> Overcommit is disabled by default
No way. Processes allocating terabytes (GHC Haskell compiled programs, AddressSanitizer, etc) work fine out of the box.
Reading tuning(7):
> Setting bit 0 of the vm.overcommit sysctl causes the virtual memory system to return failure to the process when allocation of memory causes vm.swap_reserved to exceed vm.swap_total. Bit 1 of the sysctl enforces RLIMIT_SWAP limit (see getrlimit(2)). Root is exempt from this limit. Bit 2 allows to count most of the physical memory as allocatable, except wired and free reserved pages (accounted by vm.stats.vm.v_free_target and vm.stats.vm.v_wire_count sysctls, respectively).
Soooo vm.overcommit=0 does not mean "no overcommit" (which would make sense), no, it seems to mean something like "no special flags like disabling overcommit" :D
You are totally right. I've failed at reading quite a bit on this one.