[BUG] mm/vmalloc: ___might_sleep is called under a spinlock in __purge_vmap_area_lazy

[Jia-Ju Bai]

The ___might_sleep is called under a spinlock, and the function call 
graph is:
__purge_vmap_area_lazy (acquire the spinlock)
  cond_resched_lock
    ___might_sleep

In this situation, ___might_sleep may prints error log message because a 
spinlock is held.
A possible fix is to remove ___might_sleep in cond_resched_lock.

This bug is found by my static analysis tool and my code review.


Thanks,
Jia-Ju Bai