Questions tagged [kernel]

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 components).

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Zombie processes with unidentifiable cause polluting page table and active unused memory [migrated]

I have a pretty new Windows 11 Pro installation, it has about a week. I noticed that my RAM usage is constantly going up. It was concerned because procexp readouts did not match the total used RAM ...
Sopel's user avatar
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How useful is ionice tool with modern linux kernel

Ionice tool is supposed to offer relieve on high I/O load by executing commands only when system is in specified state. https://www.linux.org/docs/man1/ionice.html states Linux supports I/O ...
Darko Miletic's user avatar
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1 answer
97 views

Debian: revert kernel installation from backports

I was running Bullseye (Debian 11?), tried to install kernel 6.x from the bullseye-backports. I am really not sure how to undo it. The new kernel does not work with the graphics driver and a few more. ...
Stephen's user avatar
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129 views

Linux Driver CH341 USB Adapter Serial Port issue

On a x86_64 miniPC, a led strip can be controlled sending some bytes on a serial port. This control works on Windows but fails on Linux. On Windows, these lines in PowerShell switch the led strip off: ...
Sylva1n's user avatar
  • 23
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1 answer
28 views

RateLimit is doing weird maths and wrong numbers on kernel

I'm trying to apply a set of rate limit within iptables, and it's doing some weird maths that i'm not able to see on the kernel why this is happen. I tried to execute same code on my local machine, ...
JustDevZero's user avatar
19 votes
2 answers
3k views

What could explain unknown I/O on new 16TB HDD on a Debian server?

I recently obtained a new 16TB HDD for my Debian server. I first created a partition (gpt) on it via my Ubuntu-like desktop, formatted it (ext4), and rsync'ed old data on it. The disk is now usable, ...
b4too's user avatar
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42 views

Kernel TLS Socket Redirect

Suppose both the client as well as the server are on the same machine and they want to do mTLS. They both choose to offload the TLS to Kernel (kTLS). Now when the key exchange happens, given the ...
ninja.coder's user avatar
1 vote
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IMSM (Intel Matrix Storage Manager) device is not detected by Linux kernels 6.6.x/6.7.x but works in 5.19.17

In kernels 6.x.x /dev/md/imsm0 does not appear at boot. The only difference I see in dmesg which seems to be relevant: block device autoloading is deprecated and will be removed. Printed in 5.x.x, ...
midenok's user avatar
  • 173
1 vote
1 answer
557 views

RHEL + how to prevent OS disk - sda to change after reboot

We installed RHEL 7.9 version on physical machine., when sda device was the OS. The machine has the following disks. sda - OS disk sdb - data disk sdc - data disk After reboot OS disk device changed ...
King David's user avatar
4 votes
0 answers
160 views

Write speed to NVME disk degrade after some time of active work

I have a fairly general question, but maybe someone already had similar behavior. I have few servers with 20 nvme micron 7450 pro 15 TB disks on each. On all servers I created raid 0 using mdadm ...
igor_shk's user avatar
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Amazon linux 2 - two kernels enabled

I recently upgraded kernel on one of the servers and I have two kernels enabled after reboot: # amazon-linux-extras |grep kernel _ kernel-5.4 available [ =stable ] 55 kernel-5.10=...
Mihai Radulescu's user avatar
1 vote
1 answer
224 views

servers unusable after boot...piix4_smbus SMBus Host Controller has stopped loading during boot, Debian Testing, various kernels

We have multiple old (14+ years) Tyan S3950 mobo servers running debian Unstable with various recent kernels like 6.1.0-3-amd64. Despite being on the bleeding edge with the unstable distro, this has ...
Andy Dorman's user avatar
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0 answers
39 views

strace restart apache server does not log accept/accept4 syscalls

We are using the following command to gather syscalls for apache server start (run as root): strace -e trace=open,close,read,write,connect,accept -f -o /home/sacumen/syscalls_start_apache.txt ...
Mahesh's user avatar
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Cannot configure VirtualBox because correct kernel RPMs cannot be found

I'm trying to configure VirtualBox on my CentOS 7.9 server. However, my kernel version is 3.10.0-1160.99.1.el7.x86_64, and I cannot find kernel-devel-3.10.0-1160.99.1.el7.x86_64.rpm or kernel-headers-...
boardrider's user avatar
1 vote
1 answer
2k views

Cannot "apt upgrade" due initramfs error - "update-initramfs: failed for /boot/initrd.img-5.15.0-86-generic with 1."

I have a Ubuntu 22.04 VM with CloudInit on a Proxmox Host which worked well, but recently I got often the issue after some time (some days, even after reinstalling) that I can't upgrade packages due ...
Jonathan's user avatar
1 vote
1 answer
794 views

Enable BTRFS in kernel (running Rocky Linux 9.2)

I am trying to read an encrypted filesystem pulled from a Fedora 38 installation on Rocky Linux 9.2. When I plug the SSD in, it shows the following error: I suppose that this means (1) the default ...
Lucky's user avatar
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0 answers
53 views

xhci_hcd errors on CentOS 6 for cp210x device

We have very old CentOS 6 installed on CheckWay Sherman with Linux kernel 2.6.32-696.1.1.el6.i686. We try to integrate external usbserial scales device but there are errors settings UART speed. stty -...
Olga Pshenichnikova's user avatar
0 votes
1 answer
365 views

I want to make Linux Kernel Source an RPM file

I am currently using Rocky Linux 8.7. The current kernel version is "4.18.0-425.13.1.el8_7.x86_64". I want to upgrade kernel through RPM, not source compile. In the kernel compile step, use ...
gotothesky's user avatar
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0 answers
153 views

Automatic TCP SYN - cookie activation

I am simulating a SYN flood attack on a Raspberry Pi 1 with KALI Linux (ARM) installed. A similar message as mentioned in this post was printed after performing the attack: How to avoid syn cookies. ...
Gerry's user avatar
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290 views

EXT4-fs error (device md0) in ext4_free_inode:357: Filesystem failed CRC

After setting up Raid1 Mirror on DNS server, now I am planning to go for a Debian upgrade from 10 to 11. I was able to update the source.list file and perform apt update but when i do apt full-upgrade ...
codelearner1029's user avatar
0 votes
1 answer
264 views

Why MACsec can not reach more than 2Gbits/s?

i am configuring macsec and i have discovered that, when using this protocol to send/received data, the bitrate is so low. I am using it over a 10Gb network adaptor, using iperf3 it almost reach that ...
RandomUser8888's user avatar
5 votes
3 answers
2k views

What are the options to monitoring page cache usage?

In essence the Page Cache is a part of Virtual File System (VFS) which main purpose, as you can guess, is improving IO latency of read and write operations. In computing, a page cache, sometimes also ...
King David's user avatar
0 votes
0 answers
176 views

production kafka clusters + How to optimize Page Cache

one of the importance things in Kafka production cluster is the page cache here is a good explains what is page cache PageCache is a typical read/write cache. The operating system uses the free ...
King David's user avatar
0 votes
1 answer
321 views

ZFS I/O Error, Kernel Panic during import

I'm running a raidz1-0 (RAID5) setup with 4 data 2TB SSDs. During midnight, somehow 2 of my data disks experience some I/O error (from /var/log/messages). When I investigated in the morning, the zpool ...
Jealous_Donut_7128's user avatar
0 votes
0 answers
122 views

Number of receiving queues is double the number of cores of my server?

I'm using Mellanox ConnectX-5 100 GB NIC, Linux kernel 5.15 and my server has 32 cores (SMT disabled). But in the /sys/net//queues, the number of rx queues is 64, which is double the number of cores ...
Anh Phan's user avatar
1 vote
1 answer
4k views

Can we use fdisk to partition a disk bigger than 2 TB without recompiling the kernel?

