Re: [PATCH V2 00/20] blk-mq-sched: improve SCSI-MQ performance

Laurence Oberman
2017-08-07T18:47:01Z

On 08/07/2017 01:29 PM, Laurence Oberman wrote:
>
>
> On 08/07/2017 11:27 AM, Bart Van Assche wrote:
>> On Mon, 2017-08-07 at 08:48 -0400, Laurence Oberman wrote:
>>> I tested this series using Ming's tests as well as my own set of tests
>>> typically run against changes to upstream code in my SRP test-bed.
>>> My tests also include very large sequential buffered and un-buffered
>>> I/O.
>>>
>>> This series seems to be fine for me. I did uncover another issue that is
>>> unrelated to these patches and also exists in 4.13-RC3 generic that I am
>>> still debugging.
>>
>> Hello Laurence,
>>
>> What kind of tests did you run? Only functional tests or also performance
>> tests?
>>
>> Has the issue you encountered with kernel 4.13-rc3 already been
>> reported on
>> the linux-rdma mailing list?
>>
>> Thanks,
>>
>> Bart.
>>
>
> Hi Bart
>
> Actually I was focusing on just performance to see if we had any
> regressions with Mings new patches for the large sequential I/O cases.
>
> Ming had already tested the small I/O performance cases so I was making
> sure the large I/O sequential tests did not suffer.
>
> The 4MB un-buffered direct read tests to DM devices seems to perform
> much the same in my test bed.
> The 4MB buffered and un-buffered 4MB writes also seem to be well behaved
> with not much improvement.
>
> These were not exhaustive tests and did not include my usual port
> disconnect and recovery tests either.
> I was just making sure we did not regress with Ming's changes.
>
> I was only just starting to baseline test the mq-deadline scheduler as
> prior to 4.13-RC3 I had not been testing any of the new MQ schedulers.
> I had always only tested with [none]
>
> The tests were with [none] and [mq-deadline]
>
> The new issue I started seeing was not yet reported yet as I was still
> investigating it.
>
> In summary:
> With buffered writes we see the clone fail in blk_get_request in both
> Mings kernel and in the upstream 4.13-RC3 stock kernel
>
> [ 885.271451] io scheduler mq-deadline registered
> [ 898.455442] device-mapper: multipath: blk_get_request() returned -11
> - requeuing
>
> This is due to
>
> multipath_clone_and_map()
>
> /*
> * Map cloned requests (request-based multipath)
> */
> static int multipath_clone_and_map(struct dm_target *ti, struct request
> *rq,
> union map_info *map_context,
> struct request **__clone)
> {
> ..
> ..
> ..
> clone = blk_get_request(q, rq->cmd_flags | REQ_NOMERGE,
> GFP_ATOMIC);
> if (IS_ERR(clone)) {
> /* EBUSY, ENODEV or EWOULDBLOCK: requeue */
> bool queue_dying = blk_queue_dying(q);
> DMERR_LIMIT("blk_get_request() returned %ld%s -
> requeuing",
> PTR_ERR(clone), queue_dying ? " (path
> offline)" : "");
> if (queue_dying) {
> atomic_inc(&m->pg_init_in_progress);
> activate_or_offline_path(pgpath);
> return DM_MAPIO_REQUEUE;
> }
> return DM_MAPIO_DELAY_REQUEUE;
> }
>
> Still investigating but it leads to a hard lockup
>
>
> So I still need to see if the hard-lockup happens in the stock kernel
> with mq-deadline and some other work before coming up with a full
> summary of the issue.
>
> I also intend to re-run all tests including disconnect and reconnect
> tests on both mq-deadline and none.
>
> Trace below
>
>
> [ 1553.167357] NMI watchdog: Watchdog detected hard LOCKUP on cpu 4
> [ 1553.167359] Modules linked in: mq_deadline binfmt_misc dm_round_robin
> xt_CHECKSUM ipt_MASQUERADE nf_nat_masquerade_ipv4 tun ip6t_rpfilter
> ipt_REJECT nf_reject_ipv4 ip6t_REJECT nf_reject_ipv6 xt_conntrack ip_set
> nfnetlink ebtable_nat ebtable_broute bridge stp llc ip6table_nat
> nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 rpcrdma ip6table_mangle
> ip6table_security ip6table_raw iptable_nat ib_isert nf_conntrack_ipv4
> iscsi_target_mod nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack ib_iser
> libiscsi scsi_transport_iscsi iptable_mangle iptable_security
> iptable_raw ebtable_filter ebtables target_core_mod ip6table_filter
> ip6_tables iptable_filter ib_srp scsi_transport_srp ib_ipoib rdma_ucm
> ib_ucm ib_uverbs ib_umad rdma_cm ib_cm iw_cm mlx5_ib ib_core
> intel_powerclamp coretemp kvm_intel kvm irqbypass crct10dif_pclmul
> [ 1553.167385] crc32_pclmul ghash_clmulni_intel pcbc aesni_intel sg
> joydev ipmi_si hpilo crypto_simd hpwdt iTCO_wdt cryptd ipmi_devintf
> glue_helper gpio_ich iTCO_vendor_support shpchp ipmi_msghandler pcspkr
> acpi_power_meter i7core_edac lpc_ich pcc_cpufreq nfsd auth_rpcgss
> nfs_acl lockd grace sunrpc dm_multipath ip_tables xfs libcrc32c sd_mod
> amdkfd amd_iommu_v2 radeon i2c_algo_bit drm_kms_helper syscopyarea
> sysfillrect sysimgblt fb_sys_fops ttm mlx5_core drm mlxfw i2c_core ptp
> serio_raw hpsa crc32c_intel bnx2 pps_core devlink scsi_transport_sas
> dm_mirror dm_region_hash dm_log dm_mod [last unloaded: ib_srpt]
> [ 1553.167410] CPU: 4 PID: 11532 Comm: dd Tainted: G I
> 4.13.0-rc3lobeming.ming_V4+ #20
> [ 1553.167411] Hardware name: HP ProLiant DL380 G7, BIOS P67 08/16/2015
> [ 1553.167412] task: ffff9d9344b0d800 task.stack: ffffb5cb913b0000
> [ 1553.167421] RIP: 0010:__blk_recalc_rq_segments+0xec/0x3d0
> [ 1553.167421] RSP: 0018:ffff9d9377a83d08 EFLAGS: 00000046
> [ 1553.167422] RAX: 0000000000001000 RBX: 0000000000001000 RCX:
> ffff9d91b8e9f500
> [ 1553.167423] RDX: fffffcd56af20f00 RSI: ffff9d91b8e9f588 RDI:
> ffff9d91b8e9f488
> [ 1553.167424] RBP: ffff9d9377a83d88 R08: 000000000003c000 R09:
> 0000000000000001
> [ 1553.167424] R10: 0000000000000000 R11: 0000000000000000 R12:
> 0000000000000000
> [ 1553.167425] R13: 0000000000000000 R14: 0000000000000000 R15:
> 0000000000000003
> [ 1553.167426] FS: 00007f3061002740(0000) GS:ffff9d9377a80000(0000)
> knlGS:0000000000000000
> [ 1553.167427] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 1553.167428] CR2: 00007f305a511000 CR3: 0000000b1bfb2000 CR4:
> 00000000000006e0
> [ 1553.167429] Call Trace:
> [ 1553.167432] <IRQ>
> [ 1553.167437] ? mempool_free+0x2b/0x80
> [ 1553.167440] blk_recalc_rq_segments+0x28/0x40
> [ 1553.167442] blk_update_request+0x249/0x310
> [ 1553.167450] end_clone_bio+0x46/0x70 [dm_mod]
