drm/amdgpu: Fix vm free pts race when process exiting

Take vm->invalidated_lock spinlock to remove vm pd and pt bos, to avoid
link list corruption with crash backtrace:

[ 2290.505111] list_del corruption. next->prev should be
 ffff9b2514ec0018, but was 4e03280211010f04
[ 2290.505154] kernel BUG at lib/list_debug.c:56!
[ 2290.505176] invalid opcode: 0000 [#1] SMP NOPTI
[ 2290.505254] Workqueue: events delayed_fput
[ 2290.505271] RIP: 0010:__list_del_entry_valid.cold.1+0x20/0x4c
[ 2290.505513] Call Trace:
[ 2290.505623]  amdgpu_vm_free_table+0x26/0x80 [amdgpu]
[ 2290.505705]  amdgpu_vm_free_pts+0x7a/0xf0 [amdgpu]
[ 2290.505786]  amdgpu_vm_fini+0x1f0/0x440 [amdgpu]
[ 2290.505864]  amdgpu_driver_postclose_kms+0x172/0x290 [amdgpu]
[ 2290.505893]  drm_file_free.part.10+0x1d4/0x270 [drm]
[ 2290.505916]  drm_release+0xa9/0xe0 [drm]
[ 2290.505930]  __fput+0xb7/0x230
[ 2290.505942]  delayed_fput+0x1c/0x30
[ 2290.505957]  process_one_work+0x1a7/0x360
[ 2290.505971]  worker_thread+0x30/0x390
[ 2290.505985]  ? create_worker+0x1a0/0x1a0
[ 2290.505999]  kthread+0x112/0x130
[ 2290.506011]  ? kthread_flush_work_fn+0x10/0x10
[ 2290.506027]  ret_from_fork+0x22/0x40

Change-Id: If086c44bb2bf3eb162306778a2f2adc84e331b94
Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c

@@ -975,7 +975,11 @@ static void amdgpu_vm_free_table(struct amdgpu_vm_pt *entry)
 {
 	if (entry->base.bo) {
 		entry->base.bo->vm_bo = NULL;
+
+		spin_lock(&entry->base.vm->invalidated_lock);
 		list_del(&entry->base.vm_status);
+		spin_unlock(&entry->base.vm->invalidated_lock);
+
 		amdgpu_bo_unref(&entry->base.bo->shadow);
 		amdgpu_bo_unref(&entry->base.bo);
 	}