On Mon, Jun 09, 2014 at 11:26:13AM +0200, Vlastimil Babka wrote: > isolate_freepages_block() rechecks if the pageblock is suitable to be a target > for migration after it has taken the zone->lock. However, the check has been > optimized to occur only once per pageblock, and compact_checklock_irqsave() > might be dropping and reacquiring lock, which means somebody else might have > changed the pageblock's migratetype meanwhile. > > Furthermore, nothing prevents the migratetype to change right after > isolate_freepages_block() has finished isolating. Given how imperfect this is, > it's simpler to just rely on the check done in isolate_freepages() without > lock, and not pretend that the recheck under lock guarantees anything. It is > just a heuristic after all. > > Signed-off-by: Vlastimil Babka <vba...@suse.cz> Acked-by: Minchan Kim <minc...@kernel.org>
-- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
