Hi YASUAKI, Thanks for your response. On Wed, Jun 28, 2017 at 03:53:16PM -0400, YASUAKI ISHIMATSU wrote: > > On 06/26/2017 02:26 AM, joeyli wrote: > > Hi all, > > > > If ACPI received ejection request for a ACPI container, kernel > > emits KOBJ_CHANGE uevent when it found online children devices > > below the acpi container. > > > > Base on the description of caa73ea15 kernel patch, user space > > is expected to offline all devices below the container and the > > container itself. Then, user space can finalize the removal of > > the container with the help of its ACPI device object's eject > > attribute in sysfs. > > > > That means that kernel relies on users space to peform the offline > > and ejection jobs to acpi container and children devices. The > > discussion is here: > > https://lkml.org/lkml/2013/11/28/520 > > > > The mail loop didn't explain why the userspace is responsible for > > the whole container offlining. Is it possible to do that transparently > > from the kernel? What's the difference between offlining memory and > > processors which happends without any cleanup and container which > > does essentially the same except it happens at once? > > We don't know what devices mount on the container device. I think > devices mount on the container device are different each vendor's server. > > If memory device mounts on the container, memory offline easily fails. > Other devices may have other concerns. So the following udev rule you > write does not work correctly. > IMHO, if the memory hot-remove(offline/ejection) has problem, then we should report the issue and fix it in mm subsystem. Michal Hocko works hard on this. I think that the CPU or IO subsystem are the same. Current kernel can not complete the container hot-remove job without userspace's involvement. So I sent the udev rule as a example to response change uevents. > I think we need to change offline processing for each device. So currently > the userspace is responsible for the whole container offlining. > It depends on what is the expectation of the deivce offline function in kernel. If a subsystem supports offline in kernel, then it should not affects the running user space application. Otherwise the issue should be fixed. Thanks a lot! Joey Lee -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
