Re: [PATCH v2] mm: huge_memory: Fix kobject cleanup in thpsize_create error

[Lorenzo Stoakes (ARM)]

On Mon, Jul 13, 2026 at 01:41:54PM +0800, Hongling Zeng wrote:
> When kobject_init_and_add() fails, the kobject API requires calling
> kobject_put() to properly clean up the memory, not direct kfree().
>
> According to the kobject API documentation, kobject_init_and_add()
> calls kobject_init() internally. If the subsequent kobject_add()
> fails, the kobject has still been initialized and must be cleaned up
> via the reference count mechanism (kobject_put), not direct kfree().
>
> Direct kfree() leaves the kobject's internal state (including the
> reference count and kset membership) uncleaned, which can cause:
>  - Memory leaks of kobject internal structures
>  - Potential use-after-free if there are pending references
>  - Inconsistent state with the rest of the error handling code
>
> This fix matches the pattern used elsewhere in the kernel and in the
> same function (err_put label) which correctly uses kobject_put().
>
> Fixes: 3485b88390b0 ("mm: thp: introduce multi-size THP sysfs interface")
> Signed-off-by: Hongling Zeng <zenghongling@xxxxxxxxxx>
> Suggested-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>

LGTM, so:

Reviewed-by: Lorenzo Stoakes (ARM) <ljs@xxxxxxxxxx>

>
> ---
>  Change in v2:
>  - Use goto err_put instead of kobject_put() + goto err for consistency
>  - Add suggested
> ---
>  mm/huge_memory.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 2bccb0a53a0a..589f7bf1f19d 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -818,10 +818,8 @@ static struct thpsize *thpsize_create(int order, struct kobject *parent)
>
>  	ret = kobject_init_and_add(&thpsize->kobj, &thpsize_ktype, parent,
>  				   "hugepages-%lukB", size);
> -	if (ret) {
> -		kfree(thpsize);
> -		goto err;
> -	}
> +	if (ret)
> +		goto err_put;
>
>
>  	ret = sysfs_add_group(&thpsize->kobj, &any_ctrl_attr_grp);
> --
> 2.25.1
>

Cheers, Lorenzo