Chapter 11. Known issues
This part describes known issues in Red Hat Enterprise Linux 9.3.
11.1. Installer and image creation
authconfig Kickstart commands require the AppStream repository
authselect-compat package is required by the
authconfig Kickstart commands during installation. Without this package, the installation fails if
authconfig are used. However, by design, the
authselect-compat package is only available in the AppStream repository.
To work around this problem, verify that the BaseOS and AppStream repositories are available to the installer or use the
authselect Kickstart command during installation.
reboot --kexec and
inst.kexec commands do not provide a predictable system state
Performing a RHEL installation with the
reboot --kexec Kickstart command or the
inst.kexec kernel boot parameters do not provide the same predictable system state as a full reboot. As a consequence, switching to the installed system without rebooting can produce unpredictable results.
Note that the
kexec feature is deprecated and will be removed in a future release of Red Hat Enterprise Linux.
Unexpected SELinux policies on systems where Anaconda is running as an application
When Anaconda is running as an application on an already installed system (for example to perform another installation to an image file using the
–image anaconda option), the system is not prohibited to modify the SELinux types and attributes during installation. As a consequence, certain elements of SELinux policy might change on the system where Anaconda is running. To work around this problem, do not run Anaconda on the production system and execute it in a temporary virtual machine. So that the SELinux policy on a production system is not modified. Running anaconda as part of the system installation process such as installing from
dvd.iso is not affected by this issue.
Local Media installation source is not detected when booting the installation from a USB that is created using a third party tool
When booting the RHEL installation from a USB that is created using a third party tool, the installer fails to detect the
Local Media installation source (only Red Hat CDN is detected).
This issue occurs because the default boot option
int.stage2= attempts to search for
iso9660 image format. However, a third party tool might create an ISO image with a different format.
As a workaround, use either of the following solution:
When booting the installation, click the
Tabkey to edit the kernel command line, and change the boot option
- To create a bootable USB device on Windows, use Fedora Media Writer.
- When using a third party tool like Rufus to create a bootable USB device, first regenerate the RHEL ISO image on a Linux system, and then use the third party tool to create a bootable USB device.
For more information on the steps involved in performing any of the specified workaround, see, Installation media is not auto detected during the installation of RHEL 8.3.
The USB CD-ROM drive is not available as an installation source in Anaconda
Installation fails when the USB CD-ROM drive is the source for it and the Kickstart
ignoredisk --only-use= command is specified. In this case, Anaconda cannot find and use this source disk.
To work around this problem, use the
harddrive --partition=sdX --dir=/ command to install from USB CD-ROM drive. As a result, the installation does not fail.
Hard drive partitioned installations with iso9660 filesystem fails
You cannot install RHEL on systems where the hard drive is partitioned with the
iso9660 filesystem. This is due to the updated installation code that is set to ignore any hard disk containing a
iso9660 file system partition. This happens even when RHEL is installed without using a DVD.
To workaround this problem, add the following script in the kickstart file to format the disc before the installation starts.
Note: Before performing the workaround, backup the data available on the disk. The
wipefs command formats all the existing data from the disk.
%pre wipefs -a /dev/sda %end
As a result, installations work as expected without any errors.
Anaconda fails to verify existence of an administrator user account
While installing RHEL using a graphical user interface, Anaconda fails to verify if the administrator account has been created. As a consequence, users might install a system without any administrator user account.
To work around this problem, ensure you configure an administrator user account or the root password is set and the root account is unlocked. As a result, users can perform administrative tasks on the installed system.
New XFS features prevent booting of PowerNV IBM POWER systems with firmware older than version 5.10
PowerNV IBM POWER systems use a Linux kernel for firmware, and use Petitboot as a replacement for GRUB. This results in the firmware kernel mounting
/boot and Petitboot reading the GRUB config and booting RHEL.
The RHEL 9 kernel introduces
inobtcount=1 features to the XFS filesystem, which kernels with firmware older than version 5.10 do not understand.
To work around this problem, you can use another filesystem for
/boot, for example ext4.
RHEL for Edge installer image fails to create mount points when installing an rpm-ostree payload
rpm-ostree payloads, used for example in a RHEL for Edge installer image, the installer does not properly create some mount points for custom partitions. As a consequence, the installation is aborted with the following error:
The command 'mount --bind /mnt/sysimage/data /mnt/sysroot/data' exited with the code 32.
To work around this issue:
- Use an automatic partitioning scheme and do not add any mount points manually.
Manually assign mount points only inside
/vardirectory. For example,
/var/my-mount-point), and the following standard directories:
As a result, the installation process finishes successfully.
NetworkManager fails to start after the installation when connected to a network but without DHCP or a static IP address configured
Starting with RHEL 9.0, Anaconda activates network devices automatically when there is no specific
ip= or kickstart network configuration set. Anaconda creates a default persistent configuration file for each Ethernet device. The connection profile has the
autoconnect value set to
true. As a consequence, during the start of the installed system, RHEL activates the network devices, and the
networkManager-wait-online service fails.
As a workaround, do one of the following:
Delete all connections using the
nmcliutility except one connection you want to use. For example:
List all connection profiles:
# nmcli connection show
Delete the connection profiles that you do not require:
# nmcli connection delete <connection_name>
Replace <connection_name> with the name of the connection you want to delete.
Disable the auto connect network feature in Anaconda if no specific
ip=or kickstart network configuration is set.
- In the Anaconda GUI, navigate to Network & Host Name.
- Select a network device to disable.
- Click Configure.
- On the General tab, deselect the Connect automatically with priority
- Click Save.
Unable to load an updated driver from the driver update disc in the installation environment
A new version of a driver from the driver update disc might not load if the same driver from the installation initial ramdisk has already been loaded. As a consequence, an updated version of the driver cannot be applied to the installation environment.
As a workaround, use the
modprobe.blacklist= kernel command line option together with the
inst.dd option. For example, to ensure that an updated version of the
virtio_blk driver from a driver update disc is loaded, use
modprobe.blacklist=virtio_blk and then continue with the usual procedure to apply drivers from the driver update disk. As a result, the system can load an updated version of the driver and use it in the installation environment.
Kickstart installations fail to configure the network connection
Anaconda performs the kickstart network configuration only through the NetworkManager API. Anaconda processes the network configuration after the
%pre kickstart section. As a consequence, some tasks from the kickstart
%pre section are blocked. For example, downloading packages from the
%pre section fails due to unavailability of the network configuration.
To work around this problem:
Configure the network, for example using the
nmclitool, as a part of the
Use the installer boot options to configure the network for the
As a result, it is possible to use the network for tasks in the
%pre section and the kickstart installation process completes.
Enabling the FIPS mode is not supported when building
rpm-ostree images with RHEL image builder
Currently, there is no support to enable the FIPS mode when building
rpm-ostree images with RHEL image builder.
Images built with the
stig profile remediation fails to boot with FIPS error
FIPS mode is not supported by RHEL image builder. When using RHEL image builder customized with the
xccdf_org.ssgproject.content_profile_stig profile remediation, the system fails to boot with the following error:
Warning: /boot//.vmlinuz-<kernel version>.x86_64.hmac does not exist FATAL: FIPS integrity test failed Refusing to continue
Enabling the FIPS policy manually after the system image installation with the
fips-mode-setup --enable command does not work, because the
/boot directory is on a different partition. System boots successfully if FIPS is disabled. Currently, there is no workaround available.
You can manually enable FIPS after installing the image by using the
fips-mode-setup --enable command.
Driver disk menu fails to display user inputs on the console
When you start RHEL installation using the
inst.dd option on the Kernel command line with a driver disk, the console fails to display the user input. Consequently, it appears that the application does not respond to the user input and freezes, but displays the output which is confusing for users. However, this behavior does not affect the functionality, and user input gets registered after pressing
As a workaround, to see the expected results, ignore the absence of user inputs in the console and press
Enter when you finish adding inputs.
