Got marked as APPLIED by kernel team (Paolo). -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/2051835
Title: [24.04 FEAT] Memory hotplug vmem pages (s390x) Status in Ubuntu on IBM z Systems: In Progress Status in linux package in Ubuntu: In Progress Status in linux source package in Noble: In Progress Bug description: The current s390 specific memory hotplug backend allocates 'struct page' management structures for all standby memory regions, when those standby regions are detected at ipl time. The reason for this is, that setting standby online memory is supposed to succeed especially in memory constrained environments, since lack of free memory is likely the reason why additional memory is brought online. If in such cases 'struct pages' would have to be allocated before memory could be brought up, this would likely fail, and contradict the whole rationale of memory hotplug. However pre-allocating memory for 'struct pages' comes with the downside that for highly unbalanced ratios of online/standby memory a system might even fail to ipl, because there is not enough memory available for all possible struct pages which are required for standby memory. The idea is to improve the situation: when standby memory is brought online, the memory for struct pages (and maybe other management structures) required for this new memory area should be taken from the online memory, instead of pre-allocating them. This would solve the problems with unbalanced ratios as described above. Note: there are intentions to tell customers that they should always define the maximum size of standby memory for their LPAR activation profiles. This would allow for maximum flexibility for all LPARs during runtime, given that the amount of standby memory cannot be changed during runtime. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/2051835/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
