* Re: [bug report] scsi host hang when running fio
2021-04-19 11:43 ` Kashyap Desai
@ 2021-04-19 15:11 ` John Garry
2021-04-27 9:41 ` John Garry
1 sibling, 0 replies; 4+ messages in thread
From: John Garry @ 2021-04-19 15:11 UTC (permalink / raw)
To: Kashyap Desai, Ming Lei, linux-scsi, linux-block, Hannes Reinecke
Cc: chenxiang, luojiaxing
Hi Kashyap,
> John - I have not seen such issue on megaraid_sas driver.
I could try to test megaraid SAS also, but the system with that card has
only 1x SATA disk, so pointless really.
> Is this something
> to do with CPU lock up ?
Seems to be.
JFYI, Enabling configs RCU_EXPERT, DEBUG_ATOMIC_SLEEP, and
DEBUG_SPINLOCK gives:
job1: (g=0): rw=randread, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T)
4096B-4096B, ioengine=libaio, iodepth=128
job1: (g=0): rw=randread, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T)
4096B-4096B, ioengine=libaio, iodepth=128
job1: (g=0): rw=randread, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T)
4096B-4096B, ioengine=libaio, iodepth=128
fio-3.1
Starting 6 processes
[ 196.342724] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:ta
01h:12m:22s]
[ 196.348816] rcu: Tasks blocked on level-1 rcu_node (CPUs 32-47):
[ 196.354913] rcu: All QSes seen, last rcu_preempt kthread activity 1
(4294941135-4294941134), jiffies_till_next_fqs=1, root ->qsmask 0x4
[ 196.367089] BUG: sleeping function called from invalid context at
include/linux/uaccess.h:174
[ 196.375605] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid:
1893, name: fio
[ 196.383502] BUG: scheduling while atomic: fio/1893/0x00000004
[ 196.389312] BUG: spinlock recursion on CPU#11, fio/1893
[ 196.394527] lock: rcu_state+0x280/0x2d00, .magic: dead4ead, .owner:
fio/1893, .owner_cpu: 11
[ 196.403046] CPU: 11 PID: 1893 Comm: fio Tainted: G W
5.12.0-rc7-00001-g3ae18ff9e445 #219
[ 196.412426] Hardware name: Huawei Taishan 2280 /D05, BIOS Hisilicon
D05 IT21 Nemo 2.0 RC0 04/18/2018
[ 196.421544] Call trace:
[ 196.423977] dump_backtrace+0x0/0x1b0
[ 196.427629] show_stack+0x18/0x68
[ 196.430932] dump_stack+0xd8/0x134
[ 196.434322] spin_dump+0x84/0x94
[ 196.437539] do_raw_spin_lock+0x108/0x120
[ 196.441539] _raw_spin_lock+0x20/0x30
[ 196.445191] rcu_note_context_switch+0xbc/0x348
[ 196.449710] __schedule+0xc8/0x6e8
[ 196.453100] preempt_schedule_notrace+0x50/0x70
[ 196.457618] __arm64_sys_io_submit+0x188/0x240
[ 196.462051] el0_svc_common.constprop.2+0x8c/0x128
[ 196.466829] do_el0_svc+0x24/0x90
[ 196.470133] el0_svc+0x24/0x38
[ 196.473175] el0_sync_handler+0x90/0xb8
[ 196.476999] el0_sync+0x154/0x180
^Cbs: 6 (f=6): [r(6)][4.2%][r=0KiB/s,w=0KiB/s][r=0,w=0 IOPS][eta
01h:11m:54s]
fio: terminating on signal 2
> Can you try your test with "rq_affinity=2" ?
I cannot see the issue with this setting.
> megaraid_sas driver detect CPU
> lockup (flood of completion on single CPU) and it use irq_poll interface to
> avoid such loop.
Can you turn it off? I guess that this is what happens to me, but the
system should not hang.
> Since you mentioned you noticed issue with hisi_sas v2 without hostwide tag
> I can think of similar stuffs in this case.
>
> How cpus to irq affinity settled in your case. ? Is it 1-1 mapping ?
We have a 4-1 CPU-HW queue mapping.
Disabling CONFIG_PREEMPT makes the issue go away for me also, so it
would be useful to try enabling it to recreate (if disabled), like:
more .config| grep PREEMPT
# CONFIG_PREEMPT_NONE is not set
# CONFIG_PREEMPT_VOLUNTARY is not set
CONFIG_PREEMPT=y
CONFIG_PREEMPT_COUNT=y
CONFIG_PREEMPTION=y
CONFIG_PREEMPT_RCU=y
CONFIG_PREEMPT_NOTIFIERS=y
# CONFIG_DEBUG_PREEMPT is not set
Thanks,
John
>
> Kashyap
>
>>
>> scsi debug or null_blk don't seem to load the system heavily enough to
>> recreate.
>>
>> I have seen it on 5.11 also. I see it on hisi_sas v2 and v3 hw drivers,
>> And I don't
>> think it's related to hostwide tags, as for hisi_sas v2 hw driver, I unset
>> that flag
>> and can still see it.
>>
>> Thanks,
>> John
>>
>> [0]
>> https://lore.kernel.org/linux-scsi/89ebc37c-21d6-c57e-4267-
>> cac49a3e5953@huawei.com/T/#t
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [bug report] scsi host hang when running fio
2021-04-19 11:43 ` Kashyap Desai
2021-04-19 15:11 ` John Garry
@ 2021-04-27 9:41 ` John Garry
1 sibling, 0 replies; 4+ messages in thread
From: John Garry @ 2021-04-27 9:41 UTC (permalink / raw)
To: Kashyap Desai, Ming Lei, linux-scsi, linux-block, Hannes Reinecke
Cc: chenxiang, luojiaxing
On 19/04/2021 12:43, Kashyap Desai wrote:
>> Hi guys,
>>
>> While investigating the performance issue reported by Ming [0], I am
>> seeing
>> this hang in certain scenarios:
>>
>> tivated0KB /s] [0/0/0 iops] [eta 1158048815d:13h:31m:49s] [ 740.499917]
>> rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:ops] [eta
>> 34722d:05h:17m:25s] [ 740.505994] rcu: Tasks blocked on level-1 rcu_node
>> (CPUs 0-15):
>> [ 740.511982] (detected by 64, t=5255 jiffies, g=6105, q=6697) [
>> 740.517703]
>> rcu: All QSes seen, last rcu_preempt kthread activity 0 (4295075897-
>> 4295075897), jiffies_till_next_fqs=1, root ->qsmask 0x1 [ 740.723625] BUG:
>> scheduling while atomic: swapper/64/0/0x00000008 [ 740.729692] Modules
>> linked in:
>> [ 740.732737] CPU: 64 PID: 0 Comm: swapper/64 Tainted: G W 5.12.0-rc7-
>> g7589ed97c1da-dirty #322 [ 740.742432] Hardware name: Huawei TaiShan
>> 2280 V2/BC82AMDC, BIOS
>> 2280-V2 CS V5.B133.01 03/25/2021
>> [ 740.751264] Call trace:
>> [ 740.753699] dump_backtrace+0x0/0x1b0
>> [ 740.757353] show_stack+0x18/0x68
>> [ 740.760654] dump_stack+0xd8/0x134
>> [ 740.764046] __schedule_bug+0x60/0x78
>> [ 740.767694] __schedule+0x620/0x6d8
>> [ 740.771168] schedule_idle+0x20/0x40
>> [ 740.774730] do_idle+0x19c/0x278
>> [ 740.777945] cpu_startup_entry+0x24/0x68 [ 740.781850]
>> secondary_start_kernel+0x178/0x188
>> [ 740.786362] 0x0
>> ^Cbs: 12 (f=12): [r(12)] [0.0% done] [1626MB/0KB/0KB /s] [416K/0/0 iops]
>> [eta
>> 34722d:05h:16m:28s]
>> fio: terminating on signal 2
>>
>> I thought it merited a separate thread.
>>
>> [ 740.723625] BUG: scheduling while atomic: swapper/64/0/0x00000008
>> Looks bad ...
>>
>> The scenario to create seems to be running fio with rw=randread and mq-
>> deadline IO scheduler. And heavily loading the system - running fio on a
>> subset of available CPUs seems to help (recreate).
>>
>> When it occurs, the system becomes totally unresponsive.
>>
>> It could be a LLDD bug, but I am doubtful.
>>
>> Has anyone else seen this or help try to recreate?
> John - I have not seen such issue on megaraid_sas driver. Is this something
> to do with CPU lock up ?
JFYI, this appears to be an issue of combination of threaded irq handler
and managed interrupts. I raised the issue with Thomas:
https://lore.kernel.org/lkml/874kfxw9zv.ffs@nanos.tec.linutronix.de/
Maybe NVMe PCI could have the same issue.
Thanks,
John
^ permalink raw reply [flat|nested] 4+ messages in thread