Re: 2.6.0-test8, DEBUG_SLAB, oops in as_latter_request()

[Nick Piggin <piggin@cyberone.com.au>]

Jens Axboe wrote:

>On Mon, Oct 20 2003, Nick Piggin wrote:
>
>>
>>Andrew Morton wrote:
>>
>>
>>>Peter Osterlund <petero2@telia.com> wrote:
>>>
>>>
>>>>I was running 2.6.0-test8 compiled with CONFIG_DEBUG_SLAB=y. When
>>>>testing the CDRW packet writing driver, I got an oops in
>>>>as_latter_request. (Full oops at the end of this message.) It is
>>>>repeatable and happens because arq->rb_node.rb_right is uninitialized.
>>>>
>>>>
>>>deadline seems to have the same problem.
>>>
>>>We may as well squish this with the big hammer?
>>>
>>>
>>Thanks for the report, Peter.
>>
>>The request is a special request, so either blk_attempt_remerge should
>>never be called on it, or blk_attempt_remerge (or as_latter_request) should
>>check for this. Its up to Jens.
>>
>>I would say to stick something like
>>if (!rq_mergeable(rq))
>>   return;
>>
>>into blk_attempt_remerge.
>>
>>I'd say we shouldn't expect drivers to try to get this right.
>>
>
>attempt_merge() already includes such a check. To me it looks really
>buggy that elv_latter_request() cannot be called on non-fs requests, I'd
>rather get that fixed like Peter suggests. elv_latter_request() should
>work on all requests in the io sched queue, period.
>

I don't have a problem with that. Peter's patch it is.