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Date: Fri, 15 Dec 2023 23:03:14 -0800
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Subject: Re: [syzbot] Re: [block?] INFO: task hung in bdev_release
From: syzbot <syzbot+4da851837827326a7cd4@syzkaller.appspotmail.com>
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Subject: Re: [block?] INFO: task hung in bdev_release
Author: eadavis@qq.com

please test task hung in bdev_release

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git  8c9660f65153

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index b6414e1e645b..3cc7993b0b67 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1137,6 +1137,7 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
 	int err;
 
 	/* Arg will be cast to int, check it to avoid overflow */
+	printk("arg: %d, nbd: %p, %s\n", arg, nbd, __func__);
 	if (arg > INT_MAX)
 		return -EINVAL;
 	sock = nbd_get_socket(nbd, arg, &err);
@@ -1188,10 +1189,12 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
 	socks[config->num_connections++] = nsock;
 	atomic_inc(&config->live_connections);
 	blk_mq_unfreeze_queue(nbd->disk->queue);
+	printk("arg: %d, nbd: %p, nd: %p, nc: %d, %s\n", arg, nbd, nbd->disk, config->num_connections, __func__);
 
 	return 0;
 
 put_socket:
+	printk("nbd: %p, %s\n", nbd, __func__);
 	blk_mq_unfreeze_queue(nbd->disk->queue);
 	sockfd_put(sock);
 	return err;
@@ -1372,6 +1375,7 @@ static int nbd_start_device(struct nbd_device *nbd)
 	int num_connections = config->num_connections;
 	int error = 0, i;
 
+	printk("dev: %p, nc: %d, pid: %d, socks: %p, %s\n", nbd, num_connections, nbd->pid, config->socks, __func__);
 	if (nbd->pid)
 		return -EBUSY;
 	if (!config->socks)
@@ -1425,6 +1429,7 @@ static int nbd_start_device(struct nbd_device *nbd)
 		args->index = i;
 		queue_work(nbd->recv_workq, &args->work);
 	}
+	printk("bs: %lld, blks: %lld, %s\n", config->bytesize, nbd_blksize(config), __func__);
 	return nbd_set_size(nbd, config->bytesize, nbd_blksize(config));
 }
 
diff --git a/block/bdev.c b/block/bdev.c
index 6f73b02d549c..59a3a23ed281 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -645,6 +645,7 @@ static int blkdev_get_whole(struct block_device *bdev, blk_mode_t mode)
 	int ret;
 
 	if (disk->fops->open) {
+		printk(" b: %p, disk: %p, %s\n", bdev, disk, __func__);
 		ret = disk->fops->open(disk, mode);
 		if (ret) {
 			/* avoid ghost partitions on a removed medium */
@@ -660,6 +661,7 @@ static int blkdev_get_whole(struct block_device *bdev, blk_mode_t mode)
 	if (test_bit(GD_NEED_PART_SCAN, &disk->state))
 		bdev_disk_changed(disk, false);
 	atomic_inc(&bdev->bd_openers);
+	printk("out, b: %p, disk: %p, %s\n", bdev, disk, __func__);
 	return 0;
 }
 
@@ -854,24 +856,31 @@ struct bdev_handle *bdev_open_by_dev(dev_t dev, blk_mode_t mode, void *holder,
 
 	disk_block_events(disk);
 
+	printk("next om, b: %p, disk: %p, %s\n", bdev, disk, __func__);
 	mutex_lock(&disk->open_mutex);
 	ret = -ENXIO;
 	if (!disk_live(disk))
 		goto abort_claiming;
+	printk("in1, b: %p, disk: %p, %s\n", bdev, disk, __func__);
 	if (!try_module_get(disk->fops->owner))
 		goto abort_claiming;
+	printk("in2, b: %p, disk: %p, %s\n", bdev, disk, __func__);
 	ret = -EBUSY;
 	if (!bdev_may_open(bdev, mode))
 		goto abort_claiming;
+	printk("in3, b: %p, disk: %p, %s\n", bdev, disk, __func__);
 	if (bdev_is_partition(bdev))
 		ret = blkdev_get_part(bdev, mode);
 	else
 		ret = blkdev_get_whole(bdev, mode);
+	printk("in4, b: %p, disk: %p, %s\n", bdev, disk, __func__);
 	if (ret)
 		goto put_module;
 	bdev_claim_write_access(bdev, mode);
+	printk("in5, b: %p, disk: %p, %s\n", bdev, disk, __func__);
 	if (holder) {
 		bd_finish_claiming(bdev, holder, hops);
+		printk("in6, b: %p, disk: %p, %s\n", bdev, disk, __func__);
 
 		/*
 		 * Block event polling for write claims if requested.  Any write
@@ -887,6 +896,7 @@ struct bdev_handle *bdev_open_by_dev(dev_t dev, blk_mode_t mode, void *holder,
 		}
 	}
 	mutex_unlock(&disk->open_mutex);
+	printk("out om, b: %p, disk: %p, %s\n", bdev, disk, __func__);
 
 	if (unblock_events)
 		disk_unblock_events(disk);
@@ -900,6 +910,7 @@ struct bdev_handle *bdev_open_by_dev(dev_t dev, blk_mode_t mode, void *holder,
 	if (holder)
 		bd_abort_claiming(bdev, holder);
 	mutex_unlock(&disk->open_mutex);
+	printk("out om, b: %p, %s\n", bdev, __func__);
 	disk_unblock_events(disk);
 put_blkdev:
 	blkdev_put_no_open(bdev);
@@ -964,6 +975,7 @@ void bdev_release(struct bdev_handle *handle)
 	if (atomic_read(&bdev->bd_openers) == 1)
 		sync_blockdev(bdev);
 
+	printk("nxt om, b: %p, dk: %p, %s\n", bdev, disk, __func__);
 	mutex_lock(&disk->open_mutex);
 	bdev_yield_write_access(bdev, handle->mode);
 
@@ -982,6 +994,7 @@ void bdev_release(struct bdev_handle *handle)
 	else
 		blkdev_put_whole(bdev);
 	mutex_unlock(&disk->open_mutex);
+	printk("out om, b: %p, dk: %p, %s\n", bdev, disk, __func__);
 
 	module_put(disk->fops->owner);
 	blkdev_put_no_open(bdev);