Vmalloc notice

this just quota

1 . vmalloc can't be used in interrupt, also can't be used in lock. please care it.

2 . Not lock-context but interrupt-context which includes soft-interrupt and hard-interrupt. It is advised that not use them in atomic-context. In another word, it can only be used in process-context. As write_lock_bh disables the soft-interrupt, itself become in soft-interrupt context.

To be your known:

atomic-context = interrupt + spinlock-context.

interrupt = soft-interrupt + hard-interrupt.

spinlock-context = spin_lock + rwlock.

process becomes in above context when it has acquired the corresponding lock or disabled corresponding interrupt. Semaphore doesn't change context.