Re: removing refrigerator does not help with s2ram vs. fuse deadlocks (was Re: [linux-pm] Re: [PATCH] Remove process freezer from suspend to RAM pathway)

Miklos Szeredi
2007-07-07T20:15:54Z

> > One task doing ptrace() can basically do whatever it wants with the
> > task being traced. This is not an exact analogy to what fuse does,
> > but close.
>
> Well, IMO userland tasks should not have power to grab VFS mutexes for
> indefinite ammount of time. ("fused is allowed to deadlock kernel, in
> a way only write to special file helps" is ugly). Unfortunately, I
> don't think there's a way to work around that deadlock within fuse
> design limits... (coda was able to get around it by working on whole
> files granularity, AFAICT), so we'll have to live with that.

That's just file I/O. You can easily deadlock coda with any other
file operation. In fact coda is _less_ robust wrt a misbehaving
userspace server than fuse by a big margin.

Miklos