Thanks Dan for the report and Cascardo for finding the offender commit that introduced this regression!
I think we have room for improvements here, my considerations are: a) KDUMP_SYSCTL is a misleading name; it seems to be related with sysctls set _when_ dumping, which is also an important thing to control. Despite this, the option meaning was related to the kdump sysctl _triggers_. b) Even by re-enabling this option we don't have a fine tuning configuration of sysctls during the dump. So, my idea to fix/improve the situation is: let's have a KDUMP_PANIC_TRIGGERS variable (that defaults to panic_on_oops) and a KDUMP_SYSCTL_ON_DUMP variable that overrides the desired sysctls set on normal kernel when the kdump kernel boots (and which should defaults to have hugepages disabled, since it's a known problem when kdumping to have hugepages "consuming" the system memory). Cheers, Guilherme -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to makedumpfile in Ubuntu. https://bugs.launchpad.net/bugs/1845048 Title: /etc/default/kdump-tools KDUMP_SYSCTL does not set sysctl params Status in makedumpfile package in Ubuntu: Confirmed Status in makedumpfile source package in Xenial: Confirmed Status in makedumpfile source package in Bionic: Confirmed Status in makedumpfile source package in Eoan: Confirmed Status in makedumpfile source package in Focal: Confirmed Bug description: [impact] Documentation, and past behavior, for kdump-tools was that the KDUMP_SYSCTL variable in the /etc/default/kdump-tools file would be applied to the system kernel params at kdump 'load'. However this is no longer true, and those params are no longer applied to the system's kernel param settings. [test case] install linux-crashdump (and kdump-tools). Edit the /etc/default/kdump-tools file to set the KDUMP_SYSCTL param to something other than default, e.g.: KDUMP_SYSCTL="kernel.panic_on_oops=1 kernel.panic_on_warn=1" reboot, or unload/reload kdump, to pick up the changes to the file. Check if the panic_on_warn param is set: $ cat /proc/sys/kernel/panic_on_warn 0 the problem does not seem to be with sysctl, as manually calling it does work: $ KDUMP_SYSCTL="kernel.panic_on_oops=1 kernel.panic_on_warn=1" $ cat /proc/sys/kernel/panic_on_warn 0 $ sudo sysctl -w $KDUMP_SYSCTL kernel.panic_on_oops = 1 kernel.panic_on_warn = 1 $ cat /proc/sys/kernel/panic_on_warn 1 [regression potential] TBD To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/makedumpfile/+bug/1845048/+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
