Davoud Teimouri - Virtualization & Datacenter

A technology blog mainly focusing on virtualization and datacenter

Category: Linux

kernel: WARNING: at fs/sysfs/dir.c:536 sysfs_add_one+0xbb/0xe0 – Oracle Enterprise Linux

Most of modern servers hardware are using UEFI instead of legacy BIOS and modern OS has dedicated partition to stores boot and EFI values.

Some times, the partition gets full or OS generate the below log:

kernel: WARNING: at fs/sysfs/dir.c:536 sysfs_add_one+0xbb/0xe0

Kernel includes a CONFIG_EFI_VARS_PSTORE feature, and a feature that dumps kernel message log (= the “dmesg” command output) into UEFI variables for persistent storage if the system is crashing (or even if the system is working normally, depending on the options chosen).

The cause of the warning is duplicate dump file in EFI partition and OS is trying to write values on same file.

There is a simple solution, remove old dump file!

I hope this article help you to find out root cause of the warning and resolve that.

Here is the complete log on our virtual machine:

kernel: WARNING: at lib/kobject.c:196 kobject_add_internal+0x205/0x260()
kernel: Hardware name: VMware7,1
kernel: kobject_add_internal failed for dump-type2-0-0-1493749396-cfc8fc79-be2e-4ddc-97f0-9f98bfe298a0 with -EEXIST, don’t try to register things with the same name in the same directory.
kernel: Modules linked in: vmw_vsock_vmci_transport vsock oracleasm autofs4 ipv6 vfat fat uinput vmw_balloon coretemp crc32c_intel ghash_clmulni_intel microcode pcspkr sg ixgbe hwmon dca vmw_vmci i2c_piix4 shpchp ext4 jbd2 mbcache dm_round_robin scsi_dh_emc sd_mod crc_t10dif sr_mod cdrom aesni_intel ablk_helper cryptd lrw aes_x86_64 xts gf128mul vmxnet3 qla2xxx scsi_transport_fc scsi_tgt mptspi mptscsih mptbase scsi_transport_spi pata_acpi ata_generic ata_piix vmwgfx ttm drm i2c_core dm_multipath dm_mirror dm_region_hash dm_log dm_mod scsi_dh_alua [last unloaded: speedstep_lib] kernel: Pid: 5934, comm: kworker/60:2 Tainted: G        W    3.8.13-16.2.1.el6uek.x86_64 #1
kernel: Call Trace:
kernel: [<ffffffff8105d2af>] warn_slowpath_common+0x7f/0xc0
kernel: [<ffffffff8105d3a6>] warn_slowpath_fmt+0x46/0x50
kernel: [<ffffffff81286865>] kobject_add_internal+0x205/0x260
kernel: [<ffffffff81286a78>] kobject_add_varg+0x38/0x60
kernel: [<ffffffff81286af3>] kobject_init_and_add+0x53/0x70
kernel: [<ffffffff8128f140>] ? sprintf+0x40/0x50
kernel: [<ffffffff814755ec>] efivar_create_sysfs_entry+0x12c/0x1b0
kernel: [<ffffffff81475b95>] efi_pstore_write+0x1b5/0x200
kernel: [<ffffffff81214b48>] pstore_console_write+0xd8/0x100
kernel: [<ffffffff8105e027>] ? msg_print_text+0xc7/0x1e0
kernel: [<ffffffff8105f063>] call_console_drivers.clone.3+0xa3/0x100
kernel: [<ffffffff8105f4c4>] console_unlock+0x274/0x2c0
kernel: [<ffffffff8105fa75>] vprintk_emit+0x325/0x520
kernel: [<ffffffff8109e5f6>] ? find_busiest_group+0x36/0x4d0
kernel: [<ffffffff8138a189>] dev_vprintk_emit+0x69/0x90
kernel: [<ffffffff8109ebbe>] ? load_balance+0x12e/0x670
kernel: [<ffffffff8138a1e9>] dev_printk_emit+0x39/0x40
kernel: [<ffffffff81079e6f>] ? insert_work+0x3f/0x60
kernel: [<ffffffff8138a22e>] __dev_printk+0x3e/0x90
kernel: [<ffffffff8138a565>] dev_printk+0x45/0x50
kernel: [<ffffffff81048099>] ? default_spin_lock_flags+0x9/0x10
kernel: [<ffffffffa0116939>] fc_timeout_deleted_rport+0x229/0x350 [scsi_transport_fc] kernel: [<ffffffff8107b6f0>] process_one_work+0x180/0x410
kernel: [<ffffffff8107d71e>] worker_thread+0x12e/0x390
kernel: [<ffffffff8107d5f0>] ? manage_workers+0x180/0x180
kernel: [<ffffffff81082a6e>] kthread+0xce/0xe0
kernel: [<ffffffff810829a0>] ? kthread_freezable_should_stop+0x70/0x70
kernel: [<ffffffff8159b66c>] ret_from_fork+0x7c/0xb0
kernel: [<ffffffff810829a0>] ? kthread_freezable_should_stop+0x70/0x70
kernel: —[ end trace 940656e1b6e55a3d ]—

