In computing, the kernel is the main component of most computer operating systems; it is a bridge between applications and the actual data processing done at the hardware level. The kernel's responsibilities include managing the system's resources (the communication between hardware and software ...

learn more… | top users | synonyms

2
votes
3answers
97 views

CentOS 6.5 new Kernel not active after reboot

Today I was running some yum updates and wanted to verify that everything went through fine by making sure I had a new kernel. To my surprise I noticed that CentOS was still running ...
1
vote
2answers
29 views

How to check if Ubuntu 14.04 Kernel has TPROXY

I'm using Digital Ocean's Ubuntu 14.04 image and needs the kernel to be compiled for TPROXY. Is there a way to check whether the current kernel supports TPROXY?
-3
votes
1answer
29 views

Running Kernel 3.x in CentOS 6.x [duplicate]

I read that using the 3.x branch in CentOS 6 is a bad idea. Is there any reason as to why I should stick to the 2.6 branch? I've played around and have ran 3.x from compile with no problems under ...
1
vote
2answers
47 views

CentOS 6 - Kernel 3 from CentOS 7 Repo?

i want to run kernel 3 on centos 6. I found out, that it cant get installed over yum and i would need to compile it by my own. My question: Could i use the centos 7 repo to install kernel 3.x from ...
6
votes
0answers
145 views

Linux kernel 3.10.0-123.4.2 processes [flush] aren't present [migrated]

I am using CentOS 7 with "3.10.0-123.4.2.el7.x86_64" version, but I don't know why the kernel threads named flush aren't present in this kernel version. I tried to look in the kernel change log, but ...
1
vote
2answers
24 views

When a socket switch to TIME_WAIT state, why I can't see its inode number?

I'm developing a program in python that parses /proc/net/tcp informations, but unfortunately, while I was doing this, I saw a strange thing. Practically, when a socket change in TIME_WAIT state, ...
-1
votes
1answer
25 views

Can you use CGroups inside an OpenVZ Container?

just a quick question, which i have had trouble finding the answer to: The OpenVZ Authors have been contributing a large amount of code to the linux kernel, in order to get virtualization features ...
0
votes
0answers
39 views

Nodes crash with kernel panic due to some bugs in autofs4 module

Recently, my computing nodes started to crash very often. In a pool of ~100 nodes running Ubuntu 12.04 for scientific computing, a machine dies every hour with the following kernel panic message: ...
0
votes
1answer
141 views

GRUB “Some modules may be missing from core image” Error

one HDD crashed from my RAID and I added a new HDD. Now I wanted to install GRUB to the new HDD: with "grub-install /dev/sdb" I get these errors: Installing for i386-pc platform. grub-install: ...
0
votes
0answers
37 views

Verify architecture of kernel file

Note: I am NOT interested in the currently running kernel, but on a kernel that I am going to boot and which is in a file in the filesystem. I am going to boot a new kernel. I have prepared grub.conf ...
3
votes
1answer
49 views

Kernel Compile crashing on Hyper-V due to memory issues

This is on a Hyper-V machine. I've set the min RAM to 512 and the max to 2048. The host machine has more then enough RAM. Does Linux have an issue with Dynamic RAM on Hyper-V? I can't seem to ...
1
vote
0answers
30 views

OpenVZ - updating kernel and all containers

Last night I upgraded to the latest kernel of openvz. I rebooted the host node. It came up with the latest kernel. However, the containers are still running the old kernel. What I did on the host ...
-3
votes
1answer
19 views

Is there anyway to specify the version of kernel update with apt-get? Debian 7 [closed]

Is possible to select the version of Kernel I need in apt-get? Actually, I need to update it but I had lot of configurations problems with 3.2. Or the only way is compiling the kernel? Thank you
2
votes
1answer
134 views

Linux read disk cache and NFS

I am interested in the impact of the read disk cache on accessing a file through NFS. Lets say I have a file on NFS. I access it (do "cat myfile") from a linux host "A". If there's enough RAM a file ...
1
vote
2answers
99 views

grub.conf missing initrd path after kernel update

I updated a server this morning and the latest kernel panics during boot. Upon review of the grub.conf file I found the initrd path was missing. Is there a way to fix this issue? Or should I remove ...
1
vote
3answers
485 views

Error installing new OpenVZ kernel

Seem to have an error when updating the kernel on a OpenVZ server when running "yum update" im getting the below Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * base: ...
0
votes
1answer
25 views

