2020-08-12 23:25:43

by Logan Gunthorpe

[permalink] [raw]
Subject: [PATCH v2] nvme: Use spin_lock_irq() when taking the ctrl->lock

When locking the ctrl->lock spinlock IRQs need to be disabled to avoid a
dead lock. The new spin_lock() calls recently added produce the
following lockdep warning when running the blktest nvme/003:

================================
WARNING: inconsistent lock state
--------------------------------
inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
ksoftirqd/2/22 [HC0[0]:SC1[1]:HE0:SE0] takes:
ffff888276a8c4c0 (&ctrl->lock){+.?.}-{2:2}, at: nvme_keep_alive_end_io+0x50/0xc0
{SOFTIRQ-ON-W} state was registered at:
lock_acquire+0x164/0x500
_raw_spin_lock+0x28/0x40
nvme_get_effects_log+0x37/0x1c0
nvme_init_identify+0x9e4/0x14f0
nvme_reset_work+0xadd/0x2360
process_one_work+0x66b/0xb70
worker_thread+0x6e/0x6c0
kthread+0x1e7/0x210
ret_from_fork+0x22/0x30
irq event stamp: 1449221
hardirqs last enabled at (1449220): [<ffffffff81c58e69>] ktime_get+0xf9/0x140
hardirqs last disabled at (1449221): [<ffffffff83129665>] _raw_spin_lock_irqsave+0x25/0x60
softirqs last enabled at (1449210): [<ffffffff83400447>] __do_softirq+0x447/0x595
softirqs last disabled at (1449215): [<ffffffff81b489b5>] run_ksoftirqd+0x35/0x50

other info that might help us debug this:
Possible unsafe locking scenario:

CPU0
----
lock(&ctrl->lock);
<Interrupt>
lock(&ctrl->lock);

*** DEADLOCK ***

no locks held by ksoftirqd/2/22.

stack backtrace:
CPU: 2 PID: 22 Comm: ksoftirqd/2 Not tainted 5.8.0-rc4-eid-vmlocalyes-dbg-00157-g7236657c6b3a #1450
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.12.0-1 04/01/2014
Call Trace:
dump_stack+0xc8/0x11a
print_usage_bug.cold.63+0x235/0x23e
mark_lock+0xa9c/0xcf0
__lock_acquire+0xd9a/0x2b50
lock_acquire+0x164/0x500
_raw_spin_lock_irqsave+0x40/0x60
nvme_keep_alive_end_io+0x50/0xc0
blk_mq_end_request+0x158/0x210
nvme_complete_rq+0x146/0x500
nvme_loop_complete_rq+0x26/0x30 [nvme_loop]
blk_done_softirq+0x187/0x1e0
__do_softirq+0x118/0x595
run_ksoftirqd+0x35/0x50
smpboot_thread_fn+0x1d3/0x310
kthread+0x1e7/0x210
ret_from_fork+0x22/0x30

Fixes: be93e87e7802 ("nvme: support for multiple Command Sets Supported and Effects log pages")
Signed-off-by: Logan Gunthorpe <[email protected]>
---

v2 uses spin_lock_irq() instead of spin_lock_irqsave() as these
functions should never be called in an interrupt disabled context.

drivers/nvme/host/core.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 15abc00db3d3..5e23fe029140 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2972,14 +2972,14 @@ static struct nvme_cel *nvme_find_cel(struct nvme_ctrl *ctrl, u8 csi)
{
struct nvme_cel *cel, *ret = NULL;

- spin_lock(&ctrl->lock);
+ spin_lock_irq(&ctrl->lock);
list_for_each_entry(cel, &ctrl->cels, entry) {
if (cel->csi == csi) {
ret = cel;
break;
}
}
- spin_unlock(&ctrl->lock);
+ spin_unlock_irq(&ctrl->lock);

return ret;
}
@@ -3006,9 +3006,9 @@ static int nvme_get_effects_log(struct nvme_ctrl *ctrl, u8 csi,

cel->csi = csi;

- spin_lock(&ctrl->lock);
+ spin_lock_irq(&ctrl->lock);
list_add_tail(&cel->entry, &ctrl->cels);
- spin_unlock(&ctrl->lock);
+ spin_unlock_irq(&ctrl->lock);
out:
*log = &cel->log;
return 0;
@@ -3179,7 +3179,7 @@ int nvme_init_identify(struct nvme_ctrl *ctrl)
ret = nvme_configure_apst(ctrl);
if (ret < 0)
return ret;
-
+
ret = nvme_configure_timestamp(ctrl);
if (ret < 0)
return ret;

base-commit: 4d3c0eaf0d44a4f8f7d53b7835e670eafc96c450
--
2.20.1


2020-08-13 00:34:55

by Keith Busch

[permalink] [raw]
Subject: Re: [PATCH v2] nvme: Use spin_lock_irq() when taking the ctrl->lock

There's an unrelated whitespace change in nvme_init_identify().
Otherwise, looks fine.