> [ 1553.167453] bio_endio+0xa1/0x120
> [ 1553.167454] blk_update_request+0xb7/0x310
> [ 1553.167457] scsi_end_request+0x38/0x1d0
> [ 1553.167458] scsi_io_completion+0x13c/0x630
> [ 1553.167460] scsi_finish_command+0xd9/0x120
> [ 1553.167462] scsi_softirq_done+0x12a/0x150
> [ 1553.167463] __blk_mq_complete_request_remote+0x13/0x20
> [ 1553.167466] flush_smp_call_function_queue+0x52/0x110
> [ 1553.167468] generic_smp_call_function_single_interrupt+0x13/0x30
> [ 1553.167470] smp_call_function_single_interrupt+0x27/0x40
> [ 1553.167471] call_function_single_interrupt+0x93/0xa0
> [ 1553.167473] RIP: 0010:radix_tree_next_chunk+0xcb/0x2e0
> [ 1553.167474] RSP: 0018:ffffb5cb913b3a68 EFLAGS: 00000203 ORIG_RAX:
> ffffffffffffff04
> [ 1553.167475] RAX: 0000000000000001 RBX: 0000000000000010 RCX:
> ffff9d9e2c556938
> [ 1553.167476] RDX: ffff9d93053c5919 RSI: 0000000000000001 RDI:
> ffff9d9e2c556910
> [ 1553.167476] RBP: ffffb5cb913b3ab8 R08: ffffb5cb913b3bc0 R09:
> 0000000ab7d52000
> [ 1553.167477] R10: fffffcd56adf5440 R11: 0000000000000000 R12:
> 0000000000000230
> [ 1553.167477] R13: 0000000000000000 R14: 000000000006e0fe R15:
> ffff9d9e2c556910
> [ 1553.167478] </IRQ>
> [ 1553.167480] ? radix_tree_next_chunk+0x10b/0x2e0
> [ 1553.167481] find_get_pages_tag+0x149/0x270
> [ 1553.167485] ? block_write_full_page+0xcd/0xe0
> [ 1553.167487] pagevec_lookup_tag+0x21/0x30
> [ 1553.167488] write_cache_pages+0x14c/0x510
> [ 1553.167490] ? __wb_calc_thresh+0x140/0x140
> [ 1553.167492] generic_writepages+0x51/0x80
> [ 1553.167493] blkdev_writepages+0x2f/0x40
> [ 1553.167494] do_writepages+0x1c/0x70
> [ 1553.167495] __filemap_fdatawrite_range+0xc6/0x100
> [ 1553.167497] filemap_write_and_wait+0x3d/0x80
> [ 1553.167498] __sync_blockdev+0x1f/0x40
> [ 1553.167499] __blkdev_put+0x74/0x200
> [ 1553.167500] blkdev_put+0x4c/0xd0
> [ 1553.167501] blkdev_close+0x25/0x30
> [ 1553.167503] __fput+0xe7/0x210
> [ 1553.167504] ____fput+0xe/0x10
> [ 1553.167508] task_work_run+0x83/0xb0
> [ 1553.167511] exit_to_usermode_loop+0x66/0x98
> [ 1553.167512] do_syscall_64+0x13a/0x150
> [ 1553.167519] entry_SYSCALL64_slow_path+0x25/0x25
> [ 1553.167520] RIP: 0033:0x7f3060b25bd0
> [ 1553.167521] RSP: 002b:00007ffc5e6b12c8 EFLAGS: 00000246 ORIG_RAX:
> 0000000000000003
> [ 1553.167522] RAX: 0000000000000000 RBX: 0000000000000000 RCX:
> 00007f3060b25bd0
> [ 1553.167522] RDX: 0000000000400000 RSI: 0000000000000000 RDI:
> 0000000000000001
> [ 1553.167523] RBP: 0000000000000320 R08: ffffffffffffffff R09:
> 0000000000402003
> [ 1553.167524] R10: 00007ffc5e6b1040 R11: 0000000000000246 R12:
> 0000000000000320
> [ 1553.167525] R13: 0000000000000000 R14: 00007ffc5e6b2618 R15:
> 00007ffc5e6b1540
> [ 1553.167526] Code: db 0f 84 92 01 00 00 45 89 f5 45 89 e2 4c 89 ee 48
> c1 e6 04 48 03 71 78 8b 46 08 48 8b 16 44 29 e0 48 89 54 24 30 39 d8 0f
> 47 c3 <44> 03 56 0c 45 84 db 89 44 24 38 44 89 54 24 3c 0f 85 2a 01 00
