The Linux kernel is the operating system kernel used by the Linux family of Unix-like operating systems. It is one of the most prominent examples of free and open source software.

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Server won't boot, kernel panic - not syncing

After a reboot of a CentOS 6.2 server we are getting a kernel panic with the following error: Kernel panic - not syncing: Attempted to kill init! Panic occurred, switching back to text console ...
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91 views

MDADM not showing RAID5? [on hold]

Background: I own a Blackarmor NAS 440. I set up 4 brand new 3TB Seagate drives in RAID 5. It has been working fine for ~2 years, until this July. This is what happened in July : HDD3 failed. I ...
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INFO : task events/2:69 blocked for more than 120 seconds

I'm using RHEL 6.3 running on VMWare vsphere and aproximatively every month there is this error message and application running above hang until I restart the server: "echo 0 > ...
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0answers
45 views

linux not replying to an arp request

I am running linux 3.14 on a system with 2 interfaces. on the first interface, i can access our local network. on the second interface, arp packets come in but linux doesn't send out reply. is it ...
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15 views

enable fanotify on oracle redhat linux kernel 2.6.39-400

As a newbie in linux environment, I am trying to install clamav daemon, which is clamd, on oracle redhat linux 6 kernel EUK 2.6.39-400. It needs to have fanotify enabled in the kernel. As I see there ...
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26 views

The default value for vm.dirty_background_ratio

Wondering why the default value for "vm.dirty_background_ratio" from Linux Server (CentOS and Ubuntu) is set to 40. Is this just a recommendation for safety? Or is there any particular reason why? ...
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30 views

Utility to list and modify kernel modules loaded during system startup

How do I list all kernel modules loaded while system startup? Is there a user space utility to list and modify the modules loaded during system startup? I am working on RHEL6 Desktop and RHEL6 ...
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2 views

device descriptor read/64, error -71 [migrated]

I have problem with USB ports on MSI WIND laptop. I have FC17 installed and usb printer sometimes not responds. If I replug a printer in USB port - it's working. Tried to change usb cable and printer ...
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1answer
35 views

View full program command line arguments in OOM killer logs

Is it possible to view full program command line arguments in OOM killler logs ? What I see now in /var/log/syslog is Memory cgroup out of memory: Kill process 29187 (beam.smp) score 998 or sacrifice ...
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1answer
692 views

web server “task blocked for more than 120 seconds”

my web server is down every 2 days. it became unresponsive and I can only see the message below on the console. task **** blocked for more than 120 seconds. The only way to bring it up is resetting ...
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1answer
51 views

Apply patch to custom kernel manually [closed]

I compiled a RHEL based kernel with a script. I've come to know that our version of kernel is vulnerable to attack and we need to apply security patches. ...
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4 views

Create a write-cache loop device for a much larger block device [migrated]

So, long story short. * I had a 5.5TB RAID5 array with a HP controller. * HP uses a really, really painful RAID5 algorithm (ref: Delayed Parity) * I wrote a new block driver that translates requests ...
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2answers
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How do I set the default kernel parameters in CentOS for all existing and future kernels?

I'd like to remove the rhgb and quiet kernel parameters which are used by default when the kernel is booted in CentOS 6, but I want this to apply to all currently installed kernels as well as any ...
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1answer
286 views

Cause of page fragmentation on “large” server with xfs, 20 disks and Ceph

Any insight from someone with a bit of experience in the linux IO system would be helpful. Here is my story: Recently brought up a cluster of six Dell PowerEdge rx720xds to serve files via Ceph. ...
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2answers
340 views

Linux (non-transparent) per-process hugepage accounting

I've recently converted some java apps to run with linux manually-configured hugepages, as desribed here. I point out "manually-configured" because they are not transparent hugepages, which gave us ...
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5answers
894 views

MySQL 5.5 degraded performance in linux kernel 3.2 compared to 2.6

Our database servers (mainly based on the Debian stable packages (=currently Wheezy) seem to have about 4 times more load for the same workload in kernel 3.2.0-4-amd64 then in it's previous ...
3
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1answer
52 views

how to determine who is using the slabs?

