linux-kernel - [RFC PATCH 3/4] drm/ttm: Handle -EAGAIN in ttm_resource

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Message-Id: <20230503083500.645848-4-maarten.lankhorst@linux.intel.com>
Date:   Wed,  3 May 2023 10:34:59 +0200
From:   Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
To:     dri-devel@...ts.freedesktop.org, cgroups@...r.kernel.org,
        intel-xe@...ts.freedesktop.org
Cc:     intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Tejun Heo <tj@...nel.org>, Zefan Li <lizefan.x@...edance.com>,
        Johannes Weiner <hannes@...xchg.org>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>, amd-gfx@...ts.freedesktop.org,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...el.com>
Subject: [RFC PATCH 3/4] drm/ttm: Handle -EAGAIN in ttm_resource_alloc as -ENOSPC.

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@...ux.intel.com>
---
 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;
-- 
2.34.1