Vaibhav, again, I think that everything was explained by Linus, let me add some details.
> > In coredump case, where thread_1 faults while thread_2 is in > > TASK_UNINTERRUPTIBLE state, it cannot handle the SIGKILL. > > Thus the process hangs on event. > > The coredump routine freezes until the thread state is > > uninterruptible. Yes. But why we should even try to "fix" coredump in this case? > > Solution: Continue for coredump, without waiting for uninterruptible > > thread, This can't work, please see below. > > as it will get killed as soon as it returns from > > uninterruptible state. Not necessarily. It can play with ->mm before it notices the pending SIGKILL. And, if nothing else, the coredumping paths do not even take mmap_sem because we assume that the dumper is the only user. But even if this doesn't happen, > > Therefore do not increament thread count for threads with > > TASK_UNINTERRUPTIBLE. This is very wrong too. This means that we can start the coredump before the _accounted_ thread exits (because a skipped thread can exit first and decrement the counter). This also means that coredump_finish() can race with the unaccounted threads. > > sigaddset(&t->pending.signal, SIGKILL); > > signal_wake_up(t, 1); > > - nr++; > > + if(!(t->state & TASK_UNINTERRUPTIBLE)) > > + nr++; Again, we can't simply check t->state & TASK_UNINTERRUPTIBLE. This can be false positive or it can sleep in TASK_UNINTERRUPTIBLE right after the check. And even "& TASK_UNINTERRUPTIBLE" is wrong, please look at TASK_KILLABLE. 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/
