Re: [PATCH 6/6] memcg: make mem_cgroup_page_stat() return valueunsigned

[Johannes Weiner]

On Tue, Nov 09, 2010 at 01:24:31AM -0800, Greg Thelen wrote:
> mem_cgroup_page_stat() used to return a negative page count
> value to indicate value.

Whoops :)

> mem_cgroup_page_stat() has changed so it never returns
> error so convert the return value to the traditional page
> count type (unsigned long).

This changelog feels a bit beside the point.

What's really interesting is that we now don't consider negative sums
to be invalid anymore, but just assume zero!  There is a real
semantical change here.

That the return type can then be changed to unsigned long is a nice
follow-up cleanup that happens to be folded into this patch.
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