[v8] dax/hmem, cxl: Coordinate Soft Reserved handling with CXL and HMEM

[PATCH v8 1/9] dax/bus: Use dax_region_put() in alloc_dax_region() error path

Posted by Smita Koralahalli 1 week, 6 days ago

alloc_dax_region() calls kref_init() on the dax_region early in the
function, but the error path for sysfs_create_groups() failure uses
kfree() directly to free the dax_region. This bypasses the kref lifecycle.

Use dax_region_put() instead to handle kref lifecycle correctly.

Suggested-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
---
 drivers/dax/bus.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index c94c09622516..299134c9b294 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -668,7 +668,7 @@ struct dax_region *alloc_dax_region(struct device *parent, int region_id,
 	};
 
 	if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
-		kfree(dax_region);
+		dax_region_put(dax_region);
 		return NULL;
 	}
 
-- 
2.17.1

Re: [PATCH v8 1/9] dax/bus: Use dax_region_put() in alloc_dax_region() error path

Posted by Dan Williams 1 week, 5 days ago

Smita Koralahalli wrote:
> alloc_dax_region() calls kref_init() on the dax_region early in the
> function, but the error path for sysfs_create_groups() failure uses
> kfree() directly to free the dax_region. This bypasses the kref lifecycle.
> 
> Use dax_region_put() instead to handle kref lifecycle correctly.

There is no correctness issue here, the object was never published.

I am ok with the change, but be clear that this is for pure symmetry
reasons, not correctness.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>

Re: [PATCH v8 1/9] dax/bus: Use dax_region_put() in alloc_dax_region() error path

Posted by Jonathan Cameron 1 week, 5 days ago

On Sun, 22 Mar 2026 19:53:34 +0000
Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com> wrote:

> alloc_dax_region() calls kref_init() on the dax_region early in the
> function, but the error path for sysfs_create_groups() failure uses
> kfree() directly to free the dax_region. This bypasses the kref lifecycle.
> 
> Use dax_region_put() instead to handle kref lifecycle correctly.
> 
> Suggested-by: Jonathan Cameron <jonathan.cameron@huawei.com>
> Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>

Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>

> ---
>  drivers/dax/bus.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
> index c94c09622516..299134c9b294 100644
> --- a/drivers/dax/bus.c
> +++ b/drivers/dax/bus.c
> @@ -668,7 +668,7 @@ struct dax_region *alloc_dax_region(struct device *parent, int region_id,
>  	};
>  
>  	if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
> -		kfree(dax_region);
> +		dax_region_put(dax_region);
>  		return NULL;
>  	}
>

Re: [PATCH v8 1/9] dax/bus: Use dax_region_put() in alloc_dax_region() error path

Posted by Dave Jiang 1 week, 5 days ago


On 3/22/26 12:53 PM, Smita Koralahalli wrote:
> alloc_dax_region() calls kref_init() on the dax_region early in the
> function, but the error path for sysfs_create_groups() failure uses
> kfree() directly to free the dax_region. This bypasses the kref lifecycle.
> 
> Use dax_region_put() instead to handle kref lifecycle correctly.
> 
> Suggested-by: Jonathan Cameron <jonathan.cameron@huawei.com>
> Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>

> ---
>  drivers/dax/bus.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
> index c94c09622516..299134c9b294 100644
> --- a/drivers/dax/bus.c
> +++ b/drivers/dax/bus.c
> @@ -668,7 +668,7 @@ struct dax_region *alloc_dax_region(struct device *parent, int region_id,
>  	};
>  
>  	if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
> -		kfree(dax_region);
> +		dax_region_put(dax_region);
>  		return NULL;
>  	}
>