When choosing between doing an address space or ranged flush, the x86
implementation of flush_tlb_mm_range takes into account whether there are
any large pages in the range. A per-page flush typically requires fewer
entries than would covered by a single large page and the check is redundant.
There is one potential exception. THP migration flushes single THP entries
and it conceivably would benefit from flushing a single entry instead
of the mm. However, this flush is after a THP allocation, copy and page
table update potentially with any other threads serialised behind it. In
comparison to that, the flush is noise. It makes more sense to optimise
balancing to require fewer flushes than to optimise the flush itself.
This patch deletes the redundant huge page check.
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>