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charset=us-ascii Content-Disposition: inline In-Reply-To: <1541725108-1468-1-git-send-email-manjunath.b.patil@oracle.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 08, 2018 at 04:58:28PM -0800, Manjunath Patil wrote: > If a hot-attaching device fails inside domU[ex:negotiate_mq() returns > with ENOMEM] we clear the blkfront_info struct in talk_to_blkback() > > When we try to detach the device, blkfront_remove() tries to access > blkfront_info leading to kernel panic. > > Typical call stack involving panic - > #10 page_fault at ffffffff816f25df > [exception RIP: blkif_free+46] > #11 blkfront_remove at ffffffffa004de47 [xen_blkfront] > #12 xenbus_dev_remove at ffffffff813faa4c > #13 __device_release_driver at ffffffff814769aa > #14 device_release_driver at ffffffff81476a63 > #15 bus_remove_device at ffffffff814762eb > #16 device_del at ffffffff81472684 > #17 device_unregister at ffffffff814727e2 > #18 xenbus_dev_changed at ffffffff813fa89f > #19 frontend_changed at ffffffff813fca19 > #20 xenwatch_thread at ffffffff813f88f9 > #21 kthread at ffffffff810a486b > #22 ret_from_fork at ffffffff816ed2a8 > > Cc: stable@vger.kernel.org > Signed-off-by: Manjunath Patil > --- > drivers/block/xen-blkfront.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c > index dc8fe25..144cda8 100644 > --- a/drivers/block/xen-blkfront.c > +++ b/drivers/block/xen-blkfront.c > @@ -2496,6 +2496,9 @@ static int blkfront_remove(struct xenbus_device *xbdev) > > dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); > > + if(!info) > + return 0; > + Always run scripts/checkpatch.pl on your patches so you do not get a grumpy maintainer telling you to run scripts/checkpatch.pl on your patches. thanks, greg k-h