Transform: failed to synchronize: cudaErrorIllegalAddress: an illegal memory access was encountered

Getting a CUDA error when trying to run my notebook. I’m using Kaggle GPU for training.

Link to my notebook:

If you need any more info I’ll provide it, just not sure what info should I provide.

Thanks for forwarding the issue! Could you post the needed input shapes used during the model training, which would reproduce the issue?

No problem. Inputs in a single batch item are:
image - tensor[3,520,704]
bbox - tensor[-1, 4]
mask - tensor[1, 520,704]

Sartorius Kaggle competition is the dataset when this bug occurred, if you need some sample data, I’ll provide it as well.

Thanks! I’ve tried to reproduce the issue using this code:

import numpy as np
import torch
import torch
from import Dataset, DataLoader
import torchvision
from torchvision.models.detection.faster_rcnn import FastRCNNPredictor
from torchvision.models.detection.mask_rcnn import MaskRCNNPredictor

def decode_rle_to_mask(rle_array, height, width, viz=False):
    mask = np.zeros((height*width, 1))
    if viz:
        color = np.random.rand(3)
        color = [1]
    for i in rle_array:
        mask[int(i[0]):int(i[0])+int(i[1]), :] = color
    result = mask.reshape(height, width)
    return result
def create_mask(df, image_id, height, width): 
    filtered_df = df[ == image_id]
    result_array = np.zeros(height * width).reshape(height, width)
    for index, row in filtered_df.iterrows():
        annotation_list = row["annotation"].split()
        annotation_list = map(int, annotation_list)
        annotation_list = list(annotation_list)
        annotation_np_array = np.array(annotation_list)
        annotation_np_array = annotation_np_array.reshape(-1, 2)
        annotation_np_array[:,0] -= 1
        result_array = result_array + decode_rle_to_mask(annotation_np_array, height, width)
    result_array[result_array > 1] = 1    
    return result_array
def mask_on_image(path_to_image, image_name, height, width, df):
    original_array = cv2.imread(os.path.join(path_to_image, image_name + '.png'))
    result_array = create_mask(df, image_name, 520, 704)
    plt.imshow(original_array, interpolation = 'none')
    plt.imshow(result_array, interpolation='none', alpha = 0.2)
def rle2bbox(rle, shape):
    rle: run-length encoded image mask, as string
    shape: (height, width) of image on which RLE was produced
    Returns (x0, y0, x1, y1) tuple describing the bounding box of the rle mask
    Note on image vs np.array dimensions:
        np.array implies the `[y, x]` indexing order in terms of image dimensions,
        so the variable on `shape[0]` is `y`, and the variable on the `shape[1]` is `x`,
        hence the result would be correct (x0,y0,x1,y1) in terms of image dimensions
        for RLE-encoded indices of np.array (which are produced by widely used kernels
        and are used in most kaggle competitions datasets)
    a = np.fromiter(rle.split(), dtype=np.uint)
    a = a.reshape((-1, 2))  # an array of (start, length) pairs
    a[:,0] -= 1  # `start` is 1-indexed
    x0 = a[:,0] % shape[1]
    x1 = x0 + a[:,1]
    if np.any(x1 > shape[1]):
        # got `y` overrun, meaning that there are a pixels in mask on 0 and shape[0] position
        x0 = 0
        x1 = shape[1]
        x0 = np.min(x0)
        x1 = np.max(x1)
    y0 = a[:,0] // shape[1]
    y1 = (a[:,0] + a[:,1]) // shape[1]
    y0 = np.min(y0)
    y1 = np.max(y1)
    if x1 > shape[1]:
        # just went out of the image dimensions
        raise ValueError("invalid RLE or image dimensions: x1=%d > shape[1]=%d" % (
            x1, shape[1]

    return x0, y0, x1, y1
def create_bbox_list_by_image(df, image_id):
    filtered_df = df[ == image_id]
    return_list = []
    for index, row in filtered_df.iterrows():
        annotation_list = row["annotation"]
        height, width = row["height"], row["width"]
        return_list.append(rle2bbox(annotation_list, (height, width)))
    return return_list

def update_dataset_with_bbox(df):
    df["bbox"] = "empty"
    for index, row in df.iterrows():
        sample_annot = row["annotation"]
        height, width = row["height"], row["width"]
        x0, y0, x1, y1 = rle2bbox(sample_annot, (height, width))
        df["bbox"][index] = f"{x0} {y0} {x1} {y1}"
    return df
def my_collate(batch):
    return tuple(zip(*batch))

num_classes = 2
model = torchvision.models.detection.maskrcnn_resnet50_fpn(pretrained = True)

for param in model.parameters():
    param.requires_grad = False

in_features = model.roi_heads.box_predictor.cls_score.in_features
model.roi_heads.box_predictor = FastRCNNPredictor(in_features, num_classes)

