On Wed 22-02-17 10:32:34, Vitaly Kuznetsov wrote: [...] > > There is a workaround in that a user could online the memory or have > > a udev rule to online the memory by using the sysfs interface. The > > sysfs interface to online memory goes through device_online() which > > should updated the dev->offline flag. I'm not sure that having kernel > > memory hotplug rely on userspace actions is the correct way to go. > > Using udev rule for memory onlining is possible when you disable > memhp_auto_online but in some cases it doesn't work well, e.g. when we > use memory hotplug to address memory pressure the loop through userspace > is really slow and memory consuming, we may hit OOM before we manage to > online newly added memory.
How does the in-kernel implementation prevents from that? > In addition to that, systemd/udev folks > continuosly refused to add this udev rule to udev calling it stupid as > it actually is an unconditional and redundant ping-pong between kernel > and udev. This is a policy and as such it doesn't belong to the kernel. The whole auto-enable in the kernel is just plain wrong IMHO and we shouldn't have merged it. -- Michal Hocko SUSE Labs
