[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <E1JCWax-0005Ck-Kg@pomaz-ex.szeredi.hu>
Date: Wed, 09 Jan 2008 09:47:31 +0100
From: Miklos Szeredi <miklos@...redi.hu>
To: nigel@...el.suspend2.net
CC: pavel@....cz, akpm@...ux-foundation.org, hch@...radead.org,
serue@...ibm.com, viro@....linux.org.uk, ebiederm@...ssion.com,
kzak@...hat.com, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, containers@...ts.osdl.org,
util-linux-ng@...r.kernel.org
Subject: Re: [patch 7/9] unprivileged mounts: allow unprivileged fuse mounts
> >> On Tue 2008-01-08 12:35:09, Miklos Szeredi wrote:
> >>> From: Miklos Szeredi <mszeredi@...e.cz>
> >>>
> >>> Use FS_SAFE for "fuse" fs type, but not for "fuseblk".
> >>>
> >>> FUSE was designed from the beginning to be safe for unprivileged users. This
> >>> has also been verified in practice over many years. In addition unprivileged
> >> Eh? So 'kill -9 no longer works' and 'suspend no longer works' is not
> >> considered important enough to even mention?
> >
> > No. Because in practice they don't seem to matter. Also because
> > there's no way in which fuse could be done differently to address
> > these issues.
>
> Could you clarify, please? I hope I'm getting the wrong end of the stick
> - it sounds to me like you and Pavel are saying that this patch breaks
> suspending to ram (and hibernating?) but you want to push it anyway
> because you haven't been able to produce an instance, don't think
> suspending or hibernating matter and couldn't fix fuse anyway?
This patch has nothing to do with suspend or hibernate. What this
patchset does, is help get rid of fusermount, a suid-root mount
helper. It also opens up new possibilities, which are not fuse
related.
Fuse has bad interactions with the freezer, theoretically. In
practice, I remember just one bug report (that sparked off this whole
"do we need freezer, or don't we" flamefest), that actually got fixed
fairly quickly, ...maybe. Rafael probably remembers better.
> > The 'kill -9' thing is basically due to VFS level locking not being
> > interruptible. It could be changed, but I'm not sure it's worth it.
> >
> > For the suspend issue, there are also no easy solutions.
>
> What are the non-easy solutions?
The ability to freeze tasks in uninterruptible sleep, or more
generally at any preempt point (except when drivers are poking
hardware).
I know this doesn't play well with userspace hibernate, and I don't
think it can be resolved without going the kexec way.
Miklos
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists