| Message ID | 20230215161405.187368-2-thomas.hellstrom@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add a TTM shrinker | expand |
Am 15.02.23 um 17:13 schrieb Thomas Hellström: > The LRU mechanism may look up a resource in the process of being removed > from an object. The locking rules here are a bit unclear but it looks > currently like res->bo assignment is protected by the LRU lock, whereas > bo->resource is protected by the object lock, while *clearing* of > bo->resource is also protected by the LRU lock. This means that if > we check that bo->resource points to the LRU resource under the LRU > lock we should be safe. > So perform that check before deciding to swap out a bo. That avoids > dereferencing a NULL bo->resource in ttm_bo_swapout(). > > Fixes: 6a9b02899402 ("drm/ttm: move the LRU into resource handling v4") > Cc: Christian König <christian.koenig@amd.com> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > Cc: Christian Koenig <christian.koenig@amd.com> > Cc: Huang Rui <ray.huang@amd.com> > Cc: Alex Deucher <alexander.deucher@amd.com> > Cc: Felix Kuehling <Felix.Kuehling@amd.com> > Cc: Philip Yang <Philip.Yang@amd.com> > Cc: Qiang Yu <qiang.yu@amd.com> > Cc: Matthew Auld <matthew.auld@intel.com> > Cc: Nirmoy Das <nirmoy.das@intel.com> > Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> > Cc: "Thomas Hellström" <thomas.hellstrom@linux.intel.com> > Cc: Anshuman Gupta <anshuman.gupta@intel.com> > Cc: Ramalingam C <ramalingam.c@intel.com> > Cc: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com> > Cc: dri-devel@lists.freedesktop.org > Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com> Reviewed-by: Christian König <christian.koenig@amd.com> > --- > drivers/gpu/drm/ttm/ttm_device.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c > index c7a1862f322a..ae2f19dc9f81 100644 > --- a/drivers/gpu/drm/ttm/ttm_device.c > +++ b/drivers/gpu/drm/ttm/ttm_device.c > @@ -158,7 +158,7 @@ int ttm_device_swapout(struct ttm_device *bdev, struct ttm_operation_ctx *ctx, > struct ttm_buffer_object *bo = res->bo; > uint32_t num_pages; > > - if (!bo) > + if (!bo || bo->resource != res) > continue; > > num_pages = PFN_UP(bo->base.size);
diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c index c7a1862f322a..ae2f19dc9f81 100644 --- a/drivers/gpu/drm/ttm/ttm_device.c +++ b/drivers/gpu/drm/ttm/ttm_device.c @@ -158,7 +158,7 @@ int ttm_device_swapout(struct ttm_device *bdev, struct ttm_operation_ctx *ctx, struct ttm_buffer_object *bo = res->bo; uint32_t num_pages; - if (!bo) + if (!bo || bo->resource != res) continue; num_pages = PFN_UP(bo->base.size);
The LRU mechanism may look up a resource in the process of being removed from an object. The locking rules here are a bit unclear but it looks currently like res->bo assignment is protected by the LRU lock, whereas bo->resource is protected by the object lock, while *clearing* of bo->resource is also protected by the LRU lock. This means that if we check that bo->resource points to the LRU resource under the LRU lock we should be safe. So perform that check before deciding to swap out a bo. That avoids dereferencing a NULL bo->resource in ttm_bo_swapout(). Fixes: 6a9b02899402 ("drm/ttm: move the LRU into resource handling v4") Cc: Christian König <christian.koenig@amd.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Christian Koenig <christian.koenig@amd.com> Cc: Huang Rui <ray.huang@amd.com> Cc: Alex Deucher <alexander.deucher@amd.com> Cc: Felix Kuehling <Felix.Kuehling@amd.com> Cc: Philip Yang <Philip.Yang@amd.com> Cc: Qiang Yu <qiang.yu@amd.com> Cc: Matthew Auld <matthew.auld@intel.com> Cc: Nirmoy Das <nirmoy.das@intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: "Thomas Hellström" <thomas.hellstrom@linux.intel.com> Cc: Anshuman Gupta <anshuman.gupta@intel.com> Cc: Ramalingam C <ramalingam.c@intel.com> Cc: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com> Cc: dri-devel@lists.freedesktop.org Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com> --- drivers/gpu/drm/ttm/ttm_device.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)