Re: [PATCH BUGFIX 1/1] block, bfq: add requeue-request hook

[Paolo Valente]

> Il giorno 06 feb 2018, alle ore 12:57, Mike Galbraith <efault@xxxxxx> ha scritto:
> 
> On Tue, 2018-02-06 at 10:38 +0100, Paolo Valente wrote:
>> 
>> Hi Mike,
>> as you can imagine, I didn't get any failure in my pre-submission
>> tests on this patch.  In addition, it is not that easy to link this
>> patch, which just adds some internal bfq housekeeping in case of a
>> requeue, with a corruption of external lists for general I/O
>> management.
>> 
>> In this respect, as Oleksandr comments point out, by switching from
>> cfq to bfq, you switch between much more than two schedulers.  Anyway,
>> who knows ...
> 
> Not me.  Box seems to be fairly sure that it is bfq.

Yeah, sorry for the too short comment: what I meant is that cfq (and
deadline) are in legacy blk, while bfq is in blk-mq.  So, to use bfq,
you must also switch from legacy-blk I/O stack to blk-mq I/O stack.


>  Twice again box
> went belly up on me in fairly short order with bfq, but seemed fine
> with deadline.  I'm currently running deadline again, and box again
> seems solid, thought I won't say _is_ solid until it's been happily
> trundling along with deadline for a quite a bit longer.
> 

As Oleksadr asked too, is it deadline or mq-deadline?

