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

Dmitry Osipenko
2020-01-26T14:47:57Z

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.