Panic with latest pmap lock changes.

[Justin Hibbits]

On Tue, Jul 10, 2012 at 4:00 PM, Alan Cox <alan.l.cox at gmail.com> wrote:

> On Sun, Jul 8, 2012 at 3:55 PM, Andreas Tobler <andreast-list at fgznet.ch>wrote:
>
>> On 07.07.12 19:39, Alan Cox wrote:
>>
>>> On 07/07/2012 09:20, Justin Hibbits wrote:
>>>
>>>> Looks like I spoke too soon about the pmap lock changes working on my
>>>> G4.  After about 24 hours of uptime, it panicked with the following:
>>>>
>>>> _rw_wlock_hard: recursing but non-recursive rw pmap pv global
>>>> @ /home/chmeee/freebsd/src/sys/**powerpc/aim/mmu_oea.c:2301
>>>>
>>>> I think the attached patch should fix it (Untested, except for
>>>> compiling).
>>>>
>>>>
>>> Ugh.  Sorry.
>>>
>>> The attached patch eliminates the lock recursion.  While I was doing
>>> that, I noticed that the pmap_ts_referenced() implementations on powerpc
>>> have the wrong return type.  Oddly, the comments in mmu_if.h have the
>>> return type correct, but the code two or three lines later has it wrong.
>>>
>>
>> Fyi, I'm building world with the patch mentioned in this thread and the
>> kernel updated to 238258. (G5-SMP 32-bit)
>>
>> So far it looks promising.
>>
>> Before 238258 I got reliable machine locks/freeze w/o any idea what was
>> happening.
>>
>> If I reverted mmu_oea.c back to 238158, one before the commit from you
>> Alan, I was able to get a successful full world/kernel build cycle.
>> Yes, I confirmed that it booted, but I was not able to run a full
>> world/kernel cycle since I lost my GEOM_APM config ;).
>>
>> Anyway, as said, it looks promising and it will take some hours to
>> complete.
>>
>>
> Should I commit the patch?
>
> Alan
>
>
>
Unfortunately the computer I was testing the patch on isn't cooperating
with me (as shown in another mail), so I haven't had a chance to test it.
 Visual inspection looks good, though, so I'm not opposed.

- Justin