Re: [PATCH 04/12] swap: restrict to regular files or block devices

["Darrick J. Wong" <djwong@kernel.org>]

On Tue, May 12, 2026 at 07:35:20AM +0200, Christoph Hellwig wrote:
> Various swap code assumes it runs either on a block device or on a
> regular file.  Make this restriction explicit using checks right
> after opening the file.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Makes sense to me.
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  mm/swapfile.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index a183c9c95695..651c1b59ff9f 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -3515,6 +3515,10 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
>  		error = -ENOENT;
>  		goto bad_swap_unlock_inode;
>  	}
> +	if (!S_ISBLK(inode->i_mode) && !S_ISREG(inode->i_mode)) {
> +		error = -EINVAL;
> +		goto bad_swap_unlock_inode;
> +	}
>  	if (IS_SWAPFILE(inode)) {
>  		error = -EBUSY;
>  		goto bad_swap_unlock_inode;
> -- 
> 2.53.0
> 
>