Thank you for reading this report.
This may caused by bugs in kernel, not in kdump. If so, I will report this to kernel team.
I need your comment to solve this.
[Impact]
* Kdump kernel can't be loaded using linux kernel 4.15.0-76.
Then,these messages are shown:
Cannot open /proc/kcore: Operation not permitted
Cannot read /proc/kcore: Operation not permitted
Cannot load /boot/vmlinuz-4.15.0-76-generic
On dmesg, these messages are shown:
....
[ 538.524718] Lockdown: /proc/kcore is restricted; see man kernel_lockdown.7
....
3) Changing OS kernel to older one(I used 4.15.0-64), kdump kernel can be loaded.
$ sudo systemctl status kdump-tools
● kdump-tools.service - Kernel crash dump capture service
Loaded: loaded (/lib/systemd/system/kdump-tools.service; enabled; vendor preset: enabled)
Active: active (exited) since Wed 2020-03-25 13:39:03 JST; 5 days ago
Main PID: 832 (code=exited, status=0/SUCCESS)
Tasks: 0 (limit: 4915)
CGroup: /system.slice/kdump-tools.service
Mar 25 13:39:02 ctrl-edgen systemd[1]: Starting Kernel crash dump capture service...
Mar 25 13:39:02 ctrl-edgen kdump-tools[832]: Starting kdump-tools: * Creating symlink /var/lib/kdump/vmlinuz
Mar 25 13:39:02 ctrl-edgen kdump-tools[832]: * Creating symlink /var/lib/kdump/initrd.img
Mar 25 13:39:03 ctrl-edgen kdump-tools[832]: * loaded kdump kernel
Mar 25 13:39:03 ctrl-edgen kdump-tools[938]: loaded kdump kernel
Mar 25 13:39:03 ctrl-edgen systemd[1]: Started Kernel crash dump capture service.
Thank you for reading this report.
This may caused by bugs in kernel, not in kdump. If so, I will report this to kernel team.
I need your comment to solve this.
[Impact]
* Kdump kernel can't be loaded using linux kernel 4.15.0-76.
[Environment]
Description: Ubuntu 18.04.4 LTS
Release: 18.04
uname:
Linux ubuntu 4.15.0-76-generic #86-Ubuntu SMP Fri Jan 17 17:24:28 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
Secure boot is enabled.
[Test case]
1)After OS booted, run systemctl status kdump-tools shows these messages below:
.... system/ kdump-tools. service; enabled; vendor preset: enabled) /etc/init. d/kdump- tools start (code=exited, status=0/SUCCESS)
● kdump-tools.service - Kernel crash dump capture service
Loaded: loaded (/lib/systemd/
Active: active (exited) since Fri 2020-03-27 16:40:31 JST; 5min ago
Process: 895 ExecStart=
Main PID: 895 (code=exited, status=0/SUCCESS)
Mar 27 16:40:31 ubuntu systemd[1]: Starting Kernel crash dump capture service... kdump/vmlinuz kdump/initrd. img
Mar 27 16:40:31 ubuntu kdump-tools[895]: Starting kdump-tools: * Creating symlink /var/lib/
Mar 27 16:40:31 ubuntu kdump-tools[895]: * Creating symlink /var/lib/
Mar 27 16:40:31 ubuntu kdump-tools[895]: kexec_file_load failed: Exec format error
Mar 27 16:40:31 ubuntu kdump-tools[895]: * failed to load kdump kernel
Mar 27 16:40:31 ubuntu systemd[1]: Started Kernel crash dump capture service.
....
2)Run kexec directly: line="/ boot/vmlinuz- 4.15.0- 76-generic root=UUID= 29a89ad8- 8923-435e- a88c-aaf5cb3795 68 ro mce=ignore_ce reset_devices systemd. unit=kdump- tools-dump. service nr_cpus=1 irqpoll nousb ata_piix. prefer_ ms_hyperv= 0" --initrd= /boot/initrd. img-4.15. 0-76-generic /boot/vmlinuz- 4.15.0- 64-generic
$ sudo /sbin/kexec -p --command-
Then,these messages are shown: 4.15.0- 76-generic
Cannot open /proc/kcore: Operation not permitted
Cannot read /proc/kcore: Operation not permitted
Cannot load /boot/vmlinuz-
On dmesg, these messages are shown:
....
[ 538.524718] Lockdown: /proc/kcore is restricted; see man kernel_lockdown.7
....
3) Changing OS kernel to older one(I used 4.15.0-64), kdump kernel can be loaded.
$ sudo systemctl status kdump-tools system/ kdump-tools. service; enabled; vendor preset: enabled) slice/kdump- tools.service
● kdump-tools.service - Kernel crash dump capture service
Loaded: loaded (/lib/systemd/
Active: active (exited) since Wed 2020-03-25 13:39:03 JST; 5 days ago
Main PID: 832 (code=exited, status=0/SUCCESS)
Tasks: 0 (limit: 4915)
CGroup: /system.
Mar 25 13:39:02 ctrl-edgen systemd[1]: Starting Kernel crash dump capture service... kdump/vmlinuz kdump/initrd. img
Mar 25 13:39:02 ctrl-edgen kdump-tools[832]: Starting kdump-tools: * Creating symlink /var/lib/
Mar 25 13:39:02 ctrl-edgen kdump-tools[832]: * Creating symlink /var/lib/
Mar 25 13:39:03 ctrl-edgen kdump-tools[832]: * loaded kdump kernel
Mar 25 13:39:03 ctrl-edgen kdump-tools[938]: loaded kdump kernel
Mar 25 13:39:03 ctrl-edgen systemd[1]: Started Kernel crash dump capture service.