tree 8ff69c7da34a2718676e6a39db4f637dc5aa0d23
parent 41a51428916ab04587bacee2dda61c4a0c4fc02f
author Chris Wilson <chris@chris-wilson.co.uk> 1284975100 +0100
committer Chris Wilson <chris@chris-wilson.co.uk> 1285012200 +0100

drm/i915: Hold a reference to the object whilst unbinding the eviction list

During heavy aperture thrashing we may be forced to wait upon several active
objects during eviction. The active list may be the last reference to
these objects and so the action of waiting upon one of them may cause
another to be freed (and itself unbound). To prevent the object
disappearing underneath us, we need to acquire and hold a reference
whilst unbinding.

This should fix the reported page refcount OOPS:

kernel BUG at drivers/gpu/drm/i915/i915_gem.c:1444!
...
RIP: 0010:[<ffffffffa0093026>]  [<ffffffffa0093026>] i915_gem_object_put_pages+0x25/0xf5 [i915]
Call Trace:
 [<ffffffffa009481d>] i915_gem_object_unbind+0xc5/0x1a7 [i915]
 [<ffffffffa0098ab2>] i915_gem_evict_something+0x3bd/0x409 [i915]
 [<ffffffffa0027923>] ? drm_gem_object_lookup+0x27/0x57 [drm]
 [<ffffffffa0093bc3>] i915_gem_object_bind_to_gtt+0x1d3/0x279 [i915]
 [<ffffffffa0095b30>] i915_gem_object_pin+0xa3/0x146 [i915]
 [<ffffffffa0027948>] ? drm_gem_object_lookup+0x4c/0x57 [drm]
 [<ffffffffa00961bc>] i915_gem_do_execbuffer+0x50d/0xe32 [i915]

Reported-by: Shawn Starr <shawn.starr@rogers.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=18902
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>