Re: [PATCH 2/5] HWPOISON: fix tasklist_lock/anon_vma locking order

[Andi Kleen]

On Thu, Jun 11, 2009 at 10:22:41PM +0800, Wu Fengguang wrote:
> To avoid possible deadlock. Proposed by Nick Piggin:

I disagree with the description. There's no possible deadlock right now.
It would be purely out of paranoia.

> 
>   You have tasklist_lock(R) nesting outside i_mmap_lock, and inside anon_vma
>   lock. And anon_vma lock nests inside i_mmap_lock.
> 
>   This seems fragile. If rwlocks ever become FIFO or tasklist_lock changes

I was a bit dubious on this reasoning. If rwlocks become FIFO a lot of
stuff will likely break.

>   type (maybe -rt kernels do it), then you could have a task holding

I think they tried but backed off quickly again

It's ok with a less scare-mongering description.

-Andi

-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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