On 04/17/2018 02:08 PM, Yang Shi wrote: > And, set the flag for hugetlbfs as well to keep the consistency, and the > applications don't have to know what filesystem is used to use huge > page, just need to check ST_HUGE flag. For hugetlbfs, setting such a flag would be for consistency only. mapping hugetlbfs files REQUIRES huge page alignment and size. If an application would want to take advantage of this flag for tmpfs, it needs to map at a fixed address (MAP_FIXED) for huge page alignment. So, it will need to do one of the 'mmap tricks' to get a mapping at a suitably aligned address. IIRC, there is code to 'suitably align' DAX mappings to appropriate huge page boundaries. Perhaps, something like this could be added for tmpfs mounted with huge=? Of course, this would not take into account 'length' but may help some. -- Mike Kravetz
