nvme: host delete_work and reset_work on separate workqueues

We need to ensure that delete_work will be hosted on a different workqueue than all the works we flush or cancel from it. Otherwise we may hit a circular dependency warning [1]. Also, given that delete_work flushes reset_work, host reset_work on nvme_reset_wq and delete_work on nvme_delete_wq. In addition, fix the flushing in the individual drivers to flush nvme_delete_wq when draining queued deletes. [1]: [ 178.491942] ============================================= [ 178.492718] [ INFO: possible recursive locking detected ] [ 178.493495] 4.9.0-rc4-c844263313a8-lb #3 Tainted: G OE [ 178.494382] --------------------------------------------- [ 178.495160] kworker/5:1/135 is trying to acquire lock: [ 178.495894] ( [ 178.496120] "nvme-wq" [ 178.496471] ){++++.+} [ 178.496599] , at: [ 178.496921] [<ffffffffa70ac206>] flush_work+0x1a6/0x2d0 [ 178.497670] but task is already holding lock: [ 178.498499] ( [ 178.498724] "nvme-wq" [ 178.499074] ){++++.+} [ 178.499202] , at: [ 178.499520] [<ffffffffa70ad6c2>] process_one_work+0x162/0x6a0 [ 178.500343] other info that might help us debug this: [ 178.501269] Possible unsafe locking scenario: [ 178.502113] CPU0 [ 178.502472] ---- [ 178.502829] lock( [ 178.503115] "nvme-wq" [ 178.503467] ); [ 178.503716] lock( [ 178.504001] "nvme-wq" [ 178.504353] ); [ 178.504601] *** DEADLOCK *** [ 178.505441] May be due to missing lock nesting notation [ 178.506453] 2 locks held by kworker/5:1/135: [ 178.507068] #0: [ 178.507330] ( [ 178.507598] "nvme-wq" [ 178.507726] ){++++.+} [ 178.508079] , at: [ 178.508173] [<ffffffffa70ad6c2>] process_one_work+0x162/0x6a0 [ 178.509004] #1: [ 178.509265] ( [ 178.509532] (&ctrl->delete_work) [ 178.509795] ){+.+.+.} [ 178.510145] , at: [ 178.510239] [<ffffffffa70ad6c2>] process_one_work+0x162/0x6a0 [ 178.511070] stack backtrace: : [ 178.511693] CPU: 5 PID: 135 Comm: kworker/5:1 Tainted: G OE 4.9.0-rc4-c844263313a8-lb #3 [ 178.512974] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.1-1ubuntu1 04/01/2014 [ 178.514247] Workqueue: nvme-wq nvme_del_ctrl_work [nvme_tcp] [ 178.515071] ffffc2668175bae0 ffffffffa7450823 ffffffffa88abd80 ffffffffa88abd80 [ 178.516195] ffffc2668175bb98 ffffffffa70eb012 ffffffffa8d8d90d ffff9c472e9ea700 [ 178.517318] ffff9c472e9ea700 ffff9c4700000000 ffff9c4700007200 ab83be61bec0d50e [ 178.518443] Call Trace: [ 178.518807] [<ffffffffa7450823>] dump_stack+0x85/0xc2 [ 178.519542] [<ffffffffa70eb012>] __lock_acquire+0x17d2/0x18f0 [ 178.520377] [<ffffffffa75839a7>] ? serial8250_console_putchar+0x27/0x30 [ 178.521330] [<ffffffffa7583980>] ? wait_for_xmitr+0xa0/0xa0 [ 178.522174] [<ffffffffa70ac1eb>] ? flush_work+0x18b/0x2d0 [ 178.522975] [<ffffffffa70eb7cb>] lock_acquire+0x11b/0x220 [ 178.523753] [<ffffffffa70ac206>] ? flush_work+0x1a6/0x2d0 [ 178.524535] [<ffffffffa70ac229>] flush_work+0x1c9/0x2d0 [ 178.525291] [<ffffffffa70ac206>] ? flush_work+0x1a6/0x2d0 [ 178.526077] [<ffffffffa70a9cf0>] ? flush_workqueue_prep_pwqs+0x220/0x220 [ 178.527040] [<ffffffffa70ae7cf>] __cancel_work_timer+0x10f/0x1d0 [ 178.527907] [<ffffffffa70fecb9>] ? vprintk_default+0x29/0x40 [ 178.528726] [<ffffffffa71cb507>] ? printk+0x48/0x50 [ 178.529434] [<ffffffffa70ae8c3>] cancel_delayed_work_sync+0x13/0x20 [ 178.530381] [<ffffffffc042100b>] nvme_stop_ctrl+0x5b/0x70 [nvme_core] [ 178.531314] [<ffffffffc0403dcc>] nvme_del_ctrl_work+0x2c/0x50 [nvme_tcp] [ 178.532271] [<ffffffffa70ad741>] process_one_work+0x1e1/0x6a0 [ 178.533101] [<ffffffffa70ad6c2>] ? process_one_work+0x162/0x6a0 [ 178.533954] [<ffffffffa70adc4e>] worker_thread+0x4e/0x490 [ 178.534735] [<ffffffffa70adc00>] ? process_one_work+0x6a0/0x6a0 [ 178.535588] [<ffffffffa70adc00>] ? process_one_work+0x6a0/0x6a0 [ 178.536441] [<ffffffffa70b48cf>] kthread+0xff/0x120 [ 178.537149] [<ffffffffa70b47d0>] ? kthread_park+0x60/0x60 [ 178.538094] [<ffffffffa70b47d0>] ? kthread_park+0x60/0x60 [ 178.538900] [<ffffffffa78e332a>] ret_from_fork+0x2a/0x40 Signed-off-by: Roy Shterman <roys@lightbitslabs.com> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Christoph Hellwig <hch@lst.de>
2018-01-14 12:39:02 +02:00 · 2018-01-14 12:39:02 +02:00 · b227c59b9b
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@ -65,9 +65,26 @@ static bool streams;
 module_param(streams, bool, 0644);
 MODULE_PARM_DESC(streams, "turn on support for Streams write directives");

