kdump-lib: check kdump service state when validating fadump load

[sourabhjains]

Currently, kdumpctl status reports kdump as operational even when the kdump service is in a failed state for fadump.

root> kdumpctl status
kdump: Dump mode is fadump
kdump: Kdump is operational

root> systemctl status kdump
× kdump.service - Crash recovery kernel arming
Loaded: loaded (/usr/lib/systemd/system/kdump.service; enabled; preset: enabled)
Active: failed (Result: exit-code) since Tue 2026-01-20 02:52:59 CST; 12s ago
<snip...>
cp: error writing '/boot/initramfs-6.12.0-180.el10.ppc64le.img.tmp': No space left on device dracut[F]: Creation of /boot/initramfs-6.12.0-180.el10.ppc64le.img.tmp failed <snip...>

This happens because the kernel registers fadump during early boot [1]. Even if the kdump service later fails to start due to a failure while updating the initrd with the fadump component, /sys/kernel/fadump/registered still remains set to 1. As a result, kdump is reported as operational, even though it is not.

Fix this by checking the kdump service state when validating the fadump load.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=607451ce0aa9bdff590db4d087173edba6d7a29d

Reported-by: Shirisha G shirisha@linux.ibm.com

[gemini-code-assist]

Summary of Changes

Hello @sourabhjains, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves an issue where the kdumpctl status command would misleadingly indicate that kdump was operational in fadump mode, even when the associated kdump.service had failed. The change introduces a crucial validation step within the is_kernel_loaded function to verify the active state of the kdump.service before declaring kdump as operational, thus improving the accuracy of system status reporting.

Highlights

• Incorrect Status Reporting: The kdumpctl status command previously reported kdump as operational for fadump mode even when the kdump.service was in a failed state, leading to misleading system information.
• Service State Validation: A new check, systemctl is-active --quiet kdump.service, has been integrated into the is_kernel_loaded() function specifically for fadump mode.
• Accurate Operational Status: This modification ensures that kdump is only reported as operational if the kdump.service is actively running, providing a more accurate reflection of the system's crash recovery readiness.

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[gemini-code-assist]

Code Review

This pull request fixes an issue where kdumpctl status could report fadump as operational even when the kdump service was in a failed state. The fix is to check the kdump.service status in is_kernel_loaded. The change is correct and effectively solves the problem. I've added one comment suggesting a potential improvement to make the check more robust by applying it to kdump mode as well, as a similar issue could exist there.

[gemini-code-assist]

This check correctly fixes the issue for fadump. However, a similar problem could exist for the kdump mode. If kdumpctl start fails for any reason after the crash kernel is loaded via kexec, the kdump.service will be in a failed state, but /sys/kernel/kexec_crash_loaded will be 1. In this scenario, kdumpctl status would incorrectly report kdump as operational.

It would be more robust to apply this service status check for the kdump mode as well. You could consider moving this check to after the case statement to cover all dump modes.

[sourabhjains]

/gemini review

[gemini-code-assist]

Code Review

The pull request effectively addresses the reported issue where kdumpctl status incorrectly reported fadump as operational even when the kdump.service was in a failed state. By introducing a check for the systemctl active status of kdump.service specifically for fadump mode, the kdumpctl command now provides a more accurate status. The changes are concise, well-placed, and directly resolve the problem described in the pull request body.