Re: Possible regression in "slab, slub: skip unnecessary kasan_cache_shutdown()"

From: Dmitry Vyukov
Date: Tue Jun 19 2018 - 09:17:25 EST


On Tue, Jun 19, 2018 at 3:04 PM, Jason A. Donenfeld <Jason@xxxxxxxxx> wrote:
> HI Dimitry,
>
> On Tue, Jun 19, 2018 at 6:55 AM Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
>> Your code frees all entries before freeing the cache, right? If you
>> add total_entries check before freeing the cache, it does not fire,
>> right?
>
> Yes, certainly.
>
>> Are you using SLAB or SLUB? We stress kernel pretty heavily, but with
>> SLAB, and I suspect Shakeel may also be using SLAB. So if you are
>> using SLUB, there is significant chance that it's a bug in the SLUB
>> part of the change.
>
> Nice intuition; I am indeed using SLUB rather than SLAB...

Now the reasonable question is: does SLUB path of
f9e13c0a5a33d1eaec374d6d4dab53a4f72756a0 have a bug?
syzbot has stressed SLAB version to death, and any such issues would
pop up very loudly, but I am not sure what is the amount of testing
for SLUB.