Here is my problem. Our operating system is Debian 11. The main hard disk is doing fine. I have a 6TB external volume. If I choose to use parted to format this disk it will entail recompiling the ...
user2338823's user avatar
1 vote
0 answers
77 views

Saving contents of /proc/net

I'm trying to archive files from /proc/net when a process crashes. This is to aid in debugging, to get understanding about the machine status when crash happened. The contents are not regular files, ...
m.divya.mohan's user avatar
0 votes
1 answer
229 views

kernel messages are complained about memory.inspite all DIMM cards was replaced

we have few DELL machines ( with RHEL 7.6) , and as we replaced the DIMM cards on machines because the Erros that we seen from kernel messages after some time we checked again the kernel messages and ...
King David's user avatar
1 vote
2 answers
117 views

iSCSI shared disks with custom device name on clients

I'm using RHEL 7.9 (Maipo) and need to setup for all iSCSI clients the same device name, like /dev/sdb or /dev/thiscustomname. I could do that by sharing the source disk using multipath, but for Db2 ...
adamitj's user avatar
  • 115
1 vote
1 answer
55 views

RHEL + how to capture fresh kernel message without machine reboot

here is example from dmesg output from important production server ( RHEL 7.2 - DELL machine HW ) as we can see the sde disk in server is dying [Wed Jun 30 11:24:58 2021] sd 0:2:4:0: [sde] tag#0 ...
King David's user avatar
0 votes
0 answers
212 views

SLURM / NFS based computing cluster with disk uniterruptible sleep issues (state : D)

Context : We have a computing cluster based on 7 servers, running Debian 11: a storage (HDD NAS, ~500TB, RAID5, LVM) a frontal server, running SLURM, nfs-common 5 nodes on which the storage is ...
Grégory Hare's user avatar
1 vote
0 answers
400 views

cat /proc/pid/cmdline hangs (no cgroups, no nfs or network fs, no memory issues)

We are a bit stumped. Once in a while ps/w hang forever (at least an hour) on our server, and it is on reading /proc/pid/cmdline for a process (happend twice today, verified with strace cat directly ...
Ariel E's user avatar
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1 vote
0 answers
176 views

RHEL server + what is the meaning of the kernel messages about Hung TX queue XX

We have 524 RHEL machines. in our Hadoop cluster ( all machines are DELL HW ) all machines are RHEL 7.2 version (old kernel version) uname -r 3.10.0-327.el7.x86_64 last week we seen the following ...
King David's user avatar
0 votes
1 answer
425 views

Why do some servers have /etc/sysconfig/kernel and others do not?

I spent some time looking into this and couldn't figure out why there are servers with and without /etc/sysconfig/kernel. What's particularly interesting is that we have some servers with the same ...
hfranco's user avatar
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0 votes
1 answer
395 views

Clear RAM Memory Cache and buffer on production Hadoop cluster with HDFS filesystem

we have Hadoop cluster with 265 Linux RHEL machines. from total 265 machines, we have 230 data nodes machines with HDFS filesystem. total memory on each data-node is 128G and we run many spark ...
King David's user avatar
0 votes
1 answer
930 views

Linux server loses network connectivity after an OOM event

We have a server runnnig Linux 5.15 and we've had multiple verified situations where a process is killed by OOM and that leaves the whole system inaccessible on the network, both for inbound and ...
Délisson Junio's user avatar
0 votes
1 answer
610 views

kernel message + how to know if we need to replace the DIMM based on kernel messages

we have RHEL 7.6 server , and we noticed about the following kernel messages. [1065085.048872] EDAC sbridge MC0: PROCESSOR 0:406f1 TIME 1676989040 SOCKET 0 APIC 0 [1065086.052107] EDAC MC1: 0 CE ...
King David's user avatar
2 votes
0 answers
4k views

Explain of OOM killer logs

I have a question about the OOM killer logs. We are expecting a lot of OOM kills. The ecosystem My ecosystem looks like below: I have a server with 4 cores and 8 GB of RAM. I am running there the ...
Daniel Hornik's user avatar
0 votes
1 answer
290 views

Is the outgoing connection from a OpenVPN client to a LAN behind an OpenVPN server forwarded by the server kernel?

