Re: [RFC PATCH 2/3] mm, compaction: use MIN_COMPACT_COSTLY_PRIORITY everywhere for costly orders

[Mel Gorman]

On Wed, Jul 24, 2019 at 10:50:13AM -0700, Mike Kravetz wrote:
> For PAGE_ALLOC_COSTLY_ORDER allocations, MIN_COMPACT_COSTLY_PRIORITY is
> minimum (highest priority).  Other places in the compaction code key off
> of MIN_COMPACT_PRIORITY.  Costly order allocations will never get to
> MIN_COMPACT_PRIORITY.  Therefore, some conditions will never be met for
> costly order allocations.
> 
> This was observed when hugetlb allocations could stall for minutes or
> hours when should_compact_retry() would return true more often then it
> should.  Specifically, this was in the case where compact_result was
> COMPACT_DEFERRED and COMPACT_PARTIAL_SKIPPED and no progress was being
> made.
> 
> Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>

Acked-by: Mel Gorman <mgorman@xxxxxxx>

-- 
Mel Gorman
SUSE Labs