Re: [patch 2/4] mempolicy: support optional mode flags

From: David Rientjes
Date: Mon Feb 11 2008 - 14:36:53 EST

On Mon, 11 Feb 2008, Lee Schermerhorn wrote:

> These patches look good--well, interesting, anyway. I'm "off on
> assignment" this week, so I won't get to review in detail, merge and
> test them until next...

If, by "interesting", you mean that they give the most power to the user
in setting up their mempolicies than they have ever had before, then I

> This helper functions introduced by this patch are similar in nature
> [but go further] to one I introduced in the reference counting cleanup
> RFC [] I posted a
> while back. I've been holding these cleanup patches until Andrew starts
> accepting this sort of thing again. I have my series based atop Mel
> Gorman's [added to cc] "two zonelist" series, as it depends on removing
> the custom zonelist from the mempolicy.

If my helper functions are similar to yours then basing either of our
patchsets on top of the other should not be difficult.

> We need to sort out with Andrew, Mel, Paul, ... the order in which these
> interdependent changes go in. Given such an order, I'm willing to merge
> them all up, test them, and post them [after running checkpatch, of
> course].

Thanks for volunteering to test the changes. I don't know how many
patchsets are currently outstanding that touch mempolicies. So far we
have mine and the refcounting cleanup of yours that you mentioned.

I think the best way of dealing with it would be for the author of
whatever patchset is merged second to rebase off the current -mm just like
I based this entire patchset on your V3 contextualize_policy() patch from
a couple days ago.

> One other thing: In the recent mempolicy patch to "silently restrict
> nodemask], I mentioned the issue with regards to whether and when to
> "contextualize" tmpfs/hugetlbfs policies--if/when we fold
> mpol_check_policy() into mpol_new(), as you suggested. Once we can
> agree on the desired semantics, I had been thinking that an additional
> mode flag could be added to policies obtained from the superblock, and
> passed via mpol_shared_policy_init() [which calls mpol_new()] could be
> used for this purpose. Your change here seems to lay the foundation for
> implementing that.

My patchset already supports contextualized tmpfs mempolicies with a
template for how to specify them (see patch 4 in this series for the
documentation update). For example, mpol=interleave:1-3 is the equivalent
of MPOL_INTERLEAVE over nodes 1-3 while mpol=interleave=static:1-3 is the

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