linux-kernel - Re: [PATCH v2 2/3] xen/privcmd: Mark pages as dirty

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Date:   Tue, 7 Jul 2020 11:38:53 +0200
From:   Jürgen Groß <jgross@...e.com>
To:     Souptick Joarder <jrdr.linux@...il.com>,
        boris.ostrovsky@...cle.com, sstabellini@...nel.org
Cc:     xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
        John Hubbard <jhubbard@...dia.com>,
        Paul Durrant <xadimgnik@...il.com>
Subject: Re: [PATCH v2 2/3] xen/privcmd: Mark pages as dirty

On 06.07.20 20:16, Souptick Joarder wrote:
> pages need to be marked as dirty before unpinned it in
> unlock_pages() which was oversight. This is fixed now.
> 
> Signed-off-by: Souptick Joarder <jrdr.linux@...il.com>
> Suggested-by: John Hubbard <jhubbard@...dia.com>
> Cc: John Hubbard <jhubbard@...dia.com>
> Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
> Cc: Paul Durrant <xadimgnik@...il.com>
> ---
>   drivers/xen/privcmd.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index 33677ea..f6c1543 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -612,8 +612,11 @@ static void unlock_pages(struct page *pages[], unsigned int nr_pages)
>   {
>   	unsigned int i;
>   
> -	for (i = 0; i < nr_pages; i++)
> +	for (i = 0; i < nr_pages; i++) {
> +		if (!PageDirty(pages[i]))
> +			set_page_dirty_lock(pages[i]);

With put_page() directly following I think you should be able to use
set_page_dirty() instead, as there is obviously a reference to the page
existing.

>   		put_page(pages[i]);
> +	}
>   }
>   
>   static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
> 

Juergen