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Subject[PATCH] blk-mq: Make running from the wrong CPU less scary
Date
The current warning looks aweful like a proper crash. This is
confusing. There is not much information to gained from the stack
trace anyway, let's drop it.

While at it print the cpumask as there might be additial helpful
information when debugging the sitation.

Signed-off-by: Daniel Wagner <dwagner@suse.de>
---
Hi,

We got a report from a customer because he was concerned about the log
entries. As it turns out, it fooled me too to be honest. What do you
think about making it a bit less look-a-like a kernel oops?


smpboot: Booting Node 0 Processor 12 APIC 0x26
WARNING, didn't collect load info for all cpus, balancing is broken
run queue from wrong CPU 0, hctx active
CPU: 0 PID: 42300 Comm: kworker/13:2H Kdump: loaded Tainted: G OE X 5.3.18-109.$
Hardware name: IBM System x3650 M5 -[5462AC1]-/00KG915, BIOS -[TCE144J-3.11]- 12/03/2019
Workqueue: kblockd blk_mq_run_work_fn
Call Trace:
dump_stack+0x66/0x8b
__blk_mq_run_hw_queue+0xee/0x100
process_one_work+0x1f4/0x3e0
worker_thread+0x2d/0x3e0
? process_one_work+0x3e0/0x3e0
kthread+0x10d/0x130
? kthread_park+0xa0/0xa0
ret_from_fork+0x35/0x40
run queue from wrong CPU 0, hctx active
CPU: 0 PID: 42300 Comm: kworker/13:2H Kdump: loaded Tainted: G OE X 5.3.18-109.$
Hardware name: IBM System x3650 M5 -[5462AC1]-/00KG915, BIOS -[TCE144J-3.11]- 12/03/2019
Workqueue: kblockd blk_mq_run_work_fn


Thanks,
Daniel

block/blk-mq.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 55bcee5dc032..0427b719d9c4 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1514,10 +1514,8 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
*/
if (!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
cpu_online(hctx->next_cpu)) {
- printk(KERN_WARNING "run queue from wrong CPU %d, hctx %s\n",
- raw_smp_processor_id(),
- cpumask_empty(hctx->cpumask) ? "inactive": "active");
- dump_stack();
+ printk(KERN_WARNING "run queue from wrong CPU %d, hctx %*pbl\n",
+ raw_smp_processor_id(), cpumask_pr_args(hctx->cpumask));
}

/*
--
2.16.4
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