linux-kernel - Re: [PATCH 1/4] mm: Assert the mmap_lock is held in __anon_vma

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Message-ID: <a9fd2bc7-a9b4-4e60-b178-f60aa5c2a6de@redhat.com>
Date: Fri, 26 Apr 2024 19:34:50 +0200
From: David Hildenbrand <david@...hat.com>
To: "Matthew Wilcox (Oracle)" <willy@...radead.org>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 Suren Baghdasaryan <surenb@...gle.com>, Peter Xu <peterx@...hat.com>
Subject: Re: [PATCH 1/4] mm: Assert the mmap_lock is held in
 __anon_vma_prepare()

On 26.04.24 16:45, Matthew Wilcox (Oracle) wrote:
> Convert the comment into an assertion.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> ---
>   mm/rmap.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 2608c40dffad..619d4d65d99b 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -182,8 +182,6 @@ static void anon_vma_chain_link(struct vm_area_struct *vma,
>    * for the new allocation. At the same time, we do not want
>    * to do any locking for the common case of already having
>    * an anon_vma.
> - *
> - * This must be called with the mmap_lock held for reading.
>    */
>   int __anon_vma_prepare(struct vm_area_struct *vma)
>   {
> @@ -191,6 +189,7 @@ int __anon_vma_prepare(struct vm_area_struct *vma)
>   	struct anon_vma *anon_vma, *allocated;
>   	struct anon_vma_chain *avc;
>   
> +	mmap_assert_locked(mm);
>   	might_sleep();
>   
>   	avc = anon_vma_chain_alloc(GFP_KERNEL);

Reviewed-by: David Hildenbrand <david@...hat.com>

-- 
Cheers,

David / dhildenb