I've observed a somewhat strange behavior that I can't quite understand. So I set up an OpenVPN connection as shown in the graphic below. (It's a TUN and client-to-client setup). My thoughts are ...
Koala's user avatar
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2 votes
1 answer
1k views

Fix kernel issues in rescue mode

I have updated the kernel in a VPS Centos 7, and after rebooting, the machine is not responding anymore, including with SSH. I connected to the VPS via a temporary rescue linux machine from where I ...
AFA Med's user avatar
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3 votes
0 answers
235 views

How to tell whether a linux tcp socket had recent activity?

Most of the time, when changing or upgrading a network service, I would do this during maintenance hours but some services are rarely used so it is tempting to just check whether it is currently in ...
Gamification's user avatar
1 vote
0 answers
297 views

how can I list all static builtin drivers in kernel, such as pcieport and pciehp?

with lspci I can see things like: Slot: 00:02.0 Class: PCI bridge [0604] Vendor: Red Hat, Inc. [1b36] Device: QEMU PCIe Root port [000c] Driver: pcieport In dmesg I can see pcieport 0000:00:02.0: ...
Wang's user avatar
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1 vote
0 answers
245 views

Kernel 6.0 and AMD-GPU/Notion app issue

Recently I installed the new linux kernel 6.0.2 on my Manjaro laptop. After using my usual apps for a while, I notice the laptop "freezed" and only a forced power off got it back. Looking ...
djalmascat's user avatar
0 votes
1 answer
360 views

How can I update php 8 on a linux server without internet access?

Operating System: Redhat 8.4 Internet access : no access to redhat server : ssl vpn Current php version : 7.4 Purpose: Make php version 8 How can I do that ?
Raafet Sword's user avatar
1 vote
0 answers
60 views

Ifconfig result on the server running PF_RING with zerocopy

I have an application which uses PF_Ring zero copy as a part of its packet sniffing capability. When this application is running would it be possible to find out the amount of RX/TX traffic using ...
user2714795's user avatar
2 votes
1 answer
667 views

RHEL 7.9 and OS compatibility with DELL server GEN 15 PowerEdge

we want to purchase the dell servers Gen 15 machines , total machines should be around 85 servers these servers should used for Hadoop cluster as data-node machines and the OS should be RHEL 7.9 ...
King David's user avatar
0 votes
1 answer
343 views

dmesg tells 1G out of 128G available?

I have a 128GB RAM server, kernel 4.18.0-305.7.1.el8_4.x86_64, "dmesg | grep Memory" outputs as follows: [ 0.000000] Memory: 1282732K/133708404K available (12293K kernel code, 2225K ...
Tao Lei's user avatar
2 votes
0 answers
386 views

Is there a utility for detecting temporary system freezes?

Is there a (unix) utility which is able to detect temporary system freezes by observation? E.g. I could imagine an utility which continuously fetches the system time, sleeps for a specific amount of ...
MRalwasser's user avatar
1 vote
2 answers
6k views

Module ip_tables not found after upgrade

Since I upgraded recently my Ubuntu server from 20.04 to 22.04 I have an issue with Docker. Docker will not start any more after reboot, because of the ip_tables module. After every reboot of Ubuntu ...
Ar_wed's user avatar
  • 13
1 vote
0 answers
544 views

Unknown kernel command line parameters "BOOT_IMAGE=/vmlinuz-5.18.11-1.el7.elrepo.x86_64", will be passed to user space

On CentOS 7, after upgrading the kernel to version 5.18.11, I observed the below message in /var/log/messages: Unknown kernel command line parameters "BOOT_IMAGE=/vmlinuz-5.18.11-1.el7.elrepo....
Sandeep's user avatar
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