I guess this because you move the resv changing out of lock of bo->resv.
Because at the beginning ttm_mem_evict_first may __ttm_bo_reserve(bo->resv) 
success, and then bo->resv has been changed by another thread. That is not 
matched and at this point bo->ttm_resv also may been freed already.

 And I think it is not easy to put it out of two lock of bo->resv and 
bo->ttm_resv.

Thanks
Roger(Hongbo.He)
-----Original Message-----
From: dri-devel [mailto:dri-devel-boun...@lists.freedesktop.org] On Behalf Of 
Michel D?nzer
Sent: Wednesday, November 08, 2017 12:16 AM
To: Christian König <ckoenig.leichtzumer...@gmail.com>
Cc: dri-de...@lists.freedesktop.org; amd-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/ttm: set bo->resv point to tbo->ttm_resv after 
individualize_resv

On 07/11/17 02:44 PM, Christian König wrote:
> Set bo->resv to ttm_resv during BO cleanup. This way freed BOs can be 
> better reaped during eviction.
> 
> Signed-off-by: Roger He <hongbo...@amd.com>
> Signed-off-by: Christian König <christian.koe...@amd.com>

KASAN caught some badness while running piglit with this applied, see the 
attached dmesg excerpts.


At least some of this might be pre-existing bugs being exposed by this change. 
E.g. I've been chasing another use-after-free, with ttm_bo_delayed_delete 
trying to reserve a BO which has already been destroyed. Looks like maybe the 
ddestroy list handling isn't quite watertight yet.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer
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