drm/i915: Release the mmap offset when purging a buffer

If we discard a buffer due to memory pressure, also release its alloted
mmap address space. As it may be sometime before userspace wakes up
and notices that it has buffers to purge from its cache, we may waste
valuable address space on unusable objects for a period of time.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=47738
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 6b1859799e6c..0a16366efaac 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1546,6 +1546,9 @@ i915_gem_object_truncate(struct drm_i915_gem_object *obj)
         inode = obj->base.filp->f_path.dentry->d_inode;
         shmem_truncate_range(inode, 0, (loff_t)-1);
 
+        if (obj->base.map_list.map)
+                drm_gem_free_mmap_offset(&obj->base);
+
         obj->madv = __I915_MADV_PURGED;
 }