Reviewed-by: Keith Busch <[email protected]>

2020-08-13 02:39:23

by Chaitanya Kulkarni

[permalink] [raw]
Subject: Re: [PATCH v2] nvme: Use spin_lock_irq() when taking the ctrl->lock

On 8/12/20 16:25, Logan Gunthorpe wrote:
> When locking the ctrl->lock spinlock IRQs need to be disabled to avoid a
> dead lock. The new spin_lock() calls recently added produce the
> following lockdep warning when running the blktest nvme/003:
>
> ================================
> WARNING: inconsistent lock state
> --------------------------------
> inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
> ksoftirqd/2/22 [HC0[0]:SC1[1]:HE0:SE0] takes:
> ffff888276a8c4c0 (&ctrl->lock){+.?.}-{2:2}, at: nvme_keep_alive_end_io+0x50/0xc0
> {SOFTIRQ-ON-W} state was registered at:
> lock_acquire+0x164/0x500
> _raw_spin_lock+0x28/0x40
> nvme_get_effects_log+0x37/0x1c0
> nvme_init_identify+0x9e4/0x14f0
> nvme_reset_work+0xadd/0x2360
> process_one_work+0x66b/0xb70
> worker_thread+0x6e/0x6c0
> kthread+0x1e7/0x210
> ret_from_fork+0x22/0x30
> irq event stamp: 1449221
> hardirqs last enabled at (1449220): [<ffffffff81c58e69>] ktime_get+0xf9/0x140
> hardirqs last disabled at (1449221): [<ffffffff83129665>] _raw_spin_lock_irqsave+0x25/0x60
> softirqs last enabled at (1449210): [<ffffffff83400447>] __do_softirq+0x447/0x595
> softirqs last disabled at (1449215): [<ffffffff81b489b5>] run_ksoftirqd+0x35/0x50
>
> other info that might help us debug this:
> Possible unsafe locking scenario:
>
> CPU0
> ----
> lock(&ctrl->lock);
> <Interrupt>
> lock(&ctrl->lock);
>
> *** DEADLOCK ***
>
> no locks held by ksoftirqd/2/22.
>
> stack backtrace:
> CPU: 2 PID: 22 Comm: ksoftirqd/2 Not tainted 5.8.0-rc4-eid-vmlocalyes-dbg-00157-g7236657c6b3a #1450
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.12.0-1 04/01/2014
> Call Trace:
> dump_stack+0xc8/0x11a
> print_usage_bug.cold.63+0x235/0x23e
> mark_lock+0xa9c/0xcf0
> __lock_acquire+0xd9a/0x2b50
> lock_acquire+0x164/0x500
> _raw_spin_lock_irqsave+0x40/0x60
> nvme_keep_alive_end_io+0x50/0xc0
> blk_mq_end_request+0x158/0x210
> nvme_complete_rq+0x146/0x500
> nvme_loop_complete_rq+0x26/0x30 [nvme_loop]
> blk_done_softirq+0x187/0x1e0
> __do_softirq+0x118/0x595
> run_ksoftirqd+0x35/0x50
> smpboot_thread_fn+0x1d3/0x310
> kthread+0x1e7/0x210
> ret_from_fork+0x22/0x30
>
> Fixes: be93e87e7802 ("nvme: support for multiple Command Sets Supported and Effects log pages")
> Signed-off-by: Logan Gunthorpe<[email protected]>

Thanks for this fix, looks good.

Tested-by: Chaitanya Kulkarni <[email protected]>
Reviewed-by: Chaitanya Kulkarni <[email protected]>

2020-08-13 03:57:50

by Logan Gunthorpe

[permalink] [raw]
Subject: Re: [PATCH v2] nvme: Use spin_lock_irq() when taking the ctrl->lock



On 2020-08-12 6:32 p.m., Keith Busch wrote:
> There's an unrelated whitespace change in nvme_init_identify().
> Otherwise, looks fine.

Oops, sorry. can this be fixed up when it's merged?

Logan

2020-08-14 06:06:05

by Sagi Grimberg

[permalink] [raw]
Subject: Re: [PATCH v2] nvme: Use spin_lock_irq() when taking the ctrl->lock


>> There's an unrelated whitespace change in nvme_init_identify().
>> Otherwise, looks fine.
>
> Oops, sorry. can this be fixed up when it's merged?

Fixed and queued.