in_features_mask = model.roi_heads.mask_predictor.conv5_mask.in_channels
hidden_layer = 256
model.roi_heads.mask_predictor = MaskRCNNPredictor(in_features_mask, hidden_layer, num_classes)

device = torch.device('cuda') if torch.cuda.is_available() else torch.device('cpu')
model =

class MyDataset(Dataset):
    def __init__(self):
        self.length = 100

    def __len__(self):
        return self.length

    def __getitem__(self, idx):
        image = torch.randn(3, 520, 704)
        bbox = torch.zeros(1, 4).long()
        bbox[0, 0] = torch.randint(0, 256, (1,))
        bbox[0, 2] = bbox[0, 0] + torch.randint(1, 256, (1,))
        bbox[0, 1] = torch.randint(0, 256, (1,))
        bbox[0, 3] = bbox[0, 1] + torch.randint(1, 256, (1,))
        mask = torch.randint(0, 2, (1, 520, 704)).float()
        return image, bbox, mask

batch_size = 1
num_epochs = 10

train = MyDataset()

trainloader =, batch_size=batch_size,
                                          shuffle=True, num_workers=0, collate_fn = my_collate)

for param in model.rpn.parameters():
    param.requires_grad = True

optimizer = torch.optim.AdamW(filter(lambda p: p.requires_grad, model.parameters()), lr=0.01, betas=(0.9, 0.999), eps=1e-08, weight_decay=0.01, amsgrad=False)
lr_scheduler = torch.optim.lr_scheduler.StepLR(optimizer, 500, gamma=0.01, last_epoch=- 1, verbose=False)

for epoch in range(num_epochs):
    running_loss = []
    loss_classifier = []
    loss_box_reg = []
    loss_mask = []
    loss_objectness = []
    loss_rpn_box_reg = []
    for images, bbox_targets, mask_targets in trainloader:
        images = list( for image in images)
        bbox_targets = list( for bbox_target in bbox_targets)
        mask_targets = list( for mask_target in mask_targets)
        targets = list({} for image in images)
        for i,target in enumerate(targets):
            target["boxes"] = bbox_targets[i]
            target["masks"] = mask_targets[i]
            target["labels"] = torch.ones(bbox_targets[i].shape[0], dtype=torch.int64).to(device)
        loss_dict = model(images, targets)
        losses = sum(loss for loss in loss_dict.values())
    if (epoch + 1) % 1 == 0:
        print(f"Epoch {epoch + 1}, loss: {sum(running_loss)/len(running_loss)}")
        print(f"Loss classifier: {sum(loss_classifier)/len(loss_classifier)}")
        print(f"Loss box regression: {sum(loss_box_reg)/len(loss_box_reg)}")
        print(f"Loss mask: {sum(loss_mask)/len(loss_mask)}")
        print(f"Loss objectness: {sum(loss_objectness)/len(loss_objectness)}")
        print(f"Loss rpn box regression: {sum(loss_rpn_box_reg)/len(loss_rpn_box_reg)}")

but it works fine in the current stable release as well as the nightly binary.
Could you check, if this code would fail in your setup?

Yes, the given code runs, however, when I change the dataset back to my original dataset, the error occurs. My guess is that it has to do smth with uneven number of bounding boxes per image, since that’s the only unusual thing that I can point to. Since some images can have 100 bounding boxes, some 300, etc…

Could you adapt the code snippet so that it would fail and I could reproduce it?

Replace your implementation of MyDataset with:

import random

class MyDataset(Dataset):
    def __init__(self):
        self.length = 100

    def __len__(self):
        return self.length

    def __getitem__(self, idx):
        image = torch.randn(3, 520, 704)
        n = random.randint(1,100)
        bbox = torch.zeros(n, 4).long()
        for i in range(n):
            bbox[i, 0] = torch.randint(0, 256, (1,))
            bbox[i, 2] = bbox[i, 0] + torch.randint(1, 256, (1,))
            bbox[i, 1] = torch.randint(0, 256, (1,))
            bbox[i, 3] = bbox[i, 1] + torch.randint(1, 256, (1,))
        mask = torch.randint(0, 2, (1, 520, 704)).float()
        return image, bbox, mask

and the error occurs

1 Like

Thank you! Your code works great and I’m seeing:

CUDA Exception: Warp Illegal Address
The exception was triggered at PC 0x555591e11f40

Thread 27 "python" received signal CUDA_EXCEPTION_14, Warp Illegal Address.
[Switching focus to CUDA kernel 0, grid 19319, block (84,0,0), thread (192,0,0), device 0, sm 0, warp 20, lane 0]
0x0000555591e12040 in void vision::ops::(anonymous namespace)::roi_align_forward_kernel_impl<float>(--Type <RET> for more, q to quit, c to continue without paging--
int, float const*, float, int, int, int, int, int, int, bool, float const*, float*)
   <<<(172,1,1),(512,1,1)>>> ()

Will debug it further, create an issue, and update you here.