Re: [PATCH v2 2/2] fuse: remove tmp folio for writebacks and internal rb tree

[Miklos Szeredi <miklos@szeredi.hu>]

On Tue, 15 Oct 2024 at 21:17, Shakeel Butt <shakeel.butt@linux.dev> wrote:

> So, any operation that the fuse server can do which can cause wait on
> writeback on the folios backed by the fuse is problematic. We know about
> one scenario i.e. memory allocation causing reclaim which may do the
> wait on unrelated folios which may be backed by the fuse server.
>
> Now there are ways fuse server can shoot itself on the foot. Like sync()
> syscall or accessing the folios backed by itself. The quesion is should
> we really need to protect fuse from such cases?

That's not the issue with sync(2).  The issue is that a fuse server
can deny service to an unrelated and possibly higher privilege task by
blocking writeback.  We really don't want that to happen.

Thanks,
Miklos