On Tue, Apr 20, 2021 at 12:34:50PM +0200, Maarten Lankhorst wrote:
> Commit e3793468b466 ("drm/i915: Use the async worker to avoid reclaim
> tainting the ggtt->mutex") moves the vma binding to dma_fence_work,
> but dma_fence_work has has signalling fence semantics.
>
> On braswell, we can call stop_machine inside fence_work, causing a splat
> because memory allocation inside stop_machine is allowed.
>
> This patch does not fix that lockdep splat yet, but will allow the next
> patch to remove it.
>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Acked-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Thomas pointed out that this removes pipelined pte writing for both ggtt
and ppgtt, and that's a bit much. So need to retract my ack here.
-Daniel
> ---
> drivers/gpu/drm/i915/gem/i915_gem_stolen.c | 3 -
> drivers/gpu/drm/i915/gt/gen6_ppgtt.c | 1 -
> drivers/gpu/drm/i915/gt/gen8_ppgtt.c | 1 -
> drivers/gpu/drm/i915/gt/intel_ggtt.c | 4 -
> drivers/gpu/drm/i915/gt/intel_gtt.h | 2 -
> drivers/gpu/drm/i915/i915_gem.c | 6 -
> drivers/gpu/drm/i915/i915_vma.c | 174 +++------------------
> drivers/gpu/drm/i915/i915_vma.h | 5 +-
> drivers/gpu/drm/i915/i915_vma_types.h | 3 -
> 9 files changed, 21 insertions(+), 178 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
> index b0597de206de..ec04df0a3b89 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
> @@ -505,9 +505,6 @@ static void dbg_poison(struct i915_ggtt *ggtt,
> if (!drm_mm_node_allocated(&ggtt->error_capture))
> return;
>
> - if (ggtt->vm.bind_async_flags & I915_VMA_GLOBAL_BIND)
> - return; /* beware stop_machine() inversion */
> -
> GEM_BUG_ON(!IS_ALIGNED(size, PAGE_SIZE));
>
> mutex_lock(&ggtt->error_mutex);
> diff --git a/drivers/gpu/drm/i915/gt/gen6_ppgtt.c b/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
> index e08dff376339..0c5a9a767849 100644
> --- a/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
> +++ b/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
> @@ -436,7 +436,6 @@ struct i915_ppgtt *gen6_ppgtt_create(struct intel_gt *gt)
> ppgtt->base.vm.pd_shift = ilog2(SZ_4K * SZ_4K / sizeof(gen6_pte_t));
> ppgtt->base.vm.top = 1;
>
> - ppgtt->base.vm.bind_async_flags = I915_VMA_LOCAL_BIND;
> ppgtt->base.vm.allocate_va_range = gen6_alloc_va_range;
> ppgtt->base.vm.clear_range = gen6_ppgtt_clear_range;
> ppgtt->base.vm.insert_entries = gen6_ppgtt_insert_entries;
> diff --git a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
> index 176c19633412..92f8a23e66cc 100644
> --- a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
> +++ b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
> @@ -736,7 +736,6 @@ struct i915_ppgtt *gen8_ppgtt_create(struct intel_gt *gt)
> goto err_free_pd;
> }
>
> - ppgtt->vm.bind_async_flags = I915_VMA_LOCAL_BIND;
> ppgtt->vm.insert_entries = gen8_ppgtt_insert;
> ppgtt->vm.allocate_va_range = gen8_ppgtt_alloc;
> ppgtt->vm.clear_range = gen8_ppgtt_clear;
> diff --git a/drivers/gpu/drm/i915/gt/intel_ggtt.c b/drivers/gpu/drm/i915/gt/intel_ggtt.c
