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From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: "K. Y. Srinivasan" <kys@microsoft.com>, devel@linuxdriverproject.org
Cc: Haiyang Zhang <haiyangz@microsoft.com>,
	linux-kernel@vger.kernel.org, Dexuan Cui <decui@microsoft.com>
Subject: [PATCH 1/3] Drivers: hv: vmbus: avoid double kfree for device_obj
Date: Wed, 21 Jan 2015 20:02:07 +0100	[thread overview]
Message-ID: <1421866929-20167-2-git-send-email-vkuznets@redhat.com> (raw)
In-Reply-To: <1421866929-20167-1-git-send-email-vkuznets@redhat.com>

On driver shutdown device_obj is being freed twice:
1) In vmbus_free_channels()
2) vmbus_device_release() (which is being triggered by device_unregister() in
   vmbus_device_unregister().
This double kfree leads to the following sporadic crash on driver unload:

[   23.469876] general protection fault: 0000 [#1] SMP
[   23.470036] Modules linked in: hv_vmbus(-)
[   23.470036] CPU: 2 PID: 213 Comm: rmmod Not tainted 3.19.0-rc5_bug923184+ #488
[   23.470036] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS 090006  05/23/2012
[   23.470036] task: ffff880036ef1cb0 ti: ffff880036ce8000 task.ti: ffff880036ce8000
[   23.470036] RIP: 0010:[<ffffffff811d2e1b>]  [<ffffffff811d2e1b>] __kmalloc_node_track_caller+0xdb/0x1e0
[   23.470036] RSP: 0018:ffff880036cebcc8  EFLAGS: 00010246
...

When this crash does not happen on driver unload the similar one is expected if
we try to load hv_vmbus again.

Remove kfree from vmbus_free_channels() as freeing it from
vmbus_device_release() seems right.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 drivers/hv/channel_mgmt.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 877a944..0141a3d 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -259,7 +259,6 @@ void vmbus_free_channels(void)
 
 	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
 		vmbus_device_unregister(channel->device_obj);
-		kfree(channel->device_obj);
 		free_channel(channel);
 	}
 }
-- 
1.9.3


  reply	other threads:[~2015-01-21 19:03 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-21 19:02 [PATCH 0/3] Drivers: hv: vmbus: fix crashes on hv_vmbus load/unload path Vitaly Kuznetsov
2015-01-21 19:02 ` Vitaly Kuznetsov [this message]
2015-01-21 19:02 ` [PATCH 2/3] Drivers: hv: vmbus: introduce vmbus_acpi_remove Vitaly Kuznetsov
2015-01-22 19:08   ` KY Srinivasan
2015-01-23 10:01     ` Vitaly Kuznetsov
2015-04-10 12:47     ` Vitaly Kuznetsov
2015-04-10 14:50       ` KY Srinivasan
2015-01-21 19:02 ` [PATCH 3/3] Drivers: hv: vmbus: teardown hv_vmbus_con workqueue and vmbus_connection pages on shutdown Vitaly Kuznetsov
2015-01-26 13:41 ` [PATCH 0/3] Drivers: hv: vmbus: fix crashes on hv_vmbus load/unload path Vitaly Kuznetsov

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