linux-kernel - Re: [PATCH v3 07/16] mm/mmap: Extract validate_mm() from vma

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Message-ID: <0699b053-607c-4230-8fbd-e7515fd8454d@lucifer.local>
Date: Fri, 5 Jul 2024 20:35:19 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: "Liam R. Howlett" <Liam.Howlett@...cle.com>
Cc: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>, Matthew Wilcox <willy@...radead.org>,
        sidhartha.kumar@...cle.com, "Paul E . McKenney" <paulmck@...nel.org>,
        Bert Karwatzki <spasswolf@....de>, Jiri Olsa <olsajiri@...il.com>,
        linux-kernel@...r.kernel.org, Kees Cook <kees@...nel.org>
Subject: Re: [PATCH v3 07/16] mm/mmap: Extract validate_mm() from
 vma_complete()

On Thu, Jul 04, 2024 at 02:27:09PM GMT, Liam R. Howlett wrote:
> vma_complete() will need to be called during an unsafe time to call
> validate_mm().  Extract the call in all places now so that only one
> location can be modified in the next change.
>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
> ---
>  mm/mmap.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 2a1a49f98fa3..8d9be791997a 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -646,7 +646,6 @@ static inline void vma_complete(struct vma_prepare *vp,
>  	}
>  	if (vp->insert && vp->file)
>  		uprobe_mmap(vp->insert);
> -	validate_mm(mm);
>  }
>
>  /*
> @@ -734,6 +733,7 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,
>  	vma_iter_store(vmi, vma);
>
>  	vma_complete(&vp, vmi, vma->vm_mm);
> +	validate_mm(vma->vm_mm);
>  	return 0;
>
>  nomem:
> @@ -775,6 +775,7 @@ int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
>  	vma_iter_clear(vmi);
>  	vma_set_range(vma, start, end, pgoff);
>  	vma_complete(&vp, vmi, vma->vm_mm);
> +	validate_mm(vma->vm_mm);
>  	return 0;
>  }
>
> @@ -1103,6 +1104,7 @@ static struct vm_area_struct
>  	}
>
>  	vma_complete(&vp, vmi, mm);
> +	validate_mm(mm);
>  	khugepaged_enter_vma(res, vm_flags);
>  	return res;
>
> @@ -2481,6 +2483,7 @@ static int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
>
>  	/* vma_complete stores the new vma */
>  	vma_complete(&vp, vmi, vma->vm_mm);
> +	validate_mm(vma->vm_mm);
>
>  	/* Success. */
>  	if (new_below)
> @@ -3353,6 +3356,7 @@ static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
>  		vma_iter_store(vmi, vma);
>
>  		vma_complete(&vp, vmi, mm);
> +		validate_mm(mm);
>  		khugepaged_enter_vma(vma, flags);
>  		goto out;
>  	}
> --
> 2.43.0
>
>

LGTM

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>