Re: Issue #5876 : assertion failure in rbd_img_obj_callback()

[Alex Elder <elder@ieee.org>]

On 03/25/2014 03:21 PM, Olivier Bonvalet wrote:
> Le mardi 25 mars 2014 à 22:18 +0200, Ilya Dryomov a écrit :
>> On Tue, Mar 25, 2014 at 9:03 PM, Alex Elder <elder@ieee.org> wrote:
>>> On 03/25/2014 01:53 PM, Olivier Bonvalet wrote:
>>>> Le mardi 25 mars 2014 à 12:43 -0500, Alex Elder a écrit :
>>>>> Please try applying this, on top of the previous patch.
>>>>> If you can then reproduce the problem we'll have a bunch
>>>>> of new information about the particular request that's
>>>>> leading to the failure.  That might tell us what more we
>>>>> can do to find the root cause.  Thank you.
>>>>>
>>>>>                                      -Alex
>>>>>
>>>>> PS  I hope my mailer doesn't botch the long lines.  It might.
>>>>>
>>>>
>>>> Here the execution will continue, no more kernel panic after this
>>>> debugging display. Is it wanted ?
>>>
>>>
>>> I guess it should panic.  I'm glad you mentioned this.
>>
>> Just in case, if you haven't done it already: stick rbd_assert(0);
>> after the last printk in that if statement, so it looks like this:
>>
>> if (which != img_request->next_completion) {
>>         printk("%s: bad image object request information:\n", __func__);
>>         printk("obj_request %p\n", obj_request);
>>         printk("    ->object_name <%s>\n", obj_request->object_name);
>>         ...
>>
>>         printk("img_request %p\n", img_request);
>>         printk("    ->snap 0x%016llx\n", img_request->snap_id);
>>         ...
>>         printk("    ->result %d\n", img_request->result);
>>
>>         rbd_assert(0);
>> }
>>
>> Thanks,
>>
>>                 Ilya
>>
> 
> Without the rbd_assert(0), I add this hang :
> 
> 
> Mar 25 21:17:58 murmillia kernel: [ 2205.255933] rbd_img_obj_callback: bad image object request information:
> Mar 25 21:17:58 murmillia kernel: [ 2205.255938] obj_request ffff88025a2b3c48
> Mar 25 21:17:58 murmillia kernel: [ 2205.255940]     ->object_name <rb.0.1536881.238e1f29.000000000439>
> Mar 25 21:17:58 murmillia kernel: [ 2205.255941]     ->offset 0
> Mar 25 21:17:58 murmillia kernel: [ 2205.255943]     ->length 28672
> Mar 25 21:17:58 murmillia kernel: [ 2205.255944]     ->type 0x1
		BIO request

> Mar 25 21:17:58 murmillia kernel: [ 2205.255945]     ->flags 0x3
	IMG_DATA, KNOWN

> Mar 25 21:17:58 murmillia kernel: [ 2205.255946]     ->which 1
	Second object in the request

> Mar 25 21:17:58 murmillia kernel: [ 2205.255948]     ->xferred 28672
> Mar 25 21:17:58 murmillia kernel: [ 2205.255949]     ->result 0
> Mar 25 21:17:58 murmillia kernel: [ 2205.255950] img_request ffff8802536c4a60
> Mar 25 21:17:58 murmillia kernel: [ 2205.255952]     ->snap 0xffff880257f85ec0
> Mar 25 21:17:58 murmillia kernel: [ 2205.255953]     ->offset 4534026240
> Mar 25 21:17:58 murmillia kernel: [ 2205.255954]     ->length 45056
> Mar 25 21:17:58 murmillia kernel: [ 2205.255955]     ->flags 0x1
> Mar 25 21:17:58 murmillia kernel: [ 2205.255957]     ->obj_request_count 1
	!!! There is only one request... (?)

So obj_request_count might be getting computed incorrectly.

					-Alex

> Mar 25 21:17:58 murmillia kernel: [ 2205.255958]     ->next_completion 2
> Mar 25 21:17:58 murmillia kernel: [ 2205.255959]     ->xferred 45056
> Mar 25 21:17:58 murmillia kernel: [ 2205.255960]     ->result 0
> Mar 25 21:17:58 murmillia kernel: [ 2205.255962] 
> Mar 25 21:17:58 murmillia kernel: [ 2205.255962] Assertion failure in rbd_img_obj_callback() at line 2162:
> Mar 25 21:17:58 murmillia kernel: [ 2205.255962] 
> Mar 25 21:17:58 murmillia kernel: [ 2205.255962] 	rbd_assert(which < img_request->obj_request_count);
> Mar 25 21:17:58 murmillia kernel: [ 2205.255962] 
> Mar 25 21:17:58 murmillia kernel: [ 2205.256141] ------------[ cut here ]------------
> Mar 25 21:17:58 murmillia kernel: [ 2205.256178] kernel BUG at drivers/block/rbd.c:2162!
> 
> 

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