Re: [PATCH v3 0/3] Fix serveral problems with kdump reloading on udev event

Currently kdump will restart for multiple times and may trigger a initramfs rebuild on memory / CPU hotplug if any configuration is modified. Besides, currently simply restart the service via systemctl directly will take a period of time as well, as kdumpctl will do a lot of config checking, which is not appreciated by udev, udev want everything to get done in a very short time. And kdumpctl may get kill for several times because systemd will kill the previous service starting process for later restart request. This may introduce extra risk too. Simply add reload support and use systemdctl reload will not work well either because systemd will ignore later reload request, so kdump may get reload earlier than the hotplug is finished. This patch series should solve the problem by applying following fixes: - Adding reload support as a fast path to reload kdump resources, bypassing most checking. So the reload progress will be faster and never trigger a initrmafs rebuild. - Let the reload request run in async mode, so udev will never get blocked. - Throttle udev events to avoid unnecessary kdump reloading and make sure kdump will reload after the udev settled. Update from V2: - Use "-ne" instead of "!=" for comparing return values of functions in kdumpctl. "!=" is used more for pattern matching. - Removed duplicated "is-system-running" check in kdump-udev-throttler - Add more detailed commit message about reason to use --no-block in udev rules Update from V1: - Add cover letter - Add --no-block option to systemd-run, starting from systemd-v220, systemd-run will run in synchronous mode by default, need to give --no-block explicitly to run in async mode. Kairui Song (3): kdumpctl: Add reload support Rewrite kdump's udev rules Throttle kdump reload request triggered by udev event 98-kexec.rules | 16 +++++++++--- kdump-udev-throttler | 47 +++++++++++++++++++++++++++++++++++ kdump.service | 1 + kdumpctl | 59 +++++++++++++++++++++++++++++++++++++------- kexec-tools.spec | 3 +++ 5 files changed, 113 insertions(+), 13 deletions(-) create mode 100755 kdump-udev-throttler -- 2.17.1