FTP server suddenly down

Suddenly I can not use anymore my FTP server and I get via ssh the following kernel report. I'm running on Debian 7.0 with ISPconfig3 kernel:[801112.466009] nf_ct_ftp: dropping packetIN= OUT=venet0 ...
1
vote
1answer
119 views

CentOS only detecting 50% of ram on IBM Server

I have IBM server with 16 GB RAM installed. Initially it showed 16 GB with free | grep Mem | awk '{print $2}' but now it shows only 8116136 but it must show 16439208 When I do dmidecode ...
7
votes
1answer
249 views

How does vm.overcommit_memory work?

When I use the default settings: vm.overcommit_memory = 0 vm.overcommit_ratio = 50 I can read these values from /proc/meminfo file: CommitLimit: 2609604 kB Committed_AS: 1579976 kB But ...
0
votes
1answer
63 views

Healthy Linux machine immediately went down

This is the last log entry in /var/log/messages and after this the machine has been stopped. How can I debug why the machine has been stopped? I am not sure but maybe the system stops comes from the ...
12
votes
2answers
443 views

Kernel stack trace to source code lines

Given a kernel stack trace as below, how do you determine the specific line of code where the issue occurred? kernel: [<ffffffff80009a14>] __link_path_walk+0x173/0xfb9 kernel: ...
2
votes
1answer
171 views

Is it possible to configure the Linux kernel I/O scheduler for an NFS mount?

On a normal block device you can change the i/o scheduler like this: # cat /sys/block/hda/queue/scheduler noop anticipatory deadline [cfq] # echo anticipatory > /sys/block/hda/queue/scheduler # ...
3
votes
1answer
58 views

Some questions about kernel.random.* parameters

I'm trying to understand the linux kernel parameters which are under /proc/sys/kernel/random/, but I have some troubles. Could you help me figure some things out? What is the boot_id parameter used ...
0
votes
0answers
18 views

collect previous kernel logs in linux after reboot

how to collect previous kernel logs in linux after reboot and how to search the old logs? Initially when system is rebooted the logs are not captured and found rest of the log's.But there is an error ...
1
vote
1answer
433 views

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 ...
0
votes
0answers
21 views

How do I configure kdump with extra_modules on ubuntu?

I need to configure extra modules to load with kdump (specifically, vga16fb.ko). On RHEL systems it's in /etc/kdump.conf, but ubuntu doesn't have this file. I've looked in /etc/default/kdump-config, ...
0
votes
1answer
66 views

Initrd and Initramfs

I have read about the differences between the two from stackoverflow. But I am still finding it difficult to understand tmpfs and the real advantages of initramfs over initrd. I find that on RedHat ...
1
vote
0answers
23 views

Kernel Compiling from Vanilla to several machines

When compiling kernels for machines is there a safe or correct way to create a template for say servers? I work with a lot of RHEL servers and want to compile them with GRSEC. However, I do not wish ...
2
votes
0answers
140 views

Linux cgroups cpuset w/ subs causes cgconfig not to start

I am having a problem trying to separate 2 groups using cpuset subsystem. This works fine, however if i go to add a subgroup to that group (in this case -- user1), cgconfig will fail to start with ...
2
votes
0answers
193 views

Ubuntu 14.04 / Apache 2.4 causes kernel fault on Amazon EC2 medium instance

Got a disturbing crash while performing 'apachectl stop'. General system: $ uname -a Linux www.example.com 3.13.0-24-generic #47-Ubuntu SMP Fri May 2 23:30:00 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux ...
0
votes
0answers
241 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 ...
-1
votes
1answer
856 views

Server freeze with “rcu_sched detected stalls on CPUs/tasks”

My web server is crashing several times a week. I see errors in syslog but I can't find a solution. I tried changing kernel to older or newer versions but no difference. I moved everything to a new ...
1
vote
1answer
161 views

preventing ipmi kernel drivers from loading

I'm trying to prevent the ipmi kernel modules from loading on a server with a SuperMicro X8DTG-D motherboard running Ubuntu 14.04. My motivation for doing so is that the modules sometimes seem to take ...
0
votes
2answers
73 views

FreeBSD Established Connections Maxing out at 300

We've previously had issues in our environment where it seemed we were reaching FreeBSDs max connection limit. We took action demonstrated by http://nginx.org/en/docs/freebsd_tuning.html and bumped up ...
1
vote
1answer
111 views

kvm hypervisor kernel panic

My kvm hypervisor had been running with 20+ vps guests for a few months. But a few days ago it went to kernel panic. There were no abnormal operation that I found would cause the problem, except that ...
1
vote
0answers
64 views

Linux kernel module “Unknown parameter” stops module from loading. How to load module anyway?

