Re: [next-20230731] Kdump fails to capture vmcore (powerpc)

On 31/07/23 7:39 pm, Sachin Sant wrote:

Kernel Crash dump(kdump) and firmware assisted dump on powerpc
fails to capture vmcore on recent linux-next builds.

Starting Kdump Vmcore Save Service...
systemd[1]: Starting Kdump Vmcore Save Service...
kdump[599]: Kdump is using the default log level(3).
kdump[635]: saving to /sysroot/var/crash/127.0.0.1-2023-07-31-09:01:28/
kdump[639]: Remounting the dump target in rw mode.
kdump[643]: saving vmcore-dmesg.txt to /sysroot/var/crash/127.0.0.1-2023-07-31-09:01:28/
kdump[649]: saving vmcore-dmesg.txt complete
kdump[651]: saving vmcore
kdump.sh[652]: readpage_elf: Attempt to read non-existent page at 0x4000000000000000.
kdump.sh[652]: readmem: type_addr: 0, addr:0, size:8
kdump.sh[652]: get_vmemmap_list_info: Can't get vmemmap region addresses
kdump.sh[652]: get_machdep_info_ppc64: Can't get vmemmap list info.
kdump.sh[652]: makedumpfile Failed.
kdump[654]: saving vmcore failed, exitcode:1
kdump[656]: saving the /run/initramfs/kexec-dmesg.log to /sysroot/var/crash/127.0.0.1-2023-07-31-09:01:28//
kdump[663]: saving vmcore failed
systemd[1]: kdump-capture.service: Main process exited, code=exited, status=1/FAILURE
systemd[1]: kdump-capture.service: Failed with result 'exit-code'.
systemd[1]: Failed to start Kdump Vmcore Save Service.
[FAILED] Failed to start Kdump Vmcore Save Service.

Git bisect points to following patch:

8dc9a0ad0c3e7f43e4e091e4e24634e21ce17a54 is the first bad commit
commit 8dc9a0ad0c3e7f43e4e091e4e24634e21ce17a54
     powerpc/book3s64/vmemmap: switch radix to use a different vmemmap handling function

Earlier, makedumpfile made use of vmemmap_list to populate all the
vmemmap regions but that changed for radix. It uses the init_mm pgtable
for vmemmap regions. A fix is needed in makedumpfile to catch up with
the above change.

Thanks
Hari