Re: [PATCH V10 00/10] famfs: port into fuse

Matthew Wilcox
2026-04-15T15:10:25Z

On Wed, Apr 15, 2026 at 04:04:50PM +0200, Miklos Szeredi wrote:
> On Wed, 15 Apr 2026 at 15:35, Gregory Price <gourry@gourry.net> wrote:
>
> > This was my first reaction when I realized the BPF program would be
> > controlling iomap return value in the fault path. Big ol' (!) popped
> > up over my head.
>
> I'm wondering which part of this triggers the big (!).
>
> BPF program being run in the fault path?
>
> Or that the return value from the BPF function is used as iomap?
>
> Or something else?

If a BPF program controls what memory address a fault now allows access
to, who validates that this is a memory address within the purview of
the BPF program, and not, say, the address of the kernel page tables?

(I have done no looking to determine if this is already considered)