OS information:

OEL 6.5 and kernel is 3.8.13-16.2.1.el6uek.x86_64

Davoud Teimouri is as a professional blogger, vExpert 2015-2016-2017, VCA, MCITP. This blog is started with simple posts and now, it has large following readers.

1,428 total views, 23 views today

New Release – Kali Linux 2017.1

Kali Linux is one of most popular Linux distributions and many security experts are using this distribution as penetration testing system. Kali Linux is a Debian based distribution and most Kali’s packages are imported from Debian repositories.

Kali has more than 300 preinstalled tools for penetration testing such as Armitage (a graphical cyber attack management tool), nmap (a port scanner), Wireshark (a packet analyzer), John the Ripper password cracker, Aircrack-ng (a software suite for penetration-testing wireless LANs), Burp suite and OWASP ZAP web application security scanners.

Kali development team has released new version and it’s available for download.

Kali Linux

Kali Linux is available for both 32-bit and 64-bit platforms and also the team focus on ARM devices and also there is an image for ARM architecture.

Also Kali Linux NetHunter is also available for smartphones such as the Nexus 5, Nexus 6, Nexus 7, Nexus 9, Nexus 10, OnePlus One, and some Samsung Galaxy models.

Kali Linux hardware requirements:

  • A minimum of 20 GB disk space for the Kali Linux install.
  • RAM for i386 and amd64 architectures, minimum: 1GB, recommended: 2GB or more.
  • CD-DVD Drive / USB boot support

Kali Linux will be installed on some Apple devices such as Apple MacBook Air, Pro, and Retina models.

Also it will be installed on virtual platforms such as VMware Workstation and Oracle VirtualBox

Read more information on Kali Linux documentation.

Davoud Teimouri is as a professional blogger, vExpert 2015-2016-2017, VCA, MCITP. This blog is started with simple posts and now, it has large following readers.

1,619 total views, 10 views today

CentOS 6.9 – New Release

After announcing new Red Hat Enterprise Linux and Oracle Linux, now CentOS developer team has released new version of the distribution. Actually and as may you know, CentOS created from RHEL source codes same as Oracle Linux and usually new CentOS version will be released after RHEL version.

You can read release announcement on this link: Release Announcement

And find more information about the new release.

Also CentOS 6.9 is available for download as ISO files:

Download links (SHA256, signature, pkglist, mirror list): CentOS-6.9-x86_64-bin-DVD1.iso (3,788MB, torrent), CentOS-6.9-x86_64-LiveDVD.iso (1,930MB, torrent), CentOS-6.9-x86_64-minimal.iso (408MB, torrent), CentOS-6.9-x86_64-netinstall.iso (230MB, torrent).

Read the below posts:

Oracle Linux 6.9 – New Release

New Release – Red Hat Enterprise Linux 6.9

Davoud Teimouri is as a professional blogger, vExpert 2015-2016-2017, VCA, MCITP. This blog is started with simple posts and now, it has large following readers.

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Oracle Linux 6.9 – New Release

Oracle Linux 6.9

After releasing RHEL 6.9 by Red Hat, Oracle has released Oracle Linux 6.9 at March 28.

The new release including some fixes and also new features. The below features are notable features:

  • Transport Layer Security (TLS) 1.2 support for all system components. Other changes include vsftpd support for TLS 1.2 and auditd support for incremental_async.
  • The cpuid utility is now available. This utility dumps detailed information about CPUs gathered from CPUID instruction and is capable of determining exact CPU models. The cpuid utilty supports Intel, AMD, and VIA CPUs.
  • Improved support when running as a Hyper-V guest.
  • Enhanced SSSD Support for Active Directory.

