On 04/08, Eric W. Biederman wrote: > > Oleg Nesterov <[EMAIL PROTECTED]> writes: > > > Perhaps it is better to add reparent_kthread() (next patch) to kthread() > > and forget about CLONE_KERNEL_THREAD. > > Please.
OK, will do tomorrow. > > Anyway, re-parenting to swapper breaks pstree, it doesn't show kernel > > threads. And if ->parent == /sbin/init, we can't remove us from ->children > > (unless we forbid sub-thread-of-init exec). So the only safe change is > > set ->exit_state = -1. > > Yes. We certainly need ->exit_state = -1. > Earlier I had forgotten about second the use of ->children to update > the parent pointer of processes when their parent exits. > > There is a practical question how much we care about pstree being > confused (I assume it doesn't crash). If this is just a confusion > issue then I say go for it. PPID == 0 is a very legitimate way to say > the kernel is the parent process. No, it doesn't crash. It just doesn't show kernel threads (ps ax is OK). I didn't look into the sources, but I guess the reason is that pstree assumes that the "root" of the tree is "pid == 1" process. I personally think this is acceptable (and Roland seems to think the same). Still, to be safe, I'll break this into 2 patches, the first one sets ->exit_state, the second re-parents to swapper. In fact, we can do some odd things to make pstree happy. We need ->parent only because /proc needs some ->parent fields. But I'd prefer to avoid these hacks. Still, it is sad that we can't have additional flags for kernel_thread(). However, I agree with your and Roland's objections. Oleg. - To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
