From 7e0180e3570cc791e95e6b6cd5fbeb0aedc62776 Mon Sep 17 00:00:00 2001
From: Thierry Reding <treding@nvidia.com>
Date: Thu, 6 Nov 2014 14:41:31 +0100
Subject: [PATCH] drm/tegra: gem: Check before freeing CMA memory

dma_free_writecombine() must not be called on a buffer that couldn't be
allocated. Check for a valid virtual address before attempting to free
the memory to avoid a crash.

Reported-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
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