PAE broken on -current, likely broken on stable/9

[Arnaud Lacombe]

Hi,

On Mon, Dec 5, 2011 at 11:12 PM, Arnaud Lacombe <lacombar at gmail.com> wrote:
> On Mon, Dec 5, 2011 at 5:15 PM, Arnaud Lacombe <lacombar at gmail.com> wrote:
>> Hi,
>>
>> The kernel tree is utterly broken when PAE is enabled, it chokes
>> [non-exclusively] on the following:
>>
> After finally having been able to complete a build, the resulting
> kernel miserably panics on:
>
> real memory: 25769803776 (24576 MB)
> panic: kmem_suballoc: bad status return of 3
>
Just for the fun, after having fought for 8h for nearly nothing with
FreeBSD, I thought it would be fair to give it a try with Linux, say
the latest -rc, that is 3.2-rc3, with a snapshot of the upcoming
openwrt. The result:

root at OpenWrt:/# free
             total       used       free     shared    buffers
Mem:      16628216      14864   16613352          0        236
-/+ buffers:            14628   16613588
Swap:            0          0          0

total time spent to get to userland: about 30 min.

too easy... Let's give it a try with a system with 32GB of RAM:

root at OpenWrt:/# free
             total       used       free     shared    buffers
Mem:      33274356      17124   33257232          0        252
-/+ buffers:            16872   33257484
Swap:            0          0          0

d'oh!

ok, I'm not entirely honest, tmpfs chocked:

tmpfs: Bad value '1.70365e+10' for mount option 'size'.

Let's give it a try with 60GB now:

root at OpenWrt:/# free
             total       used       free     shared    buffers
Mem:      62405104      17116   62387988          0        256
-/+ buffers:            16860   62388244
Swap:            0          0          0

damn... Linux' no fun... :-(

 - Arnaud

ps: the kernel actually panic with the full 64GB of RAM, while
mounting the filesystem.