On Tue, 17 May 2011, Daniel Kiper wrote: > This patch contains online_page_callback and apropriate functions for > setting/restoring online page callbacks. It allows to do some machine > specific tasks during online page stage which is required to implement > memory hotplug in virtual machines. Additionally, __online_page_set_limits(), > __online_page_increment_counters() and __online_page_free() function > was added to ease generic hotplug operation. > There are several issues with this. First, this is completely racy and only allows one global callback to be in use at a time without looping, which is probably why you had to pass an argument to restore_online_page_callback(). Your implementation also requires that a callback must be synchronized with itself for the comparison to generic_online_page to make any sense. Nobody knows which callback is effective at any given moment and has no guarantees that when they've set the callback that it will be the one called, otherwise. Second, there's no explanation offered about why you have to split online_page() into three separate functions. In addition, you've exported all of them so presumably modules will need to be doing this when loading or unloading and that further complicates the race mentioned above. Third, there are no followup patches that use this interface or show how you plan on using it (other than eluding that it will be used for virtual machines in the changelog) so we're left guessing as to why we need it implemented in this fashion and restricts the amount of help I can offer because I don't know the problem you're facing. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>