Ath driver causes kernel panic (page fault) on 7.0-STABLE during use

[Edward Ruggeri]

Hi,

I recently purchased a Lenovo ThinkPad with a ThinkPad 11a/b/g
Wireless LAN Mini Express Adapter (based on the AR5212 chipset).  I
got kernel panics while using the wireless card under 7-STABLE, so to
try to isolate the problem, I've wiped the hard-drive and reinstalled
FreeBSD from scratch.  Under 7.0-RELEASE, installed yesterday
(7/22/08) from FTP source, wireless works well; I can use the Lynx
browser, download ports/source, etc.  But when I update to 7-STABLE, I
can still establish a connection to the wireless network (i.e.,
receive an IP) and (generally) receive a few webpages, but quickly and
inevitably, I get a kernel panic (fatal trap 12: page fault while in
kernel mode).  I have been using a GENERIC kernel to isolate problems.
 This suggests (to me, at least) a problem in 7-STABLE that does not
exist in 7.0-RELEASE.

I do not have the laptop with me here at work.  When I get home, I
plan to recompile the kernel with debugging options, so I can get and
examine a core dump.  I'll also switch out the ULE for 4BSD scheduler,
and remove SMP support, to see if those might be at fault.  I did this
about a week ago when I first started having problems under 7-STABLE;
changing the scheduler and removing SMP did not seem to fix the
problem.  A backtrace at that time indicated that, in ath_start, the
following assertion failed (line 1478 in ath.c):

bf = STAILQ_FIRST(&frags);
KASSERT(bf != NULL, ("no buf for txfrag"));

I will attempt to verify those results on the new, clean install.  Any
other recommendations?  My understanding is that many people likely
have this ath chipset, and even this same ThinkPad wireless card.
>From looking over problem reports, it doesn't seem other people have
had this problem, though.  Is FreeBSD-Stable a good place to ask about
this problem, or should I proceed directly to filing a problem report
(do not pass go, do not collect $200)?

Thanks!

Sincerely,

-- Ned Ruggeri