linux-kernel - Re: [PATCH v3 1/6] dax: fix vma_is

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Date:   Mon, 26 Feb 2018 10:51:00 +0100
From:   Jan Kara <jack@...e.cz>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     linux-nvdimm@...ts.01.org, Jane Chu <jane.chu@...cle.com>,
        Haozhong Zhang <haozhong.zhang@...el.com>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux-mm@...ck.org, Gerd Rausch <gerd.rausch@...cle.com>,
        linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v3 1/6] dax: fix vma_is_fsdax() helper

On Fri 23-02-18 16:43:11, Dan Williams wrote:
> Gerd reports that ->i_mode may contain other bits besides S_IFCHR. Use
> S_ISCHR() instead. Otherwise, get_user_pages_longterm() may fail on
> device-dax instances when those are meant to be explicitly allowed.
> 
> Fixes: 2bb6d2837083 ("mm: introduce get_user_pages_longterm")
> Cc: <stable@...r.kernel.org>
> Reported-by: Gerd Rausch <gerd.rausch@...cle.com>
> Acked-by: Jane Chu <jane.chu@...cle.com>
> Reported-by: Haozhong Zhang <haozhong.zhang@...el.com>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>

I wonder how I didn't notice this when reading the original patch. Anyway
the fix looks good. You can add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  include/linux/fs.h |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 2a815560fda0..79c413985305 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -3198,7 +3198,7 @@ static inline bool vma_is_fsdax(struct vm_area_struct *vma)
>  	if (!vma_is_dax(vma))
>  		return false;
>  	inode = file_inode(vma->vm_file);
> -	if (inode->i_mode == S_IFCHR)
> +	if (S_ISCHR(inode->i_mode))
>  		return false; /* device-dax */
>  	return true;
>  }
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR