2016-03-13 00:37:15

by Shuah Khan

Subject: [PATCH] media: add dump_stack() if called in atomic context

Change media_add_link() and media_devnode_create() to dump_stack when
called in atomic context.

Signed-off-by: Shuah Khan <[email protected]>
Suggested-by: Mauro Carvalho Chehab <[email protected]>
---
drivers/media/media-entity.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
index e95070b..66a5392 100644
--- a/drivers/media/media-entity.c
+++ b/drivers/media/media-entity.c
@@ -570,6 +570,9 @@ static struct media_link *media_add_link(struct list_head *head)
{
struct media_link *link;

+ if (in_atomic())
+ dump_stack();
+
link = kzalloc(sizeof(*link), GFP_KERNEL);
if (link == NULL)
return NULL;
@@ -891,6 +894,9 @@ struct media_intf_devnode *media_devnode_create(struct media_device *mdev,
{
struct media_intf_devnode *devnode;

+ if (in_atomic())
+ dump_stack();
+
devnode = kzalloc(sizeof(*devnode), GFP_KERNEL);
if (!devnode)
return NULL;
--
2.5.0

2016-03-13 11:44:02

by Mauro Carvalho Chehab

Subject: Re: [PATCH] media: add dump_stack() if called in atomic context

Em Sat, 12 Mar 2016 17:37:05 -0700
Shuah Khan <[email protected]> escreveu:

> Change media_add_link() and media_devnode_create() to dump_stack when
> called in atomic context.
>
> Signed-off-by: Shuah Khan <[email protected]>
> Suggested-by: Mauro Carvalho Chehab <[email protected]>

Just to be clear: my suggestion is to use this in order to help you to
debug the issues with au0828/snd-usb-audio, that are sometimes producing
those Kernel messages:

[ 23.267197] BUG: sleeping function called from invalid context at mm/slub.c:1289

But I don't think that should patch should be merged upstream.

Regards,
Mauro

> ---
> drivers/media/media-entity.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
> index e95070b..66a5392 100644
> --- a/drivers/media/media-entity.c
> +++ b/drivers/media/media-entity.c
> @@ -570,6 +570,9 @@ static struct media_link *media_add_link(struct list_head *head)
> {
> struct media_link *link;
>
> + if (in_atomic())
> + dump_stack();
> +
> link = kzalloc(sizeof(*link), GFP_KERNEL);
> if (link == NULL)
> return NULL;
> @@ -891,6 +894,9 @@ struct media_intf_devnode *media_devnode_create(struct media_device *mdev,
> {
> struct media_intf_devnode *devnode;
>
> + if (in_atomic())
> + dump_stack();
> +
> devnode = kzalloc(sizeof(*devnode), GFP_KERNEL);
> if (!devnode)
> return NULL;


--
Thanks,
Mauro