| Message ID | 20230423105213.70795-3-sourabhjain@linux.ibm.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | PowerPC: In-kernel handling of CPU/Memory hotplug/online/offline events for kdump kernel | expand |
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@linux.ibm.com> > Reviewed-by: Laurent Dufour <laurent.dufour@fr.ibm.com> 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@linux.ibm.com> > --- > 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)
On 24/04/23 15:27, Laurent Dufour wrote: > 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@linux.ibm.com> >> Reviewed-by: Laurent Dufour <laurent.dufour@fr.ibm.com> > 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@linux.ibm.com> I apologies for mistakenly applying the "Reviewed-by" tag to the entire patch series, when it was intended for only one patch. I will remove the tag in next version. - Sourabh Jain
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)