Re: devfs breakage in 2.4.0 release

[Andris Pavenis]

On Sat, 6 Jan 2001, Adam J. Richter wrote:

> 	On my Sony PictureBook PCG-C1VN, 2.4.0 hangs in the boot
> process while 2.4.0-prerelease boots just fine.  At first I thought
> the problem was devfs-related, but skipping devfsd just caused the
> hang to occur a little later, this time in ifconfig.  The kernel
> call trace looked something like this:
> 
> 	neigh_ifdown
> 	sys_ioctl
> 	sock_ioctl
> 	[some addresses in modules]
> 	stext_lock
> 	__down_failed
> 	__down
> 
> 	What surprised me more was that attempting to remount the
> root filesystem for writing just before this (to record the module
> kernel symbols) caused a kenel BUG() in slab.c:1542 becuase kmalloc
> was being called with a huge negative number.
> 
> 	I know I could run ksymoops to get this trace, but I now
> think the cause of the problem probably happens much earlier than
> the symptoms.  So, I trying backing out different 2.4.0 changes.
> So far, I can tell you that reverting the linux/mm subdirectory to
> its 2.4.0-prerelease contents had no effect.  I will let you know
> if I diagnose or fix the problem, as I think you may be experiencing
> the same problem.

I think it's a different problem. I reproduced the same with 2.4.0-test12
but not 2.4.0-test10. 

There are changes (not very large) in fs/devfs/base.c between
these versions. I tried to take 2.4.0 and change back these updates and 
saw that it doesn't fix the problem. Trying all prerelaeses between
2.4.0-test10 and 2.4.0-test12 perhaps would take too much time ... 

There is no hanging (or crashes) at all for me. All these versions
boots Ok for me, but what I have is devfsd quitting with error message
that it cannot state /dev/vcc/[1-6] after some relooging from the same
terminal.

Andris