OpenSSL does not detect if a PKCS #11 token supports the creation of raw RSA or RSA-PSS signatures
The TLS 1.3 protocol requires support for RSA-PSS signatures. If a PKCS #11 token does not support raw RSA or RSA-PSS signatures, server applications that use the OpenSSL library fail to work with an RSA key if the key is held by the PKCS #11 token. As a result, TLS communication fails in the described scenario.
To work around this problem, configure servers and clients to use TLS version 1.2 as the highest TLS protocol version available.
OpenSSL incorrectly handles PKCS #11 tokens that does not support raw RSA or RSA-PSS signatures
OpenSSL library does not detect key-related capabilities of PKCS #11 tokens. Consequently, establishing a TLS connection fails when a signature is created with a token that does not support raw RSA or RSA-PSS signatures.
To work around the problem, add the following lines after the
.include line at the end of the
crypto_policy section in the
SignatureAlgorithms = RSA+SHA256:RSA+SHA512:RSA+SHA384:ECDSA+SHA256:ECDSA+SHA512:ECDSA+SHA384 MaxProtocol = TLSv1.2
As a result, a TLS connection can be established in the described scenario.
With a specific syntax,
scp empties files copied to themselves
scp utility changed from the Secure copy protocol (SCP) to the more secure SSH file transfer protocol (SFTP). Consequently, copying a file from a location to the same location erases the file content. The problem affects the following syntax:
scp localhost:/myfile localhost:/myfile
To work around this problem, do not copy files to a destination that is the same as the source location using this syntax.
The problem has been fixed for the following syntaxes:
scp /myfile localhost:/myfile
scp localhost:~/myfile ~/myfile
The OSCAP Anaconda add-on does not fetch tailored profiles in the graphical installation
The OSCAP Anaconda add-on does not provide an option to select or deselect tailoring of security profiles in the RHEL graphical installation. Starting from RHEL 8.8, the add-on does not take tailoring into account by default when installing from archives or RPM packages. Consequently, the installation displays the following error message instead of fetching an OSCAP tailored profile:
There was an unexpected problem with the supplied content.
To work around this problem, you must specify paths in the
%addon org_fedora_oscap section of your Kickstart file, for example:
xccdf-path = /usr/share/xml/scap/sc_tailoring/ds-combined.xml tailoring-path = /usr/share/xml/scap/sc_tailoring/tailoring-xccdf.xml
As a result, you can use the graphical installation for OSCAP tailored profiles only with the corresponding Kickstart specifications.
Ansible remediations require additional collections
With the replacement of Ansible Engine by the
ansible-core package, the list of Ansible modules provided with the RHEL subscription is reduced. As a consequence, running remediations that use Ansible content included within the
scap-security-guide package requires collections from the
For an Ansible remediation, perform the following steps:
Install the required packages:
# dnf install -y ansible-core scap-security-guide rhc-worker-playbook
Navigate to the
# cd /usr/share/scap-security-guide/ansible
Run the relevant Ansible playbook using environment variables that define the path to the additional Ansible collections:
# ANSIBLE_COLLECTIONS_PATH=/usr/share/rhc-worker-playbook/ansible/collections/ansible_collections/ ansible-playbook -c local -i localhost, rhel9-playbook-cis_server_l1.yml
cis_server_l1with the ID of the profile against which you want to remediate the system.
As a result, the Ansible content is processed correctly.
Support of the collections provided in
rhc-worker-playbook is limited to enabling the Ansible content sourced in
Keylime does not accept concatenated PEM certificates
When Keylime receives a certificate chain as multiple certificates in the PEM format concatenated in a single file, the
keylime-agent-rust Keylime component does not correctly use all the provided certificates during signature verification, resulting in a TLS handshake failure. As a consequence, the client components (
keylime_tenant) cannot connect to the Keylime agent. To work around this problem, use just one certificate instead of multiple certificates.
Keylime requires a specific file for
tls_dir = default
tls_dir variable is set to
default in Keylime verifier or registrar configuration, Keylime checks for the presence of the
cacert.crt file in the
/var/lib/keylime/cv_ca directory. If the file is not present, the
keylime_registrar service fails to start and records the following message in a log:
Exception: It appears that the verifier has not yet created a CA and certificates, please run the verifier first. As a consequence, Keylime rejects custom certificate authority (CA) certificates that have a different file name even when they are placed in the
To work around this problem and use custom CA certificates, manually specify
tls_dir =/var/lib/keylime/ca_cv instead of using
tls_dir = default.
Keylime refuses runtime policies whose digests start with a backslash
The current script for generating runtime policies,
create_runtime_policy.sh, uses SHA checksum functions, for example,
sha256sum, to compute the file digest. However, when the input file name contains a backslash or
\n, the checksum function adds a backslash before the digest in its output. In such cases, the generated policy file is malformed. When provided with the malformed policy file, the Keylime tenant produces the following or similar error message:
me.tenant - ERROR - Response code 400: Runtime policy is malformatted. To work around the problem, remove the backslash from the malformed policy file manually by entering the following command:
sed -i 's/^\\//g' <malformed_file_name>.
Keylime agent rejects requests from the verifier after update
When the API version number of the Keylime agent (
keylime-agent-rust) has been updated, the agent rejects requests that use a different version. As a consequence, if a Keylime agent is added to a verifier and then updated, the verifier tries to contact the agent using the old API version. The agent rejects this request and fails the attestation. To work around this problem, update the verifier (
keylime-verifier) before updating the agent (
keylime-agent-rust). As a result, when the agents are updated, the verifier detects the API change and updates its stored data accordingly.
fapolicyd utility incorrectly allows executing changed files
Correctly, the IMA hash of a file should update after any change to the file, and
fapolicyd should prevent execution of the changed file. However, this does not happen due to differences in IMA policy setup and in file hashing by the
evctml utility. As a result, the IMA hash is not updated in the extended attribute of a changed file. Consequently,
fapolicyd incorrectly allows the execution of the changed file.
Default SELinux policy allows unconfined executables to make their stack executable
The default state of the
selinuxuser_execstack boolean in the SELinux policy is on, which means that unconfined executables can make their stack executable. Executables should not use this option, and it might indicate poorly coded executables or a possible attack. However, due to compatibility with other tools, packages, and third-party products, Red Hat cannot change the value of the boolean in the default policy. If your scenario does not depend on such compatibility aspects, you can turn the boolean off in your local policy by entering the command
setsebool -P selinuxuser_execstack off.
SSH timeout rules in STIG profiles configure incorrect options
An update of OpenSSH affected the rules in the following Defense Information Systems Agency Security Technical Implementation Guide (DISA STIG) profiles:
DISA STIG for RHEL 9 (
DISA STIG with GUI for RHEL 9 (
In each of these profiles, the following two rules are affected:
Title: Set SSH Client Alive Count Max to zero CCE Identifier: CCE-90271-8 Rule ID: xccdf_org.ssgproject.content_rule_sshd_set_keepalive_0 Title: Set SSH Idle Timeout Interval CCE Identifier: CCE-90811-1 Rule ID: xccdf_org.ssgproject.content_rule_sshd_set_idle_timeout
When applied to SSH servers, each of these rules configures an option (
ClientAliveInterval) that no longer behaves as previously. As a consequence, OpenSSH no longer disconnects idle SSH users when it reaches the timeout configured by these rules. As a workaround, these rules have been temporarily removed from the DISA STIG for RHEL 9 and DISA STIG with GUI for RHEL 9 profiles until a solution is developed.
