On 2/25/20 9:13 PM, Jason Wang wrote:

On 2020/2/26 上午12:51, Suman Anna wrote:

quoted

Hi Jason,

On 2/24/20 11:39 PM, Jason Wang wrote:

quoted

On 2020/2/25 上午5:26, Suman Anna wrote:

quoted

The functions vring_new_virtqueue() and __vring_new_virtqueue() are
used
with split rings, and any allocations within these functions are
managed
outside of the .we_own_ring flag. The commit cbeedb72b97a
("virtio_ring:
allocate desc state for split ring separately") allocates the desc
state
within the __vring_new_virtqueue() but frees it only when the
.we_own_ring
flag is set. This leads to a memory leak when freeing such allocated
virtqueues with the vring_del_virtqueue() function.

Fix this by moving the desc_state free code outside the flag and only
for split rings. Issue was discovered during testing with remoteproc
and virtio_rpmsg.

Fixes: cbeedb72b97a ("virtio_ring: allocate desc state for split ring
separately")
Signed-off-by: Suman Anna<redacted>
---
   drivers/virtio/virtio_ring.c | 4 ++--
   1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c

b/drivers/virtio/virtio_ring.c
index 867c7ebd3f10..58b96baa8d48 100644

--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c

@@ -2203,10 +2203,10 @@ void vring_del_virtqueue(struct virtqueue *_vq)

                        vq->split.queue_size_in_bytes,
                        vq->split.vring.desc,
                        vq->split.queue_dma_addr);
-
-            kfree(vq->split.desc_state);
           }
       }
+    if (!vq->packed_ring)
+        kfree(vq->split.desc_state);

Nitpick, it looks to me it would be more clear if we just free
desc_state unconditionally here (and remove the kfree for packed above).

OK, are you sure you want that to be folded into this patch? It looks to
me a separate cleanup/consolidation patch, and packed desc_state does
not suffer this memleak, and need not be backported into stable kernels.

regards
Suman

Though it's just a small tweak, I'm fine for leaving it for future.

So

Acked-by: Jason Wang <jasowang@redhat.com>

Thanks Jason, will post a patch for the same once this is merged.

regards
Suman
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