+/*
+ * nvme_wq - hosts nvme related works that are not reset or delete
+ * nvme_reset_wq - hosts nvme reset works
+ * nvme_delete_wq - hosts nvme delete works
+ *
+ * nvme_wq will host works such are scan, aen handling, fw activation,
+ * keep-alive error recovery, periodic reconnects etc. nvme_reset_wq
+ * runs reset works which also flush works hosted on nvme_wq for
+ * serialization purposes. nvme_delete_wq host controller deletion
+ * works which flush reset works for serialization.
+ */
 struct workqueue_struct *nvme_wq;
 EXPORT_SYMBOL_GPL(nvme_wq);

+struct workqueue_struct *nvme_reset_wq;
+EXPORT_SYMBOL_GPL(nvme_reset_wq);
+
+struct workqueue_struct *nvme_delete_wq;
+EXPORT_SYMBOL_GPL(nvme_delete_wq);
+
 static DEFINE_IDA(nvme_subsystems_ida);
 static LIST_HEAD(nvme_subsystems);
 static DEFINE_MUTEX(nvme_subsystems_lock);
@ -89,7 +106,7 @@ int nvme_reset_ctrl(struct nvme_ctrl *ctrl)
 {
 	if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_RESETTING))
 		return -EBUSY;
-	if (!queue_work(nvme_wq, &ctrl->reset_work))
+	if (!queue_work(nvme_reset_wq, &ctrl->reset_work))
 		return -EBUSY;
 	return 0;
 }
@ -123,7 +140,7 @@ int nvme_delete_ctrl(struct nvme_ctrl *ctrl)
 {
 	if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_DELETING))
 		return -EBUSY;
-	if (!queue_work(nvme_wq, &ctrl->delete_work))
+	if (!queue_work(nvme_delete_wq, &ctrl->delete_work))
 		return -EBUSY;
 	return 0;
 }
@ -3526,16 +3543,26 @@ EXPORT_SYMBOL_GPL(nvme_reinit_tagset);

 int __init nvme_core_init(void)
 {
-	int result;
+	int result = -ENOMEM;

 	nvme_wq = alloc_workqueue("nvme-wq",
 			WQ_UNBOUND | WQ_MEM_RECLAIM | WQ_SYSFS, 0);
 	if (!nvme_wq)
-		return -ENOMEM;
+		goto out;
+
+	nvme_reset_wq = alloc_workqueue("nvme-reset-wq",
+			WQ_UNBOUND | WQ_MEM_RECLAIM | WQ_SYSFS, 0);
+	if (!nvme_reset_wq)
+		goto destroy_wq;
+
+	nvme_delete_wq = alloc_workqueue("nvme-delete-wq",
+			WQ_UNBOUND | WQ_MEM_RECLAIM | WQ_SYSFS, 0);
+	if (!nvme_delete_wq)
+		goto destroy_reset_wq;

 	result = alloc_chrdev_region(&nvme_chr_devt, 0, NVME_MINORS, "nvme");
 	if (result < 0)
-		goto destroy_wq;
+		goto destroy_delete_wq;

 	nvme_class = class_create(THIS_MODULE, "nvme");
 	if (IS_ERR(nvme_class)) {
@ -3554,8 +3581,13 @@ destroy_class:
 	class_destroy(nvme_class);
 unregister_chrdev:
 	unregister_chrdev_region(nvme_chr_devt, NVME_MINORS);
+destroy_delete_wq:
+	destroy_workqueue(nvme_delete_wq);
+destroy_reset_wq:
+	destroy_workqueue(nvme_reset_wq);
 destroy_wq:
 	destroy_workqueue(nvme_wq);
+out:
 	return result;
 }

@ -3565,6 +3597,8 @@ void nvme_core_exit(void)
 	class_destroy(nvme_subsys_class);
 	class_destroy(nvme_class);
 	unregister_chrdev_region(nvme_chr_devt, NVME_MINORS);
+	destroy_workqueue(nvme_delete_wq);
+	destroy_workqueue(nvme_reset_wq);
 	destroy_workqueue(nvme_wq);
 }

--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@ -32,6 +32,8 @@ extern unsigned int admin_timeout;
 #define NVME_KATO_GRACE		10

 extern struct workqueue_struct *nvme_wq;
+extern struct workqueue_struct *nvme_reset_wq;
+extern struct workqueue_struct *nvme_delete_wq;

 enum {
 	NVME_NS_LBA		= 0,
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@ -2029,7 +2029,7 @@ static void nvme_rdma_remove_one(struct ib_device *ib_device, void *client_data)
 	}
 	mutex_unlock(&nvme_rdma_ctrl_mutex);

-	flush_workqueue(nvme_wq);
+	flush_workqueue(nvme_delete_wq);
 }

 static struct ib_client nvme_rdma_ib_client = {
--- a/drivers/nvme/target/loop.c
+++ b/drivers/nvme/target/loop.c
@ -717,7 +717,7 @@ static void __exit nvme_loop_cleanup_module(void)
 		nvme_delete_ctrl(&ctrl->ctrl);
 	mutex_unlock(&nvme_loop_ctrl_mutex);

-	flush_workqueue(nvme_wq);
+	flush_workqueue(nvme_delete_wq);
 }

 module_init(nvme_loop_init_module);