Re: [-mm] Add an owner to the mm_struct (v2)

[Paul Menage]

On Fri, Mar 28, 2008 at 5:54 AM, Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx> wrote:
>
>  Thinking more, I don't think it makes sense for us to overload task_lock() to do
>  the mm->owner handling (we don't want to mix lock domains). task_lock() is used
>  for several things
>
>  1. We don't want to make task_lock() rules more complicated by having it protect
>  an mm member to save space
>  2. We don't want more contention on task_lock()
>

This isn't to save space, it's to provide correctness. We *have* to
hold task_lock(new_owner) before setting mm->owner = new_owner,
otherwise we have no guarantee that new_owner is still a user of mm.

Paul
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