[PATCH] drm/radeon: Override fpfn for all VRAM placements in radeon_evict_flags

[Deucher, Alexander]

> -----Original Message-----
> From: amd-gfx [mailto:amd-gfx-bounces at lists.freedesktop.org] On Behalf
> Of Michel Dänzer
> Sent: Sunday, March 26, 2017 8:59 PM
> To: amd-gfx at lists.freedesktop.org
> Cc: Zachary Michaels; Julien Isorce
> Subject: [PATCH] drm/radeon: Override fpfn for all VRAM placements in
> radeon_evict_flags
> 
> From: Michel Dänzer <michel.daenzer at amd.com>
> 
> We were accidentally only overriding the first VRAM placement. For BOs
> with the RADEON_GEM_NO_CPU_ACCESS flag set,
> radeon_ttm_placement_from_domain creates a second VRAM placment
> with
> fpfn == 0. If VRAM is almost full, the first VRAM placement with
> fpfn > 0 may not work, but the second one with fpfn == 0 always will
> (the BO's current location trivially satisfies it). Because "moving"
> the BO to its current location puts it back on the LRU list, this
> results in an infinite loop.
> 
> Fixes: 2a85aedd117c ("drm/radeon: Try evicting from CPU accessible to
>                       inaccessible VRAM first")
> Reported-by: Zachary Michaels <zmichaels at oblong.com>
> Reported-and-Tested-by: Julien Isorce <jisorce at oblong.com>
> Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>

Reviewed-by: Alex Deucher <alexander.deucher at amd.com>

> ---
>  drivers/gpu/drm/radeon/radeon_ttm.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c
> b/drivers/gpu/drm/radeon/radeon_ttm.c
> index 5c7cf644ba1d..37d68cd1f272 100644
> --- a/drivers/gpu/drm/radeon/radeon_ttm.c
> +++ b/drivers/gpu/drm/radeon/radeon_ttm.c
> @@ -213,8 +213,8 @@ static void radeon_evict_flags(struct
> ttm_buffer_object *bo,
>  			rbo->placement.num_busy_placement = 0;
>  			for (i = 0; i < rbo->placement.num_placement; i++) {
>  				if (rbo->placements[i].flags &
> TTM_PL_FLAG_VRAM) {
> -					if (rbo->placements[0].fpfn < fpfn)
> -						rbo->placements[0].fpfn =
> fpfn;
> +					if (rbo->placements[i].fpfn < fpfn)
> +						rbo->placements[i].fpfn =
> fpfn;
>  				} else {
>  					rbo->placement.busy_placement =
>  						&rbo->placements[i];
> --
> 2.11.0
> 
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