Hi Xishi, On 03/03/2015 11:30 AM, Xishi Qiu wrote: > When hot-remove a numa node, we will clear pgdat, > but is memset 0 safe in try_offline_node()? It is not safe here. In fact, this is a temporary solution here. As you know, pgdat is accessed lock-less now, so protection mechanism (RCU？) is needed to make it completely safe here, but it seems a bit over-kill. > > process A: offline node XX: > for_each_populated_zone() > find online node XX > cond_resched() > offline cpu and memory, then try_offline_node() > node_set_offline(nid), and memset(pgdat, 0, sizeof(*pgdat)) > access node XX's pgdat > NULL pointer access error It's possible, but I did not meet this condition, did you? Regards, Gu > > Thanks, > Xishi Qiu > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href