Hi,

From the dump of CPU #1, it seems indeed not related at all to "modprobe -r".

Could it be that there is some IB stack sysfs write activity?
(regardless of the modprobe -r" you issued) ?  I see some candidates
for it.

delete_child() is a method of the IB stack (ipoib/ipoib_main.c)

Maybe in order to help debug the problem, you might try to add in
delete_child() method, print of the name of the attribute which is
being deleted ?

  (struct device_attribute has a a member "struct attribute attr",
which in turn has  "const char *name").


Regards,
Rami Rosen