"Michael S. Tsirkin" <[email protected]> writes: > On Mon, Nov 30, 2015 at 02:46:31PM +0100, Greg Kurz wrote: >> On Mon, 30 Nov 2015 15:06:33 +0200 >> "Michael S. Tsirkin" <[email protected]> wrote: >>
.... >> >> On ppc64, the address space is divided in 256MB-sized segments where all >> pages >> have the same size. This is a hw limitation IIUC. I don't know if it can be >> fixed and I'll let Ben comment on it. > > But it's anonymous memory with PROT_NONE. There should be no pages there: > just a chunk of virtual memory reserved. > ppc64 use page size (called as base page size) to find the hash slot in which we find the virtual address to real address translation. All the pages in a segment should have same base page size. Hugetlb pages have a base page size of 16M whereas a regular linux page have 64K. mmap will fail to map a hugetlb mapping in a segment that already have regular pages mapped. -aneesh
