On Thu 2007-07-05 10:17:17, Miklos Szeredi wrote: > > > > I have discussed the benefits elsewhere. As for the deadlocks -- do > > > > you still observe them if you use the version of the freezer which > > > > doesn't freeze kernel threads? > > > > > > In general the only way to guarantee there are no deadlocks is to > > > construct the graph of dependencies between tasks. Those dependencies > > > are not in practice observable from outside the tasks, so it is > > > virtually impossible to construct the graph. > > > > In which way can user space tasks depend on each other in a way that > > allows a them members of that cycle to be in uninterruptible sleep? > > - process A calls rename() on a fuse fs > - process B, the fuse server, starts to process the rename request > - process B is frozen before it can reply > > Now process A is unfreezable. We cannot make rename() restartable, > hence it cannot be interruptible. Yes, we are claiming fuse is very special in this regard, and perhaps even broken. Let's see. If I SIGSTOP the fuse server, I can get unrelated tasks unkillable (even for SIGKILL!) forever. That's very special, and maybe even a FUSE bug. And that is also what makes FUSE special w.r.t. s2ram. So no, you can't claim "FUSE is just IPC". It is very special IPC. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
