Re: [patch] remove hugetlb syscalls

[Jeff Garzik <jgarzik@pobox.com>]

David Mosberger-Tang wrote:

> But that's excactly the point.  The hugepage interface returns a
> different kind of virtual memory.  There are tons of programs out
> there using mmap().  If such a program gets fed a path to the
> hugepagefs, it might end up with huge pages without knowing anything
> about huge pages.  For the most part, that might work fine, but it
> could lead to subtle failures.


Yeah, that was one of Linus's points about the syscalls, in a private 
email.  I mentioned how the new syscalls were in poor taste, when 
existing syscalls would work fine, and he flamed me right back ;-)

One of his main points to me was exactly what you are elucidating: 
there are subtle differences between normal pages and superpages that 
are exposed to userland, and we should make that explicit [with the 
syscalls] rather than hide it [with hugetlbfs/mmap/etc.].  So I think 
this is further indication Linus has a very valid point ;-)

However, that said, I think hugetlbfs will almost always get used in 
preference to the syscalls, so leaving them in may be more a statement 
of technical correctness/cleanliness than anything else.

[tangent warning]
This whole hugetlb affair is unfortunately pretty ugly, and this thread 
is just one component of that.  All these discussions occurred off-list, 
and it's _still_ a political football.  Sigh.  I just hope that the 
furor dies down soon, that smart technical [apolitical] decisions are 
made, and future discussions are at least CC'd to lkml.

	Jeff