+ if (alloc_arena_next (h) > alloc_arena_mapped (h))
+ {
+ void *base, *rv;
+ uword alloc = alloc_arena_next (h) - alloc_arena_mapped (h);
+ int mmap_flags = MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS;
+ int mmap_flags_huge = (mmap_flags | MAP_HUGETLB |
+ BIHASH_LOG2_HUGEPAGE_SIZE << MAP_HUGE_SHIFT);
+
+ /* new allocation is 25% of existing one */
+ if (alloc_arena_mapped (h) >> 2 > alloc)
+ alloc = alloc_arena_mapped (h) >> 2;
+
+ /* round allocation to page size */
+ alloc = round_pow2 (alloc, 1 << BIHASH_LOG2_HUGEPAGE_SIZE);
+
+ base = (void *) (uword) (alloc_arena (h) + alloc_arena_mapped (h));
+
+ rv = mmap (base, alloc, PROT_READ | PROT_WRITE, mmap_flags_huge, -1, 0);
+
+ /* fallback - maybe we are still able to allocate normal pages */
+ if (rv == MAP_FAILED)
+ rv = mmap (base, alloc, PROT_READ | PROT_WRITE, mmap_flags, -1, 0);
+
+ if (rv == MAP_FAILED)
+ os_out_of_memory ();
+
+ alloc_arena_mapped (h) += alloc;
+ }
+