On 8/22/19 4:02 PM, Koenig, Christian wrote:
Am 22.08.19 um 15:06 schrieb Daniel Vetter:
On Thu, Aug 22, 2019 at 07:56:56AM +0000, Koenig, Christian wrote:
Am 22.08.19 um 08:49 schrieb Daniel Vetter:
With nouveau fixed all ttm-using drives have the correct nesting of mmap_sem vs dma_resv, and we can just lock the buffer.
Assuming I didn't screw up anything with my audit of course.
v2:
- Dont forget wu_mutex (Christian König)
- Keep the mmap_sem-less wait optimization (Thomas)
- Use _lock_interruptible to be good citizens (Thomas)
Reviewed-by: Christian König christian.koenig@amd.com
btw I realized I didn't remove your r-b, since v1 was broken.
For formality, can you pls reaffirm, or still something broken?
My r-b is still valid.
Only problem I see is that neither of us seems to have a good idea about the different VM_FAULT_* replies.
I took a look in mm/gup.c. It seems like when using get_user_pages, VM_FAULT_RETRY will retry to a requesting caller telling it that a long wait was expected and not performed, whereas VM_FAULT_NOPAGE will just keep get_user_pages to spin. So the proposed patch should be correct from my understanding.
If the fault originates from user-space, I guess either is fine.
/Thomas
But that worked before so it should still work now, Christian.
Also from the other thread: Reviewed-by: Thomas Hellström thellstrom@vmware.com
Thanks, Daniel
Signed-off-by: Daniel Vetter daniel.vetter@intel.com Cc: Christian Koenig christian.koenig@amd.com Cc: Huang Rui ray.huang@amd.com Cc: Gerd Hoffmann kraxel@redhat.com Cc: "VMware Graphics" linux-graphics-maintainer@vmware.com Cc: Thomas Hellstrom thellstrom@vmware.com
drivers/gpu/drm/ttm/ttm_bo.c | 36 ------------------------------- drivers/gpu/drm/ttm/ttm_bo_util.c | 1 - drivers/gpu/drm/ttm/ttm_bo_vm.c | 18 +++++----------- include/drm/ttm/ttm_bo_api.h | 4 ---- 4 files changed, 5 insertions(+), 54 deletions(-)diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index 20ff56f27aa4..d1ce5d315d5b 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -162,7 +162,6 @@ static void ttm_bo_release_list(struct kref *list_kref) dma_fence_put(bo->moving); if (!ttm_bo_uses_embedded_gem_object(bo)) dma_resv_fini(&bo->base._resv);
- mutex_destroy(&bo->wu_mutex); bo->destroy(bo); ttm_mem_global_free(bdev->glob->mem_glob, acc_size); }
@@ -1319,7 +1318,6 @@ int ttm_bo_init_reserved(struct ttm_bo_device *bdev, INIT_LIST_HEAD(&bo->ddestroy); INIT_LIST_HEAD(&bo->swap); INIT_LIST_HEAD(&bo->io_reserve_lru);
- mutex_init(&bo->wu_mutex); bo->bdev = bdev; bo->type = type; bo->num_pages = num_pages;
@@ -1954,37 +1952,3 @@ void ttm_bo_swapout_all(struct ttm_bo_device *bdev) ; } EXPORT_SYMBOL(ttm_bo_swapout_all);
-/**
- ttm_bo_wait_unreserved - interruptible wait for a buffer object to become
- unreserved
- @bo: Pointer to buffer
- */
-int ttm_bo_wait_unreserved(struct ttm_buffer_object *bo) -{
- int ret;
- /*
* In the absense of a wait_unlocked API,* Use the bo::wu_mutex to avoid triggering livelocks due to* concurrent use of this function. Note that this use of* bo::wu_mutex can go away if we change locking order to* mmap_sem -> bo::reserve.*/- ret = mutex_lock_interruptible(&bo->wu_mutex);
- if (unlikely(ret != 0))
return -ERESTARTSYS;- if (!dma_resv_is_locked(bo->base.resv))
goto out_unlock;- ret = dma_resv_lock_interruptible(bo->base.resv, NULL);
- if (ret == -EINTR)
ret = -ERESTARTSYS;- if (unlikely(ret != 0))
goto out_unlock;- dma_resv_unlock(bo->base.resv);
-out_unlock:
- mutex_unlock(&bo->wu_mutex);
- return ret;
-} diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c index fe81c565e7ef..82ea26a49959 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_util.c +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c @@ -508,7 +508,6 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo, INIT_LIST_HEAD(&fbo->base.lru); INIT_LIST_HEAD(&fbo->base.swap); INIT_LIST_HEAD(&fbo->base.io_reserve_lru);
- mutex_init(&fbo->base.wu_mutex); fbo->base.moving = NULL; drm_vma_node_reset(&fbo->base.base.vma_node); atomic_set(&fbo->base.cpu_writers, 0);
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c index 76eedb963693..a61a35e57d1c 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c @@ -125,30 +125,22 @@ static vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf) &bdev->man[bo->mem.mem_type]; struct vm_area_struct cvma;
- /*
* Work around locking order reversal in fault / nopfn* between mmap_sem and bo_reserve: Perform a trylock operation* for reserve, and if it fails, retry the fault after waiting* for the buffer to become unreserved.*/ if (unlikely(!dma_resv_trylock(bo->base.resv))) { if (vmf->flags & FAULT_FLAG_ALLOW_RETRY) { if (!(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {Not an expert on fault handling, but shouldn't this now be one if?
E.g. if FAULT_FLAG_RETRY_NOWAIT is set we should return VM_FAULT_NOPAGE instead of VM_FAULT_RETRY.
But really take that with a grain of salt, Christian.
ttm_bo_get(bo); up_read(&vmf->vma->vm_mm->mmap_sem);
(void) ttm_bo_wait_unreserved(bo);
if (!dma_resv_lock_interruptible(bo->base.resv,NULL))dma_resv_unlock(bo->base.resv); ttm_bo_put(bo); } return VM_FAULT_RETRY; }
/** If we'd want to change locking order to* mmap_sem -> bo::reserve, we'd use a blocking reserve here* instead of retrying the fault...*/return VM_FAULT_NOPAGE;
if (dma_resv_lock_interruptible(bo->base.resv, NULL))return VM_FAULT_NOPAGE; } /*diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h index 43c4929a2171..21c7d0d28757 100644 --- a/include/drm/ttm/ttm_bo_api.h +++ b/include/drm/ttm/ttm_bo_api.h @@ -155,7 +155,6 @@ struct ttm_tt; * @offset: The current GPU offset, which can have different meanings * depending on the memory type. For SYSTEM type memory, it should be 0. * @cur_placement: Hint of current placement.
- @wu_mutex: Wait unreserved mutex.
- Base class for TTM buffer object, that deals with data placement and CPU
- mappings. GPU mappings are really up to the driver, but for simpler GPUs
@@ -229,8 +228,6 @@ struct ttm_buffer_object { uint64_t offset; /* GPU address space is independent of CPU word size */
struct sg_table *sg;
struct mutex wu_mutex; };
/**
@@ -765,7 +762,6 @@ ssize_t ttm_bo_io(struct ttm_bo_device *bdev, struct file *filp, int ttm_bo_swapout(struct ttm_bo_global *glob, struct ttm_operation_ctx *ctx); void ttm_bo_swapout_all(struct ttm_bo_device *bdev); -int ttm_bo_wait_unreserved(struct ttm_buffer_object *bo);
/** * ttm_bo_uses_embedded_gem_object - check if the given bo uses the
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