The following is happening on a Ubuntu 10.04 system I'm working on: The kernel is shipped with e1000 driver module version 7.3.21-k5-NAPI. This version of the module is causing problems. To fix, the ...
0
votes
1answer
31 views

Error during the kernel booting

After kernel update I've got a problem with booting linux, does anyone know how to fix this problem ?? I am pretty sure that everything was OK during kernel compilation. Here is a picture with the ...
0
votes
1answer
88 views

Kernel Upgrade with grsecurity - Debian

I would like to upgrade kernel on my server from version 2.6.32 to the newest with Grsecurity. But after restarting the server there is still old version of kernel, can you tell me what I have done ...
0
votes
0answers
109 views

yum update leads kernel error

When I do 'yum update', the following error is shown. Before running the suggested command, I shall better understand, what the cause is. Any advice? --> Finished Dependency Resolution Error: ...
6
votes
1answer
117 views

RHEL6 Keeping 1 old kernel and security

I have my RHEL 5&6 servers set to keep 1 old kernel after updates, I do this in case I need to recover the system for any number of reasons. My question is related to security of the system when ...
0
votes
3answers
192 views

Yum update problems on AWS with missing requirements and duplicate sendmail

I am running an AWS VM and tried: sudo yum update Result: Error: Protected multilib versions: sendmail-8.14.4-8.12.amzn1.x86_64 != sendmail-8.14.4-7.9.amzn1.i386 You could try using ...
4
votes
1answer
311 views

How to check if a process is non-blocking in linux without using a stack tracer?

A multi-cpu server is running several processes. One process has a thread that should always be in a spinning state, using 100% of the CPU it's been assigned. My current method (besides asking the ...
8
votes
1answer
229 views

TCP packet being retransmitted 7 times when sysctl tcp_retries1 is set to 3 - why?

Ubuntu 12.04 I am trying to better understand how many times TCP will attempt to retransmit a packet when it does not receive confirmation the destination received it. After reading the tcp man page ...
0
votes
0answers
20 views

Process identifier mask in z/OS

I've noticed a curious pattern to process identifier numbers on the z/OS system I'm working on (uname reports it as OS/390), they're either 1-4 digits long or 8 digits long but never in between. The ...
0
votes
0answers
351 views

Server crash : “unable to handle kernel paging request”

My fresh new Ubuntu webserver randomly crashes with the following error in the syslog. It doesn't respond anymore and I have to do a hard reboot. It happens almost one time a day. Server kernel is : ...
1
vote
1answer
107 views

backup files to a remote server with multiple versions using rsync hardlink option

To use rsync hard link option to backup files remotely so that remote backup server could keep multiple versions of the backups, both the link-dest directory and the target directory have to be on the ...
0
votes
1answer
39 views

Ubuntu 13.10 server has no kernels

Something has gone wrong and now we no longer have a Linux kernel (not even recovery mode) installed. GRUB is still there, but it runs the memory test. How can I fix this? Everything I've looked at ...
0
votes
1answer
29 views

In sysctl.conf settings, what is the difference between 'all' & 'default'?

In context of sysctl.conf settings, what is the difference between (all vs. default) like net.ipv4.conf.all.accept_source_route & net.ipv4.conf.default.accept_source_route in sysctl settings ? ...
0
votes
1answer
165 views

Modifications to sysctl.conf in openVZ container, do they even take effect?

I'm following a security guide(http://www.thefanclub.co.za/how-to/how-secure-ubuntu-1204-lts-server-part-1-basics) to strengthen my OpenVZ based VPS webserver running Ubuntu 12.04 , a part of that ...
0
votes
0answers
98 views

demonstrate Automatic Hardware Clock Synchronization By the Kernel (11 minute mode) without ntpd

From the man page of hwclock: This mode (we'll call it "11 minute mode") is off until something turns it on. The ntp daemon xntpd is one thing that turns it on. You can Ok, I have a ...