Re: [PATCH] drm/i915: Don't destroy the vma placeholder during execbuffer reservation

Daniel Vetter
2013-08-20T13:18:54Z

On Tue, Aug 20, 2013 at 12:56:40PM +0100, Chris Wilson wrote:
> The execbuffer handle and exec_link were moved from the object into the
> vma. As the vma may be unbound and destroyed whilst attempting to
> reserve the execbuffer objects (either through a forced unbind to fix up
> a misalignment or through an evict-everything call) we need to prevent
> the free of the i915_vma itself. Otherwise not only is the list of
> objects to reserve corrupt, but we continue to reference stale vma
> entries.
>
> Fixes kernel crash with i-g-t/gem_evict_everything
>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Bugzilla; https://bugs.freedesktop.org/show_bug.cgi?id=68298
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Ben Widawsky <ben@bwidawsk.net>

Yeah, I think this is about as simple&clear as it gets. vmas used by
execbuf simply have a bit a strange lifetime rule ... Queued for -next,
thanks for the patch. Merged quickly since I want to keep the bisect fail
window small, but I'll smash the test result from QA on top as soon as we
have it.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch