From: Manjunath Patil <manjunath.b.patil@oracle.com>
To: boris.ostrovsky@oracle.com, jgross@suse.com,
konrad.wilk@oracle.com, roger.pau@citrix.com
Cc: axboe@kernel.dk, xen-devel@lists.xenproject.org,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: [PATCH v2] xen-blkfront: fix kernel panic with blkfront_remove()
Date: Thu, 8 Nov 2018 17:10:43 -0800 [thread overview]
Message-ID: <1541725843-2019-1-git-send-email-manjunath.b.patil@oracle.com> (raw)
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 <manjunath.b.patil@oracle.com>
---
v2: style change. added the missing space b/w if and (
---
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..2d8b10d 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;
+
blkif_free(info, 0);
mutex_lock(&info->mutex);
--
1.7.1
next reply other threads:[~2018-11-09 1:09 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-09 1:10 Manjunath Patil [this message]
2018-11-09 6:16 ` [PATCH v2] xen-blkfront: fix kernel panic with blkfront_remove() Juergen Gross
2018-11-09 19:08 ` [Xen-devel] " Manjunath Patil
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