From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f198.google.com (mail-qk0-f198.google.com [209.85.220.198]) by kanga.kvack.org (Postfix) with ESMTP id 765616B000C for ; Thu, 26 Apr 2018 17:50:23 -0400 (EDT) Received: by mail-qk0-f198.google.com with SMTP id c73so9175556qke.2 for ; Thu, 26 Apr 2018 14:50:23 -0700 (PDT) Received: from mx1.redhat.com (mx3-rdu2.redhat.com. [66.187.233.73]) by mx.google.com with ESMTPS id r7-v6si8594875qtd.381.2018.04.26.14.50.22 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 26 Apr 2018 14:50:22 -0700 (PDT) Date: Thu, 26 Apr 2018 17:50:20 -0400 (EDT) From: Mikulas Patocka Subject: Re: [dm-devel] [PATCH v5] fault-injection: introduce kvmalloc fallback options In-Reply-To: <23266.8532.619051.784274@quad.stoffel.home> Message-ID: References: <20180421144757.GC14610@bombadil.infradead.org> <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> <23266.8532.619051.784274@quad.stoffel.home> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: John Stoffel Cc: James Bottomley , Michal@stoffel.org, eric.dumazet@gmail.com, mst@redhat.com, netdev@vger.kernel.org, jasowang@redhat.com, Randy Dunlap , linux-kernel@vger.kernel.org, Matthew Wilcox , Hocko , linux-mm@kvack.org, dm-devel@redhat.com, Vlastimil Babka , Andrew@stoffel.org, David Rientjes , Morton , virtualization@lists.linux-foundation.org, David Miller , edumazet@google.com On Thu, 26 Apr 2018, John Stoffel wrote: > >>>>> "James" == James Bottomley writes: > > James> I may be an atypical developer but I'd rather have a root canal > James> than browse through menuconfig options. The way to get people > James> to learn about new debugging options is to blog about it (or > James> write an lwn.net article) which google will find the next time > James> I ask it how I debug XXX. Google (probably as a service to > James> humanity) rarely turns up Kconfig options in response to a > James> query. > > I agree with James here. Looking at the SLAB vs SLUB Kconfig entries > tells me *nothing* about why I should pick one or the other, as an > example. > > John I see your point - and I think the misunderstanding is this. This patch is not really helping people to debug existing crashes. It is not like "you get a crash" - "you google for some keywords" - "you get a page that suggests to turn this option on" - "you turn it on and solve the crash". What this patch really does is that - it makes the kernel deliberately crash in a situation when the code violates the specification, but it would not crash otherwise or it would crash very rarely. It helps to detect specification violations. If the kernel developer (or tester) doesn't use this option, his buggy code won't crash - and if it won't crash, he won't fix the bug or report it. How is the user or developer supposed to learn about this option, if he gets no crash at all? Mikulas