linux-kernel - [patch] revert "dcdbas: add DMI-based module autloading"

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Date:	Sat, 8 Mar 2008 09:22:43 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Frank Sorenson <frank@...rocks.com>
Cc:	kay.sievers@...y.org, Matt_Domsch@...l.com,
	LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [patch] revert "dcdbas: add DMI-based module autloading"


* Frank Sorenson <frank@...rocks.com> wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Frank Sorenson wrote:
> > I did some additional debugging, and I believe you're correct about it
> > being specific to my system.  The system seems to run fine until some
> > time during the boot.  I booted with "init=/bin/sh" (that's how the
> > system stayed up for 9 minutes), then it died when I tried starting
> > things up.  I've further narrowed the OOM down to udev (though it's not
> > entirely udev's fault, since 2.6.24 runs fine).
> > 
> > I ran your debug info tool before killing the box by running
> > /sbin/start_udev.  The output of the tool is at
> > http://tuxrocks.com/tmp/cfs-debug-info-2008.03.06-14.11.24
> > 
> > Something is apparently happening between 2.6.24 and 2.6.25-rc[34] which
> > causes udev (or something it calls) to behave very badly.
> 
> Found it.  The culprit is 8f47f0b688bba7642dac4e979896e4692177670b
>     dcdbas: add DMI-based module autloading
> 
>     DMI autoload dcdbas on all Dell systems.
> 
>     This looks for BIOS Vendor or System Vendor == Dell, so this should
>     work for systems both Dell-branded and those Dell builds but brands
>     for others.  It causes udev to load the dcdbas module at startup,
>     which is used by tools called by HAL for wireless control and
>     backlight control, among other uses.
> 
> What actually happens is that when udev loads the dcdbas module at 
> startup, modprobe apparently calls "modprobe dcdbas" itself, repeating 
> until the system runs out of resources (in this case, it OOMs).

nice work! I've attached the revert below against latest -git - just in 
case no-one can think of an obvious fix to this bug.

	Ingo

--------------------->
Subject: revert "dcdbas: add DMI-based module autloading"
From: Ingo Molnar <mingo@...e.hu>
Date: Sat Mar 08 09:09:16 CET 2008

Frank Sorenson reported that 2.6.25-rc OOMs on his box and
tracked it down to commit 8f47f0b688bba7642dac4e979896e4692177670b,
"dcdbas: add DMI-based module autloading". Frank says:

> What actually happens is that when udev loads the dcdbas module at
> startup, modprobe apparently calls "modprobe dcdbas" itself, repeating
> until the system runs out of resources (in this case, it OOMs).

revert the commit.

Bisected-by: Frank Sorenson <frank@...rocks.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 drivers/firmware/dcdbas.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Index: linux/drivers/firmware/dcdbas.c
===================================================================
--- linux.orig/drivers/firmware/dcdbas.c
+++ linux/drivers/firmware/dcdbas.c
@@ -658,5 +658,4 @@ MODULE_DESCRIPTION(DRIVER_DESCRIPTION " 
 MODULE_VERSION(DRIVER_VERSION);
 MODULE_AUTHOR("Dell Inc.");
 MODULE_LICENSE("GPL");
-/* Any System or BIOS claiming to be by Dell */
-MODULE_ALIAS("dmi:*:[bs]vnD[Ee][Ll][Ll]*:*");
+
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