> [ 1553.167540] Kernel panic - not syncing: Hard LOCKUP
> [ 1553.167542] CPU: 4 PID: 11532 Comm: dd Tainted: G I
> 4.13.0-rc3lobeming.ming_V4+ #20
> [ 1553.167542] Hardware name: HP ProLiant DL380 G7, BIOS P67 08/16/2015
> [ 1553.167543] Call Trace:
> [ 1553.167543] <NMI>
> [ 1553.167545] dump_stack+0x63/0x87
> [ 1553.167548] panic+0xeb/0x245
> [ 1553.167550] nmi_panic+0x3f/0x40
> [ 1553.167553] watchdog_overflow_callback+0xce/0xf0
> [ 1553.167556] __perf_event_overflow+0x54/0xe0
> [ 1553.167559] perf_event_overflow+0x14/0x20
> [ 1553.167562] intel_pmu_handle_irq+0x203/0x4b0
> [ 1553.167566] perf_event_nmi_handler+0x2d/0x50
> [ 1553.167568] nmi_handle+0x61/0x110
> [ 1553.167569] default_do_nmi+0x44/0x120
> [ 1553.167571] do_nmi+0x113/0x190
> [ 1553.167573] end_repeat_nmi+0x1a/0x1e
> [ 1553.167574] RIP: 0010:__blk_recalc_rq_segments+0xec/0x3d0
> [ 1553.167575] RSP: 0018:ffff9d9377a83d08 EFLAGS: 00000046
> [ 1553.167576] RAX: 0000000000001000 RBX: 0000000000001000 RCX:
> ffff9d91b8e9f500
> [ 1553.167576] RDX: fffffcd56af20f00 RSI: ffff9d91b8e9f588 RDI:
> ffff9d91b8e9f488
> [ 1553.167577] RBP: ffff9d9377a83d88 R08: 000000000003c000 R09:
> 0000000000000001
> [ 1553.167577] R10: 0000000000000000 R11: 0000000000000000 R12:
> 0000000000000000
> [ 1553.167578] R13: 0000000000000000 R14: 0000000000000000 R15:
> 0000000000000003
> [ 1553.167580] ? __blk_recalc_rq_segments+0xec/0x3d0
> [ 1553.167581] ? __blk_recalc_rq_segments+0xec/0x3d0
> [ 1553.167582] </NMI>
> [ 1553.167582] <IRQ>
> [ 1553.167584] ? mempool_free+0x2b/0x80
> [ 1553.167585] blk_recalc_rq_segments+0x28/0x40
> [ 1553.167586] blk_update_request+0x249/0x310
> [ 1553.167590] end_clone_bio+0x46/0x70 [dm_mod]
> [ 1553.167592] bio_endio+0xa1/0x120
> [ 1553.167593] blk_update_request+0xb7/0x310
> [ 1553.167594] scsi_end_request+0x38/0x1d0
> [ 1553.167595] scsi_io_completion+0x13c/0x630
> [ 1553.167597] scsi_finish_command+0xd9/0x120
> [ 1553.167598] scsi_softirq_done+0x12a/0x150
> [ 1553.167599] __blk_mq_complete_request_remote+0x13/0x20
> [ 1553.167601] flush_smp_call_function_queue+0x52/0x110
> [ 1553.167602] generic_smp_call_function_single_interrupt+0x13/0x30
> [ 1553.167603] smp_call_function_single_interrupt+0x27/0x40
> [ 1553.167604] call_function_single_interrupt+0x93/0xa0
> [ 1553.167605] RIP: 0010:radix_tree_next_chunk+0xcb/0x2e0
> [ 1553.167606] RSP: 0018:ffffb5cb913b3a68 EFLAGS: 00000203 ORIG_RAX:
> ffffffffffffff04
> [ 1553.167607] RAX: 0000000000000001 RBX: 0000000000000010 RCX:
> ffff9d9e2c556938
> [ 1553.167607] RDX: ffff9d93053c5919 RSI: 0000000000000001 RDI:
> ffff9d9e2c556910
> [ 1553.167608] RBP: ffffb5cb913b3ab8 R08: ffffb5cb913b3bc0 R09:
> 0000000ab7d52000
> [ 1553.167609] R10: fffffcd56adf5440 R11: 0000000000000000 R12:
> 0000000000000230
> [ 1553.167609] R13: 0000000000000000 R14: 000000000006e0fe R15:
> ffff9d9e2c556910
