Description of problem:
Kdump kernel save vmcore failure on 4.14.* kernel. Here is some console log by test machine:
] Reached target Initrd Default Target.
Starting dracut pre-pivot and cleanup hook...
] Started dracut pre-pivot and cleanup hook.
Starting Kdump Vmcore Save Service...
kdump: dump target is /dev/mapper/rhel_ibm--x3950x6--01-root
kdump: saving to /sysroot//var/crash/127.0.0.1-2017-10-26-23:52:33/
kdump: saving vmcore-dmesg.txt
kdump: saving vmcore-dmesg.txt complete
kdump: saving vmcore
sadump: does not have partition header
sadump: read dump device as unknown format
sadump: unknown format
phys_start : 1000000
phys_end : 2388000
virt_start : ffffffff81000000
virt_end : ffffffff82388000
Buffer size for the cyclic mode: 4194304
vtop4_x86_64: Can't get the symbol of init_level4_pgt.
readmem: Can't convert a virtual address(ffffffff81c10284) to physical address.
readmem: type_addr: 0, addr:ffffffff81c10284, size:390
check_release: Can't get the address of system_utsname.
kdump: saving vmcore failed
] Failed to start Kdump Vmcore Save Service.
See 'systemctl status kdump-capture.service' for details.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Please set --message-level to 31 and also set rd.debug=3.
Confirmed in Debian as well.
Linux 4.14.0-1-rt-amd64 #1 SMP PREEMPT RT Debian 4.14.2-1 (2017-11-30)
kexec-tools 2.0.15-1 amd64
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.