Re: [PATCH 0/8] Fix memory leak of some device state in migration

From: "Michael S. Tsirkin" <mst@redhat.com>
To: g00517791 <gaojinhao@huawei.com>
Cc: "Stefan Berger" <stefanb@linux.vnet.ibm.com>,
	"Jason Wang" <jasowang@redhat.com>,
	"Juan Quintela" <quintela@redhat.com>,
	qemu-devel@nongnu.org, "Greg Kurz" <groug@kaod.org>,
	qemu-ppc@nongnu.org, wanghaibin.wang@huawei.com,
	"Marc-André Lureau" <marcandre.lureau@redhat.com>,
	zhukeqian1@huawei.com,
	"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
	"David Gibson" <david@gibson.dropbear.id.au>
Subject: Re: [PATCH 0/8] Fix memory leak of some device state in migration
Date: Sun, 27 Dec 2020 08:19:44 -0500	[thread overview]
Message-ID: <20201227081620-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20201226103347.868-1-gaojinhao@huawei.com>

On Sat, Dec 26, 2020 at 06:33:39PM +0800, g00517791 wrote:
> From: Jinhao Gao <gaojinhao@huawei.com>
> 
> For some device state having some fields of VMS_ALLOC flag, they don't
> free memory allocated for the fields in vmstate_save_state and vmstate
> _load_state. We add funcs or sentences of free memory before allocation
> of memory or after load of memory to avoid memory leak.
> 

Isn't there a way to handle it centrally?
IIUC the issue is repeated loads in case a load fails, right?
So can't we do something along the lines of:

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/migration/vmstate.c b/migration/vmstate.c
index e9d2aef66b..873f76739f 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -70,6 +70,7 @@ static void vmstate_handle_alloc(void *ptr, const VMStateField *field,
         gsize size = vmstate_size(opaque, field);
         size *= vmstate_n_elems(opaque, field);
         if (size) {
+            g_free(*(void **)ptr);
             *(void **)ptr = g_malloc(size);
         }
     }

-- 
MST


