Linux centos7系统执行yum跳出Exiting on user cancel解决办法，总是被Killed，内存不足杀死进程，无法启动锐速tcp加速，kvm虚拟化动态内存超售（HugePages）

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Linux centos7系统执行yum跳出Exiting on user cancel解决办法，总是被Killed，内存不足杀死进程，无法启动锐速tcp加速，kvm虚拟化动态内存超售（HugePages）

yum无法执行是内存不足导致的，定位到

[root@test ~]# dmesg | grep 'Out of memory'
[  297.018784] Out of memory: Kill process 1284 (yum) score 7 or sacrifice child
[  311.199801] Out of memory: Kill process 834 (tuned) score 4 or sacrifice child
[  311.419631] Out of memory: Kill process 1145 (kangle) score 3 or sacrifice child
[  311.874535] Out of memory: Kill process 833 (mysqld) score 1 or sacrifice child
[  311.908636] Out of memory: Kill process 491 (polkitd) score 1 or sacrifice child
[  311.936735] Out of memory: Kill process 1133 (cdnbest) score 1 or sacrifice child
[  312.010911] Out of memory: Kill process 561 (NetworkManager) score 0 or sacrifice child
[  312.025528] Out of memory: Kill process 562 (gmain) score 0 or sacrifice child
[  312.356744] Out of memory: Kill process 1216 (sshd) score 0 or sacrifice child
[  312.577229] Out of memory: Kill process 1216 (sshd) score 0 or sacrifice child
[  312.605899] Out of memory: Kill process 1396 (lotServer.sh) score 0 or sacrifice child
[  312.665263] Out of memory: Kill process 1112 (rsyslogd) score 0 or sacrifice child
[  312.694343] Out of memory: Kill process 1149 (in:imjournal) score 0 or sacrifice child
[  312.856384] Out of memory: Kill process 1432 (systemd-udevd) score 0 or sacrifice child
[  313.001333] Out of memory: Kill process 1431 (systemd-udevd) score 0 or sacrifice child
[  313.433675] Out of memory: Kill process 1142 (kangle) score 0 or sacrifice child
[  313.653308] Out of memory: Kill process 1118 (crond) score 0 or sacrifice child
[  313.863466] Out of memory: Kill process 1425 (acce-3.11.36.2-) score 0 or sacrifice child
[  485.989867] Out of memory: Kill process 1539 (yum) score 5 or sacrifice child
[  526.442162] Out of memory: Kill process 1540 (yum) score 7 or sacrifice child
[  527.566683] Out of memory: Kill process 1540 (yum) score 7 or sacrifice child
[  527.775615] Out of memory: Kill process 1540 (yum) score 7 or sacrifice child
[  714.152401] Out of memory: Kill process 1649 (yum) score 6 or sacrifice child
[  768.726852] Out of memory: Kill process 1656 (yum) score 6 or sacrifice child
[  769.955937] Out of memory: Kill process 1656 (yum) score 6 or sacrifice child
[  794.681401] Out of memory: Kill process 1656 (yum) score 6 or sacrifice child
[  883.994721] Out of memory: Kill process 1661 (yum) score 6 or sacrifice child
[  959.288157] Out of memory: Kill process 1667 (yum) score 6 or sacrifice child
[ 1000.197305] Out of memory: Kill process 1667 (yum) score 12 or sacrifice child

之前系统重启后锐速启动不了也是这个原因。。。


分析了下是vps服务器使用的为kvm虚拟化，查了下原来是机房kvm虚拟化做了动态内存超售
服务器总是执行不了yum跳出Exiting on user cancel，开机就自动用尽了内存，在尝试增加swap


解决办法如下，执行命令，禁止kvm虚拟化执行动态内存，优先使用这个命令尝试解决，未观察到内存下降，，基本就没戏，无法解决该问题，，，直接去服务器商提供的后台面板重装系统，安装系统完成后直接使用，不要执行reboot重启就行

1. rmmod virtio_balloon

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或者该贴试一下，类似的问题

Linux下简单通过dmesg抓包搜索被系统内核因为物理内存不足杀死进程的日志记录
https://bbs.itzmx.com/thread-89619-1-1.html

最后发现是内核开启了HugePages 2M这个东西，导致了大量的内存占用

1. cat /proc/meminfo | grep Huge

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输出，单个页面2M，一共198个页面，HugePages共占用内存396M

[root@centos ~]# cat /proc/meminfo | grep Huge
AnonHugePages:         0 kB
HugePages_Total:     198
HugePages_Free:      190
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB

解决办法，打开文件删除相关参数“vm.nr_hugepages=1172”

1. vi /etc/sysctl.conf

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一键删除

1. sed -i '/^vm\.nr_hugepages=/'d /etc/sysctl.conf

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查看系统当前值

1. cat /proc/sys/vm/nr_hugepages

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该值应该始终为0，不重启修改值命令，增大该值立即生效，降低为0关闭需要重启生效

1. sysctl -w vm.nr_hugepages=0

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某Linux系统安装脚本判断hugepages开启有BUG，导致小内存机器也强行打开2.5G hugepages，导致服务器内核崩溃无法启用开机
某些软件错误判断内存引起错误打开hugepages引起内核崩溃无法开机的BUG修复
出错相关代码，请进行修正改为-gt判断

1.   if [[ $(grep MemTotal /proc/meminfo | awk '{print $2}') > 3500000 ]]; then
   
2.     echo "[*] Enabling huge pages"
   
3.         echo "[*] 启用 huge pages"
   
4.     echo "vm.nr_hugepages=$((1168+$(nproc)))" | sudo tee -a /etc/sysctl.conf
   
5.     sudo sysctl -w vm.nr_hugepages=$((1168+$(nproc)))
   
6.   fi

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修复后代码

1.   if [[ $(grep MemTotal /proc/meminfo | awk '{print $2}') -gt 3500000 ]]; then
   
2.     echo "[*] Enabling huge pages"
   
3.         echo "[*] 启用 huge pages"
   
4.     echo "vm.nr_hugepages=$((1168+$(nproc)))" | sudo tee -a /etc/sysctl.conf
   
5.     sudo sysctl -w vm.nr_hugepages=$((1168+$(nproc)))
   
6.   fi

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AnonHugePages是一个必须禁用的系统内核优化
https://bbs.itzmx.com/thread-110231-1-1.html

不可名