To: Jeff Garzik <jgarzik@mandrakesoft.com>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: pcmcia oops problem?
In-Reply-To: <3C90BA11.40106@mandrakesoft.com>
From: Juan Quintela <quintela@mandrakesoft.com>
In-Reply-To: <3C90BA11.40106@mandrakesoft.com>
Date: 14 Mar 2002 17:16:35 +0100
Message-ID: <m2henjruos.fsf@trasno.mitica>
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>>>>> "jeff" == Jeff Garzik <jgarzik@mandrakesoft.com> writes:

jeff> Can you describe the pcmcia oops problem in detail?
jeff> What output do you get from a serial console?

Ok, trying to get better message now.

jeff> what do you mean, oops got infinite trace?  were there (a) many oops
jeff> or (b) one oops with long trace
jeff> what do you mean, double fix of /dev/XXXXX name?

I think so, but it is not possible to be sure :(

jeff> is pcmcia-cs creating and removing /dev entries too?

Ok, the problem:

plug a pcmcia card (network cards work perfect), ide_cs & modem fail).
unplug it

it just oops the kernel.

as ethX works perfect and modem & ide_cs fails, devfs is suspect
number one.

Then I boot with devfs=nomount

repeat the experiment, and everythnig works as expected (devfs is
decleared more suspect indeed). 

Really devfs & devfsd are suspect.
I know that ide_cs worked before because I used it to download pics
from my camera and I had never had a single problem.

Then I boot back with kernel-linus2.4.

Everything works perfect.

In the middle, I changed devfsd from version 2.3.24 to 2.3.23, same
problems.

kernel-linus2.4 works with both devfsd.

I relaunch kernel-mdk with devfs-2.3.23, this times also oops, but it
just hangs in devfs_unregister, that calls to kmem_cache_alloc(), and
them kmem_cache_grow (here is the Ooops), this is called from a bottom
handler.


With devfsd 2.3.24, it appears that there is a stack overflow inside
devfs, and kdb is of not help to detect it (we never end the do_BUG()
function because there is a borken stack.

I have do a diff of 2.4.18 against lastest mandrake kernel and there
are:
- no devfs differences
- no changes in register/unregister calls.

that means that the problem happens as a side effect of other thing.

Later, Juan.


-- 
In theory, practice and theory are the same, but in practice they 
are different -- Larry McVoy
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