GnuPG incorrectly allows using SHA-1 signatures even if disallowed by
The GNU Privacy Guard (GnuPG) cryptographic software can create and verify signatures that use the SHA-1 algorithm regardless of the settings defined by the system-wide cryptographic policies. Consequently, you can use SHA-1 for cryptographic purposes in the
DEFAULT cryptographic policy, which is not consistent with the system-wide deprecation of this insecure algorithm for signatures.
To work around this problem, do not use GnuPG options that involve SHA-1. As a result, you will prevent GnuPG from lowering the default system security by using the non-secure SHA-1 signatures.
OpenSCAP memory-consumption problems
On systems with limited memory, the OpenSCAP scanner might terminate prematurely or it might not generate the results files. To work around this problem, you can customize the scanning profile to deselect rules that involve recursion over the entire
/ file system:
For more details and more workarounds, see the related Knowledgebase article.
11.3. RHEL for Edge
open-vm-tools package is not available in the
open-vm-tools package is not installed by default in the
edge-vsphere image. To workaround this issue, include the package in the blueprint customization. When using the
edge-vsphere image type, add the
open-vm-tools in the blueprint for the RHEL for Edge Container image or the RHEL for Edge Commit image.
11.4. Software management
The Installation process sometimes becomes unresponsive
When you install RHEL, the installation process sometimes becomes unresponsive. The
/tmp/packaging.log file displays the following message at the end:
10:20:56,416 DDEBUG dnf: RPM transaction over.
To workaround this problem, restart the installation process.
createrepo_c on local repositories generates duplicate
When you run the
createrepo_c command on local repositories, it generates duplicate copies of
repodata files, one of the copies is compressed and one is not. There is no workaround available, however, you can safely ignore the duplicate files. The
createrepo_c command generates duplicate copies because of requirements and differences in other tools relying on repositories created by using
11.5. Shells and command-line tools
Renaming network interfaces using
ifcfg files fails
On RHEL 9, the
initscripts package is not installed by default. Consequently, renaming network interfaces using
ifcfg files fails. To solve this problem, Red Hat recommends that you use
udev rules or link files to rename interfaces. For further details, see Consistent network interface device naming and the
systemd.link(5) man page.
If you cannot use one of the recommended solutions, install the
chkconfig package is not installed by default in RHEL 9
chkconfig package, which updates and queries runlevel information for system services, is not installed by default in RHEL 9.
To manage services, use the
systemctl commands or install the
chkconfig package manually.
Setting the console
keymap requires the
libxkbcommon library on your minimal install
In RHEL 9, certain
systemd library dependencies have been converted from dynamic linking to dynamic loading, so that your system opens and uses the libraries at runtime when they are available. With this change, a functionality that depends on such libraries is not available unless you install the necessary library. This also affects setting the keyboard layout on systems with a minimal install. As a result, the
localectl --no-convert set-x11-keymap gb command fails.
To work around this problem, install the
# dnf install libxkbcommon
%vmeff metric from the
sysstat package displays incorrect values
sysstat package provides the
%vmeff metric to measure the page reclaim efficiency. The values of the
%vmeff column returned by the
sar -B command are incorrect because
sysstat does not parse all relevant
/proc/vmstat values provided by later kernel versions. To work around this problem, you can calculate the
%vmeff value manually from the
/proc/vmstat file. For details, see Why the
sar(1) tool reports
%vmeff values beyond 100 % in RHEL 8 and RHEL 9?
The Service Location Protocol (SLP) is vulnerable to an attack through UDP
The OpenSLP provides a dynamic configuration mechanism for applications in local area networks, such as printers and file servers. However, SLP is vulnerable to a reflective denial of service amplification attack through UDP on systems connected to the internet. SLP allows an unauthenticated attacker to register new services without limits set by the SLP implementation. By using UDP and spoofing the source address, an attacker can request the service list, creating a Denial of Service on the spoofed address.
To prevent external attackers from accessing the SLP service, disable SLP on all systems running on untrusted networks, such as those directly connected to the internet. Alternatively, to work around this problem, configure firewalls to block or filter traffic on UDP and TCP port 427.
11.6. Infrastructure services
unbound disable validation of SHA-1-based signatures
unbound components disable validation support of all RSA/SHA1 (algorithm number 5) and RSASHA1-NSEC3-SHA1 (algorithm number 7) signatures, and the SHA-1 usage for signatures is restricted in the DEFAULT system-wide cryptographic policy.
As a result, certain DNSSEC records signed with the SHA-1, RSA/SHA1, and RSASHA1-NSEC3-SHA1 digest algorithms fail to verify in Red Hat Enterprise Linux 9 and the affected domain names become vulnerable.
To work around this problem, upgrade to a different signature algorithm, such as RSA/SHA-256 or elliptic curve keys.
For more information and a list of top-level domains that are affected and vulnerable, see the DNSSEC records signed with RSASHA1 fail to verify solution.
named fails to start if the same writable zone file is used in multiple zones
BIND does not allow the same writable zone file in multiple zones. Consequently, if a configuration includes multiple zones which share a path to a file that can be modified by the
named fails to start. To work around this problem, use the
in-view clause to share one zone between multiple views and make sure to use different paths for different zones. For example, include the view names in the path.
Note that writable zone files are typically used in zones with allowed dynamic updates, slave zones, or zones maintained by DNSSEC.
libotr is not compliant with FIPS
libotr library and toolkit for off-the-record (OTR) messaging provides end-to-end encryption for instant messaging conversations. However, the
libotr library does not conform to the Federal Information Processing Standards (FIPS) due to its use of the
gcry_pk_verify() functions. As a result, you cannot use the
libotr library in FIPS mode.
kTLS does not support offloading of TLS 1.3 to NICs
Kernel Transport Layer Security (kTLS) does not support offloading of TLS 1.3 to NICs. Consequently, software encryption is used with TLS 1.3 even when the NICs support TLS offload. To work around this problem, disable TLS 1.3 if offload is required. As a result, you can offload only TLS 1.2. When TLS 1.3 is in use, there is lower performance, since TLS 1.3 cannot be offloaded.
Failure to update the session key causes the connection to break
Kernel Transport Layer Security (kTLS) protocol does not support updating the session key, which is used by the symmetric cipher. Consequently, the user cannot update the key, which causes a connection break. To work around this problem, disable kTLS. As a result, with the workaround, it is possible to successfully update the session key.
initscripts package is not installed by default
By default, the
initscripts package is not installed. As a consequence, the
ifdown utilities are not available. As an alternative, use the
nmcli connection up and
nmcli connection down commands to enable and disable connections. If the suggested alternative does not work for you, report the problem and install the
NetworkManager-initscripts-updown package, which provides a NetworkManager solution for the
mlx5 driver fails while using the Mellanox
In Ethernet switch device driver model (
switchdev) mode, the
mlx5 driver fails when configured with the device managed flow steering (DMFS) parameter and
ConnectX-5 adapter supported hardware. As a consequence, you can see the following error message:
BUG: Bad page cache in process umount pfn:142b4b
To work around this problem, use the software managed flow steering (SMFS) parameter instead of DMFS.
i40e adapter permanently fails on IBM Power10
i40e adapter encounters an I/O error on IBM Power10 systems, the Enhanced I/O Error Handling (EEH) kernel services trigger the network driver’s reset and recovery. However, EEH repeatedly reports I/O errors until the
i40e driver reaches the predefined maximum of EEH freezes. As a consequence, EEH causes the device to fail permanently.
kdump mechanism in kernel causes
OOM errors on the 64K kernel
The 64K kernel page size on the 64-bit ARM architecture uses more memory than the 4KB kernel. Consequently,
kdump causes a kernel panic and memory allocation fails with out of memory (OOM) errors. As a work around, manually configure the
crashkernel value to 640 MB. For example, set the
crashkernel= parameter as
As a result, the
kdump mechanism does not fail on the 64K kernel in the described scenario.
