BUG: spinlock trylock failure on UP - reverting timer patches helps

[jordan]

Hey Stano,

On Thu, Apr 17, 2014 at 6:55 PM, Stanislav Meduna <stano at meduna.org> wrote:
> On 17.04.2014 18:29, Stanislav Meduna wrote:
>
>> Note: the bug goes away reverting the very same patches that are
>> helping the Jordan's problms. I did follow
>>
>> http://www.spinics.net/lists/linux-rt-users/msg11639.html
>>
>> and no BUG while booting anymore. I'll try to let it run some
>> more time.

Yeah, i know a handful of people [amd users] that have now reported
success booting into 3.14-rt1 reverting those patches.  Personally, I
have disabled NO_HZ_FULL and have switched back to 'old tick' method
in kconfig. I don't think the latest no_hz stuff is stable enough...

> Erm.. nope
>
> # (cat /proc/meminfo ; cat /proc/meminfo) |  grep KernelStack
> KernelStack:        5920 kB
> KernelStack:        5928 kB
>
> # (cat /proc/meminfo ; cat /proc/meminfo) |  grep KernelStack
> KernelStack:        5952 kB
> KernelStack:        5960 kB
>
> maybe interrupt nesting ad nauseum? How does one debug
> such issues?
>
> It is possible that my previous posting was also caused by this -
> disregard, I'll post again if the problem persists.
>
> Jordan, could you check whether your kernel stack remains
> stable with only the 3 patches reverted?

I'll have to re-install that kernel and get back to you [ give me an
hour or so. i desperately need to eat some food ;) ]. My current
kernel differs in a couple of ways [ but yes, the KernelStack is
stable]. My running/installed rt-kernel is using the 'threadsirq'
patch for linux-rt and isn't vanilla linux-rt anyway, as i patch in
UKSM [in-kernel memory deduplication and BFQ [is scheduler]... but
yes, I'm still reverting those 3 timer[s] patches, since my machine
[and other users i know] won't boot without doing that. Here's my
running kernel's kstack;

[ninez at localhost ~]$  (cat /proc/meminfo ; cat /proc/meminfo) |  grep
KernelStack
KernelStack:        3728 kB
KernelStack:        3728 kB
[ninez at localhost ~]$  (cat /proc/meminfo ; cat /proc/meminfo) |  grep
KernelStack
KernelStack:        3696 kB
KernelStack:        3696 kB

I'll post from my old kernel in a bit.

> Thanks

No problem

Jordan