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

Ming Lei
2018-04-05T16:11:48Z

On Fri, Apr 06, 2018 at 12:05:03AM +0800, Ming Lei wrote:
> On Wed, Apr 04, 2018 at 10:18:13AM +0200, Christian Borntraeger wrote:
> >
> >
> > On 03/30/2018 04:53 AM, Ming Lei wrote:
> > > On Thu, Mar 29, 2018 at 01:49:29PM +0200, Christian Borntraeger wrote:
> > >>
> > >>
> > >> 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.
> > >
> > > OK, thanks, from the dumped mapping, looks everything is fine, each hctx
> > > is mapped to 4 CPUs, and only one of them is online.
> > >
> > > But still don't know why hctx is run from wrong CPU, looks we need more
> > > info to dump, could you apply the following debug patch and post the
> > > log?
> > >
> > > ---
> > > 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 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;
> > > }
> > >
> > > diff --git a/block/blk-mq.c b/block/blk-mq.c
> > > index 16e83e6df404..65767be7927d 100644
> > > --- a/block/blk-mq.c
> > > +++ b/block/blk-mq.c
> > > @@ -1325,9 +1325,14 @@ 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(),
> > > + int cpu;
> > > + printk(KERN_WARNING "run queue from wrong CPU %d/%d, hctx-%d %s\n",
> > > + raw_smp_processor_id(), hctx->next_cpu,
> > > + hctx->queue_num,
> > > cpumask_empty(hctx->cpumask) ? "inactive": "active");
> > > + for_each_cpu(cpu, hctx->cpumask)
> > > + printk("%d ", cpu);
> > > + printk("\n");
> > > dump_stack();
> > > }
> > >
> >
> >
> > attached. FWIW, it looks like these messages happen mostly during boot and come less
> > and less often the longer the system runs. Could it be that the workqeue is misplaced
> > before it runs for the first time, but then it is ok?
>
> Looks not workqueue's issue, and it shows that hctx->next_cpu is figured
> out as wrong by blk_mq_hctx_next_cpu(), maybe on your ARCH, either 'nr_cpu_ids'
> or 'cpu_online_mask' is too strange during booting and breaks blk_mq_hctx_next_cpu().
>
> Could you please apply the following patch and provide the dmesg boot log?

And please post out the 'lscpu' log together from the test machine too.

Thanks,
Ming