Customer applications with dependencies on kernel page size may need updating when moving from 4k to 64k page size kernel
RHEL is compatible with both 4k and 64k page size kernels. Customer applications with dependencies on a 4k kernel page size may require updating when moving from 4k to 64k page size kernels. Known instances of this include
jemalloc and dependent applications.
jemalloc memory allocator library is sensitive to the page size used in the system’s runtime environment. The library can be built to be compatible with 4k and 64k page size kernels, for example, when configured with
env JEMALLOC_SYS_WITH_LG_PAGE=16 (for
jemallocator Rust crate). Consequently, a mismatch can occur between the page size of the runtime environment and the page size that was present when compiling binaries that depend on
jemalloc. As a result, using a
jemalloc-based application triggers the following error:
<jemalloc>: Unsupported system page size
To avoid this problem, use one of the following approaches:
- Use the appropriate build configuration or environment options to create 4k and 64k page size compatible binaries.
Build any userspace packages that use
jemallocafter booting into the final 64k kernel and runtime environment.
For example, you can build the
fd-find tool, which also uses
jemalloc, with the
cargo Rust package manager. In the final 64k environment, trigger a new build of all dependencies to resolve the mismatch in the page size by entering the
# cargo install fd-find --force
Upgrading to the latest real-time kernel with
dnf does not install multiple kernel versions in parallel
Installing the latest real-time kernel with the
dnf package manager requires resolving package dependencies to retain the new and current kernel versions simultaneously. By default,
dnf removes the older
kernel-rt package during the upgrade.
As a workaround, add the current
kernel-rt package to the
installonlypkgs option in the
/etc/yum.conf configuration file, for example,
installonlypkgs option appends
kernel-rt to the default list used by
dnf. Packages listed in
installonlypkgs directive are not removed automatically and therefore support multiple kernel versions to install simultaneously.
Note that having multiple kernels installed is a way to have a fallback option when working with a new kernel version.
Delay Accounting functionality does not display the
IO% statistics columns by default
Delayed Accounting functionality, unlike early versions, is disabled by default. Consequently, the
iotop application does not show the
IO% statistics columns and displays the following warning:
CONFIG_TASK_DELAY_ACCT not enabled in kernel, cannot determine SWAPIN and IO%
Delay Accounting functionality, using the
taskstats interface, provides the delay statistics for all tasks or threads that belong to a thread group. Delays in task execution occur when they wait for a kernel resource to become available, for example, a task waiting for a free CPU to run on. The statistics help in setting a task’s CPU priority, I/O priority, and
rss limit values appropriately.
As a workaround, you can enable the
delayacct boot option either at run time or boot.
delayacctat run time, enter:
echo 1 > /proc/sys/kernel/task_delayacct
Note that this command enables the feature system wide, but only for the tasks that you start after running this command.
delayacctpermanently at boot, use one of the following procedures:
/etc/sysctl.conffile to override the default parameters:
Add the following entry to the
kernel.task_delayacct = 1
For more information, see How to set sysctl variables on Red Hat Enterprise Linux.
- Reboot the system for changes to take effect.
delayacctoption to the kernel command line.
For more information, see Configuring kernel command-line parameters.
As a result, the
iotop application displays the
IO% statistics columns.
Hardware certification of the real-time kernel on systems with large core-counts might require passing the
skew-tick=1 boot parameter
Large or moderate sized systems with numerous sockets and large core-counts can experience latency spikes due to lock contentions on
xtime_lock, which is used in the timekeeping system. As a consequence, latency spikes and delays in hardware certifications might occur on multiprocessing systems. As a workaround, you can offset the timer tick per CPU to start at a different time by adding the
skew_tick=1 boot parameter.
To avoid lock conflicts, enable
# grubby --update-kernel=ALL --args="skew_tick=1"
- Reboot for changes to take effect.
Verify the new settings by displaying the kernel parameters you pass during boot.
Note that enabling
skew_tick=1 causes a significant increase in power consumption and, therefore, it must be enabled only if you are running latency sensitive real-time workloads.
kdump mechanism fails to capture the
vmcore file on LUKS-encrypted targets
kdump on systems with Linux Unified Key Setup (LUKS) encrypted partitions, systems require a certain amount of available memory. When the available memory is less than the required amount of memory, the
systemd-cryptsetup service fails to mount the partition. Consequently, the second kernel fails to capture the crash dump file on the LUKS-encrypted targets.
As a workaround, query the
Recommended crashkernel value and gradually increase the memory size to an appropriate value. The
Recommended crashkernel value can serve as reference to set the required memory size.
Print the estimate crash kernel value.
# kdumpctl estimate
Configure the amount of required memory by increasing the
# grubby --args=crashkernel=652M --update-kernel=ALL
Reboot the system for changes to take effect.
As a result,
kdump works correctly on systems with LUKS-encrypted partitions.
kdump service fails to build the
initrd file on IBM Z systems
On the 64-bit IBM Z systems, the
kdump service fails to load the initial RAM disk (
znet related configuration information such as
s390-subchannels reside in an inactive
NetworkManager connection profile. Consequently, the
kdump mechanism fails with the following error:
dracut: Failed to set up znet kdump: mkdumprd: failed to make kdump initrd
As a workaround, use one of the following solutions:
Configure a network bond or bridge by re-using the connection profile that has the
$ nmcli connection modify enc600 master bond0 slave-type bond
znetconfiguration information from the inactive connection profile to the active connection profile:
nmclicommand to query the
# nmcli connection show NAME UUID TYPE Device bridge-br0 ed391a43-bdea-4170-b8a2 bridge br0 bridge-slave-enc600 caf7f770-1e55-4126-a2f4 ethernet enc600 enc600 bc293b8d-ef1e-45f6-bad1 ethernet --
Update the active profile with configuration information from the inactive connection:
#!/bin/bash inactive_connection=enc600 active_connection=bridge-slave-enc600 for name in nettype subchannels options; do field=802-3-ethernet.s390-$name val=$(nmcli --get-values "$field"connection show "$inactive_connection") nmcli connection modify "$active_connection" "$field" $val" done
kdumpservice for changes to take effect:
# kdumpctl restart
iwl7260-firmware breaks Wi-Fi on Intel Wi-Fi 6 AX200, AX210, and Lenovo ThinkPad P1 Gen 4
After updating the
iwl7260-wifi driver to the version provided by RHEL 9.1 and later, the hardware gets into an incorrect internal state. reports its state incorrectly. Consequently, Intel Wifi 6 cards may not work and display the error message:
kernel: iwlwifi 0000:09:00.0: Failed to start RT ucode: -110 kernel: iwlwifi 0000:09:00.0: WRT: Collecting data: ini trigger 13 fired (delay=0ms) kernel: iwlwifi 0000:09:00.0: Failed to run INIT ucode: -110
An unconfirmed work around is to power off the system and back on again. Do not reboot.
kmod fails to work with module inter-dependencies
weak-modules script provided by the
kmod package determines which modules are kABI-compatible with installed kernels. However, while checking modules' kernel compatibility,
weak-modules processes modules symbol dependencies from higher to lower release of the kernel for which they were built. As a consequence, modules with inter-dependencies built against different kernel releases might be interpreted as non-compatible, and therefore the
weak-modules script fails to work in this scenario.
To work around the problem, build or put the extra modules against the latest stock kernel before you install the new kernel.
11.9. File systems and storage
Anaconda fails to login iSCSI server using the
no authentication method after unsuccessful CHAP authentication attempt
When you add iSCSI discs using CHAP authentication and the login attempt fails due to incorrect credentials, a relogin attempt to the discs with the
no authentication method fails. To workaround this problem, close the current session and login using the
no authentication method.
