linux-kernel - Re: [PATCH] drivers/virt/fsl_hypervisor: Correcting error handling path

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Date:   Tue, 26 May 2020 10:43:52 +0530
From:   Souptick Joarder <jrdr.linux@...il.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Dan Williams <dan.j.williams@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jason Gunthorpe <jgg@...pe.ca>, dsterba@...e.com,
        Arnd Bergmann <arnd@...db.de>, Ira Weiny <ira.weiny@...el.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers/virt/fsl_hypervisor: Correcting error handling path

On Fri, May 22, 2020 at 6:24 PM Dan Carpenter <dan.carpenter@...cle.com> wrote:
>
> On Thu, May 14, 2020 at 01:53:16AM +0530, Souptick Joarder wrote:
> > First, when memory allocation for sg_list_unaligned failed, there
> > is no point of calling put_pages() as we haven't pinned any pages.
> >
> > Second, if get_user_pages_fast() failed we should unpinned num_pinned
> > pages, no point of checking till num_pages.
> >
> > This will address both.
> >
> > Signed-off-by: Souptick Joarder <jrdr.linux@...il.com>
>
> If gup_flags were | FOLL_LONGTERM then this patch would fix a double
> free because of the put_page() in __gup_longterm_locked().
>
> mm/gup.c
>   1786                  if (check_dax_vmas(vmas_tmp, rc)) {
>   1787                          for (i = 0; i < rc; i++)
>   1788                                  put_page(pages[i]);
>                                         ^^^^^^^^^^^^^^^^^^^
> put_page() here and also in the caller.
>
>   1789                          rc = -EOPNOTSUPP;
>   1790                          goto out;
>   1791                  }
>
> But since this isn't FOLL_LONGTERM the patch is a nice cleanup which
> doesn't affect run time.
>
> Reviewed-by: Dan Carpenter <dan.carpenter@...cle.com>

Hi Andrew,
Is it fine to take it through mm tree ?