Hello, On Mon, Jan 30, 2012 at 11:58:52AM -0600, Christoph Lameter wrote: > > No, NULL is never gonna be a valid return from any allocator including > > percpu. Percpu allocator doesn't and will never do so. > > How do you prevent the percpu allocator from returning NULL? I thought the > per cpu offsets can wrap around? I thought it didn't. I rememer thinking about this and determining that NULL can't be allocated for dynamic addresses. Maybe I'm imagining things. Anyways, if it can return NULL for valid allocation, it is a bug and should be fixed. > > I'm saying we don't have this for ZERO_SIZE_PTR in any meaningful way > > at this point. If somebody wants to implement it properly, please > > feel free to, but simply applying ZERO_SIZE_PTR without other changes > > doesn't make any sense. > > We have no clean notion of how a percpu pointer needs to be handled. Both > ways of handling things have drawbacks. We don't have returned addr >= PAGE_SIZE guarantee yet but I'm fairly sure that's the only acceptable direction if we want any improvement in this area. Thanks. -- tejun -- 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>