linux-kernel - [PATCH 5.10 379/452] drm/etnaviv: check for reaped mapping in etnaviv_iommu_unmap

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Message-Id: <20220607164919.857703213@linuxfoundation.org>
Date:   Tue,  7 Jun 2022 19:03:56 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Lucas Stach <l.stach@...gutronix.de>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Guido Günther <agx@...xcpu.org>
Subject: [PATCH 5.10 379/452] drm/etnaviv: check for reaped mapping in etnaviv_iommu_unmap_gem

From: Lucas Stach <l.stach@...gutronix.de>

commit e168c25526cd0368af098095c2ded4a008007e1b upstream.

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@...r.kernel.org # 5.4
Signed-off-by: Lucas Stach <l.stach@...gutronix.de>
Reviewed-by: Philipp Zabel <p.zabel@...gutronix.de>
Tested-by: Guido Günther <agx@...xcpu.org>
Acked-by: Guido Günther <agx@...xcpu.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/gpu/drm/etnaviv/etnaviv_mmu.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/gpu/drm/etnaviv/etnaviv_mmu.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_mmu.c
@@ -282,6 +282,12 @@ void etnaviv_iommu_unmap_gem(struct etna
 
 	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);