Re: [PATCH v2 bpf-next] mm: mmap: increase sockets maximum memory size pgoff for 32bits

[Ivan Khoronzhuk]

On Tue, Aug 13, 2019 at 10:02:54AM +0200, Magnus Karlsson wrote:
> On Mon, Aug 12, 2019 at 2:45 PM Ivan Khoronzhuk
> <ivan.khoronzhuk@xxxxxxxxxx> wrote:
> > The AF_XDP sockets umem mapping interface uses XDP_UMEM_PGOFF_FILL_RING
> > and XDP_UMEM_PGOFF_COMPLETION_RING offsets. The offsets seems like are
> > established already and are part of configuration interface.
> >
> > But for 32-bit systems, while AF_XDP socket configuration, the values
> > are to large to pass maximum allowed file size verification.
> > The offsets can be tuned ofc, but instead of changing existent
> > interface - extend max allowed file size for sockets.
>
> Can you use mmap2() instead that takes a larger offset (2^44) even on
> 32-bit systems?

That's for mmap2.

> /Magnus
>
> > Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@xxxxxxxxxx>
> > ---
> >
> > Based on bpf-next/master
> >
> > v2..v1:
> >         removed not necessarily #ifdev as ULL and UL for 64 has same size
> >
> >  mm/mmap.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/mm/mmap.c b/mm/mmap.c
> > index 7e8c3e8ae75f..578f52812361 100644
> > --- a/mm/mmap.c
> > +++ b/mm/mmap.c
> > @@ -1358,6 +1358,9 @@ static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
> >         if (S_ISBLK(inode->i_mode))
> >                 return MAX_LFS_FILESIZE;
> >
> > +       if (S_ISSOCK(inode->i_mode))
> > +               return MAX_LFS_FILESIZE;
> > +
> >         /* Special "we do even unsigned file positions" case */
> >         if (file->f_mode & FMODE_UNSIGNED_OFFSET)
> >                 return 0;
> > --
> > 2.17.1

--
Regards,
Ivan Khoronzhuk