Messages in this thread Patch in this message | | | From | Rob Clark <> | Subject | [PATCH 2/2] drm/shmem-helper: Avoid vm_open error paths | Date | Tue, 29 Nov 2022 12:02:42 -0800 |
| |
From: Rob Clark <robdclark@chromium.org>
vm_open() is not allowed to fail. Fortunately we are guaranteed that the pages are already pinned, and only need to increment the refcnt. So just increment it directly.
Fixes: 2194a63a818d ("drm: Add library for shmem backed GEM objects") Cc: stable@vger.kernel.org Signed-off-by: Rob Clark <robdclark@chromium.org> --- drivers/gpu/drm/drm_gem_shmem_helper.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index 110a9eac2af8..9885ba64127f 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -571,12 +571,20 @@ static void drm_gem_shmem_vm_open(struct vm_area_struct *vma) { struct drm_gem_object *obj = vma->vm_private_data; struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj); - int ret; WARN_ON(shmem->base.import_attach); - ret = drm_gem_shmem_get_pages(shmem); - WARN_ON_ONCE(ret != 0); + mutex_lock(&shmem->pages_lock); + + /* + * We should have already pinned the pages, vm_open() just grabs + * an additional reference for the new mm the vma is getting + * copied into. + */ + WARN_ON_ONCE(!shmem->pages_use_count); + + shmem->pages_use_count++; + mutex_unlock(&shmem->pages_lock); drm_gem_vm_open(vma); } -- 2.38.1
| |