Re: [PATCH] blk-mq: only run mapped hw queues in blk_mq_run_hw_queues()

Christian Borntraeger
2018-03-29T11:49:29Z

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On 03/29/2018 01:43 PM, Ming Lei wrote:
> On Thu, Mar 29, 2018 at 12:49:55PM +0200, Christian Borntraeger wrote:
>>
>>
>> On 03/29/2018 12:48 PM, Ming Lei wrote:
>>> On Thu, Mar 29, 2018 at 12:10:11PM +0200, Christian Borntraeger wrote:
>>>>
>>>>
>>>> On 03/29/2018 11:40 AM, Ming Lei wrote:
>>>>> On Thu, Mar 29, 2018 at 11:09:08AM +0200, Christian Borntraeger wrote:
>>>>>>
>>>>>>
>>>>>> On 03/29/2018 09:23 AM, Christian Borntraeger wrote:
>>>>>>>
>>>>>>>
>>>>>>> On 03/29/2018 04:00 AM, Ming Lei wrote:
>>>>>>>> On Wed, Mar 28, 2018 at 05:36:53PM +0200, Christian Borntraeger wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 03/28/2018 05:26 PM, Ming Lei wrote:
>>>>>>>>>> Hi Christian,
>>>>>>>>>>
>>>>>>>>>> On Wed, Mar 28, 2018 at 09:45:10AM +0200, Christian Borntraeger wrote:
>>>>>>>>>>> FWIW, this patch does not fix the issue for me:
>>>>>>>>>>>
>>>>>>>>>>> ostname=? addr=? terminal=? res=success'
>>>>>>>>>>> [ 21.454961] WARNING: CPU: 3 PID: 1882 at block/blk-mq.c:1410 __blk_mq_delay_run_hw_queue+0xbe/0xd8
>>>>>>>>>>> [ 21.454968] Modules linked in: scsi_dh_rdac scsi_dh_emc scsi_dh_alua dm_mirror dm_region_hash dm_log dm_multipath dm_mod autofs4
>>>>>>>>>>> [ 21.454984] CPU: 3 PID: 1882 Comm: dasdconf.sh Not tainted 4.16.0-rc7+ #26
>>>>>>>>>>> [ 21.454987] Hardware name: IBM 2964 NC9 704 (LPAR)
>>>>>>>>>>> [ 21.454990] Krnl PSW : 00000000c0131ea3 000000003ea2f7bf (__blk_mq_delay_run_hw_queue+0xbe/0xd8)
>>>>>>>>>>> [ 21.454996] R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3
>>>>>>>>>>> [ 21.455005] Krnl GPRS: 0000013abb69a000 0000013a00000000 0000013ac6c0dc00 0000000000000001
>>>>>>>>>>> [ 21.455008] 0000000000000000 0000013abb69a710 0000013a00000000 00000001b691fd98
>>>>>>>>>>> [ 21.455011] 00000001b691fd98 0000013ace4775c8 0000000000000001 0000000000000000
>>>>>>>>>>> [ 21.455014] 0000013ac6c0dc00 0000000000b47238 00000001b691fc08 00000001b691fbd0
>>>>>>>>>>> [ 21.455032] Krnl Code: 000000000069c596: ebaff0a00004 lmg %r10,%r15,160(%r15)
>>>>>>>>>>> 000000000069c59c: c0f4ffff7a5e brcl 15,68ba58
>>>>>>>>>>> #000000000069c5a2: a7f40001 brc 15,69c5a4
>>>>>>>>>>> >000000000069c5a6: e340f0c00004 lg %r4,192(%r15)
>>>>>>>>>>> 000000000069c5ac: ebaff0a00004 lmg %r10,%r15,160(%r15)
>>>>>>>>>>> 000000000069c5b2: 07f4 bcr 15,%r4
>>>>>>>>>>> 000000000069c5b4: c0e5fffffeea brasl %r14,69c388
>>>>>>>>>>> 000000000069c5ba: a7f4fff6 brc 15,69c5a6
>>>>>>>>>>> [ 21.455067] Call Trace:
>>>>>>>>>>> [ 21.455072] ([<00000001b691fd98>] 0x1b691fd98)
>>>>>>>>>>> [ 21.455079] [<000000000069c692>] blk_mq_run_hw_queue+0xba/0x100
>>>>>>>>>>> [ 21.455083] [<000000000069c740>] blk_mq_run_hw_queues+0x68/0x88
>>>>>>>>>>> [ 21.455089] [<000000000069b956>] __blk_mq_complete_request+0x11e/0x1d8
>>>>>>>>>>> [ 21.455091] [<000000000069ba9c>] blk_mq_complete_request+0x8c/0xc8
>>>>>>>>>>> [ 21.455103] [<00000000008aa250>] dasd_block_tasklet+0x158/0x490
>>>>>>>>>>> [ 21.455110] [<000000000014c742>] tasklet_hi_action+0x92/0x120
>>>>>>>>>>> [ 21.455118] [<0000000000a7cfc0>] __do_softirq+0x120/0x348
