Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <68e2fb35-141d-5505-766f-29afe0d61435@linux.ibm.com>
Date:   Tue, 6 Sep 2022 18:09:34 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0)
 Gecko/20100101 Thunderbird/102.2.0
Subject: Re: [RFC PATCH RESEND 12/28] mm/mremap: mark VMA as locked while
 remapping it to a new address range
Content-Language: fr
To:     Suren Baghdasaryan <surenb@google.com>, akpm@linux-foundation.org
Cc:     michel@lespinasse.org, jglisse@google.com, mhocko@suse.com,
        vbabka@suse.cz, hannes@cmpxchg.org, mgorman@suse.de,
        dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com,
        peterz@infradead.org, laurent.dufour@fr.ibm.com,
        paulmck@kernel.org, luto@kernel.org, songliubraving@fb.com,
        peterx@redhat.com, david@redhat.com, dhowells@redhat.com,
        hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev,
        rientjes@google.com, axelrasmussen@google.com, joelaf@google.com,
        minchan@google.com, kernel-team@android.com, linux-mm@kvack.org,
        linux-arm-kernel@lists.infradead.org,
        linuxppc-dev@lists.ozlabs.org, x86@kernel.org,
        linux-kernel@vger.kernel.org
References: <20220901173516.702122-1-surenb@google.com>
 <20220901173516.702122-13-surenb@google.com>
From:   Laurent Dufour <ldufour@linux.ibm.com>
In-Reply-To: <20220901173516.702122-13-surenb@google.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

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@google.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@fr.ibm.com>