--- Comment From hbath...@in.ibm.com 2024-04-08 07:09 EDT---
CONFIG_KFENCE is the config option that is increasing the memory requirement
significantly for radix MMU.
For radix MMU case, memory is direct mapped with 2MB size.
But when KFENCE is used, direct mapping is done at pagesize granularity (64K).
This sharply increased the page table allocation size, on a 100GB system,
from ~23MB to ~3223MB with CONFIG_KFENCE. Experimenting to find if this
memory requirement can be brought down. If not, thinking of disabling KFENCE
for dump capture environment.
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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
totalusedfree shared buff/cache
available
Mem:48Gi 1.7Gi46Gi13Mi 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
[0.00] fadump: Reserved 1024MB of memory at 0x004000 (System
RAM: 51200MB)
[0.00] fadump: Initialized 0x4000 bytes cma area at 1024MB from
0x4007 bytes of memory reserved for firmware-assisted dump
[0.00] Memory: 49316672K/52428800K available (23616K kernel code,
4096K rwdata, 25536K rodata, 8832K init, 2487K bss, 2063552K reserved, 1048576K
cma-reserved)
[0.396408] ibmvscsi 3066: 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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