On Mon, 30 Jan 2012, Tejun Heo wrote: > I'm pretty sure it never gives out NULL for a dynamic allocation. The > base might be mapped to zero but we're guaranteed to have some static > percpu areas there and IIRC the percpu addresses aren't supposed to > wrap. True but there is a check for a NULL pointer on free. So a NULL pointer currently has the semantics of being an unallocated per cpu structure. If the allocator returns NULL by accident then we cannot free the per cpu allocation anymore. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>