Re: [PATCH 5/5] block/nvme: Fix memory leak from nvme_init_queue()

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 10/7/21 15:29, Stefan Hajnoczi wrote:
> On Wed, Oct 06, 2021 at 06:49:31PM +0200, Philippe Mathieu-Daudé wrote:
>> nvme_create_queue_pair() allocates resources with qemu_vfio_dma_map(),
>> but we never release them. Do it in nvme_free_queue() which is called
>> from nvme_free_queue_pair().
>>
>> Reported by valgrind:
>>
>>   ==252858== 520,192 bytes in 1 blocks are still reachable in loss record 8,293 of 8,302
>>   ==252858==    at 0x4846803: memalign (vg_replace_malloc.c:1265)
>>   ==252858==    by 0x484691F: posix_memalign (vg_replace_malloc.c:1429)
>>   ==252858==    by 0xB8AFE4: qemu_try_memalign (oslib-posix.c:210)
>>   ==252858==    by 0xA9E315: nvme_create_queue_pair (nvme.c:229)
>>   ==252858==    by 0xAA0125: nvme_init (nvme.c:799)
>>   ==252858==    by 0xAA081C: nvme_file_open (nvme.c:953)
>>   ==252858==    by 0xA23DDD: bdrv_open_driver (block.c:1550)
>>   ==252858==    by 0xA24806: bdrv_open_common (block.c:1827)
>>   ==252858==    by 0xA2889B: bdrv_open_inherit (block.c:3747)
>>   ==252858==    by 0xA28DE4: bdrv_open (block.c:3840)
>>   ==252858==    by 0x9E0F8E: bds_tree_init (blockdev.c:675)
>>   ==252858==    by 0x9E7C74: qmp_blockdev_add (blockdev.c:3551)
>>
>> Fixes: bdd6a90a9e5 ("block: Add VFIO based NVMe driver")
>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>> ---
>>  block/nvme.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/block/nvme.c b/block/nvme.c
>> index 6e476f54b9f..903c8ffa060 100644
>> --- a/block/nvme.c
>> +++ b/block/nvme.c
>> @@ -185,6 +185,7 @@ static bool nvme_init_queue(BDRVNVMeState *s, NVMeQueue *q,
>>  
>>  static void nvme_free_queue(BDRVNVMeState *s, NVMeQueue *q)
>>  {
>> +    qemu_vfio_dma_unmap(s->vfio, q->queue);
>>      qemu_vfree(q->queue);
>>  }
> 
> I can't figure out the issue. qemu_vfree(q->queue) was already called
> before this patch. How does adding qemu_vfio_dma_unmap() help with the
> valgrind report in the commit description?

You are right, I think I didn't select the correct record
between the 8302 reported by valgrind. I will revisit, thanks.