On Sat, Mar 19, 2016 at 6:55 PM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > > What would make unlazy_walk() fail? And if it succeeds, you are not > in RCU mode anymore *without* restarting from scratch... I don't see your point. You don't want to be in RCU mode any more. You want to either succeed or fail with ECHILD/ESTALE. Then, in the failure case, you go to the thread. What I meant by restarting was the restart that do_filp_open() does, and there it just restarts with "op->lookup_flags", which has RCU_LOOKUP still set, so it would just try to do the RCU lookup again. But I actually notice now that Ben actually disabled that restart if LOOKUP_RCU was set, so that ends up not even happening. Anyway, I'm not saying it's polished and pretty. I think the changes to do_filp_open() are a bit silly, and the code should just use path_openat() directly. Possibly using a new helper (ie perhaps just introduce a "rcu_filp_openat()" thing). But from a design perspective, I think this all looks fine. Linus -- 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>