Re: [PATCH] mremap: move_ptes: check pte dirty after its removal

[Linus Torvalds]

On Mon, Nov 28, 2016 at 6:57 PM, Aaron Lu <aaron.lu@xxxxxxxxx> wrote:
>
> Here is a fix patch, sorry for the trouble.

I don't think you tested this one.. You've now essentially reverted
5d1904204c99 entirely by making the new force_flush logic a no-op.

> +               pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
>                 if (pmd_present(*old_pmd) && pmd_dirty(*old_pmd))
>                         force_flush = true;

You need to be testing "pmd", not "*old_pmd".

Because now "*old_pmd" will be zeroes.

>                 if (pte_present(*old_pte) && pte_dirty(*old_pte))
>                         force_flush = true;

Similarly here. You need to check "pte", not "*old_pte".

            Linus