Add a comment why there is a obj refcount inc before installing the vm_ops for the mmap call. Also remove the invalid older comment as drm API(drm_gem_prime_mmap()) will hold an obj reference before calling this driver mmap callback so we can't have 0-refcnted object here.
Cc: Matthew Auld <[email protected]> Cc: Andi Shyti <[email protected]> Signed-off-by: Nirmoy Das <[email protected]> --- drivers/gpu/drm/i915/gem/i915_gem_mman.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c index d3c1dee16af2..0bc8c3818443 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c @@ -952,9 +952,10 @@ int i915_gem_mmap(struct file *filp, struct vm_area_struct *vma) vma_pages(vma)); if (node && drm_vma_node_is_allowed(node, priv)) { /* - * Skip 0-refcnted objects as it is in the process of being - * destroyed and will be invalid when the vma manager lock - * is released. + * When we install vm_ops for mmap we are too late for + * the vm_ops->open() which increases the ref_count of + * this obj and then it gets decreased by the vm_ops->close(). + * To balance this increase the obj ref_count here. */ if (!node->driver_private) { mmo = container_of(node, struct i915_mmap_offset, vma_node); -- 2.39.0
