From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f199.google.com (mail-qt0-f199.google.com [209.85.216.199]) by kanga.kvack.org (Postfix) with ESMTP id 5A8EB6B0009 for ; Thu, 26 Apr 2018 11:55:34 -0400 (EDT) Received: by mail-qt0-f199.google.com with SMTP id e12-v6so20470236qtp.17 for ; Thu, 26 Apr 2018 08:55:34 -0700 (PDT) Received: from mx1.redhat.com (mx3-rdu2.redhat.com. [66.187.233.73]) by mx.google.com with ESMTPS id t2si7793118qvk.19.2018.04.26.08.55.33 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 26 Apr 2018 08:55:33 -0700 (PDT) Date: Thu, 26 Apr 2018 11:55:32 -0400 (EDT) From: Mikulas Patocka Subject: Re: [dm-devel] [PATCH v5] fault-injection: introduce kvmalloc fallback options In-Reply-To: <1524756256.3226.7.camel@HansenPartnership.com> Message-ID: References: <20180424170349.GQ17484@dhcp22.suse.cz> <20180424173836.GR17484@dhcp22.suse.cz> <1114eda5-9b1f-4db8-2090-556b4a37c532@infradead.org> <1524694663.4100.21.camel@HansenPartnership.com> <20180426125817.GO17484@dhcp22.suse.cz> <1524753932.3226.5.camel@HansenPartnership.com> <1524756256.3226.7.camel@HansenPartnership.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: James Bottomley Cc: Michal Hocko , 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 , linux-mm@kvack.org, edumazet@google.com, Andrew Morton , virtualization@lists.linux-foundation.org, David Miller , Vlastimil Babka On Thu, 26 Apr 2018, James Bottomley wrote: > So you're shifting your argument from "I have to do it as a Kconfig > option because the distros require it" to "distributions will build > separate kernel packages for this, but won't do enabling in a non > kernel package"? To be honest, I think the argument is nuts but I > don't really care. From my point of view it's usually me explaining to > people how to debug stuff and "you have to build your own kernel with > this Kconfig option" compared to "add this to the kernel command line > and reboot" is much more effort for the debugger. > > James If you have to explain to the user that he needs to turn it on, it is already wrong. In order to find the kvmalloc abuses, it should be tested by as many users as possible. And it could be tested by as many users as possible, if it can be enabled in a VISIBLE place (i.e. menuconfig) - or (in my opinion even better) it should be bound to an CONFIG_ option that is already enabled for debugging kernel - then you won't have to explain anything to the user at all. Hardly anyone - except for people who read this thread - will know about the new commandline parameters or debugfs files. I'm not arguing that the commandline parameter or debugfs files are wrong. They are OK to overridde the default settings for advanced users. But they are useless for common users because common users won't know about them. Mikulas