kexec-tools/98-kexec.rules

SUBSYSTEM=="cpu", ACTION=="add", PROGRAM="/bin/systemctl try-restart kdump.service"
SUBSYSTEM=="cpu", ACTION=="remove", PROGRAM="/bin/systemctl try-restart kdump.service"
SUBSYSTEM=="memory", ACTION=="online", PROGRAM="/bin/systemctl try-restart kdump.service"
SUBSYSTEM=="memory", ACTION=="offline", PROGRAM="/bin/systemctl try-restart kdump.service"
udev-rules: Restart kdump service on cpu ADD/REMOVE events This patch changes restart of kdump service from cpu online/offline events to cpu add/remove events. Some people have complained that they are running cpu online/offline tests at high frequency and kdump restarts at high frequency and systemd disables the service. As a temporary fix, we committed a patch to never disable kdump service. In general it probably is a good idea to restart kdump service on cpu add/remove events. Toshi Kani confirmed following. - File for /sys/devices/system/cpu/cpuX/crash_notes will be created first before ADD event goes out. That means we can not miss creating EFL notes for newly created cpu. - For REMOVE event files under /sys/devices/system/cpu/cpuX/ are removed first and then REMOVE event goes out. That means we will remove the elf note header for removed cpu. - There are some race conditions like a cpu is removed but system crashes before kdump service restarts. In that case vmcore.c has to be more robust to be able to inspect elf notes and discard empty ones. Also it is possible that after cpu remove, crash notes memory got reused for something else and after crash vmcore.c might see some random data. It does basic size checks and discards elf notes if checks don't pass. Above rance conditions can happen even with OFFLINE event and there is no good way to remove these altogether. So making vmcore.c more robust is the right solution here. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: WANG Chao <chaowang@redhat.com> 2014-09-05 20:16:25 +00:00			`SUBSYSTEM=="cpu", ACTION=="add", PROGRAM="/bin/systemctl try-restart kdump.service"`
			`SUBSYSTEM=="cpu", ACTION=="remove", PROGRAM="/bin/systemctl try-restart kdump.service"`
Fix kdump udev memory event restarts During debugging of another problem issues were noted with the kdump udev rules. The kdump service is restarted on memory add and remove events. These are the wrong events for these types of devices and result in an overly aggressive restarting of the kdump service. There are four udev events to consider, "add", "remove", "online", and "offline". The remove event is a complete removal from the system -- neither the hardware nor the kernel know about the hardware; it has been physically removed. The add event is associated with hardware being physically added to the system. The kernel has some limited knowledge of the device, however, it is not avaiable for the kernel to use until it is brought online. Online events refer to the device being available for the kernel to use. Opposite to that is the offline event, which occurs when a device is no longer in use by the kernel. Note that in all four events the kernel may have some remaining information stored about the device. In the case of memory hotplug, kdump should be restarted when a memory module is onlined or offlined. This is because the memory is not in use by the kernel until the memory is onlined, and it is unused when the memory is offlined. Making these modifications results in smooth service on systems that do heavy memory onlining and offlining. Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Prarit Bhargava <prarit@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> 2014-05-02 14:28:50 +00:00			`SUBSYSTEM=="memory", ACTION=="online", PROGRAM="/bin/systemctl try-restart kdump.service"`
			`SUBSYSTEM=="memory", ACTION=="offline", PROGRAM="/bin/systemctl try-restart kdump.service"`