> [ 1553.167610] </IRQ>
> [ 1553.167611] ? radix_tree_next_chunk+0x10b/0x2e0
> [ 1553.167613] find_get_pages_tag+0x149/0x270
> [ 1553.167615] ? block_write_full_page+0xcd/0xe0
> [ 1553.167616] pagevec_lookup_tag+0x21/0x30
> [ 1553.167617] write_cache_pages+0x14c/0x510
> [ 1553.167619] ? __wb_calc_thresh+0x140/0x140
> [ 1553.167621] generic_writepages+0x51/0x80
> [ 1553.167622] blkdev_writepages+0x2f/0x40
> [ 1553.167623] do_writepages+0x1c/0x70
> [ 1553.167627] __filemap_fdatawrite_range+0xc6/0x100
> [ 1553.167629] filemap_write_and_wait+0x3d/0x80
> [ 1553.167630] __sync_blockdev+0x1f/0x40
> [ 1553.167631] __blkdev_put+0x74/0x200
> [ 1553.167632] blkdev_put+0x4c/0xd0
> [ 1553.167633] blkdev_close+0x25/0x30
> [ 1553.167634] __fput+0xe7/0x210
> [ 1553.167635] ____fput+0xe/0x10
> [ 1553.167636] task_work_run+0x83/0xb0
> [ 1553.167637] exit_to_usermode_loop+0x66/0x98
> [ 1553.167638] do_syscall_64+0x13a/0x150
> [ 1553.167640] entry_SYSCALL64_slow_path+0x25/0x25
> [ 1553.167641] RIP: 0033:0x7f3060b25bd0
> [ 1553.167641] RSP: 002b:00007ffc5e6b12c8 EFLAGS: 00000246 ORIG_RAX:
> 0000000000000003
> [ 1553.167642] RAX: 0000000000000000 RBX: 0000000000000000 RCX:
> 00007f3060b25bd0
> [ 1553.167643] RDX: 0000000000400000 RSI: 0000000000000000 RDI:
> 0000000000000001
> [ 1553.167643] RBP: 0000000000000320 R08: ffffffffffffffff R09:
> 0000000000402003
> [ 1553.167644] R10: 00007ffc5e6b1040 R11: 0000000000000246 R12:
> 0000000000000320
> [ 1553.167645] R13: 0000000000000000 R14: 00007ffc5e6b2618 R15:
> 00007ffc5e6b1540
> [ 1553.167829] Kernel Offset: 0x2f400000 from 0xffffffff81000000
> (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
> [ 1558.119352] ---[ end Kernel panic - not syncing: Hard LOCKUP
> [ 1558.151334] sched: Unexpected reschedule of offline CPU#0!
> [ 1558.151342] ------------[ cut here ]------------
> [ 1558.151347] WARNING: CPU: 4 PID: 11532 at arch/x86/kernel/smp.c:128
> native_smp_send_reschedule+0x3c/0x40
> [ 1558.151348] Modules linked in: mq_deadline binfmt_misc dm_round_robin
> xt_CHECKSUM ipt_MASQUERADE nf_nat_masquerade_ipv4 tun ip6t_rpfilter
> ipt_REJECT nf_reject_ipv4 ip6t_REJECT nf_reject_ipv6 xt_conntrack ip_set
> nfnetlink ebtable_nat ebtable_broute bridge stp llc ip6table_nat
> nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 rpcrdma ip6table_mangle
> ip6table_security ip6table_raw iptable_nat ib_isert nf_conntrack_ipv4
> iscsi_target_mod nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack ib_iser
> libiscsi scsi_transport_iscsi iptable_mangle iptable_security
> iptable_raw ebtable_filter ebtables target_core_mod ip6table_filter
> ip6_tables iptable_filter ib_srp scsi_transport_srp ib_ipoib rdma_ucm
> ib_ucm ib_uverbs ib_umad rdma_cm ib_cm iw_cm mlx5_ib ib_core
> intel_powerclamp coretemp kvm_intel kvm irqbypass crct10dif_pclmul
> [ 1558.151363] crc32_pclmul ghash_clmulni_intel pcbc aesni_intel sg
