- 当内存过量提交之后，会出现OOM
- /proc/sys/vm/overcommit_memory
	- When this flag is 0, the kernel attempts to estimate the amount of free memory left when userspace requests more memory.
	- When this flag is 1, the kernel pretends there is always enough memory until it actually runs out.
	- When this flag is 2, the kernel uses a “never overcommit” policy that attempts to prevent any overcommit of memory. Note that user_reserve_kbytes affects this policy.
- 感觉对于确定业务的设备， 应该使用2（禁用）比较好。