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| author | Natalie Vock <natalie.vock@gmx.de> | 2026-08-04 10:25:19 +0200 |
|---|---|---|
| committer | Natalie Vock <nat@pixelcluster.dev> | 2026-08-05 10:35:55 +0200 |
| commit | 4e6d9bc1586494358e368f96e61d5689a17b31e0 (patch) | |
| tree | ccb44dd210e9e491a0dbed8e713b3c3f426a1737 /include | |
| parent | 3f356c0e36a057e45301b8279da4ed4b68fe80a6 (diff) | |
| download | linux-4e6d9bc1586494358e368f96e61d5689a17b31e0.tar.gz linux-4e6d9bc1586494358e368f96e61d5689a17b31e0.zip | |
drm/ttm: Split cgroup charge and resource allocation
Coupling resource allocation and cgroup charging is racy when charging
succeeds, but subsequent resource allocation fails. Certain eviction
decisions are made on the basis of whether the allocating cgroup is
protected, i.e. within its min/low limits, but with the charge being
tied to resource allocation (and uncharged when the resource allocation
fails), this check is done at a point where the allocation is not actually
charged to the cgroup.
This is subtly wrong if the allocation were to cause the cgroup to exceed
the min/low protection, but it's even more wrong if the same cgroup tries
allocating multiple buffers concurrently: In this case, the min/low
protection may pass for all allocation attempts when the real min/low
protection covers only some, or potentially none of the allocated
buffers.
Instead, charge the allocation to the cgroup once and keep the charge
for as long as we try to allocate a ttm_resource, and only undo the charge
if allocating the resource is ultimately unsuccessful and we move on to
a different ttm_place.
Reviewed-by: Maarten Lankhorst <dev@lankhorst.se>
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Natalie Vock <natalie.vock@gmx.de>
Link: https://patch.msgid.link/20260804-dmemcg-aggressive-protect-v8-4-07af96681bf8@gmx.de
Diffstat (limited to 'include')
| -rw-r--r-- | include/drm/ttm/ttm_resource.h | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/include/drm/ttm/ttm_resource.h b/include/drm/ttm/ttm_resource.h index a5d386583fb6..e567b7ec8218 100644 --- a/include/drm/ttm/ttm_resource.h +++ b/include/drm/ttm/ttm_resource.h @@ -458,10 +458,14 @@ void ttm_resource_init(struct ttm_buffer_object *bo, void ttm_resource_fini(struct ttm_resource_manager *man, struct ttm_resource *res); +int ttm_resource_try_charge(struct ttm_buffer_object *bo, + const struct ttm_place *place, + struct dmem_cgroup_pool_state **ret_pool, + struct dmem_cgroup_pool_state **ret_limit_pool); int ttm_resource_alloc(struct ttm_buffer_object *bo, const struct ttm_place *place, struct ttm_resource **res, - struct dmem_cgroup_pool_state **ret_limit_pool); + struct dmem_cgroup_pool_state *charge_pool); void ttm_resource_free(struct ttm_buffer_object *bo, struct ttm_resource **res); bool ttm_resource_intersects(struct ttm_device *bdev, struct ttm_resource *res, |