On 29/11/2019 13:59, Boris Brezillon wrote:

panfrost_gem_shrinker_scan() might purge a BO (release the sgt and kill the GPU mapping) that's being freed by panfrost_gem_free_object() if we don't remove the BO from the shrinker list at the beginning of panfrost_gem_free_object().

Fixes: 013b65101315 ("drm/panfrost: Add madvise and shrinker support") Cc: stable@vger.kernel.org Signed-off-by: Boris Brezillon boris.brezillon@collabora.com

Reviewed-by: Steven Price steven.price@arm.com

---

drivers/gpu/drm/panfrost/panfrost_gem.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c index acb07fe06580..daf4c55a2863 100644 --- a/drivers/gpu/drm/panfrost/panfrost_gem.c +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c @@ -19,6 +19,16 @@ static void panfrost_gem_free_object(struct drm_gem_object *obj) struct panfrost_gem_object *bo = to_panfrost_bo(obj); struct panfrost_device *pfdev = obj->dev->dev_private;

• /*

• * Make sure the BO is no longer inserted in the shrinker list before
  

• * taking care of the destruction itself. If we don't do that we have a
  

• * race condition between this function and what's done in
  

• * panfrost_gem_shrinker_scan().
  

• */
  

• mutex_lock(&pfdev->shrinker_lock);
• list_del_init(&bo->base.madv_list);
• mutex_unlock(&pfdev->shrinker_lock);
• if (bo->sgts) { int i; int n_sgt = bo->base.base.size / SZ_2M;

@@ -33,11 +43,6 @@ static void panfrost_gem_free_object(struct drm_gem_object *obj) kfree(bo->sgts); }

• mutex_lock(&pfdev->shrinker_lock);
• if (!list_empty(&bo->base.madv_list))

• list_del(&bo->base.madv_list);
  

• mutex_unlock(&pfdev->shrinker_lock);
• drm_gem_shmem_free_object(obj);

}