MAP_POPULATE vs. MADV_HUGEPAGES

[Avi Kivity]

A user is trying to allocate 1TB of anonymous memory in parallel on 48 
cores (4 NUMA nodes).  The kernel ends up spinning in 
isolate_freepages_block().


I thought to help it along by using MAP_POPULATE, but then my 
MADV_HUGEPAGE won't be seen until after mmap() completes, with pages 
already populated.  Are MAP_POPULATE and MADV_HUGEPAGE mutually exclusive?


Is my only option to serialize those memory allocations, and fault in 
those pages manually?  Or perhaps use mlock()?