------- 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. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. 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. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2060039/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