> joydev ipmi_si hpilo crypto_simd hpwdt iTCO_wdt cryptd ipmi_devintf
> glue_helper gpio_ich iTCO_vendor_support shpchp ipmi_msghandler pcspkr
> acpi_power_meter i7core_edac lpc_ich pcc_cpufreq nfsd auth_rpcgss
> nfs_acl lockd grace sunrpc dm_multipath ip_tables xfs libcrc32c sd_mod
> amdkfd amd_iommu_v2 radeon i2c_algo_bit drm_kms_helper syscopyarea
> sysfillrect sysimgblt fb_sys_fops ttm mlx5_core drm mlxfw i2c_core ptp
> serio_raw hpsa crc32c_intel bnx2 pps_core devlink scsi_transport_sas
> dm_mirror dm_region_hash dm_log dm_mod [last unloaded: ib_srpt]
> [ 1558.151377] CPU: 4 PID: 11532 Comm: dd Tainted: G I
> 4.13.0-rc3lobeming.ming_V4+ #20
> [ 1558.151378] Hardware name: HP ProLiant DL380 G7, BIOS P67 08/16/2015
> [ 1558.151379] task: ffff9d9344b0d800 task.stack: ffffb5cb913b0000
> [ 1558.151380] RIP: 0010:native_smp_send_reschedule+0x3c/0x40
> [ 1558.151381] RSP: 0018:ffff9d9377a856a0 EFLAGS: 00010046
> [ 1558.151382] RAX: 000000000000002e RBX: 0000000000000000 RCX:
> 0000000000000006
> [ 1558.151383] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
> ffff9d9377a8e010
> [ 1558.151383] RBP: ffff9d9377a856a0 R08: 000000000000002e R09:
> ffff9d9fa7029552
> [ 1558.151384] R10: 0000000000000732 R11: 0000000000000000 R12:
> ffff9d9377a1bb00
> [ 1558.151384] R13: ffff9d936ef70000 R14: ffff9d9377a85758 R15:
> ffff9d9377a1bb00
> [ 1558.151385] FS: 00007f3061002740(0000) GS:ffff9d9377a80000(0000)
> knlGS:0000000000000000
> [ 1558.151386] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 1558.151387] CR2: 00007f305a511000 CR3: 0000000b1bfb2000 CR4:
> 00000000000006e0
> [ 1558.151387] Call Trace:
> [ 1558.151388] <NMI>
> [ 1558.151391] resched_curr+0xa1/0xc0
> [ 1558.151392] check_preempt_curr+0x79/0x90
> [ 1558.151393] ttwu_do_wakeup+0x1e/0x160
> [ 1558.151395] ttwu_do_activate+0x7a/0x90
> [ 1558.151396] try_to_wake_up+0x1e1/0x470
> [ 1558.151398] ? vsnprintf+0x1fa/0x4a0
> [ 1558.151399] default_wake_function+0x12/0x20
> [ 1558.151403] __wake_up_common+0x55/0x90
> [ 1558.151405] __wake_up_locked+0x13/0x20
> [ 1558.151408] ep_poll_callback+0xd3/0x2a0
> [ 1558.151409] __wake_up_common+0x55/0x90
> [ 1558.151411] __wake_up+0x39/0x50
> [ 1558.151415] wake_up_klogd_work_func+0x40/0x60
> [ 1558.151419] irq_work_run_list+0x4d/0x70
> [ 1558.151421] ? tick_sched_do_timer+0x70/0x70
> [ 1558.151422] irq_work_tick+0x40/0x50
> [ 1558.151424] update_process_times+0x42/0x60
> [ 1558.151426] tick_sched_handle+0x2d/0x60
> [ 1558.151427] tick_sched_timer+0x39/0x70
> [ 1558.151428] __hrtimer_run_queues+0xe5/0x230
> [ 1558.151429] hrtimer_interrupt+0xa8/0x1a0
> [ 1558.151431] local_apic_timer_interrupt+0x35/0x60
> [ 1558.151432] smp_apic_timer_interrupt+0x38/0x50
> [ 1558.151433] apic_timer_interrupt+0x93/0xa0
> [ 1558.151435] RIP: 0010:panic+0x1fa/0x245
> [ 1558.151435] RSP: 0018:ffff9d9377a85b30 EFLAGS: 00000246 ORIG_RAX:
> ffffffffffffff10
