On 06/21/2012 02:52 AM, David Rientjes wrote:
If page migration cannot charge the new page to the memcg, migrate_pages() will return -ENOMEM. This isn't considered in memory compaction however, and the loop continues to iterate over all pageblocks trying in a futile attempt to continue migrations which are only bound to fail. This will short circuit and fail memory compaction if migrate_pages() returns -ENOMEM. COMPACT_PARTIAL is returned in case some migrations were successful so that the page allocator will retry.
The patch makes sense, however I wonder if it would make more sense in the long run to allow migrate/compaction to temporarily exceed the memcg memory limit for a cgroup, because the original page will get freed again soon anyway. That has the potential to improve compaction success, and reduce compaction related CPU use. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>