Re: [PATCH] module/decompress: Never use kunmap() for local un-mappings

[Ira Weiny <ira.weiny@intel.com>]

Fabio M. De Francesco wrote:
> Use kunmap_local() to unmap pages locally mapped with kmap_local_page().
> 
> kunmap_local() must be called on the kernel virtual address returned by
> kmap_local_page(), differently from how we use kunmap() which instead
> expects the mapped page as its argument.
> 
> In module_zstd_decompress() we currently map with kmap_local_page() and
> unmap with kunmap(). This breaks the code and so it should be fixed.
> 
> Cc: Piotr Gorski <piotrgorski@cachyos.org>
> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> Cc: Luis Chamberlain <mcgrof@kernel.org>
> Cc: Stephen Boyd <swboyd@chromium.org>
> Cc: Ira Weiny <ira.weiny@intel.com>

Reviewed-by: Ira Weiny <ira.weiny@intel.com>

> Fixes: 169a58ad824d ("module/decompress: Support zstd in-kernel decompression")
> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
> ---
>  kernel/module/decompress.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/module/decompress.c b/kernel/module/decompress.c
> index bb79ac1a6d8f..7ddc87bee274 100644
> --- a/kernel/module/decompress.c
> +++ b/kernel/module/decompress.c
> @@ -267,7 +267,7 @@ static ssize_t module_zstd_decompress(struct load_info *info,
>  		zstd_dec.size = PAGE_SIZE;
>  
>  		ret = zstd_decompress_stream(dstream, &zstd_dec, &zstd_buf);
> -		kunmap(page);
> +		kunmap_local(zstd_dec.dst);
>  		retval = zstd_get_error_code(ret);
>  		if (retval)
>  			break;
> -- 
> 2.39.2
>