Hi! > > > > 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. > > Actually fuse allows SIGKILL, because it's always fatal, and the > syscall may not be restarted. I think you want to stick try_to_freeze() at the same places where you do SIGKILL handling. That should solve the 'syslogd is unfreezeable' problem. Plus, it would be nice to find out where suspend/hibernation is triggering fuse activity. We can then decide where to fix it -- in fuse or in suspend parts. You said sys_sync is not implemented... so where is the problem? > > That's very special, and maybe even a FUSE bug. And that is also > > what makes FUSE special w.r.t. s2ram. > > What makes fuse special is that some file operations are synchronous > and non-restartable. That's just how the UNIX filesystem API works > and is hardly a bug in fuse. Well, unix is not plan9, and maybe userland filesystems are impossible in unix. But that is hardly a bug in unix :-). 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
