Subject: Re: [RFC PATCH v0 4/5] powerpc/mm/radix: Free PUD table when freeing pagetable

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Mon, 22 Jun 2020 18:37:27 +0530

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

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

We had changes w.r.t p4d (folded 5 level table). You may want to get
this updated to recent kernel.

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 e675c0bbf9a4..0d9ef3277579 100644
> --- a/arch/powerpc/mm/book3s64/radix_pgtable.c
> +++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
> @@ -767,6 +767,21 @@ static void free_pmd_table(pmd_t *pmd_start, pud_t *pud)
>  	pud_clear(pud);
>  }
>  
> +static void free_pud_table(pud_t *pud_start, pgd_t *pgd)
> +{
> +	pud_t *pud;
> +	int i;
> +
> +	for (i = 0; i < PTRS_PER_PUD; i++) {
> +		pud = pud_start + i;
> +		if (!pud_none(*pud))
> +			return;
> +	}
> +
> +	pud_free(&init_mm, pud_start);
> +	pgd_clear(pgd);
> +}
> +
>  struct change_mapping_params {
>  	pte_t *pte;
>  	unsigned long start;
> @@ -937,6 +952,7 @@ static void __meminit remove_pagetable(unsigned long start, unsigned long end)
>  
>  		pud_base = (pud_t *)pgd_page_vaddr(*pgd);
>  		remove_pud_table(pud_base, addr, next);
> +		free_pud_table(pud_base, pgd);
>  	}
>  
>  	spin_unlock(&init_mm.page_table_lock);
> -- 
> 2.21.0