On 23/04/2023 12:52:10, Sourabh Jain wrote: > Due to CPU/Memory hot plug/unplug or online/offline events the system > resources changes. A similar change should reflect in the loaded kdump > kernel kexec segments that describes the state of the CPU and memory of > the running kernel. > > If the kdump kernel kexec segments are not updated after the CPU/Memory > hot plug/unplug or online/offline events and kdump kernel tries to > collect the dump with the stale system resource data then this might > lead to dump collection failure or an inaccurate dump collection. > > The current method to keep the kdump kernel kexec segments up to date is > by reloading the complete kdump kernel whenever a CPU/Memory hot > plug/unplug or online/offline event is observed in userspace. Reloading > the kdump kernel for every CPU/Memory hot plug/unplug or online/offline > event is inefficient and creates a large window where the kdump service > is not available. It can be improved by doing in-kernel updates to only > necessary kdump kernel kexec segments which describe CPU and Memory > resources of the running kernel to the kdump kernel. > > The kernel changes related to in-kernel updates to the kdump kernel > kexec segments are kept under the CRASH_HOTPLUG config option. > > Later in the series, a powerpc crash hotplug handler is introduced to > update the kdump kernel kexec segments on CPU/Memory hotplug events. > This arch-specific handler is triggered from a generic crash handler > that registers with the CPU/Memory add/remove notifiers. > > The CRASH_HOTPLUG config option is enabled by default. > > Signed-off-by: Sourabh Jain <sourabhjain@xxxxxxxxxxxxx> > Reviewed-by: Laurent Dufour <laurent.dufour@xxxxxxxxxx> I can't remember having sent a review-by on that patch earlier. Anyway, I can't find any issue with that one, so replace with: Reviewed-by: Laurent Dufour <ldufour@xxxxxxxxxxxxx> > --- > arch/powerpc/Kconfig | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index a6c4407d3ec83..ac0dc0ffe89b4 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -681,6 +681,18 @@ config CRASH_DUMP > The same kernel binary can be used as production kernel and dump > capture kernel. > > +config CRASH_HOTPLUG > + bool "In-kernel update to kdump kernel on system configuration changes" > + default y > + depends on CRASH_DUMP && (HOTPLUG_CPU || MEMORY_HOTPLUG) > + help > + Quick and efficient mechanism to update the kdump kernel in the > + event of CPU/Memory hot plug/unplug or online/offline events. This > + approach does the in-kernel update to only necessary kexec segment > + instead of unload-reload entire kdump kernel from userspace. > + > + If unsure, say Y. > + > config FA_DUMP > bool "Firmware-assisted dump" > depends on PPC64 && (PPC_RTAS || PPC_POWERNV) _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
