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 <[email protected]> --- mm/compaction.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index 952dc2fb24e5..325b746068d1 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -2294,9 +2294,15 @@ static enum compact_result compact_zone_order(struct zone *zone, int order, .alloc_flags = alloc_flags, .classzone_idx = classzone_idx, .direct_compaction = true, - .whole_zone = (prio == MIN_COMPACT_PRIORITY), - .ignore_skip_hint = (prio == MIN_COMPACT_PRIORITY), - .ignore_block_suitable = (prio == MIN_COMPACT_PRIORITY) + .whole_zone = ((order > PAGE_ALLOC_COSTLY_ORDER) ? + (prio == MIN_COMPACT_COSTLY_PRIORITY) : + (prio == MIN_COMPACT_PRIORITY)), + .ignore_skip_hint = ((order > PAGE_ALLOC_COSTLY_ORDER) ? + (prio == MIN_COMPACT_COSTLY_PRIORITY) : + (prio == MIN_COMPACT_PRIORITY)), + .ignore_block_suitable = ((order > PAGE_ALLOC_COSTLY_ORDER) ? + (prio == MIN_COMPACT_COSTLY_PRIORITY) : + (prio == MIN_COMPACT_PRIORITY)) }; struct capture_control capc = { .cc = &cc, @@ -2338,6 +2344,7 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order, int may_perform_io = gfp_mask & __GFP_IO; struct zoneref *z; struct zone *zone; + int min_priority; enum compact_result rc = COMPACT_SKIPPED; /* @@ -2350,12 +2357,13 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order, trace_mm_compaction_try_to_compact_pages(order, gfp_mask, prio); /* Compact each zone in the list */ + min_priority = (order > PAGE_ALLOC_COSTLY_ORDER) ? + MIN_COMPACT_COSTLY_PRIORITY : MIN_COMPACT_PRIORITY; for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx, ac->nodemask) { enum compact_result status; - if (prio > MIN_COMPACT_PRIORITY - && compaction_deferred(zone, order)) { + if (prio > min_priority && compaction_deferred(zone, order)) { rc = max_t(enum compact_result, COMPACT_DEFERRED, rc); continue; } -- 2.20.1
