(2014/10/09 13:10), Xishi Qiu wrote:
> On 2014/10/3 18:06, Yasuaki Ishimatsu wrote:
>
>> Commit 92d585ef067d ("numa: fix NULL pointer access and memory
>> leak in unregister_one_node()") added kfree() of node struct in
>> unregister_one_node(). But node struct is freed by node_device_release()
>> which is called in unregister_node(). So by adding the kfree(),
>
> Hi,
>
> Is this path?
> unregister_node()
> device_unregister()
> device_del()
> bus_remove_device()
> device_release_driver()
> __device_release_driver()
> devres_release_all()
> release_nodes()
> dr->node.release(dev, dr->data);
> then which function is be called?
node_device_release is called as follows:
unregister_one_node()
-> unregister_node()
-> device_unregister()
-> put_device()
-> kobject_put()
-> kref_put()
-> kref_sub()
-> kobject_release()
-> kobject_cleanup()
-> device_release()
-> node_device_release()
Thanks,
Yasuaki Ishimatsu
>
> Thanks,
> Xishi Qiu
>
>> node struct is freed two times.
>>
>> While hot removing memory, the commit leads the following BUG_ON():
>>
>> kernel BUG at mm/slub.c:3346!
>> invalid opcode: 0000 [#1] SMP
>> [...]
>> Call Trace:
>> [...] unregister_one_node
>> [...] try_offline_node
>> [...] remove_memory
>> [...] acpi_memory_device_remove
>> [...] acpi_bus_trim
>> [...] acpi_bus_trim
>> [...] acpi_device_hotplug
>> [...] acpi_hotplug_work_fn
>> [...] process_one_work
>> [...] worker_thread
>> [...] ? rescuer_thread
>> [...] kthread
>> [...] ? kthread_create_on_node
>> [...] ret_from_fork
>> [...] ? kthread_create_on_node
>>
>> This patch removes unnecessary kfree() from unregister_one_node().
>>
>> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
>> Cc: Xishi Qiu <qiuxishi@xxxxxxxxxx>
>> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
>> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>> Cc: stable@xxxxxxxxxxxxxxx # v3.16+
>> Fixes: 92d585ef067d "numa: fix NULL pointer access and memory leak in unregister_one_node()"
>> ---
>> drivers/base/node.c | 1 -
>> 1 file changed, 1 deletion(-)
>>
>> diff --git a/drivers/base/node.c b/drivers/base/node.c
>> index c6d3ae0..d51c49c 100644
>> --- a/drivers/base/node.c
>> +++ b/drivers/base/node.c
>> @@ -603,7 +603,6 @@ void unregister_one_node(int nid)
>> return;
>>
>> unregister_node(node_devices[nid]);
>> - kfree(node_devices[nid]);
>> node_devices[nid] = NULL;
>> }
>>
>
>
>
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