The patch below does not apply to the 6.0-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

Possible dependencies:

f9e694964503 ("drm/amdgpu: workaround for TLB seq race")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f9e69496450352fa0504fd5a8fd9134b31116558 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Christian=20K=C3=B6nig?= christian.koenig@amd.com Date: Wed, 2 Nov 2022 14:55:13 +0100 Subject: [PATCH] drm/amdgpu: workaround for TLB seq race MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

It can happen that we query the sequence value before the callback had a chance to run.

Workaround that by grabbing the fence lock and releasing it again. Should be replaced by hw handling soon.

Signed-off-by: Christian König christian.koenig@amd.com CC: stable@vger.kernel.org # 5.19+ Fixes: 5255e146c99a6 ("drm/amdgpu: rework TLB flushing") Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2113 Acked-by: Alex Deucher alexander.deucher@amd.com Acked-by: Philip Yang Philip.Yang@amd.com Tested-by: Stefan Springer stefanspr94@gmail.com Signed-off-by: Alex Deucher alexander.deucher@amd.com

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h index 83acb7bd80fe..1d31771b4230 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h @@ -492,6 +492,21 @@ void amdgpu_debugfs_vm_bo_info(struct amdgpu_vm *vm, struct seq_file *m); */ static inline uint64_t amdgpu_vm_tlb_seq(struct amdgpu_vm *vm) { + unsigned long flags; + spinlock_t *lock; + + /* + * Workaround to stop racing between the fence signaling and handling + * the cb. The lock is static after initially setting it up, just make + * sure that the dma_fence structure isn't freed up. + */ + rcu_read_lock(); + lock = vm->last_tlb_flush->lock; + rcu_read_unlock(); + + spin_lock_irqsave(lock, flags); + spin_unlock_irqrestore(lock, flags); + return atomic64_read(&vm->tlb_seq); }