Messages in this thread | | | Date | Thu, 5 Jul 2007 11:18:01 +0200 | From | Pavel Machek <> | Subject | Re: [linux-pm] Re: [PATCH] Remove process freezer from suspend to RAM pathway |
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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 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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