This is a simple program to determine the maximum mmap size on a system with binary search.
make
./determine-max-mmap-size$ ./determine-max-mmap-size
mmap failed with length: 9223372036854775807
mmap failed with length: 4611686018427387903
mmap failed with length: 2305843009213693951
mmap failed with length: 1152921504606846975
mmap failed with length: 576460752303423487
mmap failed with length: 288230376151711743
mmap failed with length: 144115188075855871
mmap failed with length: 72057594037927935
mmap failed with length: 36028797018963967
mmap failed with length: 18014398509481983
mmap failed with length: 9007199254740991
mmap failed with length: 4503599627370495
mmap failed with length: 2251799813685247
mmap failed with length: 1125899906842623
mmap failed with length: 562949953421311
mmap failed with length: 281474976710655
mmap failed with length: 140737488355327
mmap succeeded with length: 70368744177663
mmap failed with length: 105553116266495
mmap succeeded with length: 87960930222079
mmap succeeded with length: 96757023244287
mmap succeeded with length: 101155069755391
mmap succeeded with length: 103354093010943
mmap succeeded with length: 104453604638719
mmap succeeded with length: 105003360452607
mmap failed with length: 105278238359551
mmap failed with length: 105140799406079
mmap succeeded with length: 105072079929343
mmap failed with length: 105106439667711
mmap failed with length: 105089259798527
mmap failed with length: 105080669863935
mmap failed with length: 105076374896639
mmap failed with length: 105074227412991
mmap failed with length: 105073153671167
mmap failed with length: 105072616800255
mmap failed with length: 105072348364799
mmap failed with length: 105072214147071
mmap failed with length: 105072147038207
mmap failed with length: 105072113483775
mmap failed with length: 105072096706559
mmap failed with length: 105072088317951
mmap failed with length: 105072084123647
mmap failed with length: 105072082026495
mmap failed with length: 105072080977919
mmap failed with length: 105072080453631
mmap failed with length: 105072080191487
mmap failed with length: 105072080060415
mmap failed with length: 105072079994879
mmap failed with length: 105072079962111
mmap failed with length: 105072079945727
mmap failed with length: 105072079937535
mmap failed with length: 105072079933439
mmap failed with length: 105072079931391
mmap failed with length: 105072079930367
mmap failed with length: 105072079929855
mmap failed with length: 105072079929599
mmap failed with length: 105072079929471
mmap failed with length: 105072079929407
mmap failed with length: 105072079929375
mmap failed with length: 105072079929359
mmap failed with length: 105072079929351
mmap failed with length: 105072079929347
mmap failed with length: 105072079929345
mmap succeeded with length: 105072079929344
--------------------------------------------------------------------------------
max mmap length in this system is: 105072079929344