Re: 2.6.21-rc7-mm2 crash: Eeek! page_mapcount(page) went negative! (-1)

From: Kay Sievers
Date: Wed May 02 2007 - 08:14:36 EST


On 5/2/07, Greg KH <gregkh@xxxxxxx> wrote:
On Wed, May 02, 2007 at 12:10:00AM -0700, Andrew Morton wrote:
> On Wed, 02 May 2007 09:01:22 +0200 Tilman Schmidt <tilman@xxxxxxx> wrote:
>
> > Am 30.04.2007 21:46 schrieb Andrew Morton:
> > > Not really - everything's tangled up. A bisection search on the
> > > 2.6.21-rc7-mm2 driver tree would be the best bet.
> >
> > And the winner is:
> >
> > gregkh-driver-driver-core-make-uevent-environment-available-in-uevent-file.patch
> >
> > Reverting only that from 2.6.21-rc7-mm2 gives me a working kernel
> > again.
>
> cripes.
>
> +static ssize_t show_uevent(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + struct kobject *top_kobj;
> + struct kset *kset;
> + char *envp[32];
> + char data[PAGE_SIZE];
>
> That won't work too well with 4k stacks.

Yeah, sorry.

Wait, even though this isn't good, it shouldn't have been hit by anyone,
that file used to not be readable, so I doubt userspace would have been
trying to read it...

Tilman, what version of HAL and udev do you have on your machine?

Kay, did you get the 'read the uevent file' code already into udev
and/or HAL?

Only udevtest uses this at the moment, but that is only used for debugging.
It's probably the brain-dead libsysfs, which opens and reads every
file in /sys, even when nobody is interested in the data.

Thanks,
Kay
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