When the mapping is already reaped the unmap must be a no-op, as we
would otherwise try to remove the mapping twice, corrupting the involved
data structures.

Cc: sta...@vger.kernel.org # 5.4
Signed-off-by: Lucas Stach <l.st...@pengutronix.de>
---
 drivers/gpu/drm/etnaviv/etnaviv_mmu.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_mmu.c 
b/drivers/gpu/drm/etnaviv/etnaviv_mmu.c
index 9fb1a2aadbcb..aabb997a74eb 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_mmu.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_mmu.c
@@ -286,6 +286,12 @@ void etnaviv_iommu_unmap_gem(struct etnaviv_iommu_context 
*context,
 
        mutex_lock(&context->lock);
 
+       /* Bail if the mapping has been reaped by another thread */
+       if (!mapping->context) {
+               mutex_unlock(&context->lock);
+               return;
+       }
+
        /* If the vram node is on the mm, unmap and remove the node */
        if (mapping->vram_node.mm == &context->mm)
                etnaviv_iommu_remove_mapping(context, mapping);
-- 
2.30.2

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