> index 670c1271e7d5..e1ec6edae1fb 100644
> --- a/drivers/gpu/drm/i915/gt/intel_ggtt.c
> +++ b/drivers/gpu/drm/i915/gt/intel_ggtt.c
> @@ -127,7 +127,6 @@ void i915_ggtt_suspend(struct i915_ggtt *ggtt)
>
> list_for_each_entry_safe(vma, vn, &ggtt->vm.bound_list, vm_link) {
> GEM_BUG_ON(!drm_mm_node_allocated(&vma->node));
> - i915_vma_wait_for_bind(vma);
>
> if (i915_vma_is_pinned(vma))
> continue;
> @@ -671,7 +670,6 @@ static int init_aliasing_ppgtt(struct i915_ggtt *ggtt)
> ppgtt->vm.allocate_va_range(&ppgtt->vm, &stash, 0, ggtt->vm.total);
>
> ggtt->alias = ppgtt;
> - ggtt->vm.bind_async_flags |= ppgtt->vm.bind_async_flags;
>
> GEM_BUG_ON(ggtt->vm.vma_ops.bind_vma != ggtt_bind_vma);
> ggtt->vm.vma_ops.bind_vma = aliasing_gtt_bind_vma;
> @@ -911,8 +909,6 @@ static int gen8_gmch_probe(struct i915_ggtt *ggtt)
> IS_CHERRYVIEW(i915) /* fails with concurrent use/update */) {
> ggtt->vm.insert_entries = bxt_vtd_ggtt_insert_entries__BKL;
> ggtt->vm.insert_page = bxt_vtd_ggtt_insert_page__BKL;
> - ggtt->vm.bind_async_flags =
> - I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND;
> }
>
> ggtt->invalidate = gen8_ggtt_invalidate;
> diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.h b/drivers/gpu/drm/i915/gt/intel_gtt.h
> index e67e34e17913..d9d2ca8b4b61 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gtt.h
> +++ b/drivers/gpu/drm/i915/gt/intel_gtt.h
> @@ -230,8 +230,6 @@ struct i915_address_space {
> u64 total; /* size addr space maps (ex. 2GB for ggtt) */
> u64 reserved; /* size addr space reserved */
>
> - unsigned int bind_async_flags;
> -
> /*
> * Each active user context has its own address space (in full-ppgtt).
> * Since the vm may be shared between multiple contexts, we count how
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index b23f58e94cfb..4639c47c038b 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -946,12 +946,6 @@ i915_gem_object_ggtt_pin_ww(struct drm_i915_gem_object *obj,
> mutex_unlock(&ggtt->vm.mutex);
> }
>
> - ret = i915_vma_wait_for_bind(vma);
> - if (ret) {
> - i915_vma_unpin(vma);
> - return ERR_PTR(ret);
> - }
> -
> return vma;
> }
>
> diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
> index 07490db51cdc..e4b2590d41ce 100644
> --- a/drivers/gpu/drm/i915/i915_vma.c
> +++ b/drivers/gpu/drm/i915/i915_vma.c
> @@ -289,79 +289,6 @@ i915_vma_instance(struct drm_i915_gem_object *obj,
> return vma;
> }
>
> -struct i915_vma_work {
> - struct dma_fence_work base;
> - struct i915_address_space *vm;
> - struct i915_vm_pt_stash stash;
> - struct i915_vma *vma;
> - struct drm_i915_gem_object *pinned;
> - struct i915_sw_dma_fence_cb cb;
> - enum i915_cache_level cache_level;
> - unsigned int flags;
> -};
> -
> -static int __vma_bind(struct dma_fence_work *work)
> -{
> - struct i915_vma_work *vw = container_of(work, typeof(*vw), base);
> - struct i915_vma *vma = vw->vma;
> -
> - vma->ops->bind_vma(vw->vm, &vw->stash,
> - vma, vw->cache_level, vw->flags);
> - return 0;
> -}
> -
