This is a note to let you know that I've just added the patch titled drm/amdgpu: workaround for TLB seq race to the 6.0-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drm-amdgpu-workaround-for-tlb-seq-race.patch and it can be found in the queue-6.0 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 77c092e054262b594614bad5e5f47e57c5d29639 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@xxxxxxx> Date: Wed, 2 Nov 2022 14:55:13 +0100 Subject: drm/amdgpu: workaround for TLB seq race MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Christian König <christian.koenig@xxxxxxx> commit 77c092e054262b594614bad5e5f47e57c5d29639 upstream. 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@xxxxxxx> CC: stable@xxxxxxxxxxxxxxx # 5.19+ Fixes: 5255e146c99a6 ("drm/amdgpu: rework TLB flushing") Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2113 Acked-by: Alex Deucher <alexander.deucher@xxxxxxx> Acked-by: Philip Yang <Philip.Yang@xxxxxxx> Tested-by: Stefan Springer <stefanspr94@xxxxxxxxx> Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h @@ -485,6 +485,21 @@ void amdgpu_debugfs_vm_bo_info(struct am */ 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); } Patches currently in stable-queue which might be from christian.koenig@xxxxxxx are queue-6.0/drm-amdgpu-workaround-for-tlb-seq-race.patch queue-6.0/drm-amdgpu-fix-the-lpfn-checking-condition-in-drm-buddy.patch