Panic with latest pmap lock changes.

[Andreas Tobler]

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.

Thanks,
Andreas