Re: 2.4.17-rc2 BUG at slab.c:1110

[Richard Gooch <rgooch@ras.ucalgary.ca>]

Andrew Morton writes:
> Paul Mackerras wrote:
> > 
> > So, is this devfs's fault for not allowing devfs_unregister to be
> > called from interrupt context, or is it ide-cs's fault for calling
> > ide_unregister from interrupt context?
> > 
> 
> ide-cs, I'd say.

Definately. It's always been illegal to call into the devfs API from
interrupt context, and in fact given that devfs_register() always
called kmalloc() with GFP_KERNEL, it should have caught any interrupt
context callers of devfs.

It just happened that in the old devfs core, you could often get away
with a call to devfs_unregister(), since it didn't do any allocations.
However, doing so was unsafe due to races (no locking/irq disabling),
even on UP systems. So it was always a driver bug to do this.

> The way hotplug generally avoids this problem is via schedule_task()
> - that was why it was written in the first place, I think.
> 
> And given that we need to bump the event up to process context, we may
> as well do it at the earliest stage.  Looks like the fix it to kill
> off the timer altogether, replace it with a tqueue and ask keventd
> to run ide_release.

Sounds good to me. I look forward to seeing your patch in -rc3 :-)

				Regards,

					Richard....
Permanent: rgooch@atnf.csiro.au
Current:   rgooch@ras.ucalgary.ca