Hello, At 2015/1/30 20:34, Joonsoo Kim wrote: > What we want to check here is whether there is highorder freepage > in buddy list of other migratetype in order to steal it without > fragmentation. But, current code just checks cc->order which means > allocation request order. So, this is wrong. > > Without this fix, non-movable synchronous compaction below pageblock order > would not stopped until compaction is complete, because migratetype of most > pageblocks are movable and high order freepage made by compaction is usually > on movable type buddy list. > > There is some report related to this bug. See below link. > > http://www.spinics.net/lists/linux-mm/msg81666.html > > Although the issued system still has load spike comes from compaction, > this makes that system completely stable and responsive according to > his report. > > stress-highalloc test in mmtests with non movable order 7 allocation doesn't > show any notable difference in allocation success rate, but, it shows more > compaction success rate. > > Compaction success rate (Compaction success * 100 / Compaction stalls, %) > 18.47 : 28.94 > > Cc: <stable@xxxxxxxxxxxxxxx> > Acked-by: Vlastimil Babka <vbabka@xxxxxxx> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Reviewed-by: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx> > --- > mm/compaction.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/compaction.c b/mm/compaction.c > index b68736c..4954e19 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -1173,7 +1173,7 @@ static int __compact_finished(struct zone *zone, struct compact_control *cc, > return COMPACT_PARTIAL; > > /* Job done if allocation would set block type */ > - if (cc->order >= pageblock_order && area->nr_free) > + if (order >= pageblock_order && area->nr_free) > return COMPACT_PARTIAL; > } > > -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html