On 08/02, Oleg Nesterov wrote: > > On 08/02, Adrian Reber wrote: > > > > On Wed, Jul 31, 2019 at 07:41:36PM +0200, Oleg Nesterov wrote: > > > But the main question is how it can really help if ns->level > 0, unlikely > > > CRIU will ever need to clone the process with the same pid_nr == set_tid > > > in the ns->parent chain. > > > > Not sure I understand what you mean. For CRIU only the PID in the PID > > namespace is relevant. > > If it runs "inside" this namespace. But in this case alloc_pid() should > use nr == set_tid only once in the main loop, when i == ns->level.
and I just noticed that your patch does exactly this, it clears set_tid after the 1st usage when i == ns->level. > > > So may be kernel_clone_args->set_tid should be pid_t __user > > > *set_tid_array? > > > Or I missed something ? > > > > Not sure why and how an array would be needed. Could you give me some > > more details why you think this is needed. > > IIURC, criu can restore the process tree along with nested pid namespaces. > > how can this patch help in this case? > > But again, perhaps I missed something. I forgot everything about criu. Yes... I guess in this case it can "safely" modify ns_last_pid in the child namespaces it needs to create. So Adrian, sorry for confusion, I think your patch is fine. Oleg.