Device Mapper Multipath is not supported with NVMe/TCP
Using Device Mapper Multipath with the
nvme-tcp driver can result in the Call Trace warnings and system instability. To work around this problem, NVMe/TCP users must enable native NVMe multipathing and not use the
device-mapper-multipath tools with NVMe.
By default, Native NVMe multipathing is enabled in RHEL 9. For more information, see Enabling multipathing on NVMe devices.
blk-availability systemd service deactivates complex device stacks
systemd, the default block deactivation code does not always handle complex stacks of virtual block devices correctly. In some configurations, virtual devices might not be removed during the shutdown, which causes error messages to be logged. To work around this problem, deactivate complex block device stacks by executing the following command:
# systemctl enable --now blk-availability.service
As a result, complex virtual device stacks are correctly deactivated during shutdown and do not produce error messages.
Disabling quota accounting is no longer possible for an XFS filesystem mounted with quotas enabled
Starting with RHEL 9.2, it is no longer possible to disable quota accounting on an XFS filesystem which has been mounted with quotas enabled.
To work around this issue, disable quota accounting by remounting the filesystem, with the quota option removed.
System fails to boot when adding an NVMe-FC device as a mount point in
The Non-volatile Memory Express over Fibre Channel (NVMe-FC) devices mounted through the
/etc/fstab file fails to mount at boot and the system enters into emergency mode. This is due to a known bug in the
nvme-cli nvmf-autoconnect systemd services.
udev rule change for NVMe devices
There is a udev rule change for NVMe devices that adds
OPTIONS="string_escape=replace" parameter. This leads to a disk by-id naming change for some vendors, if the serial number of your device has leading whitespace.
NVMe/FC devices cannot be reliably used in a kickstart file
NVMe/FC devices can be unavailable during parsing or execution of pre-scripts of the kickstart file, which can cause the kickstart installation to fail. To work around this issue, update the boot argument to
inst.wait_for_disks=30. This option causes a delay of 30 seconds, and should provide enough time for the NVMe/FC device to connect. With this workaround along with the NVMe/FC devices connecting in time, the kickstart installation proceeds without issues.
Kernel panic while using the
While using the
qedi iSCSI driver, the kernel panics after OS boots. To work around this issue, disable the
kfence runtime memory error detector feature by adding
kfence.sample_interval=0 to the kernel boot command line.
Unable to boot ARM based system with Kernel-64k page size
While installing the
vdo package, a kernel with 4k page size is installed as a dependency. As a consequence, the system boots with the 4k page size kernel even if you select 64k page size on the Software Selection screen. To work around this issue, select Minimal Install under Base Environment and 64k as page size under Kernel options. When the system boots for the first time, install additional softwares using the DNF package manager.
11.10. Dynamic programming languages, web and database servers
python3.11-lxml does not provide the
python3.11-lxml package is distributed without the
lxml.isoschematron submodule because it is not under an open source license. The submodule implements ISO Schematron support. As an alternative, pre-ISO-Schematron validation is available in the
lxml.etree.Schematron class. The remaining content of the
python3.11-lxml package is unaffected.
--ssl-fips-mode option in
MariaDB does not change FIPS mode
--ssl-fips-mode option in
MariaDB in RHEL works differently than in upstream.
In RHEL 9, if you use
--ssl-fips-mode as an argument for the
mariadbd daemon, or if you use
ssl-fips-mode in the
MariaDB server configuration files,
--ssl-fips-mode does not change FIPS mode for these database servers.
If you set
mariadbdserver daemon does not start.
If you set
OFFon a FIPS-enabled system, the
mariadbdserver daemons still run in FIPS mode.
This is expected because FIPS mode should be enabled or disabled for the whole RHEL system, not for specific components.
Therefore, do not use the
--ssl-fips-mode option in
MariaDB in RHEL. Instead, ensure FIPS mode is enabled on the whole RHEL system:
- Preferably, install RHEL with FIPS mode enabled. Enabling FIPS mode during the installation ensures that the system generates all keys with FIPS-approved algorithms and continuous monitoring tests in place. For information about installing RHEL in FIPS mode, see Installing the system in FIPS mode.
- Alternatively, you can switch FIPS mode for the entire RHEL system by following the procedure in Switching the system to FIPS mode.
11.11. Identity Management
MIT Kerberos does not support ECC certificates for PKINIT
MIT Kerberos does not implement the RFC5349 request for comments document, which describes the design of elliptic-curve cryptography (ECC) support in Public Key Cryptography for initial authentication (PKINIT). Consequently, the MIT
krb5-pkinit package, used by RHEL, does not support ECC certificates. For more information, see Elliptic Curve Cryptography (ECC) Support for Public Key Cryptography for Initial Authentication in Kerberos (PKINIT).
The DEFAULT:SHA1 subpolicy has to be set on RHEL 9 clients for PKINIT to work against AD KDCs
The SHA-1 digest algorithm has been deprecated in RHEL 9, and CMS messages for Public Key Cryptography for initial authentication (PKINIT) are now signed with the stronger SHA-256 algorithm.
However, the Active Directory (AD) Kerberos Distribution Center (KDC) still uses the SHA-1 digest algorithm to sign CMS messages. As a result, RHEL 9 Kerberos clients fail to authenticate users by using PKINIT against an AD KDC.
To work around the problem, enable support for the SHA-1 algorithm on your RHEL 9 systems with the following command:
# update-crypto-policies --set DEFAULT:SHA1
The PKINIT authentication of a user fails if a RHEL 9 Kerberos agent communicates with a non-RHEL-9 and non-AD Kerberos agent
If a RHEL 9 Kerberos agent, either a client or Kerberos Distribution Center (KDC), interacts with a non-RHEL-9 Kerberos agent that is not an Active Directory (AD) agent, the PKINIT authentication of the user fails. To work around the problem, perform one of the following actions:
Set the RHEL 9 agent’s crypto-policy to
DEFAULT:SHA1to allow the verification of SHA-1 signatures:
# update-crypto-policies --set DEFAULT:SHA1
Update the non-RHEL-9 and non-AD agent to ensure it does not sign CMS data using the SHA-1 algorithm. For this, update your Kerberos client or KDC packages to the versions that use SHA-256 instead of SHA-1:
- CentOS 9 Stream: krb5-1.19.1-15
- RHEL 8.7: krb5-1.18.2-17
- RHEL 7.9: krb5-1.15.1-53
- Fedora Rawhide/36: krb5-1.19.2-7
- Fedora 35/34: krb5-1.19.2-3
As a result, the PKINIT authentication of the user works correctly.
Note that for other operating systems, it is the krb5-1.20 release that ensures that the agent signs CMS data with SHA-256 instead of SHA-1.
FIPS support for AD trust requires the AD-SUPPORT crypto subpolicy
Active Directory (AD) uses AES SHA-1 HMAC encryption types, which are not allowed in FIPS mode on RHEL 9 by default. If you want to use RHEL 9 IdM hosts with an AD trust, enable support for AES SHA-1 HMAC encryption types before installing IdM software.
Since FIPS compliance is a process that involves both technical and organizational agreements, consult your FIPS auditor before enabling the
AD-SUPPORT subpolicy to allow technical measures to support AES SHA-1 HMAC encryption types, and then install RHEL IdM:
# update-crypto-policies --set FIPS:AD-SUPPORT
Heimdal client fails to authenticate a user using PKINIT against RHEL 9 KDC
By default, a Heimdal Kerberos client initiates the PKINIT authentication of an IdM user by using Modular Exponential (MODP) Diffie-Hellman Group 2 for Internet Key Exchange (IKE). However, the MIT Kerberos Distribution Center (KDC) on RHEL 9 only supports MODP Group 14 and 16.
