[PATCH 1/4] drm/etnaviv: check for reaped mapping in etnaviv_iommu_unmap_gem

From: Lucas Stach <l.stach@pengutronix.de>
To: etnaviv@lists.freedesktop.org
Cc: patchwork-lst@pengutronix.de, kernel@pengutronix.de,
	dri-devel@lists.freedesktop.org,
	Russell King <linux+etnaviv@armlinux.org.uk>
Subject: [PATCH 1/4] drm/etnaviv: check for reaped mapping in etnaviv_iommu_unmap_gem
Date: Wed, 23 Mar 2022 17:08:22 +0100	[thread overview]
Message-ID: <20220323160825.3858619-1-l.stach@pengutronix.de> (raw)

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: stable@vger.kernel.org # 5.4
Signed-off-by: Lucas Stach <l.stach@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

