Re: [PATCH v5 1/6] userfaultfd: convert mfill_atomic_pte_copy() to use a folio

Mike Kravetz
2023-04-06T21:32:10Z

On 03/31/23 17:39, Peng Zhang wrote:
> From: ZhangPeng <zhangpeng362@huawei.com>
>
> Call vma_alloc_folio() directly instead of alloc_page_vma() and convert
> page_kaddr to kaddr in mfill_atomic_pte_copy(). Removes several calls to
> compound_head().
>
> Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>
> Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
> ---
> mm/userfaultfd.c | 33 +++++++++++++++++----------------
> 1 file changed, 17 insertions(+), 16 deletions(-)

Looks good,

Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>

> } else {
> - page = *pagep;
> + folio = page_folio(*pagep);
> + VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
> *pagep = NULL;
> }

However, I am still unsure about the reason for adding the VM_BUG_ON_FOLIO
here.
--
Mike Kravetz