Consequently, the pre-autentication request fails with the
krb5_get_init_creds: PREAUTH_FAILED error on the Heimdal client and
Key parameters not accepted on the RHEL MIT KDC.
To work around this problem, ensure that the Heimdal client uses MODP Group 14. Set the
pkinit_dh_min_bits parameter in the
libdefaults section of the client configuration file to 1759:
[libdefaults] pkinit_dh_min_bits = 1759
As a result, the Heimdal client completes the PKINIT pre-authentication against the RHEL MIT KDC.
IdM in FIPS mode does not support using the NTLMSSP protocol to establish a two-way cross-forest trust
Establishing a two-way cross-forest trust between Active Directory (AD) and Identity Management (IdM) with FIPS mode enabled fails because the New Technology LAN Manager Security Support Provider (NTLMSSP) authentication is not FIPS-compliant. IdM in FIPS mode does not accept the RC4 NTLM hash that the AD domain controller uses when attempting to authenticate.
IdM Vault encryption and decryption fails in FIPS mode
The OpenSSL RSA-PKCS1v15 padding encryption is blocked if FIPS mode is enabled. Consequently, Identity Management (IdM) Vaults fail to work correctly as IdM is currently using the PKCS1v15 padding for wrapping the session key with the transport certificate.
Users without SIDs cannot log in to IdM after an upgrade
After upgrading your IdM replica to RHEL 9.2, the IdM Kerberos Distribution Centre (KDC) might fail to issue ticket-granting tickets (TGTs) to users who do not have Security Identifiers (SIDs) assigned to their accounts. Consequently, the users cannot log in to their accounts.
To work around the problem, generate SIDs by running the following command as an IdM administrator on another IdM replica in the topology:
# ipa config-mod --enable-sid --add-sids
Afterward, if users still cannot log in, examine the Directory Server error log. You might have to adjust ID ranges to include user POSIX identities.
See the When upgrading to RHEL9, IDM users are not able to login anymore Knowledgebase solution for more information.
Migrated IdM users might be unable to log in due to mismatching domain SIDs
If you have used the
ipa migrate-ds script to migrate users from one IdM deployment to another, those users might have problems using IdM services because their previously existing Security Identifiers (SIDs) do not have the domain SID of the current IdM environment. For example, those users can retrieve a Kerberos ticket with the
kinit utility, but they cannot log in. To work around this problem, see the following Knowledgebase article: Migrated IdM users unable to log in due to mismatching domain SIDs.
krb5 user fails to obtain an AD TGT because of incompatible encryption types generating the user PAC
krb5 1.20 and later packages, a Privilege Attribute Certificate (PAC) is included in all Kerberos tickets by default. The MIT Kerberos Distribution Center (KDC) selects the strongest encryption type available to generate the KDC checksum in the PAC, which currently is the
AES HMAC-SHA2 encryption types defined in RFC8009. However, Active Directory (AD) does not support this RFC. Consequently, in an AD-MIT cross-realm setup, an MIT
krb5 user fails to obtain an AD ticket-granting ticket (TGT) because the cross-realm TGT generated by MIT KDC contains an incompatible KDC checksum type in the PAC.
To work around the problem, set the
disable_pac parameter to
true for the MIT realm in the
[realms] section of the
/var/kerberos/krb5kdc/kdc.conf configuration file. As a result, the MIT KDC generates tickets without PAC, which means that AD skips the failing checksum verification and an MIT
krb5 user can obtain an AD TGT.
Potential risk when using the default value for
ldap:// without TLS for identity lookups, it can pose a risk for an attack vector. Particularly a man-in-the-middle (MITM) attack which could allow an attacker to impersonate a user by altering, for example, the UID or GID of an object returned in an LDAP search.
Currently, the SSSD configuration option to enforce TLS,
ldap_id_use_start_tls, defaults to
false. Ensure that your setup operates in a trusted environment and decide if it is safe to use unencrypted communication for
id_provider = ldap. Note
id_provider = ad and
id_provider = ipa are not affected as they use encrypted connections protected by SASL and GSSAPI.
If it is not safe to use unencrypted communication, enforce TLS by setting the
ldap_id_use_start_tls option to
true in the
/etc/sssd/sssd.conf file. The default behavior is planned to be changed in a future release of RHEL.
Adding a RHEL 9 replica in FIPS mode to an IdM deployment in FIPS mode that was initialized with RHEL 8.6 or earlier fails
The default RHEL 9 FIPS cryptographic policy aiming to comply with FIPS 140-3 does not allow the use of the AES HMAC-SHA1 encryption types' key derivation function as defined by RFC3961, section 5.1.
This constraint is a blocker when adding a RHEL 9 Identity Management (IdM) replica in FIPS mode to a RHEL 8 IdM environment in FIPS mode in which the first server was installed on a RHEL 8.6 system or earlier. This is because there are no common encryption types between RHEL 9 and the previous RHEL versions, which commonly use the AES HMAC-SHA1 encryption types but do not use the AES HMAC-SHA2 encryption types.
You can view the encryption type of your IdM master key by entering the following command on the server:
# kadmin.local getprinc K/M | grep -E '^Key:'
To work around the problem, enable the use of AES HMAC-SHA1 on the RHEL 9 replica:
update-crypto-policies --set FIPS:AD-SUPPORT
- This workaround might violate FIPS compliance.
As a result, adding the RHEL 9 replica to the IdM deployment proceeds correctly.
Note that there is ongoing work to provide a procedure to generate missing AES HMAC-SHA2-encrypted Kerberos keys on RHEL 7 and RHEL 8 servers. This will achieve FIPS 140-3 compliance on the RHEL 9 replica. However, this process will not be fully automated, because the design of Kerberos key cryptography makes it impossible to convert existing keys to different encryption types. The only way is to ask users to renew their passwords.
SSSD registers the DNS names properly
Previously, if the DNS was set up incorrectly, SSSD always failed the first attempt to register the DNS name. To work around the problem, this update provides a new parameter
dns_resolver_use_search_list = false to avoid using the DNS search list.
Installing a RHEL 7 IdM client with a RHEL 9.2+ IdM server in FIPS mode fails due to EMS enforcement
Extended Master Secret (EMS) extension (RFC 7627) is now mandatory for TLS 1.2 connections on FIPS-enabled RHEL 9.2 and later systems. This is in accordance with FIPS-140-3 requirements. However, the
openssl version available in RHEL 7.9 and lower does not support EMS. In consequence, installing a RHEL 7 Identity Management (IdM) client with a FIPS-enabled IdM server running on RHEL 9.2 and later fails.
If upgrading the host to RHEL 8 before installing an IdM client on it is not an option, work around the problem by removing the requirement for EMS usage on the RHEL 9 server by applying a NO-ENFORCE-EMS subpolicy on top of the FIPS crypto policy:
# update-crypto-policies --set FIPS:NO-ENFORCE-EMS
Note that this removal goes against the FIPS 140-3 requirements. As a result, you can establish and accept TLS 1.2 connections that do not use EMS, and the installation of a RHEL 7 IdM client succeeds.
nsslapd-numlisteners attribute value is more than
2, Directory Server fails
nsslapd-numlisteners attribute value is higher than
2, Directory Server might close the listening file descriptor instead of the accepted file descriptor. As a result, after some time, Directory Server stops listening on some ports and fails.
To work around the problem, set the
nsslapd-numlisteners attribute value to
VNC is not running after upgrading to RHEL 9
After upgrading from RHEL 8 to RHEL 9, the VNC server fails to start, even if it was previously enabled.
To work around the problem, manually enable the
vncserver service after the system upgrade:
# systemctl enable --now vncserver@:port-number
As a result, VNC is now enabled and starts after every system boot as expected.
