[powerpc] Dump capture failure with recent linux-next

[Sachin Sant]

Kdump fails to save vmcore with recent linux-next builds on IBM Power server
with following messages

         Starting Kdump Vmcore Save Service...
[ 17.349599] kdump[367]: Kdump is using the default log level(3).
[ 17.407407] kdump[391]: saving to /sysroot//var/crash//127.0.0.1-2024-02-21-15:03:55/
[ 17.441270] EXT4-fs (sda2): re-mounted 630dfb4e-74bd-45c4-a8de-232992bc8724 r/w. Quota mode: none.
[ 17.444404] kdump[395]: saving vmcore-dmesg.txt to /sysroot//var/crash//127.0.0.1-2024-02-21-15:03:55/
[ 17.464859] kdump[401]: saving vmcore-dmesg.txt complete
[ 17.466636] kdump[403]: saving vmcore
[ 17.551589] kdump.sh[404]: 
Checking for memory holes : [ 0.0 %] / 
Checking for memory holes : [100.0 %] | readpage_elf: Attempt to read non-existent page at 0xc000000000000.
[ 17.551718] kdump.sh[404]: readmem: type_addr: 0, addr:c00c000000000000, size:16384
[ 17.551793] kdump.sh[404]: __exclude_unnecessary_pages: Can't read the buffer of struct page.
[ 17.551864] kdump.sh[404]: create_2nd_bitmap: Can't exclude unnecessary pages.
[ 17.562632] kdump.sh[404]: The kernel version is not supported.
[ 17.562708] kdump.sh[404]: The makedumpfile operation may be incomplete.
[ 17.562773] kdump.sh[404]: makedumpfile Failed.
[ 17.564335] kdump[406]: saving vmcore failed, _exitcode:1
[ 17.566013] kdump[408]: saving the /run/initramfs/kexec-dmesg.log to /sysroot//var/crash//127.0.0.1-2024-02-21-15:03:55/
[ 17.583658] kdump[414]: saving vmcore failed

Git bisect points to following patch

commit 378eb24a0658dd922b29524e0ce35c6c43f56cba
    mm/vmalloc: remove vmap_area_list

Reverting this patch allows kdump to save vmcore file correctly.

Does this change require any corresponding changes to makedumpfile?

- Sachin