Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753810AbdFMTU7 (ORCPT ); Tue, 13 Jun 2017 15:20:59 -0400 Received: from hydra.sdinet.de ([136.243.3.21]:45538 "EHLO mail.sdinet.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753448AbdFMTU5 (ORCPT ); Tue, 13 Jun 2017 15:20:57 -0400 X-Greylist: delayed 368 seconds by postgrey-1.27 at vger.kernel.org; Tue, 13 Jun 2017 15:20:56 EDT Date: Tue, 13 Jun 2017 21:13:32 +0200 (CEST) From: Sven-Haegar Koch To: Greg Kroah-Hartman cc: Logan Gunthorpe , Bjorn Helgaas , kernel test robot , Linus Torvalds , LKP , linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-doc@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Bjorn Helgaas , wfg@linux.intel.com, Alan Cox , Arnd Bergmann , Linus Walleij , David Airlie , David Herrmann , Daniel Vetter Subject: Re: [Merge tag 'pci-v4.12-changes' of git] 857f864014: BUG: unable to handle kernel NULL pointer dereference at 00000000000000a8 In-Reply-To: <20170613163508.GA31961@kroah.com> Message-ID: References: <5933fe2d.V33ODGPU9noDVuyF%fengguang.wu@intel.com> <20170606175552.GA12672@bhelgaas-glaptop.roam.corp.google.com> <20170612200852.GA28578@bhelgaas-glaptop.roam.corp.google.com> <61e11e67-6c1b-ef1e-5fb8-a7c9efb17666@deltatee.com> <20170613041842.GA13308@kroah.com> <20170613043416.GB14217@kroah.com> <20170613043518.GA14621@kroah.com> <8462abee-0a7f-00fb-6111-1f78362ea3f7@deltatee.com> <20170613163508.GA31961@kroah.com> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) 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 Content-Length: 1276 Lines: 31 On Tue, 13 Jun 2017, Greg Kroah-Hartman wrote: > On Tue, Jun 13, 2017 at 10:25:40AM -0600, Logan Gunthorpe wrote: > > > > On 12/06/17 10:35 PM, Greg Kroah-Hartman wrote: > > > Or better yet, just turn all char major allocations into dynamic, which > > > would be really good for test systems. I thought someone proposed > > > patches for that a long time ago, but I can't find them anymore. That > > > would be the simplest solution here. > > > > Would people not complain about that? I would not be surprised if some > > crazy application is using hard coded major numbers in userspace. So > > such a change could potentially break userspace... > > For char devices, I doubt it, but we can't take the chance, which is why > you make it an option. Then, it's enabled for 'allmodconfig' builds, > which helps testers out. At least for /dev/null, /dev/zero, and perhaps /dev/tty it would definitely break things if the major+minor number is not static. I have multiple chroot environments having only some minimal needed static /dev subdir, with naturally no daemons or filesystem creating those on-demand. For the main /dev I use whatever the system sets up, so devtmpfs with udev. c'ya sven-haegar -- Three may keep a secret, if two of them are dead. - Ben F.