我有一个docker容器,它通过bash脚本启动一个简单的java(基于jgroups的)应用程序. java进程通过Xmx限制128m,容器允许使用256m(禁用交换).不幸的是,我不时会面对以下OOM消息：

Jul 07 02:43:54 ip-10-1-2-125 kernel: oom_kill_process: 16 callbacks suppressed
Jul 07 02:43:54 ip-10-1-2-125 kernel: java invoked oom-killer: gfp_mask=0x2400040,order=0,oom_score_adj=0
Jul 07 02:43:54 ip-10-1-2-125 kernel: java cpuset=0ead341e639c2f2bd27a38666aa0834c969e8c7e6d2fb21516a2c698adce8d5f mems_allowed=0
Jul 07 02:43:54 ip-10-1-2-125 kernel: cpu: 0 PID: 26686 Comm: java Not tainted 4.4.0-28-generic #47-Ubuntu
Jul 07 02:43:54 ip-10-1-2-125 kernel: Hardware name: Xen HVM domU,BIOS 4.2.amazon 05/12/2016
Jul 07 02:43:54 ip-10-1-2-125 kernel:  0000000000000286 000000006ffe9d71 ffff8800bb3c7c88 ffffffff813eb1a3
Jul 07 02:43:54 ip-10-1-2-125 kernel:  ffff8800bb3c7d68 ffff880033aea940 ffff8800bb3c7cf8 ffffffff812094fe
Jul 07 02:43:54 ip-10-1-2-125 kernel:  000000000000258c 000000000000000a ffffffff81e66760 0000000000000206
Jul 07 02:43:54 ip-10-1-2-125 kernel: Call Trace:
Jul 07 02:43:54 ip-10-1-2-125 kernel:  [RSS:262048KB RSS_huge:135168KB mapped_file:16
Jul 07 02:43:54 ip-10-1-2-125 kernel: [ pid ]   uid  tgid total_vm      RSS nr_ptes nr_pmds swapents oom_score_adj name
Jul 07 02:43:54 ip-10-1-2-125 kernel: [26659]     0 26659     1127       20       7       3        0             0 sh
Jul 07 02:43:54 ip-10-1-2-125 kernel: [26665]     0 26665     1127       20       7       3        0             0 run.sh
Jul 07 02:43:54 ip-10-1-2-125 kernel: [26675]     0 26675   688639    64577     204       7        0             0 java
Jul 07 02:43:54 ip-10-1-2-125 kernel: Memory cgroup out of memory: Kill process 26675 (java) score 988 or sacrifice child
Jul 07 02:43:54 ip-10-1-2-125 kernel: Killed process 26675 (java) total-vm:2754556kB,anon-RSS:258308kB,file-RSS:0kB
Jul 07 02:43:54 ip-10-1-2-125 docker[977]: Killed

如您所见,我的应用程序的RSS大约只有64M.但由于某些原因,cgroup的RSS为256M(包括128M的大页面).

这是一种操作系统缓存吗？如果是这样,为什么OOM在杀死用户的应用程序之前不会刷新它们？