Re: [linux-pm] Re: [PATCH] Remove process freezer from suspend to RAM pathway

Miklos Szeredi
2007-07-04T08:27:33Z

> > That's weird, I never had a suspend problem due to a fuse mount,
> > though I have them all the time. And I suspect, that even the sync()
>
> Well, I don't either, because we don't freeze processes on
> powerbooks. But I have heard that other people have problems with
> suspending with a fuse filesystem mounted. Maybe the difference is
> whether or not the filesystem is writable?
>
> > thing that suspend does is not the real cause, because sync() actually
> > does nothing in fuse filesystems.
>
> It's not the filesystem sync method, as I understand it, it's that if
> there are dirty pages in the page cache for files on the fuse
> filesystem,

Currently fuse doesn't produce dirty pages. Normal writes are done
synchronously, and writable mmap is not supported. So sync() should
really be a no-op for fuse.

> the system will initiate a write-out on them and wait for it to
> finish. But if the fuse userspace is frozen, the write-out will
> never complete.

Maybe there is some other fs operation being done, possibly not
directly, but by waiting for a kernel thread, that does that.

It would be nice, if someone who can reproduce the deadlock could
debug it. Does sysrq still work during suspend?

Miklos