On Fri, May 8, 2015 at 1:49 PM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > What I mean is: allow userspace to consume ZONE_MIRROR memory because > we can snatch it back if it is needed for kernel memory. For suitable interpretations of "snatch it back" ... if there is none free in a GFP_NOWAIT request, then we are doomed. But we could maintain some high/low watermarks to arrange the snatching when mirrored memory is getting low, rather than all the way out. It's worth a look - but perhaps at phase three. It would make life a bit easier for people to get the right amount of mirror. If they guess too high they are still wasting some memory because every mirrored page has two pages in DIMM. But without this sort of trick all the extra mirrored memory would be totally wasted. -Tony -- 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>