host_ack_bmp is allocated with vzalloc but is currently freed via
bitmap_free (which ends up using kfree).  This is incorrect as
allocation and deallocation functions should be paired.

Using mismatched alloc/free may lead to undefined behavior, memory leaks,
or system instability.

This patch fixes the mismatch by freeing host_ack_bmp with vfree to
match the vzalloc allocation.

Signed-off-by: Zilin Guan <zilin@seu.edu.cn>
---
 drivers/vfio/pci/pds/dirty.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vfio/pci/pds/dirty.c b/drivers/vfio/pci/pds/dirty.c
index c51f5e4c3dd6..481992142f79 100644
--- a/drivers/vfio/pci/pds/dirty.c
+++ b/drivers/vfio/pci/pds/dirty.c
@@ -82,7 +82,7 @@ static int pds_vfio_dirty_alloc_bitmaps(struct pds_vfio_region *region,
 
 	host_ack_bmp = vzalloc(bytes);
 	if (!host_ack_bmp) {
-		bitmap_free(host_seq_bmp);
+		vfree(host_seq_bmp);
 		return -ENOMEM;
 	}
 
-- 
2.34.1

On Fri, 12 Sep 2025 15:04:18 +0000
Zilin Guan <zilin@seu.edu.cn> wrote:

> host_ack_bmp is allocated with vzalloc but is currently freed via
> bitmap_free (which ends up using kfree).  This is incorrect as
> allocation and deallocation functions should be paired.

This patch is fixing the freeing of host_seq_bmp, not host_ack_bmp.
Both are allocated with vzalloc().  The same logic applies but the
commit log is incorrect.
 
> Using mismatched alloc/free may lead to undefined behavior, memory leaks,
> or system instability.
> 
> This patch fixes the mismatch by freeing host_ack_bmp with vfree to
> match the vzalloc allocation.
> 

Fixes: f232836a9152 ("vfio/pds: Add support for dirty page tracking")

Thanks,
Alex

> Signed-off-by: Zilin Guan <zilin@seu.edu.cn>
> ---
>  drivers/vfio/pci/pds/dirty.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/pci/pds/dirty.c b/drivers/vfio/pci/pds/dirty.c
> index c51f5e4c3dd6..481992142f79 100644
> --- a/drivers/vfio/pci/pds/dirty.c
> +++ b/drivers/vfio/pci/pds/dirty.c
> @@ -82,7 +82,7 @@ static int pds_vfio_dirty_alloc_bitmaps(struct pds_vfio_region *region,
>  
>  	host_ack_bmp = vzalloc(bytes);
>  	if (!host_ack_bmp) {
> -		bitmap_free(host_seq_bmp);
> +		vfree(host_seq_bmp);
>  		return -ENOMEM;
>  	}
>

…
> This patch fixes the mismatch by …

* See also:
  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.17-rc5#n94

* Would it be helpful to append parentheses to function names?

* How do you think about to add any tags (like “Fixes” and “Cc”) accordingly?


Regards,
Markus