Re: [PATCH] writeback: verify that underlying dev exists before getting its name

[Sasha Levin]

On 09/04/2015 01:36 PM, Tejun Heo wrote:
> Hello,
> 
> On Fri, Sep 04, 2015 at 01:20:42PM -0400, Sasha Levin wrote:
>>> Do you have backtrace of this happening?  There's a bug in cleanup
>>> path which causes oops (patch is being tested) and this may just be a
>>> symptom of the same problem.
>>
>> [268773.335933] kasan: GPF could be caused by NULL-ptr deref or user memory accessgeneral protection fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC KASAN
>> [268773.337986] Modules linked in:
>> [268773.338470] CPU: 3 PID: 12812 Comm: trinity-c10 Not tainted 4.2.0-next-20150902-sasha-00045-gd0866f3-dirty #2528
>> [268773.339903] task: ffff8802f56e4000 ti: ffff880322e10000 task.ti: ffff880322e10000
>> [268773.340943] RIP: 0010:[<ffffffffaa8b8284>]  [<ffffffffaa8b8284>] trace_event_raw_event_writeback_dirty_page+0x1b4/0x420
> 
> Hmm.... did this happen while or around a device removal event?  I'm
> trying to figure out whether an unregistered bdi can have inodes.

I ran some more tests, and I didn't see device removal events close to it.


Thanks,
Sasha

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