Comment # 1 on bug 1157339 from Takashi Iwai

I couldn't find any issues on a freshly installed VM.

What I don't understand is:
> $ sudo modprobe loop
> 
> would eventually fail everytime (but taking a lot of time, spawning a lot of
> child processes) whereas
> 
> $ sudo insmod /lib/modules/$(uname -r)/kernel/drivers/block/loop.ko
> 
> would succeed (and afterwards, 

What does "modinfo loop | grep filename" show?  Does it point to the very same
module as you tried insmod?