Re: BUG: KASAN: use-after-free in amdgpu_job_free_cb

[Johannes Hirte <johannes.hirte-rSzmJuYucINa7YElYzY8/Q@public.gmane.org>]

On 2018 Jan 12, Andrey Grodzovsky wrote:
> Hi, looks to me  like a different issue (not related) then the one  
> Johannes, reports, your issue was already reported by some one (can't 
> remember the thread of hand) and looks like in shader hang or GPU 
> scheduler synchronization issue while  Johannes's use after free is pure 
> software logic issue in either KMS atomic framework or more probably in 
> AMDGPU/DC (DAL).
> 
> 
> Johanes, I attached a debug patch which forces the cursor update to wait 
> for any  page flip in progress, can you give it a try and see if the 
> issue is gone ? This is not an actual fix but just to evaluate the reason.
> 

> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 5a70682..323d020 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -4908,7 +4908,7 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
>          * synchronization events.
>          */
>  
> -       if (lock_and_validation_needed) {
> +       if (lock_and_validation_needed || state->legacy_cursor_update == true) {
>  
>                 ret = do_aquire_global_lock(dev, state);
>                 if (ret)
> diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c
> index a1a751b..6d6ffdf 100644
> --- a/drivers/gpu/drm/ttm/ttm_page_alloc.c
> +++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c

The patch seems incomplete. 

-- 
Regards,
  Johannes

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