timeout for memory offline

[Michal Hocko]

Hi Kamezawa,
I've been wondering why do we have a hardcoded 120s timeout for
offline_pages. This goes all the way down to when the offlining
has been implemented. I am asking because I have seen many cases
where memory offline fails just because of the timeout on a large
machines under heavy memory load during offline operation. So I
am really wondering whether we should make the timeout configurable or
just remove it altogether. I would be more inclined for the later
but there might have been an explicit reason for the timeout which is
not clear to me. Could you clarify?
-- 
Michal Hocko
SUSE Labs