Re: [REGRESSION][v4.14.y][v4.15] x86/intel_rdt/cqm: Improve limbo list processing

[Thomas Gleixner]

On Fri, 12 Jan 2018, Joseph Salisbury wrote:

> Hi Vikas,
> 
> A kernel bug report was opened against Ubuntu [0]. After a kernel
> bisect, it was found that reverting the following commit resolved this bug:
> 
> commit 24247aeeabe99eab13b798ccccc2dec066dd6f07
> Author: Vikas Shivappa <vikas.shivappa@xxxxxxxxxxxxxxx>
> Date:ÂÂ Tue Aug 15 18:00:43 2017 -0700
> 
> ÂÂÂ x86/intel_rdt/cqm: Improve limbo list processing
> 
> 
> The regression was introduced as of v4.14-r1 and still exists with
> current mainline. The trace with v4.15-rc7 is in comment #44[1].
> 
> I was hoping to get your feedback, since you are the patch author. Do
> you think gathering any additional data will help diagnose this issue,
> or would it be best to submit a revert request?

That stinks like a use after free. Can you run with KASAN enabled?

Thanks,

	tglx