Note: This bug is displayed in read-only format because
the product is no longer active in Red Hat Bugzilla.
RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.
This bug was initially created as a copy of Bug #2118897
I am copying this bug because:
Corresponding to kernel change, the user space need adjustment too to make the feature take effect. For kexec_file_load, things as below need bedone:
- Prevent udev from updating kdump crash kernel on hot un/plug changes.
Add the following as the first lines to the udev rule file
/usr/lib/udev/rules.d/98-kexec.rules:
# The kernel handles updates to crash elfcorehdr for cpu and memory changes
SUBSYSTEM=="cpu", ATTRS{crash_hotplug}=="1", GOTO="kdump_reload_end"
SUBSYSTEM=="memory", ATTRS{crash_hotplug}=="1", GOTO="kdump_reload_end"
These lines will cause cpu and memory hot un/plug events to be
skipped within this rule file, if the kernel has these changes
enabled.
Description of problem:
When kdump service is loaded, if a CPU or memory is hot un/plugged, the crash elfcorehdr, which describes the CPUs and memory in the system, must also be updated, else the resulting vmcore is inaccurate (eg. missing either CPU context or memory regions).
The current solution utilizes udev to initiate an unload-then-reload of the kdump image (e. kernel, initrd, boot_params, puratory and elfcorehdr) by the userspace kexec utility. This brings significant performance problems related to offloading this activity to userspace.
In upstream, a patchset introduces a generic crash hot un/plug handler that registers with the CPU and memory notifiers. Upon CPU or memory changes, this generic handler is invoked and invokes architecture specific handler to do the appropriate updates.
In the case of x86_64, the arch specific handler generates a new
elfcorehdr, and overwrites the old one in memory. No involvement
with userspace needed.
[PATCH v10 0/8] crash: Kernel handling of CPU and memory hot un/plug
https://lore.kernel.org/all/20220721181747.1640-1-eric.devolder@oracle.com/T/#u
Version-Release number of selected component (if applicable):
How reproducible:
Steps to Reproduce:
1.
2.
3.
Actual results:
Expected results:
Additional info:
Defer this to rhel9.4 since the upstream patches are still under discussion.
Comment 5RHEL Program Management
2023-09-25 17:39:00 UTC
Issue migration from Bugzilla to Jira is in process at this time. This will be the last message in Jira copied from the Bugzilla bug.
Comment 6RHEL Program Management
2023-09-25 17:53:26 UTC
This BZ has been automatically migrated to the issues.redhat.com Red Hat Issue Tracker. All future work related to this report will be managed there.
Due to differences in account names between systems, some fields were not replicated. Be sure to add yourself to Jira issue's "Watchers" field to continue receiving updates and add others to the "Need Info From" field to continue requesting information.
To find the migrated issue, look in the "Links" section for a direct link to the new issue location. The issue key will have an icon of 2 footprints next to it, and begin with "RHEL-" followed by an integer. You can also find this issue by visiting https://issues.redhat.com/issues/?jql= and searching the "Bugzilla Bug" field for this BZ's number, e.g. a search like:
"Bugzilla Bug" = 1234567
In the event you have trouble locating or viewing this issue, you can file an issue by sending mail to rh-issues. You can also visit https://access.redhat.com/articles/7032570 for general account information.