Subject: Re: [PATCH] powerpc/hugetlb: Call mm_dec_nr_pmds() in hugetlb_free_pmd_range()

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Tue, 14 Apr 2015 12:44:10 +0530

Scott Wood <[email-masked]> writes:

> Commit dc6c9a35b66b5 ("mm: account pmd page tables to the process")
> added a counter that is incremented whenever a PMD is allocated and
> decremented whenever a PMD is freed.  For hugepages on PPC, common code
> is used to allocated PMDs, but arch-specific code is used to free PMDs.
>
> This results in kernel output such as "BUG: non-zero nr_pmds on freeing
> mm: 1" when using hugepages.
>
> Update the PPC hugepage PMD freeing code to decrement the count, just
> as the above commit did for free_pmd_range().
>
> Fixes: dc6c9a35b66b5 ("mm: account pmd page tables to the process")
> Signed-off-by: Scott Wood <[email-masked]>

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

May be we need to move that mm_dec_nr_pmds to pmd_free_tlb() ?

> ---
> Should we also be touching nr_ptes when we alloc/free hugepage PTEs?
>
>  arch/powerpc/mm/hugetlbpage.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
> index 7e408bf..cecbe00 100644
> --- a/arch/powerpc/mm/hugetlbpage.c
> +++ b/arch/powerpc/mm/hugetlbpage.c
> @@ -581,6 +581,7 @@ static void hugetlb_free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
>  	pmd = pmd_offset(pud, start);
>  	pud_clear(pud);
>  	pmd_free_tlb(tlb, pmd, start);
> +	mm_dec_nr_pmds(tlb->mm);
>  }
>  
>  static void hugetlb_free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
> -- 
> 2.1.0
>
> _______________________________________________
> Linuxppc-dev mailing list
> [email-masked]
> https://lists.ozlabs.org/listinfo/linuxppc-dev