As discussed on linux-mm (https://marc.info/?l=linux-mm&m=161528594100612&w=2), MAP_POPULATE can fail silently if the hugetlb cgroup settings allow huge page reservation but prevents huge pages being allocated. Closes https://bugzilla.kernel.org/show_bug.cgi?id=212153. --- man2/mmap.2 | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/man2/mmap.2 b/man2/mmap.2 index 164ba196e..03f2eeb2c 100644 --- a/man2/mmap.2 +++ b/man2/mmap.2 @@ -400,6 +400,11 @@ private writable mappings. Populate (prefault) page tables for a mapping. For a file mapping, this causes read-ahead on the file. This will help to reduce blocking on page faults later. +The +.BR mmap () +call doesn't fail if the mapping cannot be populated (for example, due +to limitations on the number of mapped huge pages when using +.BR MAP_HUGETLB ). .BR MAP_POPULATE is supported for private mappings only since Linux 2.6.23. .TP -- 2.25.1
