On Fri, 08 Jun 2007 14:19:18 -0500 Will Schmidt <[EMAIL PROTECTED]> wrote:
> > > > zap_other_threads() requires tasklist_lock. > > Yup, I missed that. Thanks for pointing it out. > > > > > > > > > If we're going to do this then we should probably create some new > > > > function > > > > (with a better name) which takes tasklsit_lock and then calls > > > > zap_other_threads(). > > I expect this will be a write_lock_irq() since zap_other_threads will be > doing a bit more than just reading the task info. No, I think read_lock() will be sufficient. In fact, it's probably the case that rcu_read_lock() is now sufficient locking coverage for zap_other_threads() (cc's people). It had better be, because do_group_exit() forgot to take tasklist_lock. It is perhaps relying upon spin_lock()'s hidden rcu_read_lock() properties without so much as a code comment, which would be somewhat nasty of it. You could perhaps just call do_group_exit() from within the fault handler, btw. > This will be down in a do-page-fault failure path (see > arch/*/mm/fault.c). I wonder if calling write_lock is going to be safe, > or if its possible to get into a deadlock? i.e. should I branch back up > to the survive: label if I can't take the lock? Would that even be > sufficient? or is it not an issue here? You can take the lock in the fault handler. Nobody should be getting pagefaults while holding tasklist_lock. (Well, a vmalloc fault might, but that's a special-case which doesn't allocate memory or anything like that). - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