Is there any way to figure out who or what is allocating size-256 slabs, like in the slabtop output below? I had to reboot a server yesterday that had 5G out of 8G RAM in size-256 slabs and was ...
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15 views

systemrescuecd 4.3.1: parted cannot inform kernel of change

I am trying to use parted (3.2) on systemrescuecd (4.3.1), but keep getting the error message similar to below. Error: Partition(s) 2, 3, 4 on /dev/sdd have been written, but we have been unable to ...
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0answers
64 views

task fstrim blocked for more than 120 seconds

I'm experiencing random crashes on my system. I've narrowed the problem to the fstrim program that's launched weekly by cron. In the console, I've got a set of blocked tasks among whigetch I find ...
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1answer
107 views

WANem doesn't boot after install

I'm using WANem live cd (based on knoppix) to perform network bandwidth tests. In order to keep the current configuration, I've installed it on hard disk (using the gui installation tool provided ...
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2answers
9k views

Effects of configuring vm.overcommit_memory

My VPS web server running on CentOS 5.4 (Linux kernel 2.6.16.33-xenU) irregularly (like once a month give or take a few weeks) becomes unresponsive due to oom-killer kicking in. Monitoring of the ...
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1answer
416 views

Kernel panic - not syncing: VFS: Unable to mount root

I uploaded a centos 6.2 VMDK to s3 and then converted it to volume using ec2 import volume. Then i took the snapshot of the volume and deleted it.Now I am trying to create a instance from the snapshot ...
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1answer
870 views

RHEL 6.0 upgrading kernel from 2.6.32-71.el6.x86_64 to 2.6.32-358.2.1.el6.x86_64

[root@localhost ~]# rpm -ivh kernel-2.6.32-358.2.1.el6.x86_64.rpm error: Failed dependencies: bfa-firmware < 3.0.3.1 conflicts with kernel-2.6.32-358.2.1.el6.x86_64 [root@localhost ~]# rpm ...
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105 views

shorewall can'T start: UNTRACKED state requires Raw Table in your kernel and iptables

I'm trying setting up my firewall and installed and configured shorewall. Unfortunately I tried to directly configure iptables first, but this didn't work. When I start shorewall, I get this messages ...
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1answer
236 views

dummy network interface in Linux

When i create a dummy network interface and then bring it up it show up being in UNKNOWN state: root@5b8dd2855a9c:# ip l a boom type dummy root@5b8dd2855a9c:# ip l show boom 58: boom: ...
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47 views

“Nosy Neighbor” and the CFQ scheduler

I'm trying to understand how does using CFQ affects the "Nosy Neighbor" problem. I'll ask it a bit naively, can a "Nosy Neighbor" even exist when using CFQ? Isn't that CFQ should make sure all ...
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2answers
179 views

order 4 allocation failure disaster

Some environment details first: Hardware: Intel Server Board S2600GZ 2 x Intel Xeon CPU E5-2620 64GB DDR3 RAM Intel RAID Controller RS2BL (LSI SAS2108) with 4TB LVM Volume made of SAS disks ...
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1answer
3k views

CentOS 6.3 task blocked for more than 120 seconds

Recently have been getting Zabbix alerts about our mail system being unavailable, the uptime on the machine is 30+ days. I've been tracing the Zabbix logs and it looks like the communication between ...
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1answer
41 views

CentOS 5.10 TCP Sequence Number

We have done a security check on a server and its come back with Linux Kernel TCP Sequence Number Generation Security Weakness. We are looking to correct this being flagged up on the check We are ...
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2answers
263 views

Linux NFS hangs after about 15 minutes

I'm somewhat new when it comes to administering Linux and NFS, so please bear with me. We are trying to setup a small cluster at work. Currently the system is just 2 DELL high-end workstations, ...
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1answer
2k views

Linux Kernel complaining about TSC when selected clock source is Hyper V

We are running RHEL 6 boxes on HyperV with Windows Server 2012. On a few on our RHEL boxes, I am seeing this error in /var/log/messages kernel: Clocksource tsc unstable (delta = -62519781 ns). ...
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2answers
568 views

Linux: echo 3 > /proc/sys/vm/drop_caches takes hours to complete

I have a Thecus N8900 NAS, which is a Linux based file server, providing files via NFS to six clients. For some reason that Thecus support has yet to explain, it runs a script that checks ...
4
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1answer
680 views

linux initcwnd and initrwnd via /etc/sysctl.conf

Folks, As we know, the 3.x kernels have higher TCP default connection values, such as initcwnd and initrwnd. For 2.x friends, is there a way to set these in /etc/sysctl.conf instead of the ip route ...
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1answer
72 views

Can high disk cache usage lead to external fragmentation and ultimately to page allocation failures?

