2019-03-18 07:30:44

by Oscar Salvador

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

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

Fixes: 1c6fb1d89e73c ("mm: print more information about mapping in __dump_page")
Signed-off-by: Oscar Salvador <[email protected]>
Acked-by: Michal Hocko <[email protected]>
---
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

2019-03-19 19:23:34

by Hugh Dickins

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

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 <[email protected]>
> Acked-by: Michal Hocko <[email protected]>

Acked-by: Hugh Dickins <[email protected]>
Cc: [email protected]

> ---
> 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