> I was ssh'd in during the last episode, got this out.  I should be
> getting crash dumps, but seems kdump is only working intermittently
> atm.  I did get one earlier, but 3 of 4 times not.  Hohum.
> 
> [  484.179292] BUG: unable to handle kernel paging request at ffffffffa0817000
> [  484.179436] IP: __trace_note_message+0x1f/0xd0
> [  484.179576] PGD 1e0c067 P4D 1e0c067 PUD 1e0d063 PMD 3faff2067 PTE 0
> [  484.179719] Oops: 0000 [#1] SMP PTI
> [  484.179861] Dumping ftrace buffer:
> [  484.180011]    (ftrace buffer empty)
> [  484.180138] Modules linked in: fuse(E) ebtable_filter(E) ebtables(E) af_packet(E) bridge(E) stp(E) llc(E) iscsi_ibft(E) iscsi_boot_sysfs(E) nf_conntrack_ipv6(E) nf_defrag_ipv6(E) ipt_REJECT(E) xt_tcpudp(E) iptable_filter(E) ip6table_mangle(E) nf_conntrack_netbios_ns(E) nf_conntrack_broadcast(E) nf_conntrack_ipv4(E) nf_defrag_ipv4(E) ip_tables(E) xt_conntrack(E) nf_conntrack(E) ip6table_filter(E) ip6_tables(E) x_tables(E) nls_iso8859_1(E) nls_cp437(E) intel_rapl(E) x86_pkg_temp_thermal(E) intel_powerclamp(E) snd_hda_codec_hdmi(E) coretemp(E) kvm_intel(E) snd_hda_codec_realtek(E) kvm(E) snd_hda_codec_generic(E) snd_hda_intel(E) snd_hda_codec(E) sr_mod(E) snd_hwdep(E) cdrom(E) joydev(E) snd_hda_core(E) snd_pcm(E) snd_timer(E) irqbypass(E) snd(E) crct10dif_pclmul(E) crc32_pclmul(E) crc32c_intel(E) r8169(E)
> [  484.180740]  iTCO_wdt(E) ghash_clmulni_intel(E) mii(E) iTCO_vendor_support(E) pcbc(E) aesni_intel(E) soundcore(E) aes_x86_64(E) shpchp(E) crypto_simd(E) lpc_ich(E) glue_helper(E) i2c_i801(E) mei_me(E) mfd_core(E) mei(E) cryptd(E) intel_smartconnect(E) pcspkr(E) fan(E) thermal(E) nfsd(E) auth_rpcgss(E) nfs_acl(E) lockd(E) grace(E) sunrpc(E) hid_logitech_hidpp(E) hid_logitech_dj(E) uas(E) usb_storage(E) hid_generic(E) usbhid(E) nouveau(E) wmi(E) i2c_algo_bit(E) drm_kms_helper(E) syscopyarea(E) sysfillrect(E) sysimgblt(E) fb_sys_fops(E) ahci(E) xhci_pci(E) ehci_pci(E) libahci(E) ttm(E) ehci_hcd(E) xhci_hcd(E) libata(E) drm(E) usbcore(E) video(E) button(E) sd_mod(E) vfat(E) fat(E) virtio_blk(E) virtio_mmio(E) virtio_pci(E) virtio_ring(E) virtio(E) ext4(E) crc16(E) mbcache(E) jbd2(E) loop(E) sg(E) dm_multipath(E)
> [  484.181421]  dm_mod(E) scsi_dh_rdac(E) scsi_dh_emc(E) scsi_dh_alua(E) scsi_mod(E) efivarfs(E) autofs4(E)
> [  484.181583] CPU: 3 PID: 500 Comm: kworker/3:1H Tainted: G            E    4.15.0.ge237f98-master #609
> [  484.181746] Hardware name: MEDION MS-7848/MS-7848, BIOS M7848W08.20C 09/23/2013
> [  484.181910] Workqueue: kblockd blk_mq_requeue_work
> [  484.182076] RIP: 0010:__trace_note_message+0x1f/0xd0
> [  484.182250] RSP: 0018:ffff8803f45bfc20 EFLAGS: 00010282
> [  484.182436] RAX: 0000000000000000 RBX: ffffffffa0817000 RCX: 00000000ffff8803
> [  484.182622] RDX: ffffffff81bf514d RSI: 0000000000000000 RDI: ffffffffa0817000
> [  484.182810] RBP: ffff8803f45bfc80 R08: 0000000000000041 R09: ffff8803f69cc5d0
> [  484.182998] R10: ffff8803f80b47d0 R11: 0000000000001000 R12: ffff8803f45e8000
> [  484.183185] R13: 000000000000000d R14: 0000000000000000 R15: ffff8803fba112c0
> [  484.183372] FS:  0000000000000000(0000) GS:ffff88041ecc0000(0000) knlGS:0000000000000000
> [  484.183561] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  484.183747] CR2: ffffffffa0817000 CR3: 0000000001e0a006 CR4: 00000000001606e0
> [  484.183934] Call Trace:
> [  484.184122]  bfq_put_queue+0xd3/0xe0
> [  484.184305]  bfq_finish_requeue_request+0x72/0x350
> [  484.184493]  __blk_mq_requeue_request+0x8f/0x120
> [  484.184678]  blk_mq_dispatch_rq_list+0x342/0x550
> [  484.184866]  ? kyber_dispatch_request+0xd0/0xd0
> [  484.185053]  blk_mq_sched_dispatch_requests+0xf7/0x180
> [  484.185238]  __blk_mq_run_hw_queue+0x58/0xd0
> [  484.185429]  __blk_mq_delay_run_hw_queue+0x99/0xa0
> [  484.185614]  blk_mq_run_hw_queue+0x54/0xf0
> [  484.185805]  blk_mq_run_hw_queues+0x4b/0x60
> [  484.185994]  blk_mq_requeue_work+0x13a/0x150
> [  484.186192]  process_one_work+0x147/0x350
> [  484.186383]  worker_thread+0x47/0x3e0
> [  484.186572]  kthread+0xf8/0x130
> [  484.186760]  ? rescuer_thread+0x360/0x360
> [  484.186948]  ? kthread_stop+0x120/0x120
> [  484.187137]  ret_from_fork+0x35/0x40
> [  484.187321] Code: ff 48 89 44 24 10 e9 58 fd ff ff 90 55 48 89 e5 41 55 41 54 53 48 89 fb 48 83 ec 48 48 89 4c 24 30 4c 89 44 24 38 4c 89 4c 24 40 <83> 3f 02 0f 85 87 00 00 00 f6 43 21 04 75 0b 48 83 c4 48 5b 41 
> [  484.187525] RIP: __trace_note_message+0x1f/0xd0 RSP: ffff8803f45bfc20
> [  484.187727] CR2: ffffffffa0817000

ok, right in the middle of bfq this time ... Was this the first OOPS in your kernel log?

Thanks,
Paolo