[PATCH net v2] net: ethernet: mtk_eth_soc: fix memory leak in LRO rings release

[PATCH net v2] net: ethernet: mtk_eth_soc: fix memory leak in LRO rings release

[Elad Yifee]

For LRO we allocate more than one page, yet 'skb_free_frag' is used
to free the buffer, which only frees a single page.
Fix it by using 'free_pages' instead.

Fixes: 2f2c0d2919a1 ("net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag")
Signed-off-by: Elad Yifee <eladwf@gmail.com>
---
v2: fixed compilation warnings
---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 16ca427cf4c3..e25b552d70f7 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -1762,8 +1762,10 @@ static void mtk_rx_put_buff(struct mtk_rx_ring *ring, void *data, bool napi)
 	if (ring->page_pool)
 		page_pool_put_full_page(ring->page_pool,
 					virt_to_head_page(data), napi);
-	else
+	else if (ring->frag_size <= PAGE_SIZE)
 		skb_free_frag(data);
+	else
+		free_pages(unsigned long)data, get_order(mtk_max_frag_size(ring->frag_size)));
 }
 
 static int mtk_xdp_frame_map(struct mtk_eth *eth, struct net_device *dev,
@@ -2132,7 +2134,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
 				ring->buf_size, DMA_FROM_DEVICE);
 			if (unlikely(dma_mapping_error(eth->dma_dev,
 						       dma_addr))) {
-				skb_free_frag(new_data);
+				mtk_rx_put_buff(ring, new_data, true);
 				netdev->stats.rx_dropped++;
 				goto release_desc;
 			}
@@ -2146,7 +2148,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
 			skb = build_skb(data, ring->frag_size);
 			if (unlikely(!skb)) {
 				netdev->stats.rx_dropped++;
-				skb_free_frag(data);
+				mtk_rx_put_buff(ring, data, true);
 				goto skip_rx;
 			}
 
@@ -2691,7 +2693,7 @@ static int mtk_rx_alloc(struct mtk_eth *eth, int ring_no, int rx_flag)
 				ring->buf_size, DMA_FROM_DEVICE);
 			if (unlikely(dma_mapping_error(eth->dma_dev,
 						       dma_addr))) {
-				skb_free_frag(data);
+				mtk_rx_put_buff(ring, data, false);
 				return -ENOMEM;
 			}
 		}
-- 
2.45.2

Re: [PATCH net v2] net: ethernet: mtk_eth_soc: fix memory leak in LRO rings release

[Daniel Golle]

On Mon, Aug 12, 2024 at 06:21:19PM +0300, Elad Yifee wrote:
> For LRO we allocate more than one page, yet 'skb_free_frag' is used
> to free the buffer, which only frees a single page.
> Fix it by using 'free_pages' instead.
> 
> Fixes: 2f2c0d2919a1 ("net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag")
> Signed-off-by: Elad Yifee <eladwf@gmail.com>
> ---
> v2: fixed compilation warnings
> ---
>  drivers/net/ethernet/mediatek/mtk_eth_soc.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> index 16ca427cf4c3..e25b552d70f7 100644
> --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> @@ -1762,8 +1762,10 @@ static void mtk_rx_put_buff(struct mtk_rx_ring *ring, void *data, bool napi)
>  	if (ring->page_pool)
>  		page_pool_put_full_page(ring->page_pool,
>  					virt_to_head_page(data), napi);
> -	else
> +	else if (ring->frag_size <= PAGE_SIZE)
>  		skb_free_frag(data);
> +	else
> +		free_pages(unsigned long)data, get_order(mtk_max_frag_size(ring->frag_size)));
You miss on open '(' there. Won't even compile like that.
Please always compile- and run-time test patches before sending them
to the mailing list.

>  }
>  
>  static int mtk_xdp_frame_map(struct mtk_eth *eth, struct net_device *dev,
> @@ -2132,7 +2134,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
>  				ring->buf_size, DMA_FROM_DEVICE);
>  			if (unlikely(dma_mapping_error(eth->dma_dev,
>  						       dma_addr))) {
> -				skb_free_frag(new_data);
> +				mtk_rx_put_buff(ring, new_data, true);
>  				netdev->stats.rx_dropped++;
>  				goto release_desc;
>  			}
> @@ -2146,7 +2148,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
>  			skb = build_skb(data, ring->frag_size);
>  			if (unlikely(!skb)) {
>  				netdev->stats.rx_dropped++;
> -				skb_free_frag(data);
> +				mtk_rx_put_buff(ring, data, true);
>  				goto skip_rx;
>  			}
>  
> @@ -2691,7 +2693,7 @@ static int mtk_rx_alloc(struct mtk_eth *eth, int ring_no, int rx_flag)
>  				ring->buf_size, DMA_FROM_DEVICE);
>  			if (unlikely(dma_mapping_error(eth->dma_dev,
>  						       dma_addr))) {
> -				skb_free_frag(data);
> +				mtk_rx_put_buff(ring, data, false);
>  				return -ENOMEM;
>  			}
>  		}
> -- 
> 2.45.2
> 

Re: [PATCH net v2] net: ethernet: mtk_eth_soc: fix memory leak in LRO rings release

[Felix Fietkau]

On 12.08.24 17:21, Elad Yifee wrote:
> For LRO we allocate more than one page, yet 'skb_free_frag' is used
> to free the buffer, which only frees a single page.
> Fix it by using 'free_pages' instead.
> 
> Fixes: 2f2c0d2919a1 ("net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag")
> Signed-off-by: Elad Yifee <eladwf@gmail.com>

Are you sure about this change? From what I can see, the LRO buffer is 
(or at least should be) allocated as a compound page. Because of that, 
skb_free_frag should work on it. If it doesn't, wouldn't we run into the 
same issue when the network stack frees received packets?

- Felix

Re: [PATCH net v2] net: ethernet: mtk_eth_soc: fix memory leak in LRO rings release

[Elad Yifee]

On Mon, Aug 12, 2024 at 6:34 PM Felix Fietkau <nbd@nbd.name> wrote:
>
> On 12.08.24 17:21, Elad Yifee wrote:
> > For LRO we allocate more than one page, yet 'skb_free_frag' is used
> > to free the buffer, which only frees a single page.
> > Fix it by using 'free_pages' instead.
> >
> > Fixes: 2f2c0d2919a1 ("net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag")
> > Signed-off-by: Elad Yifee <eladwf@gmail.com>
>
> Are you sure about this change? From what I can see, the LRO buffer is
> (or at least should be) allocated as a compound page. Because of that,
> skb_free_frag should work on it. If it doesn't, wouldn't we run into the
> same issue when the network stack frees received packets?
>
> - Felix
>
Hey Felix,
I encountered this problem while testing the HWLRO operation on NETSYS3,
but it was part of a series of changes, so you’re right, with GFP_COMP
it shouldn’t be a problem. I automatically assumed it was a necessary
fix.
Sorry for the mess, I'll continue testing HWLRO and resubmit this
patch if I still find it necessary.

Re: [PATCH net v2] net: ethernet: mtk_eth_soc: fix memory leak in LRO rings release

[kernel test robot]

Hi Elad,

kernel test robot noticed the following build errors:

[auto build test ERROR on net/main]

url:    https://github.com/intel-lab-lkp/linux/commits/Elad-Yifee/net-ethernet-mtk_eth_soc-fix-memory-leak-in-LRO-rings-release/20240813-015755
base:   net/main
patch link:    https://lore.kernel.org/r/20240812152126.14598-1-eladwf%40gmail.com
patch subject: [PATCH net v2] net: ethernet: mtk_eth_soc: fix memory leak in LRO rings release
config: arm-randconfig-003-20240813 (https://download.01.org/0day-ci/archive/20240814/202408140256.AkgMaR7u-lkp@intel.com/config)
compiler: arm-linux-gnueabi-gcc (GCC) 14.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240814/202408140256.AkgMaR7u-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202408140256.AkgMaR7u-lkp@intel.com/

All error/warnings (new ones prefixed by >>):

   drivers/net/ethernet/mediatek/mtk_eth_soc.c: In function 'mtk_rx_put_buff':
>> drivers/net/ethernet/mediatek/mtk_eth_soc.c:1768:28: error: expected expression before 'unsigned'
    1768 |                 free_pages(unsigned long)data, get_order(mtk_max_frag_size(ring->frag_size)));
         |                            ^~~~~~~~
>> drivers/net/ethernet/mediatek/mtk_eth_soc.c:1768:17: error: too few arguments to function 'free_pages'
    1768 |                 free_pages(unsigned long)data, get_order(mtk_max_frag_size(ring->frag_size)));
         |                 ^~~~~~~~~~
   In file included from include/linux/xarray.h:16,
                    from include/linux/radix-tree.h:21,
                    from include/linux/idr.h:15,
                    from include/linux/kernfs.h:12,
                    from include/linux/sysfs.h:16,
                    from include/linux/kobject.h:20,
                    from include/linux/of.h:18,
                    from drivers/net/ethernet/mediatek/mtk_eth_soc.c:9:
   include/linux/gfp.h:372:13: note: declared here
     372 | extern void free_pages(unsigned long addr, unsigned int order);
         |             ^~~~~~~~~~
>> drivers/net/ethernet/mediatek/mtk_eth_soc.c:1768:42: error: expected ';' before 'data'
    1768 |                 free_pages(unsigned long)data, get_order(mtk_max_frag_size(ring->frag_size)));
         |                                          ^~~~
         |                                          ;
>> drivers/net/ethernet/mediatek/mtk_eth_soc.c:1767:9: warning: this 'else' clause does not guard... [-Wmisleading-indentation]
    1767 |         else
         |         ^~~~
   drivers/net/ethernet/mediatek/mtk_eth_soc.c:1768:93: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'else'
    1768 |                 free_pages(unsigned long)data, get_order(mtk_max_frag_size(ring->frag_size)));
         |                                                                                             ^
>> drivers/net/ethernet/mediatek/mtk_eth_soc.c:1768:93: error: expected statement before ')' token


vim +/unsigned +1768 drivers/net/ethernet/mediatek/mtk_eth_soc.c

  1759	
  1760	static void mtk_rx_put_buff(struct mtk_rx_ring *ring, void *data, bool napi)
  1761	{
  1762		if (ring->page_pool)
  1763			page_pool_put_full_page(ring->page_pool,
  1764						virt_to_head_page(data), napi);
  1765		else if (ring->frag_size <= PAGE_SIZE)
  1766			skb_free_frag(data);
> 1767		else
> 1768			free_pages(unsigned long)data, get_order(mtk_max_frag_size(ring->frag_size)));
  1769	}
  1770	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH net v2] net: ethernet: mtk_eth_soc: fix memory leak in LRO rings release

[kernel test robot]

Hi Elad,

kernel test robot noticed the following build errors:

[auto build test ERROR on net/main]

url:    https://github.com/intel-lab-lkp/linux/commits/Elad-Yifee/net-ethernet-mtk_eth_soc-fix-memory-leak-in-LRO-rings-release/20240813-015755
base:   net/main
patch link:    https://lore.kernel.org/r/20240812152126.14598-1-eladwf%40gmail.com
patch subject: [PATCH net v2] net: ethernet: mtk_eth_soc: fix memory leak in LRO rings release
config: x86_64-allyesconfig (https://download.01.org/0day-ci/archive/20240814/202408140408.smKpJgMF-lkp@intel.com/config)
compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240814/202408140408.smKpJgMF-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202408140408.smKpJgMF-lkp@intel.com/

All errors (new ones prefixed by >>):

>> drivers/net/ethernet/mediatek/mtk_eth_soc.c:1768:14: error: expected expression
    1768 |                 free_pages(unsigned long)data, get_order(mtk_max_frag_size(ring->frag_size)));
         |                            ^
   1 error generated.


vim +1768 drivers/net/ethernet/mediatek/mtk_eth_soc.c

  1759	
  1760	static void mtk_rx_put_buff(struct mtk_rx_ring *ring, void *data, bool napi)
  1761	{
  1762		if (ring->page_pool)
  1763			page_pool_put_full_page(ring->page_pool,
  1764						virt_to_head_page(data), napi);
  1765		else if (ring->frag_size <= PAGE_SIZE)
  1766			skb_free_frag(data);
  1767		else
> 1768			free_pages(unsigned long)data, get_order(mtk_max_frag_size(ring->frag_size)));
  1769	}
  1770	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki