Re: [Intel-xe] [RFC PATCH 3/4] drm/ttm: Handle -EAGAIN in ttm_resource_alloc as -ENOSPC.

Thomas Hellström
2023-05-03T09:12:23Z

Hi, Maarten

On 5/3/23 10:34, Maarten Lankhorst wrote:
> This allows the drm cgroup controller to return no space is available..
>
> XXX: This is a hopeless simplification that changes behavior, and
> returns -ENOSPC even if we could evict ourselves from the current
> cgroup.
>
> Ideally, the eviction code becomes cgroup aware, and will force eviction
> from the current cgroup or its parents.
>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

Thinking of the shrinker analogy, do non-cgroup aware shrinkers just
shrink blindly or do they reject shrinking like this patch when a cgroup
limit is reached?

/Thomas

> ---
> drivers/gpu/drm/ttm/ttm_bo.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index bd5dae4d1624..e057d5d8f09a 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -731,6 +731,8 @@ static int ttm_bo_mem_force_space(struct ttm_buffer_object *bo,
> ret = ttm_resource_alloc(bo, place, mem);
> if (likely(!ret))
> break;
> + if (ret == -EAGAIN)
> + return -ENOSPC;
> if (unlikely(ret != -ENOSPC))
> return ret;
> ret = ttm_mem_evict_first(bdev, man, place, ctx,
> @@ -783,7 +785,7 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
>
> type_found = true;
> ret = ttm_resource_alloc(bo, place, mem);
> - if (ret == -ENOSPC)
> + if (ret == -ENOSPC || ret == -EAGAIN)
> continue;
> if (unlikely(ret))
> goto error;