On Sun, May 24, 2020 at 8:34 AM Greg Kroah-Hartman <gre...@linuxfoundation.org> wrote: > > It is possible for a KOBJ_REMOVE uevent to be sent to userspace way > after the files are actually gone from sysfs, due to how reference > counting for kobjects work. This should not be a problem, but it would > be good to properly send the information when things are going away, not > at some later point in time in the future. > > Before this move, if a kobject's parent was torn down before the child,
^^^^ And this is the root of the problem and what has to be fixed. > when the call to kobject_uevent() happened, the parent walk to try to > reconstruct the full path of the kobject could be a total mess and cause > crashes. It's not good to try to tear down a kobject tree from top > down, but let's at least try to not to crash if a user does so. One can try, but if we keep proper reference counting then kobject core should take care of actually releasing objects in the right order. I do not think you should keep this patch, and instead see if we can push call to kobject_put(kobj->parent) into kobject_cleanup(). Thanks. -- Dmitry