Re: [patch 3/4] mempolicy: add MPOL_F_STATIC_NODES flag

[Paul Jackson <pj@sgi.com>]

Lee wrote:
> 1) we've discussed the issue of returning EINVAL for non-empty nodemasks
> with MPOL_DEFAULT.  By removing this restriction, we run the risk of
> breaking applications if we should ever want to define a semantic to
> non-empty node mask for MPOL_DEFAULT. 

The bigger risk, in my view, is breaking some piece of existing user code.
Properly written user code wouldn't break, but that doesn't mean much.
Changes, even minor corner case changes, often break something, so should
not be done with out cause.  Whether or not code cleanup in mempolicy.c is
sufficient cause here is not clear to me.

Future room for growth doesn't mean so much for me here; if we close one
future alternative, we always have others, such as more mode flag bits.

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