linux-kernel - Re: [PATCH 2/2] virtio: don't free memory until the underlying struct device has been released

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Message-ID: <54A9563F.3070902@oracle.com>
Date:	Sun, 04 Jan 2015 10:03:27 -0500
From:	Sasha Levin <sasha.levin@...cle.com>
To:	"Michael S. Tsirkin" <mst@...hat.com>,
	Sasha Levin <sasha.levin@...cle.com>
CC:	linux-kernel@...r.kernel.org,
	Rusty Russell <rusty@...tcorp.com.au>,
	"open list:VIRTIO CORE, NET..." 
	<virtualization@...ts.linux-foundation.org>
Subject: Re: [PATCH 2/2] virtio: don't free memory until the underlying struct
 device has been released

On 01/04/2015 06:26 AM, Michael S. Tsirkin wrote:
> On Fri, Jan 02, 2015 at 02:47:40PM -0500, Sasha Levin wrote:
>> > When releasing a virtio device, We can't free a struct virtio_device until the
>> > underlying struct device has been released, which might not happen immediately
>> > on device_unregister() even if that was the device's last reference.
>> > 
>> > Instead, free the memory only once we know the device is gone in the release
>> > callback.
>> > 
>> > Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
> 
> Isn't this an old bug: do we need to copy stable on a fix?
> 
> What is the behaviour without this patch?
> Is there a way to make this cause a crash?

It will oops if CONFIG_DEBUG_KOBJECT_RELEASE is enabled. I guess
it needs to go to stable as well.


Thanks,
Sasha

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