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SubjectRe: [PATCH v2] nvme: Use spin_lock_irq() when taking the ctrl->lock
Date
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<logang@deltatee.com>

Thanks for this fix, looks good.

Tested-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>

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