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From:   Daniel Vetter <daniel.vetter@ffwll.ch>
To:     DRI Development <dri-devel@lists.freedesktop.org>
Cc:     Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>, linux-rdma@vger.kernel.org,
        amd-gfx@lists.freedesktop.org,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org,
        Chris Wilson <chris@chris-wilson.co.uk>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>,
        Daniel Vetter <daniel.vetter@intel.com>
Subject: [PATCH 11/18] drm/amdgpu: s/GFP_KERNEL/GFP_ATOMIC in scheduler code
Date:   Thu,  4 Jun 2020 10:12:17 +0200
Message-Id: <20200604081224.863494-12-daniel.vetter@ffwll.ch>
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My dma-fence lockdep annotations caught an inversion because we
allocate memory where we really shouldn't:

	kmem_cache_alloc+0x2b/0x6d0
	amdgpu_fence_emit+0x30/0x330 [amdgpu]
	amdgpu_ib_schedule+0x306/0x550 [amdgpu]
	amdgpu_job_run+0x10f/0x260 [amdgpu]
	drm_sched_main+0x1b9/0x490 [gpu_sched]
	kthread+0x12e/0x150

Trouble right now is that lockdep only validates against GFP_FS, which
would be good enough for shrinkers. But for mmu_notifiers we actually
need !GFP_ATOMIC, since they can be called from any page laundering,
even if GFP_NOFS or GFP_NOIO are set.

I guess we should improve the lockdep annotations for
fs_reclaim_acquire/release.

Ofc real fix is to properly preallocate this fence and stuff it into
the amdgpu job structure. But GFP_ATOMIC gets the lockdep splat out of
the way.

v2: Two more allocations in scheduler paths.

Frist one:

	__kmalloc+0x58/0x720
	amdgpu_vmid_grab+0x100/0xca0 [amdgpu]
	amdgpu_job_dependency+0xf9/0x120 [amdgpu]
	drm_sched_entity_pop_job+0x3f/0x440 [gpu_sched]
	drm_sched_main+0xf9/0x490 [gpu_sched]

Second one:

	kmem_cache_alloc+0x2b/0x6d0
	amdgpu_sync_fence+0x7e/0x110 [amdgpu]
	amdgpu_vmid_grab+0x86b/0xca0 [amdgpu]
	amdgpu_job_dependency+0xf9/0x120 [amdgpu]
	drm_sched_entity_pop_job+0x3f/0x440 [gpu_sched]
	drm_sched_main+0xf9/0x490 [gpu_sched]

Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Cc: linux-rdma@vger.kernel.org
Cc: amd-gfx@lists.freedesktop.org
Cc: intel-gfx@lists.freedesktop.org
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Christian König <christian.koenig@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c | 2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c   | 2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c  | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
index d878fe7fee51..055b47241bb1 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
@@ -143,7 +143,7 @@ int amdgpu_fence_emit(struct amdgpu_ring *ring, struct dma_fence **f,
 	uint32_t seq;
 	int r;
 
-	fence = kmem_cache_alloc(amdgpu_fence_slab, GFP_KERNEL);
+	fence = kmem_cache_alloc(amdgpu_fence_slab, GFP_ATOMIC);
 	if (fence == NULL)
 		return -ENOMEM;
 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c
index fe92dcd94d4a..fdcd6659f5ad 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c
@@ -208,7 +208,7 @@ static int amdgpu_vmid_grab_idle(struct amdgpu_vm *vm,
 	if (ring->vmid_wait && !dma_fence_is_signaled(ring->vmid_wait))
 		return amdgpu_sync_fence(sync, ring->vmid_wait, false);
 
-	fences = kmalloc_array(sizeof(void *), id_mgr->num_ids, GFP_KERNEL);
+	fences = kmalloc_array(sizeof(void *), id_mgr->num_ids, GFP_ATOMIC);
 	if (!fences)
 		return -ENOMEM;
 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
index b87ca171986a..330476cc0c86 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
@@ -168,7 +168,7 @@ int amdgpu_sync_fence(struct amdgpu_sync *sync, struct dma_fence *f,
 	if (amdgpu_sync_add_later(sync, f, explicit))
 		return 0;
 
-	e = kmem_cache_alloc(amdgpu_sync_slab, GFP_KERNEL);
+	e = kmem_cache_alloc(amdgpu_sync_slab, GFP_ATOMIC);
 	if (!e)
 		return -ENOMEM;
 
-- 
2.26.2