On 08/21, David Howells wrote: > > Oleg Nesterov <[email protected]> wrote: > > > David, any other reason why ->real_cred can be NULL ? (assuming that I > > interpret this asm correctly). > > It should only be possible to see ->real_cred as being NULL after exit_creds() > has been called from __put_task_struct() for a task that has finished > construction.
Yes, thanks, this was my understanding... > Is there a race between kill() and exit() brought on by the kill path only > using the RCU read lock? This doesn't prevent ->real_cred from being > modified, but it looks like this should, in combination with > delayed_put_task_struct(), prevent it from being cleared. Yes, rcu should protect us from both delayed_put_pid() and delayed_put_task(). Everything looks correct... And there are a lot of other similar users of find_vpid/find_task_by_vpid/pid_task/etc under rcu, I can't recall any bug in this area. I am puzzled. Note also that ->signal == NULL. Will try to think more, but so far I have no any idea. Oleg. -- 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/