Oracle Linux 6.9 ships with the following kernel packages:

  • Unbreakable Enterprise Kernel (UEK) Release 4 (kernel-uek-4.1.12-61.1.28.el6uek) for x86-64
  • Unbreakable Enterprise Kernel (UEK) Release 2 (kernel-uek-2.6.39-400.294.3.el6uek) for i386
  • Red Hat Compatible Kernel (kernel-2.6.32-696.el6) for i386 and x86-64

Oracle Linux 6.9 is available for download on Oracle Software Delivery Cloud

Also RPM packages are available on Oracle Linux Yum

Also read the below posts:

New Release – Red Hat Enterprise Linux 6.9

Oracle Linux Yum Server

Davoud Teimouri is as a professional blogger, vExpert 2015-2016-2017, VCA, MCITP. This blog is started with simple posts and now, it has large following readers.

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New Release – Red Hat Enterprise Linux 6.9

New release of Red Hat Enterprise Linux has been released by Red Hat at 21st March 2017. Red Hat Enterprise Linux 6.9 comes with lot of new features and updates.

Red Hat Enterprise Linux 6.9

New Features

Here is new features and major enhancements introduced in Red Hat Enterprise Linux 6.9:

  1. General Updates
  2. Authentication and Interoperability
  3. Clustering
  4. Compiler and Tools
  5. Directory Server in Red Hat Enterprise Linux
  6. Hardware Enablement
  7. Installation and Booting
  8. Kernel
  9. Networking
  10. Security
  11. Servers and Services
  12. Storage
  13. Virtualization
  14. Red Hat Software Collections

Updated Components

Also here is updated components:

Component
Version
Kernel
2.6.32-696
QLogic qla2xxx driver
8.07.00.26.06.8-k
QLogic ql2xxx firmware
ql2100-firmware-1.19.38-3.1
ql2200-firmware-2.02.08-3.1
ql23xx-firmware-3.03.27-3.1
ql2400-firmware-7.03.00-1
ql2500-firmware-7.03.00-1
Emulex lpfc driver
0:11.0.0.5
iSCSI initiator utils
iscsi-initiator-utils-6.2.0.873-26
DM-Multipath
device-mapper-multipath-0.4.9-100
LVM
lvm2-2.02.143-12

The release announcement also contains a note about the upcoming change in the product’s support status: “Note that Red Hat Enterprise Linux 6 enters Production Phase 3 on May 10, 2017, meaning that subsequent updates to Red Hat Enterprise Linux 6 will be limited to qualified critical security fixes and business-impacting urgent issues.” See also the release notes for more information. As always, existing RHEL clients can update to this version free of charge, while potential new customers should consider downloading the 30-day evaluation edition of the product’s 7.x branch instead.

Hardware Support

This new release supporting hardware same as previous versions, you can check your hardware before installation on this link: Certified Hardware

Davoud Teimouri is as a professional blogger, vExpert 2015-2016-2017, VCA, MCITP. This blog is started with simple posts and now, it has large following readers.

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Monitoring Temperature And Fan Speed In Linux By LM-Sensors

What’s LM-Sensors

Health monitoring is very important for critical servers because administrators can do proper actions before any impact on service. There is many third-party software for monitoring Linux and Windows servers but native agents are also useful.

We are going to review one of native solutions for hardware health monitoring in Linux.
Read More

Davoud Teimouri is as a professional blogger, vExpert 2015-2016-2017, VCA, MCITP. This blog is started with simple posts and now, it has large following readers.

2,206 total views, 6 views today

Remove Multipath Device – Map in use!

Multipath Device, Remove From Linux

Based on Red Hat solution (https://access.redhat.com/solutions/47438), the below steps should be done before flush any multipath device, otherwise the command will be failed:

  • Locate any subsystem or process holding the multipath device open.
  • For any subsystem or process holding the multipath device open, stop the process, or issue commands to release the multipath device.
  • Some examples of possible holders of a multipath device and the commands to release it:
  • One or more partition mapping(s) still exists on the multipath device.
    • Use “kpartx -d” on the multipath device to remove the device partition mapping(s).
  • A filesystem exists on the multipath device and is currently mounted.
    • Unmount the filesystem and if it exists in /etc/fstab, remove it.
  • The multipath device was used by LVM, and still has device mapper state in the kernel.
    • Use “lvchange -an” to deactivate any logical volume(s) associated with the multipath device.  A list of logical volumes associated with the multipath device may be found by examining the output of “lvs -o +devices“.
    • If “lvchange -an” fails, the logical volume is only partially removed, or there are blocked processes with I/O outstanding on the device, use “dmsetup remove -f” followed by “dmsetup clear” on the multipath device.  See dmsetup man page for full explanation of these commands.

Read More

Davoud Teimouri is as a professional blogger, vExpert 2015-2016-2017, VCA, MCITP. This blog is started with simple posts and now, it has large following readers.

1,319 total views, 20 views today

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