Re: block, bfq: NULL pointer dereference in bfq_rq_pos_tree_lookup()

[Paolo Valente]

> Il giorno 8 mag 2021, alle ore 06:49, Mike Galbraith <efault@xxxxxx> ha scritto:
> 
> On Mon, 2021-05-03 at 14:41 +0200, Mike Galbraith wrote:
>> On Mon, 2021-05-03 at 11:52 +0200, Paolo Valente wrote:
>>> Hi Mike,
>>> I've waited a little bit before replying, because I've worked on a dev
>>> patch series, for debugging another crash. I'd like to use
>>> this series for your failure too, as the OOPS you report
>>> unfortunately does not ring any bell :(
>>> 
>>> So, could you please try to apply this patch series?  If it doesn't
>>> apply, I'll rebase it.
>> 
>> This bug isn't deterministic, but I can wedge your set into my devel
>> trees, and see if anything falls out.
> 
> What fell out was not the least bit useful.  After days of box working
> just fine despite bug being given ample enticement, it didn't take the
> bait.  I then build master sans patch set, which exploded on its very
> first distro build, after which bug (snickered mightily and) went back
> to into hiding.
> 

Not easy to debug this way :)

At any rate, I've just posted the fix contained in my debug patch series.

Thanks,
Paolo

> 	-Mike
>