> [ 1558.151436] RAX: 0000000000000030 RBX: ffff9d890c5d0000 RCX:
> 0000000000000006
> [ 1558.151437] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
> ffff9d9377a8e010
> [ 1558.151438] RBP: ffff9d9377a85ba0 R08: 0000000000000030 R09:
> ffff9d9fa7029514
> [ 1558.151438] R10: 0000000000000731 R11: 0000000000000000 R12:
> ffffffffb0e63f7f
> [ 1558.151439] R13: 0000000000000000 R14: 0000000000000000 R15:
> 0000000000000000
> [ 1558.151441] nmi_panic+0x3f/0x40
> [ 1558.151442] watchdog_overflow_callback+0xce/0xf0
> [ 1558.151444] __perf_event_overflow+0x54/0xe0
> [ 1558.151445] perf_event_overflow+0x14/0x20
> [ 1558.151446] intel_pmu_handle_irq+0x203/0x4b0
> [ 1558.151449] perf_event_nmi_handler+0x2d/0x50
> [ 1558.151450] nmi_handle+0x61/0x110
> [ 1558.151452] default_do_nmi+0x44/0x120
> [ 1558.151453] do_nmi+0x113/0x190
> [ 1558.151454] end_repeat_nmi+0x1a/0x1e
> [ 1558.151456] RIP: 0010:__blk_recalc_rq_segments+0xec/0x3d0
> [ 1558.151456] RSP: 0018:ffff9d9377a83d08 EFLAGS: 00000046
> [ 1558.151457] RAX: 0000000000001000 RBX: 0000000000001000 RCX:
> ffff9d91b8e9f500
> [ 1558.151458] RDX: fffffcd56af20f00 RSI: ffff9d91b8e9f588 RDI:
> ffff9d91b8e9f488
> [ 1558.151458] RBP: ffff9d9377a83d88 R08: 000000000003c000 R09:
> 0000000000000001
> [ 1558.151459] R10: 0000000000000000 R11: 0000000000000000 R12:
> 0000000000000000
> [ 1558.151459] R13: 0000000000000000 R14: 0000000000000000 R15:
> 0000000000000003
> [ 1558.151461] ? __blk_recalc_rq_segments+0xec/0x3d0
> [ 1558.151463] ? __blk_recalc_rq_segments+0xec/0x3d0
> [ 1558.151463] </NMI>
> [ 1558.151464] <IRQ>
> [ 1558.151465] ? mempool_free+0x2b/0x80
> [ 1558.151467] blk_recalc_rq_segments+0x28/0x40
> [ 1558.151468] blk_update_request+0x249/0x310
> [ 1558.151472] end_clone_bio+0x46/0x70 [dm_mod]
> [ 1558.151473] bio_endio+0xa1/0x120
> [ 1558.151474] blk_update_request+0xb7/0x310
> [ 1558.151476] scsi_end_request+0x38/0x1d0
> [ 1558.151477] scsi_io_completion+0x13c/0x630
> [ 1558.151478] scsi_finish_command+0xd9/0x120
> [ 1558.151480] scsi_softirq_done+0x12a/0x150
> [ 1558.151481] __blk_mq_complete_request_remote+0x13/0x20
> [ 1558.151483] flush_smp_call_function_queue+0x52/0x110
> [ 1558.151484] generic_smp_call_function_single_interrupt+0x13/0x30
> [ 1558.151485] smp_call_function_single_interrupt+0x27/0x40
> [ 1558.151486] call_function_single_interrupt+0x93/0xa0
> [ 1558.151487] RIP: 0010:radix_tree_next_chunk+0xcb/0x2e0
> [ 1558.151488] RSP: 0018:ffffb5cb913b3a68 EFLAGS: 00000203 ORIG_RAX:
> ffffffffffffff04
> [ 1558.151489] RAX: 0000000000000001 RBX: 0000000000000010 RCX:
> ffff9d9e2c556938
> [ 1558.151490] RDX: ffff9d93053c5919 RSI: 0000000000000001 RDI:
> ffff9d9e2c556910
> [ 1558.151490] RBP: ffffb5cb913b3ab8 R08: ffffb5cb913b3bc0 R09:
> 0000000ab7d52000
> [ 1558.151491] R10: fffffcd56adf5440 R11: 0000000000000000 R12:
> 0000000000000230
