Re: blk_mq_sched_insert_request: inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage
From: Jens Axboe <axboe@kernel.dk>
Date: 2017-07-27 14:02:56
Also in:
linux-block, lkml
Subsystem:
scsi subsystem, the rest · Maintainers:
"James E.J. Bottomley", "Martin K. Petersen", Linus Torvalds
On 07/26/2017 11:10 PM, Michael Ellerman wrote:
Hi Jens, I'm seeing the lockdep warning below on shutdown on a Power8 machine using IPR. If I'm reading it right it looks like the spin_lock() (non-irq) in blk_mq_sched_insert_request() is the immediate cause.
All the users of ctx->lock should be from process context.
Looking at blk_mq_requeue_work() (the caller), it is doing spin_lock_irqsave(). So is switching blk_mq_sched_insert_request() to spin_lock_irqsave() the right fix?
That's because the requeue lock needs to be IRQ safe. However, the context allows for just spin_lock_irq() for that lock there, so that should be fixed up. Not your issue, of course, but we don't need to save flags there.
quoted hunk ↗ jump to hunk
ipr 0001:08:00.0: shutdown ================================ WARNING: inconsistent lock state 4.13.0-rc2-gcc6x-gf74c89b #1 Not tainted -------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. swapper/28/0 [HC0[0]:SC1[1]:HE1:SE0] takes: (&(&hctx->lock)->rlock){+.?...}, at: [<c0000000005b60f4>] blk_mq_sched_dispatch_requests+0xa4/0x2a0 {SOFTIRQ-ON-W} state was registered at: lock_acquire+0xec/0x2e0 _raw_spin_lock+0x44/0x70 blk_mq_sched_insert_request+0x88/0x1f0 blk_mq_requeue_work+0x108/0x180 process_one_work+0x310/0x800 worker_thread+0x88/0x520 kthread+0x164/0x1b0 ret_from_kernel_thread+0x5c/0x74 irq event stamp: 3572314 hardirqs last enabled at (3572314): [<c000000000b71998>] _raw_spin_unlock_irqrestore+0x58/0xb0 hardirqs last disabled at (3572313): [<c000000000b716ec>] _raw_spin_lock_irqsave+0x3c/0x90 softirqs last enabled at (3572302): [<c0000000000df17c>] irq_enter+0x9c/0xe0 softirqs last disabled at (3572303): [<c0000000000df2c8>] irq_exit+0x108/0x150 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&(&hctx->lock)->rlock); <Interrupt> lock(&(&hctx->lock)->rlock); *** DEADLOCK *** 2 locks held by swapper/28/0: #0: ((&ipr_cmd->timer)){+.-...}, at: [<c0000000001936f0>] call_timer_fn+0x10/0x4b0 #1: (rcu_read_lock){......}, at: [<c0000000005aca60>] __blk_mq_run_hw_queue+0xa0/0x2c0 stack backtrace: CPU: 28 PID: 0 Comm: swapper/28 Not tainted 4.13.0-rc2-gcc6x-gf74c89b #1 Call Trace: [c000001fffe97550] [c000000000b50818] dump_stack+0xe8/0x160 (unreliable) [c000001fffe97590] [c0000000001586d0] print_usage_bug+0x2d0/0x390 [c000001fffe97640] [c000000000158f34] mark_lock+0x7a4/0x8e0 [c000001fffe976f0] [c00000000015a000] __lock_acquire+0x6a0/0x1a70 [c000001fffe97860] [c00000000015befc] lock_acquire+0xec/0x2e0 [c000001fffe97930] [c000000000b71514] _raw_spin_lock+0x44/0x70 [c000001fffe97960] [c0000000005b60f4] blk_mq_sched_dispatch_requests+0xa4/0x2a0 [c000001fffe979c0] [c0000000005acac0] __blk_mq_run_hw_queue+0x100/0x2c0 [c000001fffe97a00] [c0000000005ad478] __blk_mq_delay_run_hw_queue+0x118/0x130 [c000001fffe97a40] [c0000000005ad61c] blk_mq_start_hw_queues+0x6c/0xa0 [c000001fffe97a80] [c000000000797aac] scsi_kick_queue+0x2c/0x60 [c000001fffe97aa0] [c000000000797cf0] scsi_run_queue+0x210/0x360 [c000001fffe97b10] [c00000000079b888] scsi_run_host_queues+0x48/0x80 [c000001fffe97b40] [c0000000007b6090] ipr_ioa_bringdown_done+0x70/0x1e0 [c000001fffe97bc0] [c0000000007bc860] ipr_reset_ioa_job+0x80/0xf0 [c000001fffe97bf0] [c0000000007b4d50] ipr_reset_timer_done+0xd0/0x100 [c000001fffe97c30] [c0000000001937bc] call_timer_fn+0xdc/0x4b0 [c000001fffe97cf0] [c000000000193d08] expire_timers+0x178/0x330 [c000001fffe97d60] [c0000000001940c8] run_timer_softirq+0xb8/0x120 [c000001fffe97de0] [c000000000b726a8] __do_softirq+0x168/0x6d8 [c000001fffe97ef0] [c0000000000df2c8] irq_exit+0x108/0x150 [c000001fffe97f10] [c000000000017bf4] __do_irq+0x2a4/0x4a0 [c000001fffe97f90] [c00000000002da50] call_do_irq+0x14/0x24 [c0000007fad93aa0] [c000000000017e8c] do_IRQ+0x9c/0x140 [c0000007fad93af0] [c000000000008b98] hardware_interrupt_common+0x138/0x140--- interrupt: 501 at .L1.42+0x0/0x4 LR = arch_local_irq_restore.part.4+0x84/0xb0[c0000007fad93de0] [c0000007ffc1f7d8] 0xc0000007ffc1f7d8 (unreliable) [c0000007fad93e00] [c000000000988d3c] cpuidle_enter_state+0x1bc/0x530 [c0000007fad93e60] [c0000000001457cc] call_cpuidle+0x4c/0x90 [c0000007fad93e80] [c000000000145b28] do_idle+0x208/0x2f0 [c0000007fad93ef0] [c000000000145f8c] cpu_startup_entry+0x3c/0x50 [c0000007fad93f20] [c000000000042bc0] start_secondary+0x3b0/0x4b0 [c0000007fad93f90] [c00000000000ac6c] start_secondary_prolog+0x10/0x14
The bug looks like SCSI running the queue inline from IRQ context, that's not a good idea. Can you confirm the below works for you?
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index f6097b89d5d3..78740ebf966c 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c@@ -497,7 +497,7 @@ static void scsi_run_queue(struct request_queue *q) scsi_starved_list_run(sdev->host); if (q->mq_ops) - blk_mq_run_hw_queues(q, false); + blk_mq_run_hw_queues(q, true); else blk_run_queue(q); }
--
Jens Axboe
--
Jens Axboe