[PATCH v2 07/19] mm/fork: Accept huge pfnmap entries

[David Hildenbrand]

On 26.08.24 22:43, Peter Xu wrote:
> Teach the fork code to properly copy pfnmaps for pmd/pud levels.  Pud is
> much easier, the write bit needs to be persisted though for writable and
> shared pud mappings like PFNMAP ones, otherwise a follow up write in either
> parent or child process will trigger a write fault.
> 
> Do the same for pmd level.
> 
> Signed-off-by: Peter Xu <peterx at redhat.com>
> ---
>   mm/huge_memory.c | 29 ++++++++++++++++++++++++++---
>   1 file changed, 26 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index e2c314f631f3..15418ffdd377 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1559,6 +1559,24 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
>   	pgtable_t pgtable = NULL;
>   	int ret = -ENOMEM;
>   
> +	pmd = pmdp_get_lockless(src_pmd);
> +	if (unlikely(pmd_special(pmd))) {

I assume I have to clean up your mess here as well?

-- 
Cheers,

David / dhildenb