Re: [PATCH v4 1/4] mm/gup: fix wrongly calculated returned value in fault_in_safe_writeable()

Baoquan He
2025-04-11T05:32:58Z

On 04/10/25 at 08:43pm, Andrew Morton wrote:
> On Thu, 10 Apr 2025 11:57:14 +0800 Baoquan He <bhe@redhat.com> wrote:
>
> > Not like fault_in_readable() or fault_in_writeable(), in
> > fault_in_safe_writeable() local variable 'start' is increased page
> > by page to loop till the whole address range is handled. However,
> > it mistakenly calcalates the size of handled range with 'uaddr - start'.
>
> What are the userspace-visible runtime effects of this change?

I see it mainly affect gfs2_file_direct_read(). Not sure if GFS2 people
can sense any exceptional behaviour caused by this code bug.

>