linux-kernel - Re: [PATCH 9/9] xen/privcmd-buf.c: Convert to use vm_insert_range

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Date:   Tue, 15 Jan 2019 11:11:56 +0530
From:   Souptick Joarder <jrdr.linux@...il.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Matthew Wilcox <willy@...radead.org>,
        Michal Hocko <mhocko@...e.com>,
        Juergen Gross <jgross@...e.com>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        robin.murphy@....com, xen-devel@...ts.xenproject.org,
        linux-kernel@...r.kernel.org, Linux-MM <linux-mm@...ck.org>
Subject: Re: [PATCH 9/9] xen/privcmd-buf.c: Convert to use vm_insert_range_buggy

On Tue, Jan 15, 2019 at 5:01 AM Boris Ostrovsky
<boris.ostrovsky@...cle.com> wrote:
>
> On 1/11/19 10:13 AM, Souptick Joarder wrote:
> > Convert to use vm_insert_range_buggy() to map range of kernel
> > memory to user vma.
> >
> > This driver has ignored vm_pgoff. We could later "fix" these drivers
> > to behave according to the normal vm_pgoff offsetting simply by
> > removing the _buggy suffix on the function name and if that causes
> > regressions, it gives us an easy way to revert.
> >
> > Signed-off-by: Souptick Joarder <jrdr.linux@...il.com>
> > ---
> >  drivers/xen/privcmd-buf.c | 8 ++------
> >  1 file changed, 2 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/xen/privcmd-buf.c b/drivers/xen/privcmd-buf.c
> > index de01a6d..a9d7e97 100644
> > --- a/drivers/xen/privcmd-buf.c
> > +++ b/drivers/xen/privcmd-buf.c
> > @@ -166,12 +166,8 @@ static int privcmd_buf_mmap(struct file *file, struct vm_area_struct *vma)
> >       if (vma_priv->n_pages != count)
> >               ret = -ENOMEM;
> >       else
> > -             for (i = 0; i < vma_priv->n_pages; i++) {
> > -                     ret = vm_insert_page(vma, vma->vm_start + i * PAGE_SIZE,
> > -                                          vma_priv->pages[i]);
> > -                     if (ret)
> > -                             break;
> > -             }
> > +             ret = vm_insert_range_buggy(vma, vma_priv->pages,
> > +                                             vma_priv->n_pages);
>
> This can use the non-buggy version. But since the original code was
> indeed buggy in this respect I can submit this as a separate patch later.
>
> So
>
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>

Thanks Boris.
>
>
> >
> >       if (ret)
> >               privcmd_buf_vmapriv_free(vma_priv);
>