On 03/28/22 at 11:08am, Eric DeVolder wrote: > Baoquan, a comment below. > eric > > On 3/24/22 09:37, Eric DeVolder wrote: > > > > > > On 3/24/22 09:33, Baoquan He wrote: > > > On 03/24/22 at 08:53am, Eric DeVolder wrote: > > > > Baoquan, > > > > Thanks, I've offered a minor correction below. > > > > eric > > > > > > > > On 3/24/22 08:49, Baoquan He wrote: > > > > > On 03/24/22 at 09:38pm, Baoquan He wrote: > > > > > > On 03/03/22 at 11:27am, Eric DeVolder wrote: > > > > > > > This patch introduces a generic crash hot plug/unplug infrastructure > > > > > > > for CPU and memory changes. Upon CPU and memory changes, a generic > > > > > > > crash_hotplug_handler() obtains the appropriate lock, does some > > > > > > > important house keeping and then dispatches the hot plug/unplug event > > > > > > > to the architecture specific arch_crash_hotplug_handler(), and when > > > > > > > that handler returns, the lock is released. > > > > > > > > > > > > > > This patch modifies crash_core.c to implement a subsys_initcall() > > > > > > > function that installs handlers for hot plug/unplug events. If CPU > > > > > > > hotplug is enabled, then cpuhp_setup_state() is invoked to register a > > > > > > > handler for CPU changes. Similarly, if memory hotplug is enabled, then > > > > > > > register_memory_notifier() is invoked to install a handler for memory > > > > > > > changes. These handlers in turn invoke the common generic handler > > > > > > > crash_hotplug_handler(). > > > > > > > > > > > > > > On the CPU side, cpuhp_setup_state_nocalls() is invoked with parameter > > > > > > > CPUHP_AP_ONLINE_DYN. While this works, when a CPU is being unplugged, > > > > > > > the CPU still shows up in foreach_present_cpu() during the regeneration > > > > > > > of the new CPU list, thus the need to explicitly check and exclude the > > > > > > > soon-to-be offlined CPU in crash_prepare_elf64_headers(). > > > > > > > > > > > > > > On the memory side, each un/plugged memory block passes through the > > > > > > > handler. For example, if a 1GiB DIMM is hotplugged, that generate 8 > > > > > > > memory events, one for each 128MiB memblock. > > > > > > > > > > > > I rewrite the log as below with my understanding. Hope it's simpler to > > > > > > help people get what's going on here. Please consider to take if it's > > > > > > OK to you or adjust based on this. The code looks good to me. > > > > > > > > > > > Made some tuning: > > > > > > > > > > crash: add generic infrastructure for crash hotplug support > > > > > > > > > > Upon CPU and memory changes, a generic crash_hotplug_handler() is added > > > > > to dispatch the hot plug/unplug event to the architecture specific > > > > > arch_crash_hotplug_handler(). During the process, kexec_mutex need be > > > > > held. > > > > > > > > > > To support cpu hotplug, one callback pair are registered to capture > > > > > KEXEC_CRASH_HP_ADD_CPU and KEXEC_CRASH_HP_REMOVE_CPU events via > > > > > cpuhp_setup_state_nocalls(). > > > > s/KEXEC_CRASH_HP_ADD}REMOVE_CPU/CPUHP_AP_ONLINE_DYN/ as the KEXEC_CRASH are the > > > > names I've introduced with this patch? > > > > > > Right. > > > > > > While checking it, I notice hp_action which you don't use actually. > > > Can you reconsider that part of design, the hp_action, the a, b > > > parameter passed to handler? > > > > Sure I can remove. I initially put in there as this was generic > > infrastructure and not sure if it would benefit others. > > eric > > > > Actually, I will keep the hp_action as the work by Sourabh Jain for PPC uses > the hp_action. I'll drop the a and b. Sounds great. > > Also, shall I post v6, or are you still looking at patches 7 and 8? Will check today, thanks for the effort. _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
