2.6.15-rt20, "bad page state", jackd

[Fernando Lopez-Lezcano <nando@ccrma.Stanford.EDU>]

Hi all, I reported this in mid January (I thought I had sent to the list
but the report went to Ingo and Steven off list)

I'm seeing the same problem in 2.6.15-rt21 in some of my machines. After
a reboot into the kernel I just login as root in a terminal, start the
jackd sound server ("jackd -d alsa -d hw") and when stopping it (just
doing a <ctrl>c) I get a bunch of messages of this form:

> Trying to fix it up, but a reboot is needed
> Bad page state at __free_pages_ok (in process 'jackd', page c10012fc)

Has anyone else seen this?

I'm in the process of building an -rt21 kernel before posting more
detailed error messages (this kernel is patched with some additional
stuff). 

Ingo had suggested at the time I enable DEBUG_PAGEALLOC and DEBUG_SLAB
to get more information (Jan 21 or so), I was never able to get the
machine to boot into that kernel, I kept getting oopses. Weird, I'm
trying to find the post I sent to lkml (I have it in my mailbox) in the
lkml archives to include a link and can't find it...

More details later...
-- Fernando