On 13/05/2016 10:04, Michal Hocko wrote: > On Tue 10-05-16 13:56:30, Sebastian Frias wrote: > [...] >> NOTE: I understand that the overcommit mode can be changed dynamically thru >> sysctl, but on embedded systems, where we know in advance that overcommit >> will be disabled, there's no reason to postpone such setting. > > To be honest I am not particularly happy about yet another config > option. At least not without a strong reason (the one above doesn't > sound that way). The config space is really large already. > So why a later initialization matters at all? Early userspace shouldn't > consume too much address space to blow up later, no? One thing I'm not quite clear on is: why was the default set to over-commit on? I suppose the biggest use-case is when a "large" process forks only to exec microseconds later into a "small" process, it would be silly to refuse that fork. But isn't that what the COW optimization addresses, without the need for over-commit? Another issue with overcommit=on is that some programmers seem to take for granted that "allocations will never fail" and so neglect to handle malloc == NULL conditions gracefully. I tried to run LTP with overcommit off, and I vaguely recall that I had more failures than with overcommit on. (Perhaps only those tests that tickle the dreaded OOM assassin.) Regards. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>