Messages in this thread | | | Date | Fri, 28 Mar 2008 07:06:52 -0700 | From | "Paul Menage" <> | Subject | Re: [-mm] Add an owner to the mm_struct (v2) |
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On Fri, Mar 28, 2008 at 5:54 AM, Balbir Singh <balbir@linux.vnet.ibm.com> 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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