> [ 1558.151492] R13: 0000000000000000 R14: 000000000006e0fe R15:
> ffff9d9e2c556910
> [ 1558.151492] </IRQ>
> [ 1558.151494] ? radix_tree_next_chunk+0x10b/0x2e0
> [ 1558.151496] find_get_pages_tag+0x149/0x270
> [ 1558.151497] ? block_write_full_page+0xcd/0xe0
> [ 1558.151499] pagevec_lookup_tag+0x21/0x30
> [ 1558.151500] write_cache_pages+0x14c/0x510
> [ 1558.151502] ? __wb_calc_thresh+0x140/0x140
> [ 1558.151504] generic_writepages+0x51/0x80
> [ 1558.151505] blkdev_writepages+0x2f/0x40
> [ 1558.151506] do_writepages+0x1c/0x70
> [ 1558.151507] __filemap_fdatawrite_range+0xc6/0x100
> [ 1558.151509] filemap_write_and_wait+0x3d/0x80
> [ 1558.151510] __sync_blockdev+0x1f/0x40
> [ 1558.151511] __blkdev_put+0x74/0x200
> [ 1558.151512] blkdev_put+0x4c/0xd0
> [ 1558.151513] blkdev_close+0x25/0x30
> [ 1558.151514] __fput+0xe7/0x210
> [ 1558.151515] ____fput+0xe/0x10
> [ 1558.151517] task_work_run+0x83/0xb0
> [ 1558.151518] exit_to_usermode_loop+0x66/0x98
> [ 1558.151519] do_syscall_64+0x13a/0x150
> [ 1558.151521] entry_SYSCALL64_slow_path+0x25/0x25
> [ 1558.151522] RIP: 0033:0x7f3060b25bd0
> [ 1558.151522] RSP: 002b:00007ffc5e6b12c8 EFLAGS: 00000246 ORIG_RAX:
> 0000000000000003
> [ 1558.151523] RAX: 0000000000000000 RBX: 0000000000000000 RCX:
> 00007f3060b25bd0
> [ 1558.151524] RDX: 0000000000400000 RSI: 0000000000000000 RDI:
> 0000000000000001
> [ 1558.151524] RBP: 0000000000000320 R08: ffffffffffffffff R09:
> 0000000000402003
> [ 1558.151525] R10: 00007ffc5e6b1040 R11: 0000000000000246 R12:
> 0000000000000320
> [ 1558.151526] R13: 0000000000000000 R14: 00007ffc5e6b2618 R15:
> 00007ffc5e6b1540
> [ 1558.151527] Code: dc 00 0f 92 c0 84 c0 74 14 48 8b 05 ff 9d a9 00 be
> fd 00 00 00 ff 90 a0 00 00 00 5d c3 89 fe 48 c7 c7 90 4d e3 b0 e8 c7 db
> 09 00 <0f> ff 5d c3 66 66 66 66 90 55 48 89 e5 48 83 ec 20 65 48 8b 04
> [ 1558.151540] ---[ end trace 408c28f8c132530c ]---

Replying to my own email:

Hello Bart

So with the stock 4.13-RC3 using [none] I get the failing clones but no
hard lockup.

[ 526.677611] multipath_clone_and_map: 148 callbacks suppressed
[ 526.707429] device-mapper: multipath: blk_get_request() returned -11
- requeuing
[ 527.283432] device-mapper: multipath: blk_get_request() returned -11
- requeuing
[ 528.324566] device-mapper: multipath: blk_get_request() returned -11
- requeuing
[ 528.367118] device-mapper: multipath: blk_get_request() returned -11
- requeuing

Then on the same kernel
modprobe mq-deadline and running with [mq-deadline] on stock upstream I
DO not get the clone failures and I don't seem to get hard lockups.

I will reach out to Ming once I confirm going back to his kernel gets me
back into hard lockups again.
I will also mention to him that we see the clone failure when using his
kernel with [mq-deadline]

Perhaps his enhancements are indeed contributing

Thanks
Laurence

I also intend to test qla2xxx and mq-deadline shortly