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Subject[PATCH AUTOSEL for 4.15 004/189] nvme: host delete_work and reset_work on separate workqueues
Date
From: Roy Shterman <roys@lightbitslabs.com>

[ Upstream commit b227c59b9b5b8ae52639c8980af853d2f654f90a ]

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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
drivers/nvme/host/core.c | 44 +++++++++++++++++++++++++++++++++++++++-----
drivers/nvme/host/nvme.h | 2 ++
drivers/nvme/host/rdma.c | 2 +-
drivers/nvme/target/loop.c | 2 +-
4 files changed, 43 insertions(+), 7 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 935593032123..93a4fa053e7f 100644
--- 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;
}
@@ -122,7 +139,7 @@ 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;
}
@@ -3491,16 +3508,26 @@ 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)) {
@@ -3519,8 +3546,13 @@ 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;
}

@@ -3530,6 +3562,8 @@ 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);
}

diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 55c49a1aa231..d320df9ab588 100644
--- 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,
diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index 2a0bba7f50cf..145aa97067d4 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -2040,7 +2040,7 @@ 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 = {
diff --git a/drivers/nvme/target/loop.c b/drivers/nvme/target/loop.c
index 1e21b286f299..5d8054f9a412 100644
--- a/drivers/nvme/target/loop.c
+++ b/drivers/nvme/target/loop.c
@@ -716,7 +716,7 @@ 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);
--
2.15.1
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