Re: [PATCH 3/5] mm/mremap: use pmd_addr_end to calculate next in move_page_tables()

Andrew Morton
2020-01-27T02:59:51Z

On Sun, 26 Jan 2020 17:47:57 +0300 Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> 18.01.2020 02:22, Wei Yang пишет:
> > Use the general helper instead of do it by hand.
> >
> > Signed-off-by: Wei Yang <richardw.yang-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> > ---
> > mm/mremap.c | 7 ++-----
> > 1 file changed, 2 insertions(+), 5 deletions(-)
> >
> > diff --git a/mm/mremap.c b/mm/mremap.c
> > index c2af8ba4ba43..a258914f3ee1 100644
> > --- a/mm/mremap.c
> > +++ b/mm/mremap.c
> > @@ -253,11 +253,8 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
> >
> > for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
> > cond_resched();
> > - next = (old_addr + PMD_SIZE) & PMD_MASK;
> > - /* even if next overflowed, extent below will be ok */
> > + next = pmd_addr_end(old_addr, old_end);
> > extent = next - old_addr;
> > - if (extent > old_end - old_addr)
> > - extent = old_end - old_addr;
> > old_pmd = get_old_pmd(vma->vm_mm, old_addr);
> > if (!old_pmd)
> > continue;
> > @@ -301,7 +298,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
> >
> > if (pte_alloc(new_vma->vm_mm, new_pmd))
> > break;
> > - next = (new_addr + PMD_SIZE) & PMD_MASK;
> > + next = pmd_addr_end(new_addr, new_addr + len);
> > if (extent > next - new_addr)
> > extent = next - new_addr;
> > move_ptes(vma, old_pmd, old_addr, old_addr + extent, new_vma,
> >
>
> Hello Wei,
>
> Starting with next-20200122, I'm seeing the following in KMSG on NVIDIA
> Tegra (ARM32):
>
> BUG: Bad rss-counter state mm:(ptrval) type:MM_ANONPAGES val:190
>
> and eventually kernel hangs.
>
> Git's bisection points to this patch and reverting it helps. Please fix,
> thanks in advance.

Thanks. I had these tagged for 5.7-rc1 anyway, so I'll drop all five
patches.