@@ -260,7 +260,7 @@ static void nbd_dev_remove(struct nbd_device *nbd)
mutex_lock(&nbd_index_mutex);
idr_remove(&nbd_index_idr, nbd->index);
mutex_unlock(&nbd_index_mutex);
-
+ destroy_workqueue(nbd->recv_workq);
kfree(nbd);
}
@@ -1314,10 +1314,6 @@ static void nbd_config_put(struct nbd_device *nbd)
kfree(nbd->config);
nbd->config = NULL;
- if (nbd->recv_workq)
- destroy_workqueue(nbd->recv_workq);
- nbd->recv_workq = NULL;
-
nbd->tag_set.timeout = 0;
nbd->disk->queue->limits.discard_granularity = 0;
nbd->disk->queue->limits.discard_alignment = 0;
@@ -1346,14 +1342,6 @@ static int nbd_start_device(struct nbd_device *nbd)
return -EINVAL;
}
- nbd->recv_workq = alloc_workqueue("knbd%d-recv",
- WQ_MEM_RECLAIM | WQ_HIGHPRI |
- WQ_UNBOUND, 0, nbd->index);
- if (!nbd->recv_workq) {
- dev_err(disk_to_dev(nbd->disk), "Could not allocate knbd recv work queue.\n");
- return -ENOMEM;
- }
-
blk_mq_update_nr_hw_queues(&nbd->tag_set, config->num_connections);
nbd->pid = task_pid_nr(current);
@@ -1779,6 +1767,15 @@ static struct nbd_device *nbd_dev_add(int index, unsigned int refs)
}
nbd->disk = disk;
+ nbd->recv_workq = alloc_workqueue("nbd%d-recv",
+ WQ_MEM_RECLAIM | WQ_HIGHPRI |
+ WQ_UNBOUND, 0, nbd->index);
+ if (!nbd->recv_workq) {
+ dev_err(disk_to_dev(nbd->disk), "Could not allocate knbd recv work queue.\n");
+ err = -ENOMEM;
+ goto out_err_disk;
+ }
+
/*
* Tell the block layer that we are not a rotational device
*/
@@ -1809,7 +1806,7 @@ static struct nbd_device *nbd_dev_add(int index, unsigned int refs)
disk->first_minor = index << part_shift;
if (disk->first_minor < index || disk->first_minor > MINORMASK) {
err = -EINVAL;
- goto out_err_disk;
+ goto out_free_work;
}
disk->minors = 1 << part_shift;
@@ -1818,7 +1815,7 @@ static struct nbd_device *nbd_dev_add(int index, unsigned int refs)
sprintf(disk->disk_name, "nbd%d", index);
err = add_disk(disk);
if (err)
- goto out_err_disk;
+ goto out_free_work;
/*
* Now publish the device.
@@ -1827,6 +1824,8 @@ static struct nbd_device *nbd_dev_add(int index, unsigned int refs)
nbd_total_devices++;
return nbd;
+out_free_work:
+ destroy_workqueue(nbd->recv_workq);
out_err_disk:
blk_cleanup_disk(disk);
out_free_idr:
@@ -2082,13 +2081,10 @@ static void nbd_disconnect_and_put(struct nbd_device *nbd)
nbd_disconnect(nbd);
sock_shutdown(nbd);
/*
- * Make sure recv thread has finished, so it does not drop the last
- * config ref and try to destroy the workqueue from inside the work
- * queue. And this also ensure that we can safely call nbd_clear_que()
+ * Make sure recv thread has finished, we can safely call nbd_clear_que()
* to cancel the inflight I/Os.
*/
- if (nbd->recv_workq)
- flush_workqueue(nbd->recv_workq);
+ flush_workqueue(nbd->recv_workq);
nbd_clear_que(nbd);
nbd->task_setup = NULL;
mutex_unlock(&nbd->config_lock);
I got follow issue: [ 247.381177] INFO: task kworker/u10:0:47 blocked for more than 120 seconds. [ 247.382644] Not tainted 4.19.90-dirty #140 [ 247.383502] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 247.385027] Call Trace: [ 247.388384] schedule+0xb8/0x3c0 [ 247.388966] schedule_timeout+0x2b4/0x380 [ 247.392815] wait_for_completion+0x367/0x510 [ 247.397713] flush_workqueue+0x32b/0x1340 [ 247.402700] drain_workqueue+0xda/0x3c0 [ 247.403442] destroy_workqueue+0x7b/0x690 [ 247.405014] nbd_config_put.cold+0x2f9/0x5b6 [ 247.405823] recv_work+0x1fd/0x2b0 [ 247.406485] process_one_work+0x70b/0x1610 [ 247.407262] worker_thread+0x5a9/0x1060 [ 247.408699] kthread+0x35e/0x430 [ 247.410918] ret_from_fork+0x1f/0x30 We can reproduce issue as follows: 1. Inject memory fault in nbd_start_device -1244,10 +1248,18 @@ static int nbd_start_device(struct nbd_device *nbd) nbd_dev_dbg_init(nbd); for (i = 0; i < num_connections; i++) { struct recv_thread_args *args; - - args = kzalloc(sizeof(*args), GFP_KERNEL); + + if (i == 1) { + args = NULL; + printk("%s: inject malloc error\n", __func__); + } + else + args = kzalloc(sizeof(*args), GFP_KERNEL); 2. Inject delay in recv_work -757,6 +760,8 @@ static void recv_work(struct work_struct *work) blk_mq_complete_request(blk_mq_rq_from_pdu(cmd)); } + printk("%s: comm=%s pid=%d\n", __func__, current->comm, current->pid); + mdelay(5 * 1000); nbd_config_put(nbd); atomic_dec(&config->recv_threads); wake_up(&config->recv_wq); 3. Create nbd server nbd-server 8000 /tmp/disk 4. Create nbd client nbd-client localhost 8000 /dev/nbd1 Then will trigger above issue. Reason is when add delay in recv_work, lead to release the last reference of 'nbd->config_refs'. nbd_config_put will call flush_workqueue to make all work finish. Obviously, it will lead to deadloop. To solve this issue, according to Josef's suggestion move 'recv_work' init from start device to nbd_dev_add, then destroy 'recv_work'when nbd device teardown. Signed-off-by: Ye Bin <yebin10@huawei.com> --- drivers/block/nbd.c | 36 ++++++++++++++++-------------------- 1 file changed, 16 insertions(+), 20 deletions(-)