Loading

×Sorry to interrupt
CSS Error

Refresh

Cookie Preference Center

General Information on cookies

When you visit our website, we use cookies to ensure that we give you the best experience. This information does not usually directly identify you, but it can give you a more personalized web experience. Because we respect your right to privacy, you can choose not to allow some types of cookies by clicking on the different category headings to find out more and change your settings. However, blocking some types of cookies may impact your experience on the site and the services we are able to offer. Further information can be found in our

Cookie Policy.

Strictly Necessary

Strictly Necessary

Always Active

Strictly Necessary

Strictly necessary cookies are always enabled since they are essential for our website to function. They enable core functionality such as security, network management, and website accessibility. You can set your browser to block or alert you about these cookies, but this may affect how the website functions. For more information please visit www.aboutcookies.org or www.allaboutcookies.org.

Cookie Details‎

Performance

Performance

Performance

Performance cookies are used to analyze the user experience to improve our website by collecting and reporting information on how you use it. They allow us to know which pages are the most and least popular, see how visitors move around the site, optimize our website and make it easier to navigate.

Cookie Details‎

Please confirm your settings by refreshing the page.

Functional

Functional

Functional

Functional cookies help us keep track of your past browsing choices so we can improve usability and customize your experience. These cookies enable the website to remember your preferred settings, language preferences, location and other customizable elements such as font or text size. If you do not allow these cookies, then some or all of these services may not function properly.

Cookie Details‎

Advertising

Advertising

Advertising

Advertising cookies are used to send you relevant advertising and promotional information. They may be set through our site by third parties to build a profile of your interests and show you relevant advertisements on other sites. These cookies do not directly store personal information, but their function is based on uniquely identifying your browser and internet device.

Cookie Details‎

Advertising Cookies

Consent Leg.Interest

Select All Vendors

Select All Vendors

Select All Hosts

Select All

Clear Filters

Information storage and access

Apply

Confirm My Choices Reject All Allow All

My Subscriptions

Loading

Knowledge Base

Linux Guest OS may become unresponsive after hot-adding memory from under 3 GB to over 3 GB (1019401)

Last Updated: 6/30/2021Categories: Total Views: 7896Language:
English

Subscribe to get an email
newsletter with new updates

Please provide article feedback:

Symptoms

Virtual machines installed with the some 64-bit Linux guest operating systems (RHEL 5, SLES 11) may become unresponsive if the virtual machine is started with an IDE device attached, and if memory is hot-added from below 3 GB to above 3 GB.

If you hot-add memory to the virtual machine, you see the following messages within the virtual machine:

nommu_map_sg: overflow 137c1e000+4096 of device mask ffffffff

This issue does not occur with 32-bit operating systems.

This issue does not occur if the virtual machine is created with >4 GB memory and more memory is hot-added.

Resolution

When the initial virtual machine memory is less than 3072 MB, the Linux OS kernel boots without enabling swiotlb. When you hot-add memory to such a kernel and increase beyond this limit, swiotlb remains disabled.

To workaround this issue, you must enable swiotlb.

To enable swiotlb:

If the virtual machine is configured with < 3 GB memory, try this option to the kernel at boot time:<br>
iommu=soft

If this did not work the first time, try:

swiotlb=force

When the system boots, verify by executing the command:

dmesg | grep SWIOTLB

You see output similar to:

PCI-DMA: Using software bounce buffering for IO (SWIOTLB)

Do not use memory hot-add to change the virtual machine size from less than or equal to 3072 MB to greater than 3072 MB. Instead, power off the virtual machine to perform this reconfiguration. For more information on hot-add memory in a Linux virtual machine and bringing it online, see Hot adding memory in Linux (1012764).

Notes:

This problem occurs only when the 3 GB mark is crossed while the operating system is running.

If the guest OS is already unresponsive, restart the virtual machine.

Related Information

Hot adding memory in Linux

Detectable by VMware SkylineTM

Actions

Copy

link to clipboard
copied!

Print

Language:
English

Attachments

Additional Resources

KB
•
End Of General Availability of the Free vSphere Hypervisor (ESXi 7.x and 8.x) (2107518)

KB
•
Alarma persistente/recurrente para el clúster de vSAN 'Se suprimen las alarmas de estado' (76843)

KB
•
Download and Install VMware Fusion (2014097)

KB
•
Alarme persistente/recorrente para o cluster vSAN 'alarmes de integridade vSAN são suprimidos' (76843)

Results 1-4 of 4

Ask The Community

Get answers quickly from VMware experts in the community

Post Subject

CONTINUE IN COMMUNITIES

Related Products:

Related Versions:

Take Our Survey

Support Assistant