Re: [PATCH 09/11] mm, compaction: Abstract compaction feedback to helpers

[Michal Hocko]

On Mon 11-04-16 17:14:10, Michal Hocko wrote:
> On Mon 11-04-16 16:39:21, Vlastimil Babka wrote:
> > On 04/05/2016 01:25 PM, Michal Hocko wrote:
[...]
> > >+	/*
> > >+	 * Checks for THP-specific high-order allocations and back off
> > >+	 * if the the compaction backed off
> > >+	 */
> > >+	if (is_thp_gfp_mask(gfp_mask) && compaction_withdrawn(compact_result))
> > >+		goto nopage;
> > 
> > The change of semantics for THP is not trivial here and should at least be
> > discussed in changelog. CONTENDED and DEFERRED is only subset of
> > compaction_withdrawn() as seen above.
> 
> True. My main motivation was to get rid of the compaction specific code
> from the allocator path as much as possible. I can drop the above hunk

I was thinking about this some more and will drop the hunk. I would
rather have this patch without side effects as much as possible. A
follow up patch can get rid of the specific checks and use a simpler
ones. I will post -fix patch to Andrew.
-- 
Michal Hocko
SUSE Labs