it to CONFIG_DEBUG_SG (or any other commonly used debugging option) would be ideal, because driver developers already enable CONFIG_DEBUG_SG, so they'll get this kvmalloc test for free. >>From your point of view, you should introduce a sysfs file and a kernel parameter that no one knows about - and then start blogging about it - to let people know. Why would you bother people with this knowledge? They'll forget about it anyway and won't turn it on. Mikulas --185206533-886270301-1524754049=:9108-- From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f199.google.com (mail-qk0-f199.google.com [209.85.220.199]) by kanga.kvack.org (Postfix) with ESMTP id C7BB96B0005 for ; Thu, 26 Apr 2018 10:55:46 -0400 (EDT) Received: by mail-qk0-f199.google.com with SMTP id b202so8320136qkc.6 for ; Thu, 26 Apr 2018 07:55:46 -0700 (PDT) Received: from mx1.redhat.com (mx3-rdu2.redhat.com. [66.187.233.73]) by mx.google.com with ESMTPS id p52-v6si5907972qtc.122.2018.04.26.07.55.45 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 26 Apr 2018 07:55:45 -0700 (PDT) Date: Thu, 26 Apr 2018 10:55:44 -0400 (EDT) From: Mikulas Patocka Subject: Re: [dm-devel] [PATCH v5] fault-injection: introduce kvmalloc fallback options In-Reply-To: <1524697697.4100.23.camel@HansenPartnership.com> Message-ID: References: <20180421144757.GC14610@bombadil.infradead.org> <20180423151545.GU17484@dhcp22.suse.cz> <20180424125121.GA17484@dhcp22.suse.cz> <20180424162906.GM17484@dhcp22.suse.cz> <20180424170349.GQ17484@dhcp22.suse.cz> <20180424173836.GR17484@dhcp22.suse.cz> <1114eda5-9b1f-4db8-2090-556b4a37c532@infradead.org> <1524694663.4100.21.camel@HansenPartnership.com> <1524697697.4100.23.camel@HansenPartnership.com> MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="185206533-886270301-1524754049=:9108" Content-ID: Sender: owner-linux-mm@kvack.org List-ID: To: James Bottomley Cc: David Rientjes , dm-devel@redhat.com, eric.dumazet@gmail.com, mst@redhat.com, netdev@vger.kernel.org, jasowang@redhat.com, Randy Dunlap , linux-kernel@vger.kernel.org, Matthew Wilcox , Michal Hocko , linux-mm@kvack.org, edumazet@google.com, Andrew Morton , virtualization@lists.linux-foundation.org, David Miller , Vlastimil Babka This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --185206533-886270301-1524754049=:9108 Content-Type: TEXT/PLAIN; CHARSET=ISO-8859-15 Content-Transfer-Encoding: 8BIT Content-ID: On Wed, 25 Apr 2018, James Bottomley wrote: > > BTW. even developers who compile their own kernel should have this > > enabled by a CONFIG option - because if the developer sees the option > > when browsing through menuconfig, he may enable it. If he doesn't see > > the option, he won't even know that such an option exists. > > I may be an atypical developer but I'd rather have a root canal than > browse through menuconfig options. The way to get people to learn > about new debugging options is to blog about it (or write an lwn.net > article) which google will find the next time I ask it how I debug XXX. > Google (probably as a service to humanity) rarely turns up Kconfig > options in response to a query. >>From my point of view, this feature should be as little disruptive to the developer as possible. It should work automatically behind the scenes without the developer or the tester even knowing that it is working. From this point of view, binding it to CONFIG_DEBUG_SG (or any other commonly used debugging option) would be ideal, because driver developers already enable CONFIG_DEBUG_SG, so they'll get this kvmalloc test for free. >>From your point of view, you should introduce a sysfs file and a kernel parameter that no one knows about - and then start blogging about it - to let people know. Why would you bother people with this knowledge? They'll forget about it anyway and won't turn it on. Mikulas --185206533-886270301-1524754049=:9108-- From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mikulas Patocka Subject: Re: [dm-devel] [PATCH v5] fault-injection: introduce kvmalloc fallback options Date: Thu, 26 Apr 2018 10:55:44 -0400 (EDT) Message-ID: References: <20180421144757.GC14610@bombadil.infradead.org> <20180423151545.GU17484@dhcp22.suse.cz> <20180424125121.GA17484@dhcp22.suse.cz> <20180424162906.GM17484@dhcp22.suse.cz> <20180424170349.GQ17484@dhcp22.suse.cz> <20180424173836.GR17484@dhcp22.suse.cz> <1114eda5-9b1f-4db8-2090-556b4a37c532@infradead.org> <1524694663.4100.21.camel@HansenPartnership.com> <1524697697.4100.23.camel@HansenPartnership.com> Mime-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="185206533-886270301-1524754049=:9108" Return-path: In-Reply-To: <1524697697.4100.23.camel@HansenPartnership.com> Content-ID: Sender: linux-kernel-owner@vger.kernel.org To: James Bottomley Cc: David Rientjes , dm-devel@redhat.com, eric.dumazet@gmail.com, mst@redhat.com, netdev@vger.kernel.org, jasowang@redhat.com, Randy Dunlap , linux-kernel@vger.kernel.org, Matthew Wilcox , Michal Hocko , linux-mm@kvack.org, edumazet@google.com, Andrew Morton , virtualization@lists.linux-foundation.org, David Miller , Vlastimil Babka List-Id: dm-devel.ids This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --185206533-886270301-1524754049=:9108 Content-Type: TEXT/PLAIN; CHARSET=ISO-8859-15 Content-Transfer-Encoding: 8BIT Content-ID: On Wed, 25 Apr 2018, James Bottomley wrote: > > BTW. even developers who compile their own kernel should have this > > enabled by a CONFIG option - because if the developer sees the option > > when browsing through menuconfig, he may enable it. If he doesn't see > > the option, he won't even know that such an option exists. > > I may be an atypical developer but I'd rather have a root canal than > browse through menuconfig options. The way to get people to learn > about new debugging options is to blog about it (or write an lwn.net > article) which google will find the next time I ask it how I debug XXX. > Google (probably as a service to humanity) rarely turns up Kconfig > options in response to a query. >From my point of view, this feature should be as little disruptive to the developer as possible. It should work automatically behind the scenes without the developer or the tester even knowing that it is working. From this point of view, binding it to CONFIG_DEBUG_SG (or any other commonly used debugging option) would be ideal, because driver developers already enable CONFIG_DEBUG_SG, so they'll get this kvmalloc test for free. >From your point of view, you should introduce a sysfs file and a kernel parameter that no one knows about - and then start blogging about it - to let people know. Why would you bother people with this knowledge? They'll forget about it anyway and won't turn it on. Mikulas --185206533-886270301-1524754049=:9108--