On Wed, 17 Oct 2012, KOSAKI Motohiro wrote:
> > I think this refcounting is better than using task_lock().
>
> I don't think so. get_vma_policy() is used from fast path. In other
> words, number of
> atomic ops is sensible for allocation performance.
There are enhancements that we can make with refcounting: for instance, we
may want to avoid doing it in the super-fast path when the policy is
default_policy and then just do
if (mpol != &default_policy)
mpol_put(mpol);
> Instead, I'd like
> to use spinlock
> for shared mempolicy instead of mutex.
>
Um, this was just changed to a mutex last week in commit b22d127a39dd
("mempolicy: fix a race in shared_policy_replace()") so that sp_alloc()
can be done with GFP_KERNEL, so I didn't consider reverting that behavior.
Are you nacking that patch, which you acked, now?
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