[Intel-gfx] [PATCH 2/3] drm/i915/userptr: Hold mmref whilst calling get-user-pages

[Michał Winiarski]

On Sun, Apr 03, 2016 at 06:14:06PM +0100, Chris Wilson wrote:
> Holding a reference to the containing task_struct is not sufficient to
> prevent the mm_struct from being reaped under memory pressure. If this
> happens whilst we are calling get_user_pages(), explosions errupt -
> sometimes an immediate GPF, sometimes page flag corruption. To prevent
> the target mm from being reaped as we are reading from it, acquire a
> reference before we begin.
> 
> Testcase: igt/gem_shrink/*userptr
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> Cc: Michał Winiarski <michal.winiarski at intel.com>
> Cc: stable at vger.kernel.org

Reviewed-by: Michał Winiarski <michal.winiarski at intel.com>

-Michał

> ---
>  drivers/gpu/drm/i915/i915_gem_userptr.c | 29 +++++++++++++++++------------
>  1 file changed, 17 insertions(+), 12 deletions(-)