From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932626AbeDWXUP (ORCPT ); Mon, 23 Apr 2018 19:20:15 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:38208 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932558AbeDWXUN (ORCPT ); Mon, 23 Apr 2018 19:20:13 -0400 Date: Mon, 23 Apr 2018 19:20:11 -0400 (EDT) From: Mikulas Patocka X-X-Sender: mpatocka@file01.intranet.prod.int.rdu2.redhat.com To: Michal Hocko cc: Matthew Wilcox , David Miller , Andrew Morton , linux-mm@kvack.org, eric.dumazet@gmail.com, edumazet@google.com, bhutchings@solarflare.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, mst@redhat.com, jasowang@redhat.com, virtualization@lists.linux-foundation.org, dm-devel@redhat.com, Vlastimil Babka Subject: Re: [PATCH] kvmalloc: always use vmalloc if CONFIG_DEBUG_VM In-Reply-To: <20180423151015.GT17484@dhcp22.suse.cz> Message-ID: References: <20180418.134651.2225112489265654270.davem@davemloft.net> <20180420130852.GC16083@dhcp22.suse.cz> <20180420210200.GH10788@bombadil.infradead.org> <20180421144757.GC14610@bombadil.infradead.org> <20180422130356.GG17484@dhcp22.suse.cz> <20180423151015.GT17484@dhcp22.suse.cz> User-Agent: Alpine 2.02 (LRH 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 23 Apr 2018, Michal Hocko wrote: > On Mon 23-04-18 10:24:02, Mikulas Patocka wrote: > > > > Really, we have a fault injection framework and this sounds like > > > something to hook in there. > > > > The testing people won't set it up. They install the "kernel-debug" > > package and run the tests in it. > > > > If you introduce a hidden option that no one knows about, no one will use > > it. > > then make sure people know about it. Fuzzers already do test fault > injections. I think that in the long term we can introduce a kernel parameter like "debug_level=1", "debug_level=2", "debug_level=3" that will turn on debugging features across all kernel subsystems and we can teach users to use it to diagnose problems. But it won't work if every subsystem has different debug parameters. There are 192 distinct filenames in debugfs, if we add 193rd one, harly anyone notices it. Mikulas From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mikulas Patocka Subject: Re: [PATCH] kvmalloc: always use vmalloc if CONFIG_DEBUG_VM Date: Mon, 23 Apr 2018 19:20:11 -0400 (EDT) Message-ID: References: <20180418.134651.2225112489265654270.davem@davemloft.net> <20180420130852.GC16083@dhcp22.suse.cz> <20180420210200.GH10788@bombadil.infradead.org> <20180421144757.GC14610@bombadil.infradead.org> <20180422130356.GG17484@dhcp22.suse.cz> <20180423151015.GT17484@dhcp22.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: dm-devel@redhat.com, eric.dumazet@gmail.com, mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Matthew Wilcox , virtualization@lists.linux-foundation.org, linux-mm@kvack.org, edumazet@google.com, bhutchings@solarflare.com, Andrew Morton , David Miller , Vlastimil Babka To: Michal Hocko Return-path: In-Reply-To: <20180423151015.GT17484@dhcp22.suse.cz> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org On Mon, 23 Apr 2018, Michal Hocko wrote: > On Mon 23-04-18 10:24:02, Mikulas Patocka wrote: > > > > Really, we have a fault injection framework and this sounds like > > > something to hook in there. > > > > The testing people won't set it up. They install the "kernel-debug" > > package and run the tests in it. > > > > If you introduce a hidden option that no one knows about, no one will use > > it. > > then make sure people know about it. Fuzzers already do test fault > injections. I think that in the long term we can introduce a kernel parameter like "debug_level=1", "debug_level=2", "debug_level=3" that will turn on debugging features across all kernel subsystems and we can teach users to use it to diagnose problems. But it won't work if every subsystem has different debug parameters. There are 192 distinct filenames in debugfs, if we add 193rd one, harly anyone notices it. Mikulas