From 38fc4856ad98f230bc91da0421dec69e4aee40f8 Mon Sep 17 00:00:00 2001
From: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Date: Thu, 9 Feb 2017 11:33:36 +0100
Subject: [PATCH] drm/amdgpu: fix a potential deadlock in
amdgpu_bo_create_restricted()
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When ttm_bo_init() fails, the reservation mutex should be unlocked.
In debug build, the kernel reported "possible recursive locking
detected" in this codepath. For debugging purposes, I also added
a "WARN_ON(ww_mutex_is_locked())" when ttm_bo_init() fails and the
mutex was locked as expected.
This should fix (random) GPU hangs. The easy way to reproduce the
issue is to change the "Super Sampling" option from 1.0 to 2.0 in
Hitman. It will create a huge buffer, evict a bunch of buffers
(around ~5k) and deadlock.
This regression has been introduced pretty recently.
v2: only release the mutex if resv is NULL
Fixes: 12a852219583 ("drm/amdgpu: improve AMDGPU_GEM_CREATE_VRAM_CLEARED handling (v2)")
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index da3a53a39d0b..993c003a42e4 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -405,8 +405,11 @@ int amdgpu_bo_create_restricted(struct amdgpu_device *adev,
&bo->placement, page_align, !kernel, NULL,
acc_size, sg, resv ? resv : &bo->tbo.ttm_resv,
&amdgpu_ttm_bo_destroy);
- if (unlikely(r != 0))
+ if (unlikely(r != 0)) {
+ if (!resv)
+ ww_mutex_unlock(&bo->tbo.resv->lock);
return r;
+ }
bo->tbo.priority = ilog2(bo->tbo.num_pages);
if (kernel)
--
2.20.1