Usually THREAD_SIZE_ORDER is 2, it means we need to alloc 16kb continuous physical memory during fork a new process. If the system's memory is very small, especially the smart phone, maybe there is only 1G memory. So the free memory is very small and compaction is not always success in slowpath(__alloc_pages_slowpath), then alloc thread stack may be failed for memory fragment. Can we use vmalloc to alloc thread stack if compaction failed in slowpath? e.g. Use vmalloc as a fallback if alloc_page/kamlloc failed. I think the performance may be a little regression, and any other problems? Thanks, Xishi Qiu -- 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>