Hi,

From: Jack Steiner <steiner@sgi.com>
Subject: percpu data for non-existant cpus
Date: Mon, 3 Nov 2003 18:55:24 -0600

> It was neccessary in 2.4 to allocate cpu_data areas for
> non-existent cpus. I forget where, but some generic
> initialization code expected to be able to reference cpu_data 
> for all cpus up to NR_CPUS.
> 
> Does 2.6 have the same requirement or can I allocate cpu_data
> areas only for cpus that exist or might exist (cpu_possible()).

The current discontig (for both 2.4 & 2.6) only allocate
cpu_data on existing nodes (which means existing cpus
eventually), doesn't it?

We've found wrap_mmu_context() refers to all percpu data
and if the any of the cpu_data is not valid,
it may cause panic.

Attached patches are for 2.4 & 2.6, which are harmless
even when percpu data are allocated for non-existing
cpus.

---
Takayoshi Kochi