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SubjectRe: [PATCH] drivers/virt/fsl_hypervisor: Correcting error handling path
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@gmail.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@oracle.com>

regards,
dan carpenter

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