> -static void __vma_release(struct dma_fence_work *work)
> -{
> - struct i915_vma_work *vw = container_of(work, typeof(*vw), base);
> -
> - if (vw->pinned) {
> - __i915_gem_object_unpin_pages(vw->pinned);
> - i915_gem_object_put(vw->pinned);
> - }
> -
> - i915_vm_free_pt_stash(vw->vm, &vw->stash);
> - i915_vm_put(vw->vm);
> -}
> -
> -static const struct dma_fence_work_ops bind_ops = {
> - .name = "bind",
> - .work = __vma_bind,
> - .release = __vma_release,
> -};
> -
> -struct i915_vma_work *i915_vma_work(void)
> -{
> - struct i915_vma_work *vw;
> -
> - vw = kzalloc(sizeof(*vw), GFP_KERNEL);
> - if (!vw)
> - return NULL;
> -
> - dma_fence_work_init(&vw->base, &bind_ops);
> - vw->base.dma.error = -EAGAIN; /* disable the worker by default */
> -
> - return vw;
> -}
> -
> -int i915_vma_wait_for_bind(struct i915_vma *vma)
> -{
> - int err = 0;
> -
> - if (rcu_access_pointer(vma->active.excl.fence)) {
> - struct dma_fence *fence;
> -
> - rcu_read_lock();
> - fence = dma_fence_get_rcu_safe(&vma->active.excl.fence);
> - rcu_read_unlock();
> - if (fence) {
> - err = dma_fence_wait(fence, MAX_SCHEDULE_TIMEOUT);
> - dma_fence_put(fence);
> - }
> - }
> -
> - return err;
> -}
> -
> /**
> * i915_vma_bind - Sets up PTEs for an VMA in it's corresponding address space.
> * @vma: VMA to map
> @@ -375,8 +302,7 @@ int i915_vma_wait_for_bind(struct i915_vma *vma)
> */
> int i915_vma_bind(struct i915_vma *vma,
> enum i915_cache_level cache_level,
> - u32 flags,
> - struct i915_vma_work *work)
> + u32 flags, struct i915_vm_pt_stash *stash)
> {
> u32 bind_flags;
> u32 vma_flags;
> @@ -405,39 +331,7 @@ int i915_vma_bind(struct i915_vma *vma,
> GEM_BUG_ON(!vma->pages);
>
> trace_i915_vma_bind(vma, bind_flags);
> - if (work && bind_flags & vma->vm->bind_async_flags) {
> - struct dma_fence *prev;
> -
> - work->vma = vma;
> - work->cache_level = cache_level;
> - work->flags = bind_flags;
> -
> - /*
> - * Note we only want to chain up to the migration fence on
> - * the pages (not the object itself). As we don't track that,
> - * yet, we have to use the exclusive fence instead.
> - *
> - * Also note that we do not want to track the async vma as
> - * part of the obj->resv->excl_fence as it only affects
> - * execution and not content or object's backing store lifetime.
> - */
> - prev = i915_active_set_exclusive(&vma->active, &work->base.dma);
> - if (prev) {
> - __i915_sw_fence_await_dma_fence(&work->base.chain,
> - prev,
> - &work->cb);
> - dma_fence_put(prev);
> - }
> -
> - work->base.dma.error = 0; /* enable the queue_work() */
> -
> - if (vma->obj) {
> - __i915_gem_object_pin_pages(vma->obj);
> - work->pinned = i915_gem_object_get(vma->obj);
> - }
> - } else {
> - vma->ops->bind_vma(vma->vm, NULL, vma, cache_level, bind_flags);
> - }
> + vma->ops->bind_vma(vma->vm, stash, vma, cache_level, bind_flags);
>
> atomic_or(bind_flags, &vma->flags);
> return 0;
> @@ -531,9 +425,6 @@ bool i915_vma_misplaced(const struct i915_vma *vma,
> if (!drm_mm_node_allocated(&vma->node))