We're getting page allocation failures on a Linux server (3.2 kernel). We've been told the problem is directly related to the high use of the memory for cache; this would lead to external ...
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2answers
131 views

All terminal windows suddenly disappear in Linux [closed]

Sorry in advance for the wall of text. I'm having a problem which is leaving me with very few clues as to what might be going on. Also, I apologize if ServerFault isn't the ideal place for this ...
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34 views

Upgrading to PAE Kernel

I have Fedora 15 running in a box with 8GB ram and a 32 bit kernel; I would like to make use of the entire RAM real estate by upgrading to a PAE Kernel; however the machine is in a remote location and ...
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108 views

zeroshell unsupported onboard Intel Ethernet I217-V and I210

I recently installed zeroshell 3.0.0 on a machine with a supermicro motherboard that has 2 onboard ethernet cards. It seems that this version of ZS does not support both of ethernet. I've read from ...
4
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1answer
170 views

CVE-2014-0196 Vulnerability for CentOS

Trying to patch CVE-2014-0196 Vulnerability but yum can't find packages updates CentOS 6.5 (Final) Panel version: 11.0.9 Update #61 # uname -r 2.6.32-358.11.1.el6.x86_64 # yum update kernel Loaded ...
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2answers
445 views

ext3/ext4 physical block size view

I'm using a suse 11 server with xfs and using "xfs_info /srv" command i seen this. xfs_info /srv/ meta-data=/dev/mapper/vg01-srvvol isize=256 agcount=38, agsize=1964032 blks = ...
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68 views

Cassandra hangs with kernel exception when adding jna jar to classpath

I have a fresh installation of cassandra v2.0.8 on a RedHat Enterprise Linux v5. I have added a sym link of the jna.jar in cassandra's /lib folder. I start cassandra and it hangs after printing out ...
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1answer
51 views

“sock_sendmsg-error 22” error in RHEL

I am using RHEL 5.10 servers ( which are in cluster using some shared services). When I restart them using "init 6" or "reboot". the servers hang while shutting down, continuously showing the below ...
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457 views

Linode Kernel Headers

I am trying to install the Idera (R1soft) linux agent on a Linode running Ubuntu 12.04LTS. The agent requires a driver which in turn requires the kernel headers. Linode uses custom kernels though so ...
12
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2answers
656 views

Why does /proc/net/tcp6 represents ::1 as ::100:0

I was writing an utility to check /proc/net/tcp and tcp6 for active connections as its faster than parsing netstat output. As I dont actually have ipv6 enabled I was mainly utilizing localhost as my ...
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1answer
572 views

“show_signal_msg: N callbacks suppressed” then pegged at 100% and machine unresponsive

This happened on an Ubuntu 14.04 64-bit DigitalOcean Droplet: Apr 22 02:17:02 localhost CRON[32514]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly) Apr 22 03:16:59 localhost ...
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Linux meminfo “Buffers” takes more than 10% total memory? [duplicate]

I noticed that meminfo - Buffers occupies significant amount of RAM on some servers in my work environment. I'd like to know what is exactly is "Buffers" and why it takes that much amount of RAM. ...
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1answer
360 views

Removeing ulimit from boot / init

In CentOs as from version 6 there is a by default process limit 1024 for every user i.e /etc/security/limits.d/90-nproc.conf * soft nproc 1024 I have to execute a backend ...
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10 views

Ignoring Uboot's cmdline using a pre-built one

I'm trying to compile a custom Linux kernel for my tablet, but, for debugging purposes, I have to use my custom cmdline. The U-Boot passes to the kernel his own cmdline, but it's not suitable. I can't ...
2
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1answer
135 views

How can I make my own linux distro? [closed]

My question is bit off-topic or may be impractical. The thing is, on the web too many material available to download customized linux distro. But what if I want to make my own linux distro ? ...
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1answer
2k views

Can't update linux kernel on VPS

I recently started using VPS from OVH: http://www.ovh.co.uk/vps/vps-classic.xml This is likely problem very specific to this one provider. My goal is to install and run Docker on it, for this I need ...
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104 views

Cannot enable NMI Watchdog on HM65 Core i5

I'm trying to enable the NMI Watchdog on Linux on an AFL-12A-HM65 touch screen with an Intel HM65 Core i5 CPU. The user manual has an implementation for DOS (real helpful) but not for Linux. There ...