linux-kernel - Re: [RFC PATCH RESEND 12/28] mm/mremap: mark VMA as locked while remapping it to a new address range

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Date:   Tue, 6 Sep 2022 18:09:34 +0200
From:   Laurent Dufour <ldufour@...ux.ibm.com>
To:     Suren Baghdasaryan <surenb@...gle.com>, akpm@...ux-foundation.org
Cc:     michel@...pinasse.org, jglisse@...gle.com, mhocko@...e.com,
        vbabka@...e.cz, hannes@...xchg.org, mgorman@...e.de,
        dave@...olabs.net, willy@...radead.org, liam.howlett@...cle.com,
        peterz@...radead.org, laurent.dufour@...ibm.com,
        paulmck@...nel.org, luto@...nel.org, songliubraving@...com,
        peterx@...hat.com, david@...hat.com, dhowells@...hat.com,
        hughd@...gle.com, bigeasy@...utronix.de, kent.overstreet@...ux.dev,
        rientjes@...gle.com, axelrasmussen@...gle.com, joelaf@...gle.com,
        minchan@...gle.com, kernel-team@...roid.com, linux-mm@...ck.org,
        linux-arm-kernel@...ts.infradead.org,
        linuxppc-dev@...ts.ozlabs.org, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH RESEND 12/28] mm/mremap: mark VMA as locked while
 remapping it to a new address range

Le 01/09/2022 à 19:35, Suren Baghdasaryan a écrit :
> Mark VMA as locked before copying it and when copy_vma produces a new VMA.
> 
> Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
> ---
>  mm/mmap.c   | 1 +
>  mm/mremap.c | 1 +
>  2 files changed, 2 insertions(+)
> 
> diff --git a/mm/mmap.c b/mm/mmap.c
> index ade3909c89b4..121544fd90de 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -3248,6 +3248,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
>  			get_file(new_vma->vm_file);
>  		if (new_vma->vm_ops && new_vma->vm_ops->open)
>  			new_vma->vm_ops->open(new_vma);
> +		vma_mark_locked(new_vma);
>  		vma_link(mm, new_vma, prev, rb_link, rb_parent);
>  		*need_rmap_locks = false;
>  	}

Sounds good in the both case the returned new_vma is locked, either in
copy_vma() or in vma_merge().

> diff --git a/mm/mremap.c b/mm/mremap.c
> index b522cd0259a0..bdbf96254e43 100644
> --- a/mm/mremap.c
> +++ b/mm/mremap.c
> @@ -620,6 +620,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
>  			return -ENOMEM;
>  	}
>  
> +	vma_mark_locked(vma);
>  	new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
>  	new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff,
>  			   &need_rmap_locks);

Reviewed-by: Laurent Dufour <laurent.dufour@...ibm.com>