Subject: Re: [PATCH v1 3/3] powerpc/mm/radix: Free PUD table when freeing pagetable

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Tue, 23 Jun 2020 16:10:45 +0530

Bharata B Rao <[email-masked]> writes:

> remove_pagetable() isn't freeing PUD table. This causes memory
> leak during memory unplug. Fix this.
>

Reviewed-by: Aneesh Kumar K.V <[email-masked]>

> Signed-off-by: Bharata B Rao <[email-masked]>
> ---
>  arch/powerpc/mm/book3s64/radix_pgtable.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
> index 58e42393d5e8..8ec2110eaa1a 100644
> --- a/arch/powerpc/mm/book3s64/radix_pgtable.c
> +++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
> @@ -782,6 +782,21 @@ static void free_pmd_table(pmd_t *pmd_start, pud_t *pud)
>  	pud_clear(pud);
>  }
>  
> +static void free_pud_table(pud_t *pud_start, p4d_t *p4d)
> +{
> +	pud_t *pud;
> +	int i;
> +
> +	for (i = 0; i < PTRS_PER_PUD; i++) {
> +		pud = pud_start + i;
> +		if (!pud_none(*pud))
> +			return;

Should we do a VM_WARN() here?

> +	}
> +
> +	pud_free(&init_mm, pud_start);
> +	p4d_clear(p4d);
> +}
> +
>  struct change_mapping_params {
>  	pte_t *pte;
>  	unsigned long start;
> @@ -956,6 +971,7 @@ static void __meminit remove_pagetable(unsigned long start, unsigned long end)
>  
>  		pud_base = (pud_t *)p4d_page_vaddr(*p4d);
>  		remove_pud_table(pud_base, addr, next);
> +		free_pud_table(pud_base, p4d);
>  	}
>  
>  	spin_unlock(&init_mm.page_table_lock);
> -- 
> 2.21.3