Re: [Merge tag 'pci-v4.12-changes' of git] 857f864014: BUG: unable to handle kernel NULL pointer dereference at 00000000000000a8

On Tue, Jun 13, 2017 at 09:13:32PM +0200, Sven-Haegar Koch wrote:

On Tue, 13 Jun 2017, Greg Kroah-Hartman wrote:

quoted

On Tue, Jun 13, 2017 at 10:25:40AM -0600, Logan Gunthorpe wrote:

quoted

On 12/06/17 10:35 PM, Greg Kroah-Hartman wrote:

quoted

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.

No, it wouldn't be required, it would be an option for those people
using devtmpfs.

thanks,

greg k-h