User Creation screen is unresponsive
When installing RHEL using a graphical user interface, the User Creation screen is unresponsive. As a consequence, creating users during installation is more difficult.
To work around this problem, use one of the following solutions to create users:
- Run the installation in VNC mode and resize the VNC window.
- Create users after completing the installation process.
WebKitGTK fails to display web pages on IBM Z
The WebKitGTK web browser engine fails when trying to display web pages on the IBM Z architecture. The web page remains blank and the WebKitGTK process terminates unexpectedly.
As a consequence, you cannot use certain features of applications that use WebKitGTK to display web pages, such as the following:
- The Evolution mail client
- The GNOME Online Accounts settings
- The GNOME Help application
11.13. Graphics infrastructures
NVIDIA drivers might revert to X.org
Under certain conditions, the proprietary NVIDIA drivers disable the Wayland display protocol and revert to the X.org display server:
- If the version of the NVIDIA driver is lower than 470.
- If the system is a laptop that uses hybrid graphics.
- If you have not enabled the required NVIDIA driver options.
Additionally, Wayland is enabled but the desktop session uses X.org by default if the version of the NVIDIA driver is lower than 510.
Night Light is not available on Wayland with NVIDIA
When the proprietary NVIDIA drivers are enabled on your system, the Night Light feature of GNOME is not available in Wayland sessions. The NVIDIA drivers do not currently support Night Light.
X.org configuration utilities do not work under Wayland
X.org utilities for manipulating the screen do not work in the Wayland session. Notably, the
xrandr utility does not work under Wayland due to its different approach to handling, resolutions, rotations, and layout.
11.14. Red Hat Enterprise Linux System Roles
firewalld.service is masked, using the
firewall RHEL System Role fails
firewalld.service is masked on a RHEL system, the
firewall RHEL System Role fails. To work around this problem, unmask the
systemctl unmask firewalld.service
Unable to register systems with environment names
rhc system role fails to register the system when specifying environment names in
rhc_environment. As a workaround, use environment IDs instead of environment names while registering.
Installing a virtual machine over https or ssh in some cases fails
virt-install utility fails when attempting to install a guest operating system (OS) from an ISO source over a https or ssh connection - for example using
virt-install --cdrom https://example/path/to/image.iso. Instead of creating a virtual machine (VM), the described operation terminates unexpectedly with an
internal error: process exited while connecting to monitor message.
Similarly, using the RHEL 9 web console to install a guest OS fails and displays an
Unknown driver 'https' error if you use an https or ssh URL, or the
Download OS function.
To work around this problem, install
qemu-kvm-block-ssh on the host to enable https and ssh protocol support, respectively. Alternatively, use a different connection protocol or a different installation source.
Using NVIDIA drivers in virtual machines disables Wayland
Currently, NVIDIA drivers are not compatible with the Wayland graphical session. As a consequence, RHEL guest operating systems that use NVIDIA drivers automatically disable Wayland and load an Xorg session instead. This primarily occurs in the following scenarios:
- When you pass through an NVIDIA GPU device to a RHEL virtual machine (VM)
- When you assign an NVIDIA vGPU mediated device to a RHEL VM
Milan VM CPU type is sometimes not available on AMD Milan systems
On certain AMD Milan systems, the Enhanced REP MOVSB (
erms) and Fast Short REP MOVSB (
fsrm) feature flags are disabled in the BIOS by default. Consequently, the
Milan CPU type might not be available on these systems. In addition, VM live migration between Milan hosts with different feature flag settings might fail. To work around these problems, manually turn on
fsrm in the BIOS of your host.
hostdev interface with failover settings cannot be hot-plugged after being hot-unplugged
After removing a
hostdev network interface with failover configuration from a running virtual machine (VM), the interface currently cannot be re-attached to the same running VM.
Live post-copy migration of VMs with failover VFs fails
Currently, attempting to post-copy migrate a running virtual machine (VM) fails if the VM uses a device with the virtual function (VF) failover capability enabled. To work around the problem, use the standard migration type, rather than post-copy migration.
Host network cannot ping VMs with VFs during live migration
When live migrating a virtual machine (VM) with a configured virtual function (VF), such as a VMs that uses virtual SR-IOV software, the network of the VM is not visible to other devices and the VM cannot be reached by commands such as
ping. After the migration is finished, however, the problem no longer occurs.
Disabling AVX causes VMs to become unbootable
On a host machine that uses a CPU with Advanced Vector Extensions (AVX) support, attempting to boot a VM with AVX explicitly disabled currently fails, and instead triggers a kernel panic in the VM.
Windows VM fails to get IP address after network interface reset
Sometimes, Windows virtual machines fail to get an IP address after an automatic network interface reset. As a consequence, the VM fails to connect to the network. To work around this problem, disable and re-enable the network adapter driver in the Windows Device Manager.
Windows Server 2016 VMs sometimes stops working after hot-plugging a vCPU
Currently, assigning a vCPU to a running virtual machine (VM) with a Windows Server 2016 guest operating system might cause a variety of problems, such as the VM terminating unexpectedly, becoming unresponsive, or rebooting.
Using a large number of queues might cause VMs to fail
Virtual machines (VMs) might fail when the virtual Trusted Platform Module (vTPM) device is enabled and the multi-queue virtio-net feature is configured to use more than 250 queues.
This problem is caused by a limitation in the vTPM device. The vTPM device has a hardcoded limit on the maximum number of opened file descriptors. Since multiple file descriptors are opened for every new queue, the internal vTPM limit can be exceeded, causing the VM to fail.
To work around this problem, choose one of the following two options:
- Keep the vTPM device enabled, but use less than 250 queues.
- Disable the vTPM device to use more than 250 queues.
Redundant error messages on VMs with NVIDIA passthrough devices
When using an Intel host machine with a RHEL 9.2 and later operating system, virtual machines (VMs) with a passed through NVDIA GPU device frequently log the following error message:
Spurious APIC interrupt (vector 0xFF) on CPU#2, should never happen.
However, this error message does not impact the functionality of the VM and can be ignored. For details, see the Red Hat KnoweldgeBase.
Some Windows guests fail to boot after a v2v conversion on hosts with AMD EPYC CPUs
After using the
virt-v2v utility to convert a virtual machine (VM) that uses Windows 11 or a Windows Server 2022 as the guest OS, the VM currently fails to boot. This occurs on hosts that use AMD EPYC series CPUs.
Restarting the OVS service on a host might block network connectivity on its running VMs
When the Open vSwitch (OVS) service restarts or crashes on a host, virtual machines (VMs) that are running on this host cannot recover the state of the networking device. As a consequence, VMs might be completely unable to receive packets.
This problem only affects systems that use the packed virtqueue format in their
virtio networking stack.
To work around this problem, use the
packed=off parameter in the
virtio networking device definition to disable packed virtqueue. With packed virtqueue disabled, the state of the networking device can, in some situations, be recovered from RAM.
Recovering an interrupted post-copy VM migration might fail
If a post-copy migration of a virtual machine (VM) is interrupted and then immediately resumed on the same incoming port, the migration might fail with the following error:
Address already in use
To work around this problem, wait at least 10 seconds before resuming the post-copy migration or switch to another port for migration recovery.
NUMA node mapping not working correctly on AMD EPYC CPUs
QEMU does not handle NUMA node mapping on AMD EPYC CPUs correctly. As a result, the performance of virtual machines (VMs) with these CPUs might be negatively impacted if using a NUMA node configuration. In addition, the VMs display a warning similar to the following during boot.
sched: CPU #4's llc-sibling CPU #3 is not on the same node! [node: 1 != 0]. Ignoring dependency. WARNING: CPU: 4 PID: 0 at arch/x86/kernel/smpboot.c:415 topology_sane.isra.0+0x6b/0x80
To work around this issue, do not use AMD EPYC CPUs for NUMA node configurations.