> return false;
>
> - if (test_bit(I915_VMA_ERROR_BIT, __i915_vma_flags(vma)))
> - return true;
> -
> if (vma->node.size < size)
> return true;
>
> @@ -752,7 +643,7 @@ static bool try_qad_pin(struct i915_vma *vma, unsigned int flags)
> if (unlikely(flags & ~bound))
> return false;
>
> - if (unlikely(bound & (I915_VMA_OVERFLOW | I915_VMA_ERROR)))
> + if (unlikely(bound & I915_VMA_OVERFLOW))
> return false;
>
> if (!(bound & I915_VMA_PIN_MASK))
> @@ -770,7 +661,7 @@ static bool try_qad_pin(struct i915_vma *vma, unsigned int flags)
> */
> mutex_lock(&vma->vm->mutex);
> do {
> - if (unlikely(bound & (I915_VMA_OVERFLOW | I915_VMA_ERROR))) {
> + if (unlikely(bound & I915_VMA_OVERFLOW)) {
> pinned = false;
> break;
> }
> @@ -857,10 +748,10 @@ static void vma_unbind_pages(struct i915_vma *vma)
> int i915_vma_pin_ww(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
> u64 size, u64 alignment, u64 flags)
> {
> - struct i915_vma_work *work = NULL;
> intel_wakeref_t wakeref = 0;
> unsigned int bound;
> int err;
> + struct i915_vm_pt_stash stash = {};
>
> #ifdef CONFIG_PROVE_LOCKING
> if (debug_locks && !WARN_ON(!ww) && vma->resv)
> @@ -883,33 +774,21 @@ int i915_vma_pin_ww(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
> if (flags & PIN_GLOBAL)
> wakeref = intel_runtime_pm_get(&vma->vm->i915->runtime_pm);
>
> - if (flags & vma->vm->bind_async_flags) {
> - /* lock VM */
> - err = i915_vm_lock_objects(vma->vm, ww);
> + if (vma->vm->allocate_va_range) {
> + err = i915_vm_alloc_pt_stash(vma->vm,
> + &stash,
> + vma->size);
> if (err)
> goto err_rpm;
>
> - work = i915_vma_work();
> - if (!work) {
> - err = -ENOMEM;
> + err = i915_vm_lock_objects(vma->vm, ww);
> + if (err)
> goto err_rpm;
> - }
>
> - work->vm = i915_vm_get(vma->vm);
> -
> - /* Allocate enough page directories to used PTE */
> - if (vma->vm->allocate_va_range) {
> - err = i915_vm_alloc_pt_stash(vma->vm,
> - &work->stash,
> - vma->size);
> - if (err)
> - goto err_fence;
> -
> - err = i915_vm_pin_pt_stash(vma->vm,
> - &work->stash);
> - if (err)
> - goto err_fence;
> - }
> + err = i915_vm_pin_pt_stash(vma->vm,
> + &stash);
> + if (err)
> + goto err_rpm;
> }
>
> /*
> @@ -932,7 +811,7 @@ int i915_vma_pin_ww(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
> err = mutex_lock_interruptible_nested(&vma->vm->mutex,
> !(flags & PIN_GLOBAL));
> if (err)
> - goto err_fence;
> + goto err_rpm;
>
> /* No more allocations allowed now we hold vm->mutex */
>
> @@ -942,11 +821,6 @@ int i915_vma_pin_ww(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
> }
>
> bound = atomic_read(&vma->flags);
> - if (unlikely(bound & I915_VMA_ERROR)) {
> - err = -ENOMEM;
> - goto err_unlock;
> - }
> -
> if (unlikely(!((bound + 1) & I915_VMA_PIN_MASK))) {
> err = -EAGAIN; /* pins are meant to be fairly temporary */
> goto err_unlock;
> @@ -973,7 +847,7 @@ int i915_vma_pin_ww(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
> GEM_BUG_ON(!vma->pages);
> err = i915_vma_bind(vma,
