Re: [PATCH v5 24/26] mm/pagemap: Recognize uffd-wp bit for shmem/hugetlbfs

Tiberiu Georgescu
2021-07-19T09:54:24Z

Hello Peter,

> On 15 Jul 2021, at 21:16, Peter Xu <peterx@redhat.com> wrote:
>
> This requires the pagemap code to be able to recognize the newly introduced
> swap special pte for uffd-wp, meanwhile the general case for hugetlb that we
> recently start to support. It should make pagemap uffd-wp support complete.
>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
> fs/proc/task_mmu.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 9c5af77b5290..988e29fa1f00 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -1389,6 +1389,8 @@ static pagemap_entry_t pte_to_pagemap_entry(struct pagemapread *pm,
> flags |= PM_SWAP;
> if (is_pfn_swap_entry(entry))
> page = pfn_swap_entry_to_page(entry);
> + } else if (pte_swp_uffd_wp_special(pte)) {
> + flags |= PM_UFFD_WP;
> }

^ Would it not be important to also add PM_SWAP to flags?

Kind regards,
Tibi