NFS failure during VM migration causes migration failure and source VM coredump
Currently, if the NFS service or server is shut down during virtual machine (VM) migration, the source VM’s QEMU is unable to reconnect to the NFS server when it starts running again. As a result, the migration fails and a coredump is initiated on the source VM. Currently, there is no workaround available.
PCIe ATS devices do not work on Windows VMs
When you configure a PCIe Address Translation Services (ATS) device in the XML configuration of virtual machine (VM) with a Windows guest operating system, the guest does not enable the ATS device after booting the VM. This is because Windows currently does not support ATS on
For more information, see the Red Hat KnowledgeBase.
virsh blkiotune --weight command fails to set the correct cgroup I/O controller value
Currently, using the
virsh blkiotune --weight command to set the VM weight does not work as expected. The command fails to set the correct
io.bfq.weight value in the cgroup I/O controller interface file. There is no workaround at this time.
Starting a VM with an NVIDIA A16 GPU sometimes causes the host GPU to stop working
Currently, if you start a VM that uses an NVIDIA A16 GPU passthrough device, the NVIDIA A16 GPU physical device on the host system in some cases stops working.
To work around the problem, reboot the hypervisor and set the
reset_method for the GPU device to
# echo bus > /sys/bus/pci/devices/<DEVICE-PCI-ADDRESS>/reset_method # cat /sys/bus/pci/devices/<DEVICE-PCI-ADDRESS>/reset_method bus
For details, see the Red Hat Knowledgebase.
Windows VMs might become unresponsive due to storage errors
On virtual machines (VMs) that use Windows guest operating systems, the system in some cases becomes unresponsive when under high I/O load. When this happens, the system logs a
viostor Reset to device, \Device\RaidPort3, was issued error.
Windows 10 VMs with certain PCI devices might become unresponsive on boot
Currently, a virtual machine (VM) that uses a Windows 10 guest operating system might become unresponsive during boot if a
virtio-win-scsi PCI device with a local disk back end is attached to the VM. To work around the problem, boot the VM with the
multi_queue option enabled.
The repair function of virtio-win-guest-tool for the virtio-win drivers does not work
Currently, when using the
Repair button of
virtio-win-guest-tool for a
virtio-win driver, such as the Virtio Balloon Driver, the button has no effect. As a consequence, the driver cannot be reinstalled after being removed on the guest.
Windows 11 VMs with a memory balloon device set might terminate unexpectedly during reboot
Currently, rebooting virtual machines (VMs) that use a Windows 11 guest operating system and a memory balloon device in some cases fails with a
DRIVER POWER STAT FAILURE blue-screen error.
Migrating a Windows 11 or Windows Server 2022 VM under high network load sometimes fails
When live-migrating a virtual machine (VM) that uses Windows Server 2022 or Windows 11 as the guest operating system, the migration might become unresponsive or terminate unexpectedly if the network is impacted by high packed loss.
The virtio balloon driver sometimes does not work on Windows 10 VMs
Under certain circumstances, the virtio-balloon driver does not work correctly on virtual machines (VMs) that use a Windows 10 guest operating system. As a consequence, such VMs might not use their assigned memory efficiently.
The virtio file system has suboptimal performance in Windows VMs
Currently, when a virtio file system (virtiofs) is configured on a virtual machine (VM) that uses a Windows guest operating system, the performance of virtiofs in the VM is significantly worse than in VMs that use Linux guests.
Hot-unplugging a storage device on Windows VMs might fail
On virtual machines (VMs) that use a Windows guest operating system, removing a storage device when the VM is running (also known as a device hot-unplug) in some cases fails. As a consequence, the storage device remains attached to the VM and the disk manager service might become unresponsive.
virtio drivers on Windows VMs might fail
When updating the KVM paravirtualized (
virtio) drivers on a Windows virtual machine (VM), the update might cause the mouse to stop working and the newly installed drivers might not be signed. This problem occurs when updating the
virtio drivers by installing from the
virtio-win-guest-tools package, which is a part of the
To work around this problem, update the
virtio drivers by using Windows Device Manager.
11.16. RHEL in cloud environments
Cloning or restoring RHEL 9 virtual machines that use LVM on Nutanix AHV causes non-root partitions to disappear
When running a RHEL 9 guest operating system on a virtual machine (VM) hosted on the Nutanix AHV hypervisor, restoring the VM from a snapshot or cloning the VM currently causes non-root partitions in the VM to disappear if the guest is using Logical Volume Management (LVM). As a consequence, the following problems occur:
- After restoring the VM from a snapshot, the VM cannot boot, and instead enters emergency mode.
- A VM created by cloning cannot boot, and instead enters emergency mode.
To work around these problems, do the following in emergency mode of the VM:
Remove the LVM system devices file:
Recreate LVM device settings:
- Reboot the VM
This makes it possible for the cloned or restored VM to boot up correctly.
Alternatively, to prevent the issue from occurring, do the following before cloning a VM or creating a VM snapshot:
use_devicesfile = 0line in the
- Reboot the VM
Customizing RHEL 9 guests on ESXi sometimes causes networking problems
Currently, customizing a RHEL 9 guest operating system in the VMware ESXi hypervisor does not work correctly with NetworkManager key files. As a consequence, if the guest is using such a key file, it will have incorrect network settings, such as the IP address or the gateway.
For details and workaround instructions, see the VMware Knowledge Base.
RHEL instances on Azure fail to boot if provisioned by
cloud-init and configured with an NFSv3 mount entry
Currently, booting a RHEL virtual machine (VM) on the Microsoft Azure cloud platform fails if the VM was provisioned by the
cloud-init tool and the guest operating system of the VM has an NFSv3 mount entry in the
Setting static IP in a RHEL virtual machine on a VMware host does not work
Currently, when using RHEL as a guest operating system of a virtual machine (VM) on a VMware host, the DatasourceOVF function does not work correctly. As a consequence, if you use the
cloud-init utility to set the VM’s network to static IP and then reboot the VM, the VM’s network will be changed to DHCP.
To work around this issue, see the VMware Knowledge Base.
Timeout when running
sos report on IBM Power Systems, Little Endian
When running the
sos report command on IBM Power Systems, Little Endian with hundreds or thousands of CPUs, the processor plugin reaches its default timeout of 300 seconds when collecting huge content of the
/sys/devices/system/cpu directory. As a workaround, increase the plugin’s timeout accordingly:
- For one-time setting, run:
# sos report -k processor.timeout=1800
For a permanent change, edit the
[plugin_options]section of the
[plugin_options] # Specify any plugin options and their values here. These options take the form # plugin_name.option_name = value #rpm.rpmva = off processor.timeout = 1800
The example value is set to 1800. The particular timeout value highly depends on a specific system. To set the plugin’s timeout appropriately, you can first estimate the time needed to collect the one plugin with no timeout by running the following command:
# time sos report -o processor -k processor.timeout=0 --batch --build
Running systemd within an older container image does not work
Running systemd within an older container image, for example,
centos:7, does not work:
$ podman run --rm -ti centos:7 /usr/lib/systemd/systemd Storing signatures Failed to mount cgroup at /sys/fs/cgroup/systemd: Operation not permitted [!!!!!!] Failed to mount API filesystems, freezing.
To work around this problem, use the following commands:
# mkdir /sys/fs/cgroup/systemd # mount none -t cgroup -o none,name=systemd /sys/fs/cgroup/systemd # podman run --runtime /usr/bin/crun --annotation=run.oci.systemd.force_cgroup_v1=/sys/fs/cgroup --rm -ti centos:7 /usr/lib/systemd/systemd