>>>>>>>>>>> [ 21.455122] [<000000000014c212>] irq_exit+0xba/0xd0
>>>>>>>>>>> [ 21.455130] [<000000000010bf92>] do_IRQ+0x8a/0xb8
>>>>>>>>>>> [ 21.455133] [<0000000000a7c298>] io_int_handler+0x130/0x298
>>>>>>>>>>> [ 21.455136] Last Breaking-Event-Address:
>>>>>>>>>>> [ 21.455138] [<000000000069c5a2>] __blk_mq_delay_run_hw_queue+0xba/0xd8
>>>>>>>>>>> [ 21.455140] ---[ end trace be43f99a5d1e553e ]---
>>>>>>>>>>> [ 21.510046] dasdconf.sh Warning: 0.0.241e is already online, not configuring
>>>>>>>>>>
>>>>>>>>>> Thinking about this issue further, I can't understand the root cause for
>>>>>>>>>> this issue.
>>>>>>
>>>>>> FWIW, Limiting CONFIG_NR_CPUS to 64 seems to make the problem go away.
>>>>>
>>>>> I think the following patch is needed, and this way aligns to the mapping
>>>>> created via managed IRQ at least.
>>>>>
>>>>> diff --git a/block/blk-mq-cpumap.c b/block/blk-mq-cpumap.c
>>>>> index 9f8cffc8a701..638ab5c11b3c 100644
>>>>> --- a/block/blk-mq-cpumap.c
>>>>> +++ b/block/blk-mq-cpumap.c
>>>>> @@ -14,13 +14,12 @@
>>>>> #include "blk.h"
>>>>> #include "blk-mq.h"
>>>>>
>>>>> +/*
>>>>> + * Given there isn't CPU hotplug handler in blk-mq, map all possible CPUs to
>>>>> + * queues even it isn't present yet.
>>>>> + */
>>>>> static int cpu_to_queue_index(unsigned int nr_queues, const int cpu)
>>>>> {
>>>>> - /*
>>>>> - * Non present CPU will be mapped to queue index 0.
>>>>> - */
>>>>> - if (!cpu_present(cpu))
>>>>> - return 0;
>>>>> return cpu % nr_queues;
>>>>> }
>>>>>
>>>>> Thanks,
>>>>> Ming
>>>>>
>>>>
>>>> With that I no longer see the WARN_ON but the other warning instead:
>>>>
>>>> [ 31.903096] audit: type=1130 audit(1522318064.439:41): pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=systemd-tmpfiles-setup-dev comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
>>>> [ 31.903100] audit: type=1131 audit(1522318064.439:42): pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=systemd-tmpfiles-setup-dev comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
>>>> [ 31.985756] systemd-journald[379]: Received SIGTERM from PID 1 (systemd).
>>>> [ 32.000543] systemd: 18 output lines suppressed due to ratelimiting
>>>> [ 32.209496] EXT4-fs (dasdc1): re-mounted. Opts: (null)
>>>> [ 32.234808] systemd-journald[2490]: Received request to flush runtime journal from PID 1
>>>> [ 32.359832] tun: Universal TUN/TAP device driver, 1.6
>>>> [ 32.470841] run queue from wrong CPU 18, hctx active
>>>
>>> But your 'lscpu' log showed that you only have 16 CPUs online(0~15) and
>>> you also said CPU hotplug isn't involved in your test, so I am just
>>> wondering where the CPU 18 is from?
>>
>>
>> I have 2 test systems. One with 44CPU the other with 16.
>> The one with 16 now has the same flood of messages:
>>
>>
>> 4.454510] dasdc:VOL1/ 0X3F77: dasdc1
>> [ 4.454592] dasdd:VOL1/ 0X3F74: dasdd1
>> [ 4.593711] run queue from wrong CPU 0, hctx active
>
> Still can't reproduce your issue, could you please collect debugfs
> log again on your 16-core system after applying the patch on blk_mq_cpumap.c?

done.

If you need anything quick, you can reach mit via irc freenode or oftc (user borntraeger)

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