Re: [PATCH] fix workqueue oops during cpu offline

[Ashok Raj]

On Thu, Jan 05, 2006 at 01:45:50PM -0800, Tony Luck wrote:
> On 1/4/06, Nathan Lynch <ntl@xxxxxxxxx> wrote:
> > This is where things go wrong -- any_online_cpu() now gets 1, not 0.
> > In queue_work, the cpu_workqueue_struct at per_cpu_ptr(wq->cpu_wq, 1) is
> > uninitialized.
> 
> Same issue on ia64 when I tried to add Ashok' s patch to allow
> removal of cpu0 (BSP in ia64-speak).  Ashok told me that this fix
> solves the problem for us too.
> 

Is this safe to use in NUMA path as well? Not that memory hot-remove is there
yet today, but if a NUMA node is being removed, i would assume the memory for 
that node goes with it. i.e assuming alloc_percpu() gets node local memory for 
each cpu.

So is it safe to continue to reference an area of an offline cpu that may not
exist?



-- 
Cheers,
Ashok Raj
- Open Source Technology Center
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