Re: [PATCH RFC] fs/fcntl: add fcntl F_GET_RSS

[Matthew Wilcox]

On Mon, Oct 28, 2019 at 01:28:09PM +0300, Konstantin Khlebnikov wrote:
> +	if (dax_mapping(mapping))
> +		pages = READ_ONCE(mapping->nrexceptional);
> +	else
> +		pages = READ_ONCE(mapping->nrpages);

I'm not sure this is the right calculation for DAX files.  We haven't
allocated any memory for DAX; we're just accessing storage directly.
The entries in the page caache are just translation from file offset to
physical address.