linux-kernel - Re: [PATCH] mm: Update mask post pxd_clear

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Message-ID: <495ec80f-6cf1-4be8-bc2a-9115562fe60d@arm.com>
Date: Thu, 13 Mar 2025 23:58:48 +0530
From: Dev Jain <dev.jain@....com>
To: jroedel@...e.de, akpm@...ux-foundation.org
Cc: ryan.roberts@....com, david@...hat.com, willy@...radead.org, hch@....de,
 linux-mm@...ck.org, linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] mm: Update mask post pxd_clear_bad()



On 13/03/25 11:44 pm, Dev Jain wrote:
> Since pxd_clear_bad() is an operation changing the state of the page tables,
> we should call arch_sync_kernel_mappings() post this.
> 
> Fixes: e80d3909be42 ("mm: track page table modifications in __apply_to_page_range()")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Dev Jain <dev.jain@....com>
> ---
>   mm/memory.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index 78c7ee62795e..9a4a8c710be0 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2987,6 +2987,7 @@ static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
>   			if (!create)
>   				continue;
>   			pmd_clear_bad(pmd);
> +			*mask = PGTBL_PMD_MODIFIED;

Oh well, I guess these should have been *mask |= PGTBL_PMD_MODIFIED.


>   		}
>   		err = apply_to_pte_range(mm, pmd, addr, next,
>   					 fn, data, create, mask);
> @@ -3023,6 +3024,7 @@ static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
>   			if (!create)
>   				continue;
>   			pud_clear_bad(pud);
> +			*mask = PGTBL_PUD_MODIFIED;
>   		}
>   		err = apply_to_pmd_range(mm, pud, addr, next,
>   					 fn, data, create, mask);
> @@ -3059,6 +3061,7 @@ static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
>   			if (!create)
>   				continue;
>   			p4d_clear_bad(p4d);
> +			*mask = PGTBL_P4D_MODIFIED;
>   		}
>   		err = apply_to_pud_range(mm, p4d, addr, next,
>   					 fn, data, create, mask);
> @@ -3095,6 +3098,7 @@ static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr,
>   			if (!create)
>   				continue;
>   			pgd_clear_bad(pgd);
> +			mask = PGTBL_PGD_MODIFIED;
>   		}
>   		err = apply_to_p4d_range(mm, pgd, addr, next,
>   					 fn, data, create, &mask);