Re: [PATCH v2] mm: Fix __dump_page when mapping->host is not set

[Hugh Dickins]

On Mon, 18 Mar 2019, Oscar Salvador wrote:

> Swap mapping->host is NULL, so let us protect __dump_page() for such cases.

Thanks :)

> 
> Fixes: 1c6fb1d89e73c ("mm: print more information about mapping in __dump_page")
> Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
> Acked-by: Michal Hocko <mhocko@xxxxxxxx>

Acked-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx

> ---
>  mm/debug.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/debug.c b/mm/debug.c
> index c0b31b6c3877..7759f12a8fbb 100644
> --- a/mm/debug.c
> +++ b/mm/debug.c
> @@ -79,7 +79,7 @@ void __dump_page(struct page *page, const char *reason)
>  		pr_warn("ksm ");
>  	else if (mapping) {
>  		pr_warn("%ps ", mapping->a_ops);
> -		if (mapping->host->i_dentry.first) {
> +		if (mapping->host && mapping->host->i_dentry.first) {
>  			struct dentry *dentry;
>  			dentry = container_of(mapping->host->i_dentry.first, struct dentry, d_u.d_alias);
>  			pr_warn("name:\"%pd\" ", dentry);
> -- 
> 2.13.7