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

[Magnus Karlsson <magnus.karlsson@gmail.com>]

On Mon, Aug 12, 2019 at 2:45 PM Ivan Khoronzhuk
<ivan.khoronzhuk@linaro.org> 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?

/Magnus

> Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
> ---
>
> 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
>