> vma->obj ? vma->obj->cache_level : 0,
> - flags, work);
> + flags, &stash);
> if (err)
> goto err_remove;
>
> @@ -996,10 +870,8 @@ int i915_vma_pin_ww(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
> i915_active_release(&vma->active);
> err_unlock:
> mutex_unlock(&vma->vm->mutex);
> -err_fence:
> - if (work)
> - dma_fence_work_commit_imm(&work->base);
> err_rpm:
> + i915_vm_free_pt_stash(vma->vm, &stash);
> if (wakeref)
> intel_runtime_pm_put(&vma->vm->i915->runtime_pm, wakeref);
> vma_put_pages(vma);
> @@ -1034,14 +906,8 @@ int i915_ggtt_pin(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
> err = i915_vma_pin_ww(vma, ww, 0, align, flags | PIN_GLOBAL);
> else
> err = i915_vma_pin(vma, 0, align, flags | PIN_GLOBAL);
> - if (err != -ENOSPC) {
> - if (!err) {
> - err = i915_vma_wait_for_bind(vma);
> - if (err)
> - i915_vma_unpin(vma);
> - }
> + if (err != -ENOSPC)
> return err;
> - }
>
> /* Unlike i915_vma_pin, we don't take no for an answer! */
> flush_idle_contexts(vm->gt);
> @@ -1306,7 +1172,7 @@ void __i915_vma_evict(struct i915_vma *vma)
> trace_i915_vma_unbind(vma);
> vma->ops->unbind_vma(vma->vm, vma);
> }
> - atomic_and(~(I915_VMA_BIND_MASK | I915_VMA_ERROR | I915_VMA_GGTT_WRITE),
> + atomic_and(~(I915_VMA_BIND_MASK | I915_VMA_GGTT_WRITE),
> &vma->flags);
>
> i915_vma_detach(vma);
> diff --git a/drivers/gpu/drm/i915/i915_vma.h b/drivers/gpu/drm/i915/i915_vma.h
> index 8df784a026d2..d1d0fc76ef99 100644
> --- a/drivers/gpu/drm/i915/i915_vma.h
> +++ b/drivers/gpu/drm/i915/i915_vma.h
> @@ -195,11 +195,10 @@ i915_vma_compare(struct i915_vma *vma,
> return memcmp(&vma->ggtt_view.partial, &view->partial, view->type);
> }
>
> -struct i915_vma_work *i915_vma_work(void);
> int i915_vma_bind(struct i915_vma *vma,
> enum i915_cache_level cache_level,
> u32 flags,
> - struct i915_vma_work *work);
> + struct i915_vm_pt_stash *stash);
>
> bool i915_gem_valid_gtt_space(struct i915_vma *vma, unsigned long color);
> bool i915_vma_misplaced(const struct i915_vma *vma,
> @@ -418,8 +417,6 @@ struct i915_vma *i915_vma_make_unshrinkable(struct i915_vma *vma);
> void i915_vma_make_shrinkable(struct i915_vma *vma);
> void i915_vma_make_purgeable(struct i915_vma *vma);
>
> -int i915_vma_wait_for_bind(struct i915_vma *vma);
> -
> static inline int i915_vma_sync(struct i915_vma *vma)
> {
> /* Wait for the asynchronous bindings and pending GPU reads */
> diff --git a/drivers/gpu/drm/i915/i915_vma_types.h b/drivers/gpu/drm/i915/i915_vma_types.h
> index 6b1bfa230b82..82868a755a96 100644
> --- a/drivers/gpu/drm/i915/i915_vma_types.h
> +++ b/drivers/gpu/drm/i915/i915_vma_types.h
> @@ -240,9 +240,6 @@ struct i915_vma {
>
> #define I915_VMA_ALLOC_BIT 12
>
> -#define I915_VMA_ERROR_BIT 13
> -#define I915_VMA_ERROR ((int)BIT(I915_VMA_ERROR_BIT))
> -
> #define I915_VMA_GGTT_BIT 14
> #define I915_VMA_CAN_FENCE_BIT 15
> #define I915_VMA_USERFAULT_BIT 16
> --
> 2.31.0
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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