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From: Amit Shah <amit.shah@redhat.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Virtualization List <virtualization@lists.linux-foundation.org>
Subject: Re: [PATCH 0/2] Fix hot-unplug: device removal while port in use
Date: Wed, 2 Mar 2011 19:08:35 +0530	[thread overview]
Message-ID: <20110302133835.GA3055@amit-x200.redhat.com> (raw)
In-Reply-To: <87aahdn5k7.fsf@rustcorp.com.au>

On (Wed) 02 Mar 2011 [21:38:08], Rusty Russell wrote:
> On Wed,  2 Mar 2011 13:53:06 +0530, Amit Shah <amit.shah@redhat.com> wrote:
> > A crash was observed when a device gets removed while a port is in
> > use.  When the port gets removed, we tried to free vq buffers.  The vq
> > no longer exists at this stage, just ensure we don't access it.
> > 
> > The second patch fixes a warning where the pci region is already
> > freed.  I'm not sure what or how the region gets freed, any clues
> > there will be helpful.
> 
> Put a printk and WARN_ON() in the pci region freeing code, look through
> the backtraces?

Well what seems to be happening is kref_put() in port_fops_release()
calls remove_port(), which calls device_destroy().  Now this triggers
another fput() on the same file, causing port_fops_release() to be
called again, which leads to device_destroy() being called on the same
region.

Slightly more clueful, but still clueless as to why this happens.

		Amit

  reply	other threads:[~2011-03-02 13:38 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-02  8:23 [PATCH 0/2] Fix hot-unplug: device removal while port in use Amit Shah
2011-03-02  8:23 ` [PATCH 1/2] virtio: console: Don't access vqs if device was unplugged Amit Shah
2011-03-02  8:23 ` [PATCH 2/2] virtio: console: Don't call device_destroy() on port device Amit Shah
2011-03-02 11:08 ` [PATCH 0/2] Fix hot-unplug: device removal while port in use Rusty Russell
2011-03-02 13:38   ` Amit Shah [this message]
2011-03-11 11:16 ` Amit Shah
2011-03-16  4:01   ` Rusty Russell

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