[Bug 2060039] Comment bridged from LTC Bugzilla

------- Comment From hbathini@in.ibm.com 2024-06-19 06:54 EDT-------
Posted v2 upstream:

https://lore.kernel.org/linuxppc-dev/20240619104919.20772-1-hbathini@linux.ibm.com/
("[PATCH v2] radix/kfence: map __kfence_pool at page granularity")

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https://bugs.launchpad.net/bugs/2060039

Title:
[Ubuntu-24.04] FADump with recommended crash size is making the L1
hang

Status in linux package in Ubuntu:
Confirmed

Bug description:
Problem description :
======================

Triggered FADump with the recommended crash. L1 host got hung.

As per the public document
https://wiki.ubuntu.com/ppc64el/Recommendations recommended crash
kernel size is 1024M for the system. But with 1024M and 2048M, the L1
is getting hanged. with 4096, crash is generated and collected.


root@ubuntu2404:~# uname -ar
Linux ubuntu2404 6.8.0-11-generic #11-Ubuntu SMP Wed Feb 14 00:33:03 UTC 2024 ppc64le ppc64le ppc64le GNU/Linux


root@ubuntu2404:~# free -h
total used free shared buff/cache available
Mem: 48Gi 1.7Gi 46Gi 13Mi 687Mi 46Gi
Swap: 8.0Gi 0B 8.0Gi


root@ubuntu2404:~# cat /proc/cmdline
BOOT_IMAGE=/vmlinux-6.8.0-11-generic root=/dev/mapper/ubuntu--vg-ubuntu--lv ro fadump=on crashkernel=1024M


root@ubuntu2404:~# dmesg | grep -i reser
[ 0.000000] fadump: Reserved 1024MB of memory at 0x00000040000000 (System RAM: 51200MB)
[ 0.000000] fadump: Initialized 0x40000000 bytes cma area at 1024MB from 0x40070000 bytes of memory reserved for firmware-assisted dump
[ 0.000000] Memory: 49316672K/52428800K available (23616K kernel code, 4096K rwdata, 25536K rodata, 8832K init, 2487K bss, 2063552K reserved, 1048576K cma-reserved)
[ 0.396408] ibmvscsi 30000066: Client reserve enabled


root@ubuntu2404:~# kdump-config show
DUMP_MODE: fadump
USE_KDUMP: 1
KDUMP_COREDIR: /var/crash
/var/lib/kdump/vmlinuz
kdump initrd:
/var/lib/kdump/initrd.img
current state: ready to fadump

IBM is looking to update the crash kernel reservations section of the
wiki for Power.

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